The Impact of Organic Manures on the Soil Quality. A study on Organic Nutrition in Crop Rotation of Okra-Dhaincha-Broccoli

LIST OF CONTENT

LIST OF TABLES

ABSTRACT

CHAPTER 1

CHAPTER 2

CHAPTER 3

CHAPTER 4

CHAPTER 5

CHAPTER 6

REFERENCES

Abstract

A study was conducted to assess the impact of different organic manures on soil properties and growth parameters in okra-broccoli cropping sequence. Study area lies in between 32°39'35.5"N latitude and 74°47'35.0"E longitude at an elevation of 332 meters above the mean sea level in the Shivalik foothill plains of North-Western Himalayas. Surface soil sampling from 0-15 cm depth was done randomly from four spots of the field prior to start of the experiment. The data on various characters studied during the course of investigation were statistically analyzed by using Tukey’s test with an aim to figure out which groups in our sample differ by using “Honest Significant Difference”. Further, influence of organic manures on soil physical, chemical and biological properties was studied and was found that there was a significant impact of organic manures on soil physical properties viz. WHC, BD and IR. In 2016, WHC increased from 38.67 to 41.26% in okra, 39.53 to 42.21% in broccoli whereas in 2017, it increased from39.98 to 42.69 % and 40.88 to 43.68 % in okra and broccoli. In contrast to this the chemical properties like pH, EC and OC were found to be non-significant; however CEC was found significant in experiment. Highest value of CEC 21.69 cmol (p+) kg-[1] was observed in okra and 24.19 cmol (p+) kg-[1] in broccoli as compared to control T1 which was 19.89 cmol (p+) kg-[1] in okra and 20.89 cmol (p+) kg-[1] in broccoli in 2016. In 2017, significant variation in CEC was noted with highest to lowest value observed 23.19 cmol (p+) kg-[1] to 21.39 cmol (p+) kg-[1] in okra and 24.19 to 22.39 cmol (p+) kg-[1] in broccoli. In nutrient status, organic manures reviewed a positive impact on Available N, P and Fe. However, available K, S, Zn, Cu, Mn, Total N, Exch. Ca and Mg were found to be non-significant in the experiment. Significant results were obtained in N with highest value 273.8 kg ha-[1] in okra and 279.3 kg ha-[1] in broccoli as compared to control which was 252.9 kg ha-[1] in okra and 258.0 kg ha-[1] in broccoli in 2016. In 2017, significant variation in N was noted with highest to lowest value observed 282.1 to 260.6 kg ha-[1] in okra and 283.5 to 261.9 kg ha-[1] in broccoli. In case of P, significant variation was noted with highest value 16.89 kg ha-[1] in okra and 17.74 kg ha-[1] in broccoli as compared to control which was 15.98 kg ha-[1] in okra and 16.79 kg ha-[1] in broccoli. In 2017, variation in P was noted with highest to lowest value observed 20.40 to 19.31 kg ha-[1] in okra and 21.44 to 20.29 kg ha-[1] in broccoli. In 2016, significant results were obtained in Fe with highest value 31.26 kg ha-[1] in okra and 32.21 kg ha-[1] in broccoli as compared to control which was 28.67 kg ha-[1] in okra and 29.53 kg ha-[1] in broccoli. In 2017, again significant variation in Fe was noted with highest to lowest value observed 32.69 to 29.98 kg ha-[1] in okra and 33.68 to 30.88 kg ha-[1] in broccoli. In biological properties, the MBC and dehydrogenase enzyme activity showed significant variation as compared to control; however the MBN and enzyme acid phosphatase showed non-significant variation. In 2016, significant results were obtained in MBC with highest value 43.02 µg g-[1] in okra and 44.75 µg g-[1] in broccoli as compared to control which was 40.35 µg g-[1] in okra and 41.98 µg g-[1] in broccoli. In 2017, highest to lowest value observed was 2.80 µg g-[1] to 2.63 µg g-[1] in okra and 3.20 µg g-[1] to 2.89 µg g-[1] in broccoli. In case of dehydrogenase, significant results were obtained with highest value 121.73 µg TPF g-[1] soil day-[1] in okra and 122.12 µg TPF g-[1] soil day-[1] in broccoli as compared to control which was 110.67 µg TPF g-[1] soil day-[1] in okra and 111.45 µg TPF g-[1] soil day-[1] in broccoli. In 2017, variation in dehydrogenase was noted with highest to lowest value observed 122.55 to 111.84 µg TPF g-[1] soil day-[1] in okra and 123.41 to 120.73 µg TPF g-[1] soil day-[1] in broccoli. All growth parameters of okra and broccoli including okra yield and curd weight showed significant increase except number of leaves in broccoli.

Keywords: FYM, Poultry Manure, Vermicompost, Neem Cake, Soil properties, Okra, Broccoli

LIST OF TABLES

Abbildung in dieser Leseprobe nicht enthalten

ABSTRACT

Abbildung in dieser Leseprobe nicht enthalten

Abstract

A study was conducted to assess the impact of different organic manures on soil properties and growth parameters in okra-broccoli cropping sequence. Study area lies in between 32°39'35.5"N latitude and 74°47'35.0"E longitude at an elevation of 332 meters above the mean sea level in the Shivalik foothill plains of North-Western Himalayas. Surface soil sampling from 0-15 cm depth was done randomly from four spots of the field prior to start of the experiment. The data on various characters studied during the course of investigation were statistically analyzed by using Tukey’s test with an aim to figure out which groups in our sample differ by using “Honest Significant Difference”. Further, influence of organic manures on soil physical, chemical and biological properties was studied and was found that there was a significant impact of organic manures on soil physical properties viz. WHC, BD and IR. In 2016, WHC increased from 38.67 to 41.26% in okra, 39.53 to 42.21% in broccoli whereas in 2017, it increased from39.98 to 42.69 % and 40.88 to 43.68 % in okra and broccoli. In contrast to this the chemical properties like pH, EC and OC were found to be non-significant; however CEC was found significant in experiment. Highest value of CEC 21.69 cmol (p+) kg-[1] was observed in okra and 24.19 cmol (p+) kg-[1] in broccoli as compared to control T1 which was 19.89 cmol (p+) kg-[1] in okra and 20.89 cmol (p+) kg-[1] in broccoli in 2016. In 2017, significant variation in CEC was noted with highest to lowest value observed 23.19 cmol (p+) kg-[1] to 21.39 cmol (p+) kg-[1] in okra and 24.19 to 22.39 cmol (p+) kg-[1] in broccoli. In nutrient status, organic manures reviewed a positive impact on Available N, P and Fe. However, available K, S, Zn, Cu, Mn, Total N, Exch. Ca and Mg were found to be non-significant in the experiment. Significant results were obtained in N with highest value 273.8 kg ha-[1] in okra and 279.3 kg ha-[1] in broccoli as compared to control which was 252.9 kg ha-[1] in okra and 258.0 kg ha-[1] in broccoli in 2016. In 2017, significant variation in N was noted with highest to lowest value observed 282.1 to 260.6 kg ha-[1] in okra and 283.5 to 261.9 kg ha-[1] in broccoli. In case of P, significant variation was noted with highest value 16.89 kg ha-[1] in okra and 17.74 kg ha-[1] in broccoli as compared to control which was 15.98 kg ha-[1] in okra and 16.79 kg ha-[1] in broccoli. In 2017, variation in P was noted with highest to lowest value observed 20.40 to 19.31 kg ha-[1] in okra and 21.44 to 20.29 kg ha-[1] in broccoli. In 2016, significant results were obtained in Fe with highest value 31.26 kg ha-[1] in okra and 32.21 kg ha-[1] in broccoli as compared to control which was 28.67 kg ha-[1] in okra and 29.53 kg ha-[1] in broccoli. In 2017, again significant variation in Fe was noted with highest to lowest value observed 32.69 to 29.98 kg ha-[1] in okra and 33.68 to 30.88 kg ha-[1] in broccoli. In biological properties, the MBC and dehydrogenase enzyme activity showed significant variation as compared to control; however the MBN and enzyme acid phosphatase showed non-significant variation. In 2016, significant results were obtained in MBC with highest value 43.02 µg g-[1] in okra and 44.75 µg g-[1] in broccoli as compared to control which was 40.35 µg g-[1] in okra and 41.98 µg g-[1] in broccoli. In 2017, highest to lowest value observed was 2.80 µg g-[1] to 2.63 µg g-[1] in okra and 3.20 µg g-[1] to 2.89 µg g-[1] in broccoli. In case of dehydrogenase, significant results were obtained with highest value 121.73 µg TPF g-[1] soil day-[1] in okra and 122.12 µg TPF g-[1] soil day-[1] in broccoli as compared to control which was 110.67 µg TPF g-[1] soil day-[1] in okra and 111.45 µg TPF g-[1] soil day-[1] in broccoli. In 2017, variation in dehydrogenase was noted with highest to lowest value observed 122.55 to 111.84 µg TPF g-[1] soil day-[1] in okra and 123.41 to 120.73 µg TPF g-[1] soil day-[1] in broccoli. All growth parameters of okra and broccoli including okra yield and curd weight showed significant increase except number of leaves in broccoli.

Keywords: FYM, Poultry Manure, Vermicompost, Neem Cake, Soil properties, Okra, Broccoli

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CHAPTER 1

INTRODUCTION

Continuous and massive application of fertilizers during early seventies helped in improving the soil fertility and also the replenishment of nutrients lost due to abiotic factors or consumed by the plants and ushered an era of green revolution. After 50 years of green revolution, the continuous trend of application of fertilizers in imbalanced way because of some govt. policies like subsidy on urea led to the emergence of problem of soil and water bodies’ pollution by nitrate. As a result, economic efficiency of fertilizers use as well as quality of crop products deteriorated. History is the witness that organic manure based agro-production systems continues to support the agriculture growth both quantitatively as well as qualitatively. Researchers concluded that Organic Nutrient Management in agriculture as a way tends to be more promising and reliable to take on all the issues pertaining soil, climate and crop productivity sustainably (Larson and Clapp 1984; Doran and Parkin 1994 and Sudha and Chandini 2003). Organic manure has the tendency to improve soil physical properties through increased soil aggregation, decrease in the volume of micropores while increasing macropores, increased saturated hydraulic conductivity and water infiltration rate thereby improving soil water-holding capacity at both field capacity and wilting point. Organic manures and compost applications has resulted in higher SOC (soil organic carbon) content compared to same amount of inorganic fertilizers applications (Gregorich et al., 2001). Although, the accumulation of SOM (soil organic matter) through applied organic manures depends upon the rate of decomposition process. Soil management practices greatly affect the SOM and soil fertility. Pimental et al. (2005) indicated that the highest total aerial dry matter and grain yields were associated with the highest organic matter contents of the soils. In addition, crop production based on the use of organic manures rather than chemical fertilizers is assumed to be a more sustainable type of agriculture. In recent years, the application of organic fertilizers have received great attention from environmentalists, agriculturists and consumers alike (Chang et al. 2007). Gabriel et al. (2010) found that depending on crops, soil and weather conditions, organically managed crops yield on ha-[1] basis was equal to those from conventional agriculture. Organic farming has become very popular and is steadily occupying the area of production around the globe and possesses the higher adoption in Asia.

In recent years, because of a renewed awareness of the relationship between human population and the Earth’s capacity to produce enough food to sustain the world’s burgeoning population much has been written about soil quality in relation to food security (Lal and Stewart 2010). In the context of this brief discussion of organic fertilizers and soil health, it is pertinent to put the global situation with respect to food in perspective. The food balance sheets prepared by the United Nations Food and Agricultural Organization (FAO) show that more than 99.7% of human food (calories) comes from the terrestrial environment, i.e., agricultural land (Pimentel and Wilson 2004). Of the 13 billion ha of land area on Earth, cropland accounts for only 11%. About 78% of the average per capita calorie consumption or energy needs worldwide comes from crops grown directly in soil, and another more than 20% comes from other terrestrial food sources such as meat, eggs and milk that rely indirectly on soil (Brevik 2013). Hence, soil is fundamental to crop production and thus constitutes the natural resource that provides mankind the most of its food and nutrients. (Liu et al. 2009; Yu et al. 2012; Cavagnaro, 2014; Xie et al.,2014; Molina - Herrera , Romanya , 2015; Srivastava et al. 2015; Wang et al. 2015; Ling et al. 2016).

Ponisio et al. (2014) through their meta-analysis showed that organic yields are only 19.2% lower than conventional yields, a smaller yield gap than previous estimates. Effects of crop types and management practices on the yield gap, two agricultural diversification practices, multi-cropping and crop rotations substantially reduce the yield gap when the methods were applied in only organic systems. The nutrients released after the biological breakdown of the soil organic matters supply the nutrients essential for plant growth in organic farming. However in general, the mineralization rates of soil organic matter is slow both in humid tropical and humid arid region (Fernandez et al. 2006 and Mary and Sanchez 1990). Therefore, to establish and maintain soil organic matter content to a certain level in such regions through the continuous application of compost can be effective strategies in organic farming. However, climate and soil significantly affect the accumulation and storage of organic matter in the soil because of the interactions of temperature and moisture on plant productivity and the ability of the soil mineral components to retain organic matter. Under tropical and subtropical climatic conditions, due to high cultivation frequency, and a low input of the organic matter content in the farmland soil is noticed and generally it is common for the soil organic matter content to be lower than 20 g kg−[1] (Huang SN 1994). The biological component of soils usually responds more rapidly to changing soil conditions than either the chemical or physical properties (Forge et al. 2008; Kukreja and Meredith, 2011).

Soil enzymatic activities have been used as indicators of soil fertility because they are a reflection of the effects of cultivation, soil properties and soil amendments (Pokharel et al. 2015). Ensuring a sustained supply of wholesome, fresh and healthy food while maintaining ecological or environmental integrity and social harmony has become a major challenge and a central issue in the agricultural sector for researchers, producers and policy-makers. One of the most important principles for making a farm more sustainable is reducing the use of synthetic fertilizers by increasing on-farm nutrient cycling and preventing pests and diseases by building healthy and biologically active soil (Nelson 2004). The category of organic fertilizers includes organic material mixtures such as Farmyard Manure, Vermicompost, Neem cake, Poultry manure etc. Addition of such organic mixtures will result in higher soil organic matter accumulation and biological activity due to increased plant biomass production and organic matter returns to soil in the form of decaying roots, litter and crop residues. Addition of SOM enhances soil organic carbon content, which is an important indicator of soil quality and crop productivity as discussed earlier (Lal 2003).

Several studies have reported that FYM applications in irrigated systems resulted in reduced bulk density, higher SOC and hydraulic conductivity and improved soil structure and microbial communities (Bhattacharyya et al. 2007). Vermicompost as an organic fertilizer enriched with all beneficial soil microbes and also contains all the essential plant nutrients like N, P and K. Since vermicompost helps in enhancing the activity of microorganisms in soil which further increase solubility of nutrients and their consequent availability to plants is known to be altered by microorganism by reducing soil pH at microsites, chelating action of organic acids produced by them and intraphyl mobility in the fungal filaments (Parthasarathi et al. 2008). Indian soils are poor to medium status within available nitrogen and available phosphorus therefore vermicompost can have a direct effect on soil organic matter content, soil fertility, soil physical characteristics and augment microbial activities Organic manures have been proven to enhance efficiency and reduce the need for chemical fertilizers, to improve the soil fertility and soil health. Rodriguez Vila et al. (2016) found that organic amendments sustain soil properties by increasing OM, nutrient content, microbial activity and thus increase crop growth and yield. Various other organic studies (Galende et al. 2014; Mackie et al. 2015; Pena et al. 2015; Puga et al. 2015) proved that organic amendments help recover degraded soils.

Using organic fertilizers, composts and additions of rock minerals not only supplies plant nutrients but increases tolerance and resistance to insects and diseases, helps control weeds, retains soil moisture, and ensures produce quality (Barker and Bryson, 2006; Diver et al. 1999; Montemurro et al. 2005; Zhang et al. 1998). They may have direct anti-disease effects or stimulate competitor micro-organisms and or induce plant resistance (Ghorbani et al. 2006). Liquid pig manure, matured cattle manure and sugarcane husks applied directly to the soil showed promising results for control of some crop diseases (DeCeuster and Hoitink, 1999; Viana et al. 2000). However, there are reports suggesting that using organic fertilizers increased development of some diseases. For example, Chauhan et al. (2000) found that increasing application of farm yard manure from 25 to 75 t ha-[1] increased disease severity of stem rot in cauliflower. Compost extracts, which are filtrated solutions of mixtures of compost materials and water, have shown promising results against crop diseases (Brinton et al. 1996; Goldstein, 1998) but the mechanisms of effects seem to vary depending on the host /pathogen relationship and the mode of application. Compost extracts were reported to show good activity against some plant diseases, especially when enriched with selected microbial antagonists (Weltzien 1989). Goldstein (1998) reported that composts and compost extracts activate disease resistance genes in plants. These genes are activated in response to the presence of a pathogen. They mobilize chemical defenses against the pathogen invasion, although often it is too late to avoid the disease.

In organic manure production, vermicomposting is referred to the production of compost through the action of earth-worm. It is an eco-biological process that transforms energy-rich and complex organic substances into stabilized humus-like product vermicompost. Preparation of vermicompost is an efficient as well as easily adoptable technique of compost preparation. This composting system can not only decompose a huge amount of organic wastes but also help to maintain higher nutrient status in composted materials (Hema and Rajkumar, 2012). Vermicomposting technology using earthworms (as versatile natural bioreactors for effective recycling of organic wastes to the soil) is an environmentally acceptable means of converting waste into nutritious composts for crop production (Edward et al. 1985; Yadav et al. 2011). Moreover, by processing of garbage, this technology converts the problem into a resource and provides good manure which can be used to enhance quality of the soil (Azarmi et al., 2008). Yadav and Garg (2011) explored the use of vermicomposting technology in food industry waste management. In view of the above, an approach has been made in the proposed experiment to partially or entirely supplement the chemical fertilizer with the use of vermicompost for improving the productivity of crops. Earthworms are often referred to as farmer’s friends and nature’s ploughmen are extremely important in soil formation, principally through their activities in consuming organic matter, fragmenting and mixing it intimately with mineral particles to form aggregates. During their feeding, earthworms promote microbial activity greatly, which in turn accelerates the breakdown of organic matter and stabilization of soil aggregates. The ability of some earthworms to consume a wide range of organic residues such as sewage sludge, animal wastes, crop residues, and industrial refuse has been fully established. In the process of feeding, earthworms fragment the waste substrate, enhance microbial activity and the rates of decomposition of the material, leading to a composting or humification effect by which the unstable organic matter is oxidized and stabilized. The end product, commonly termed vermicompost and obtained as the organic wastes pass through the earthworm gut, is quite different from the parent waste material. Vermicomposting is a simple biological process of composting, in which certain species of earthworms are used to enhance the process of waste conversion and produce a better end product. Vermicomposting differs from composting in several ways. It is a mesophilic process, utilizing microorganisms and earthworms that are active at 10–32°C (not ambient temperature but temperature within the pile of moist organic material). The process is faster than composting because the material passes through the earthworm gut and transformation takes place, whereby the resulting earthworm castings (worm manure) are rich in microbial activity and plant growth regulators, and fortified with pest repellence attributes as well in short, earthworms, through a type of biological alchemy are capable of transforming garbage into ‘gold’.

Organic materials such as FYM have traditionally been used by farmers. FYM supplies all major nutrients (N, P, K, Ca, Mg, S,) necessary for plant growth, as well as micronutrients (Fe, Mn, Cu and Zn). Hence, it acts as a multi-nutrient fertilizer. FYM improves soil physical, chemical and biological properties. Improvement in the soil structure due to FYM application leads to a better environment for root development. FYM also improves soil water holding capacity. The fact that the use of organic fertilizers improves soil structure, nutrient exchange, and maintains soil health has raised interests in organic farming. In general, the application of organic amendments such as crop residues and/or farmyard manure increases significantly SOC (Yadav et al. 2000). Sustaining soil organic carbon (SOC) is of primary importance in terms of cycling plant nutrients and improving the soils’ physical, chemical and biological properties. SOC is an important index of soil quality because of its relationship with crop productivity (Lal 1997). A decrease in SOC leads to a decrease in soil’s structural stability (Le Bissonnais and Arrouays, 1997). Also restoration of SOC in arable lands represents a potential sink for atmospheric CO2 (Lal and Kimble 1997). Agricultural utilization of organic materials, particularly farmyard manure (FYM) has been a rather common traditional practice (Shen et al. 1997), Alam et al. (2014). As it enhances the soil organic C level, which has direct and indirect effect on soil physical properties.

Neem seed cake is the residue obtained after the extraction of oil from Neem Seed. It contains more nitrogen (2-5%), phosphorus (0.5-1.0%), calcium (0.5-3%), magnesium (0.3–1 %) and potassium (1-2 %) than farm yard manure or sewage sludge (Radwanksi and Wickens 1981). According to Soon and Bottrel (1994) Neem seed cake acts as natural fertilizer with pesticidal properties. This dual activity has made it a favored input in agricultural production. Moreover, Parmar (1986) reported that Neem seed cake exhibits the properties of insecticides, nitrification retardation and inhibiter of pesticide degradation. Usha and Patra (2003) stated that the use of Azadirachtin (active ingredient of Neem) to coat urea is a common practice as it reduces the loss of nitrogen by preventing the activity of Nitrifiers. Microbial communities in soil have large impact on overall soil health due to their production of secondary metabolites and nutrients recycling and decomposition. The increasingly demand of chicken meat has prompted more poultry farming with consequent effects on increased utilization of organic wastes (e.g. chicken manure) as fertilizers. Organic wastes contain varying amounts of water, mineral nutrients, organic matter (Brady and Weil 1996). While the use of organic wastes as manure has been in practice for centuries world-wide and in the recent times (López-Masquera et al. 2008), there still exists a need to assess the potential impacts of chicken manure on soil chemical properties and crop yield and in particular evaluating the critical application levels. Moreover, the need and utilization of chicken manure has overtaken the use of other animal manure (e.g. pig manure, kraal manure) because of its high content of nitrogen, phosphorus and potassium (Schjegel 1992). Escalating prices of inorganic fertilizers due to the increase in the fuel prices has also prompted the use of chicken manure (Duncan 2005). Similarly, organic wastes are also being advocated for by different environmental organizations world-wide to preserve the sustainability of agricultural systems.

Organic farming practices deliberately integrate traditional farming practices and make use of locally available resources. As such they are highly relevant to smallholder farmers who produce for themselves and local markets (Kolavalli and Adam 2011). In aspect of changing climatic patterns, global temperatures rise and weather patterns become more erratic, the intersection between climate change and agriculture is crucial in understanding the role that agriculture plays in contributing to and mitigating global warming. Carbon sequestration, lower-input of fossil fuel dependant resources, and use of renewable energy all present opportunities for organic agriculture is to lead the way in reducing energy consumption and mitigating the negative effects of energy emissions.

Organic agriculture thus provides management practices that can help farmers adapt to climate change through strengthening agro-ecosystems, diversifying crop and livestock production, and building farmers’ knowledge base to best prevent and confront changes in climate. Life cycle assessments show that greenhouse gases emissions in conventional production systems are always higher than those of organic systems, based on production area. Soil emissions of nitrous oxides and methane from arable or pasture use of dried peat lands can be avoided by organic management practices. Many field trials worldwide show that organic fertilization compared to mineral fertilization is increasing soil organic carbon and thus, sequestering large amounts of CO2 from the atmosphere to the soil. Lower greenhouse gas emissions for crop production and enhanced carbon sequestration, coupled with additional benefits of biodiversity and other environmental services, make organic agriculture a farming method with many advantages and considerable potential for mitigating and adapting to climate change. Keeping in view the diverse role and quite high potential of organic manures in soil biology, carbon harvesting, nutrient recycling, farm waste management and climate change management, the investigation was carried with the following objectives:-

1. To find out the effect of organic sources of nutrients on physical properties of soil.
2. To find out the effect of organics on biochemical parameters of soil
3. To study the impact of organics on soil quality.
4. To assess the influence of organics on growth and yield of crops.

CHAPTER 2

REVIEW OF LITERATURE

The importance of organic manures in the maintenance and improvement of soil quality particularly under okra-dhaincha-broccoli cropping pattern has been well documented in the literature. Organic manures are the valuable byproducts of farming and allied industries derived from plant and animal resources. The work pertaining to the objectives of the study has been discussed in this chapter under the following sub-heads:-

2.1 Effect of organics on soil physical properties
2.2 Effect of organics on soil chemical properties
2.3 Effect of organics on biochemical changes
2.4 Effect of organics on growth parameters

2.1 Effect of organics on soil physical properties

Organic manures increase the humus content of the soil, which improves the soil physical properties by causing an increase in aggregation (Elson 1943; Sommerfeldt and Chang 1985; Sharma et al. 2000) and water holding capacity (Acharya et al. 1988) and a decrease in soil bulk density (Hafez 1974). The decrease in bulk density can be ascribed to an increased volume of micropores as well as a decreased particle density in soil amended with organic manure (Schjonning et al. 1994).

According to Pagliai and Vignozzi (1998), application of organic manures improves the soil physical properties by improving porosity and aggregate stability and reducing the formation of surface crusts. Studying the influence of continuous long-term application of manures and fertilizers on the physical properties of sandy loam soil, Muthuvel et al. (1982) reported a decrease in bulk density with increase in organic matter content due to better aggregation.

A decrease in bulk density has also been reported by Khaleel et al. (1981) and Anderson et al. (1990) after addition of manures. According to Mathan and Thilagavathi (1997), the decreased bulk density might be due to higher application and advanced decomposed organic matter and formation of better stable aggregates. The greatest influence of organic matter on water holding capacity is attributed to the structural changes in pore size both within and between the soil aggregates (Larson and Clapp 1984).

Studies conducted by Lourduraj (1997) revealed that coir pith application favorably influences soil physical properties like hydraulic conductivity and moisture holding capacity in groundnut growing soil. High carbonaceous material in organic manures contributes towards enhancing the water holding capacity of the soil (Ranganathan and Selvaseelan 1997). Tiwari et al. (1998) and Patidar and Ali (2004) observed that incorporation of FYM results in improvement of soil physical properties, water-holding capacity, porosity and bulk density of soil. Similar findings were reported by Suja et al. (2004) in white yam cultivation. The experiment carried out by Tennakoon (1990) using goat manure showed improvement in water holding capacity of soil. The results of physical analysis of soils amended with organics in horticultural crops indicated that apart from ameliorating the poor physical properties of the compacted soil, additions of the composted organic amendments significantly increased soil pH, organic carbon content and the available supplies of phosphate and Mg in the soil (Mishra and Sharma 1997; Wein and Allen 1997; Tiwari et al. 1998).

An experiment was conducted by Pal et al. (2017) during kharif (July-October) season 2016 on crop research farm of Department of Soil Science and Agricultural Chemistry, Naini Agricultural Institute, Allahabad to evaluate the effect of different treatment of poultry manure and PSB culture with levels of phosphorus. The Soil parameters viz. bulk density (Mg m-[3]), particle density (Mg m-[3]), Pore space (%) and water holding capacity (%), pH, EC (dSm-[1]), organic carbon (%), available nitrogen (kg ha-[1]), phosphorus (kg ha-[1]) and potassium (kg ha-[1]) were analyzed. All parameters of soil properties are found significant accept Pore space (%). Physical properties viz., Bulk density (Mg m-[3]), Particle density (Mg m-[3]), and Water holding capacity (%) was recorded as 1.30, 2.85, 52.94, 64.69. Chemical properties viz., pH, EC, organic carbon (%), available nitrogen (kg ha-[1]), available phosphorus (kg ha-[1])and potassium (kg ha-[1]) was recorded as 7.19, 0.19, 0.79, 263.01, 23.89, 132.57 respectively in the treatment was significantly higher as compared to other treatment combination. Bulk density (Mg m-[3]), particle density (Mg m-[3]), Pore space (%), water holding capacity (%), organic carbon (%), available nitrogen (kg ha-[1]), and potassium (kg ha-[1]) T8 (P 100% + poultry manure) and pH, EC (dSm-[1]) and available phosphorus (kg ha-[1]) T9[P 100% + PSB culture] was found to be the best, for improvement of the physico-chemical properties of soil

Studies have revealed that soil physical properties improve significantly in soils amended with organic manure. The hydraulic conductivity and soil porosity increase whereas bulk density decreases. Soil aggregation contributes to the fertility, because it is crucial to soil porosity, aeration and infiltration of water. Organic agriculture results in continuous buildup of soil organic carbon, available P and microbial biomass in the organic system, resulting in the improvement of the hydro physical environment (Singh et al. 1997; Kairon et al. 1998). The decrease in bulk density could be attributed to the fixing of the low density materials with dense mineral fraction of the soil.

Decrease in bulk density with the addition of organic matter has been reported by many workers (Singh and Singh 2000; Ray and Gupta 2001; Sharma et al. 2001). Thakur et al. (1995) reported significant decrease in bulk density of silty clay loam soil at Palampur due to incorporation of dhaincha (Sesbania aculeata)and French bean biomass at an average rate of 18.3 and 1.3 t ha-[1] year after every 3 years, respectively. The effect of dhaincha (Sesbania aculeata) was significantly higher than French bean probably because of much higher biomass addition of the former than the latter. In a clay loam soil at Kaul (Haryana) incorporation of dhaincha (Sesbania aculeata) @ 33 t ha-[1] decreased the bulk density by 8.1 per cent at 0-15 cm and 2.3 per cent at 15-30 cm depths over the control (Gupta et al. 1995). Ray and Gupta (2001) reported that incorporation of green manure before puddling of rice field improved soil aggregation and thereby decreased bulk density. Thus, from above cited literature it is evident that the bulk density decreased with application of FYM and green manures, over a period of 2-7 years. The water-holding capacity is controlled primarily by the number of pores, their size distribution, and specific surface area of soils. Porosity is also a soil physical property derived from bulk density and particle density and indicates the total pores in the solids. Some sources of organic matter like coir pith have high water retention i.e., they increase soil water holding capacity.

Patil (1998) reported that similarly in the Vertisols of Bijapur, incorporation of FYM @ 2.5 t ha-[1] vermicompost @ 1.01 ha-[1] and subabul lopping @ 2.51 ha-[1] enhanced the soil moisture content compared to only fertilizer application. According to Hussain et al. (2001) the most efficient treatment was the combination of gypsum, sulfuric acid and FYM. There is inverse relationship between bulk density and porosity/void ratio. Therefore, a decrease in the value of former resulted in an increase in the latter. Total pore space is typically increased by addition of organic matter, thereby maintained the continuity of pores (Barzegar et al. 2002; Dorado et al. 2003). Sarkar et al. (2003) have reported that addition of organic materials had increased moisture-retention capacity and infiltration rate of the surface soil.

Celik et al. (2004) found that total porosity of soil increased with inorganic chemical fertilizer and compost application. Malathesh (2005) stressed that the farm yard manure seems to act directly by increasing crop yields either by acceleration of respiratory process by cell permeability or by hormone growth action. It supplied nitrogen, phosphorus and sulphur in available forms to the plants through biological decomposition. Indirectly, it improved physical properties of soil such as aggregation, aeration, permeability and water holding capacity. Organic matters not only increased the water holding capacity of the soil but also the portion of water available for plant growth and improved physical properties of soil (Bolan et al. 2004; Sial et al. 2007).

Suganya (2006) concluded that vermiculite or FYM or Bentonite at the rate of 1 % (or) 20 t ha-[1] or humic acid @ 20 kg ha-[1] could bring out large scale improvement in the moisture retention and fertility of sandy soils ensuring better yield of crops. Organic matter content and available water holding capacity in NPK+Zn+FYM were increased consistently over time and can explain the increase of yield (Jadoon et al. 2003; Dong et al. 2006). Similar results were shown by Shamsher Ali et al. (2008).

The average water holding capacity (WHC) and total porosity of soil during maize was (21%) higher in FYM plots than in control plots, whereas it was 11% higher in N100 P50 K50 plots as revealed by Rasool et al. (2008). As regards organics, PMC and FYM proved their superiority over control to conserve greater moisture in soil significantly in Kharif season (Dhamak et al. 2010). The highest water holding capacity (54.67%) registered 32.41% more total porosity than the control treatment was also observed under continuous application of 100% NPK and FYM, biofertilizer, and lime (Saha et al. 2010). This might be due to more organic-matter content, better aggregation, and changing pore-size distribution of the soil (Aggelides and Londra 2000). According to Palve et al. (2011) soil moisture and soil moisture efficiency were also more in treatment using 100% RDF with FYM @ 51 ha over control plot.

In an experiment conducted by Khan et al. (2010) it was noticed that tillage methods and farm yard manure carries its impact on soil physical properties and health. Farm yard manure has positive role in maintaining physical properties of soil as it takes time to decompose completely. Farm yard manure significantly increased saturated hydraulic conductivity in deep tillage method and reduced bulk density of soil. The farm yard manure (FYM) also affected the physical properties as it increased hydraulic conductivity.

In a field experiment performed by Bing et al. (2013), the findings of this study suggest that farmyard manure incorporation and mulch application had individual and interactive impacts on soil physical properties, particularly in the 0-10 cm soil layer because of the tillage depth. Soil capillary water holding capacity, saturated water content and saturated hydraulic conductivity increased with decrease in the soil cone index and bulk density under the treatments of farmyard manure, polythene film mulch and straw mulch, especially beneath the integrated application of farmyard manure and mulch. On one hand, the better soil physical environment amelioration resulted in a better salt leaching, soil quality and productivity improvement of the reclaimed coastal tidal flat saline soil; on the other hand, the agricultural utilization of crop straw avoided the environment issues caused by conventional straw burning in the study area and increased the soil carbon pool.

Water permeability is the ease with which gases and liquids penetrate or pass through a bulk mass of soil or a layer of soil. The hydraulic conductivity measurements provide an indication of relative water transmission rate of the soil. Bower et al. (1951) regarded combination of amendments as the best. The improvement in bulk density in different combinations of organic manure may be the main cause of increase in hydraulic conductivity. All treatments increased the hydraulic conductivity except simple leaching.

Gorbunov (1980) observed improvement of soil structure and increased water permeability. Ohu et al. (1994) & Flowers and Lai (1998) reported that addition of organics and balanced fertilizer caused better aggregation and may have resulted in an increase in effective pore volume. As soil permeability is a function of effective pore volume, increased pore volume has a direct influence on hydraulic conductivity of the soil. So adding manure would increase soil hydraulic conductivity. The application of gypsum, FYM and sulfuric acid according to Hussain et al. (2001), improved the bulk density & porosity and has contributed to enhanced water permeability & hydraulic conductivity. Addition of organic matter was reported to enhance soil organic carbon (SOC) content, which directly or indirectly affects soil physical properties and processes such as aggregation, water infiltration, water holding capacity, hydraulic conductivity, bulk density, and resistance of soil to water and wind erosion (Franzluebbers, 2002; Celik et al. 2004).

Binitha (2006) explained that FYM improved the soil health indirectly through increase of water stable aggregates, soil aeration, permeability, infiltration rate and water holding capacity of the soil. Increase in the hydraulic conductivity due to application of FYM to inorganic fertilizer might be attributed to the improvement in soil structural stability, increase in organic matter content, and biological activity of the surface soil (Hati et al. 2006). Similar findings were also reported by Bellakki et al. (1998) and Reddy and Reddy (2008).

A study was conducted by Aboutayeb et al. (2014) to evaluate the short-term effect of chicken manure on soil properties of cultivated horizon (0-20 cm) under silage maize. The field experiment was conducted using a randomized complete block design. In total, twelve plots were arranged; it consisted of four treatments and three repetitions. Applied treatments included a control (C) and spreading of chicken manure at 5 t ha-[1] (T1), 10 t ha-[1] (T2) and 15 t ha-[1] (T3). The results obtained showed that the application of chicken manure improves several soil properties. It induced a significant increase in the soil electrical conductivity (EC), the phosphorus and nitrates content (NO3-) depending on the amount applied. A slight acidification was recorded after manure application. This acidification is probably due to mineralization of organic matter activated after incorporation of manure into the soil. Trends of increasing soil organic matter (OM) were registered. Its contents ranged from 4.60%, 5.65%, 5.57% and 5.66% for C, T1, T2 and T3 respectively. The total nitrogen and potassium content were higher after application without marking a significant difference. The nitrogen contents varied from 0.20 to 0.23% and those of potassium from 277 to 350 ppm. The production of corn silage was significantly higher in plots (T3), with a production of 17.8 t ha-[1]. For other treatments, production has not registered a significant difference. They ranged from 10.7 to 13.4 ton hectare-[1].

An experiment was carried out by Joshi et al. (2016) on loamy sand soil to evaluate the effect of organic manures (farmyard manure, vermicompost, poultry manure, neem cake and castor cake) on soil and quality parameters of cowpea during summer season of 2014. Nine treatments were tried out in randomized block design with four replications. Recommended Dose Fertilizer (RDF) i.e. 20- 40-0 NPK kg ha-[1] recorded significantly higher chlorophyll content of leaves at 60 DAS and crude protein content in green seed over rest of the treatments except, vermicompost 2 t ha-[1] and poultry manure 2 t ha-[1]. Soil chemical parameters viz., Organic Carbon (OC), EC, available N, P2O5 and K2O were found to be affected significantly due to different treatments. Higher OC content after harvest of the crop was reported under treatment Poultry manure 2 t ha-[1]. Whereas, treatment vermicompost @ 2 t ha-[1] recorded significantly reduction in EC over control, however, different treatments failed to exert their significant influence on soil pH after harvest of the crop. Significantly higher values of available nutrients (N, P2O5 and K2O) in the soil after harvest of the crop was observed under the treatment VC 2 t ha-[1], FYM 2.5 t ha-[1] and PM 2 t ha-[1], respectively. RDF 20-40-0 kg NPK ha-[1] recorded the maximum value of net realization with BCR value followed by treatment PM 2 t ha-[1].

A research experiment was conducted by Lemanowicz (2013) based on the mobility of phosphorus and sulphur in winter wheat fertilized with several rates (0, 20, 40, 60, 80 t ha-[1]) of farmyard manure and nitrogen (0, 40, 80, 120 kg N ha-[1]). The content of these nutrients was related to the activity of acid phosphatase and aryl sulphatase in a Haplic Luvisol. The highest content of available phosphorus (91.58 mg P kg-[1]) was reported in the soil amended with farmyard manure at the rate of 60 t ha-[1]. The content of sulphates (VI) in the Haplic Luvisol was high and, on average, equal to 25.22 mg kg-[1]. The activity of acid phosphatase in the soil increased with increasing mineral nitrogen rates. The highest content of sulphates (VI) and the lowest activity of aryl sulphatase were identified at the nitrogen rate of 40 kg N ha-[1]. The mobility of phosphorus in winter wheat was the highest when farmyard manure at the rate of 60 t ha-[1] and mineral nitrogen at the rate of 120 kg N ha-[1] were incorporated into the soil. The greatest translocation of sulphur was reported at the high farmyard manure rates (40, 60 and 80 t ha-[1]) and the nitrogen rate of 80 kg N ha-[1].

Application of organic residues had significantly increased hydraulic conductivity as observed by Mubarak et al. (2009). Naveed Iqbal Khan et al. (2010) positively correlated the mean increase in hydraulic conductivity as 62.2% and 35.5% with FYM @ 40 and 20 Mg ha-[1] respectively when compared to recommended NPK values. The findings are in conformity with those of Shirani et al. (2002) who reported that manure application improved hydraulic conductivity.

Dhamak et al. (2010) proposed that the effect of amending the soil with pig manure compost (PMC) and FYM was also found promising and significant to improve hydraulic conductivity of soil. Organic amendments to the soil were found better for seedbed preparation by breaking the clods as well as improved the hydraulic conductivity of soil significantly. Investigations of Saha et al. (2010) revealed that better aggregation and increased porosity as a consequence of the addition of organics have favorable effects on hydraulic conductivity, which influenced the soil water dynamics

2.2 Effect of organics on soil chemical properties

While some workers have reported increases in pH (Sarkar 1998; Tembhare et al. 1998; Singh et al. 1998) others have reported a net decrease in it (Sudhir et al, 1998; Swarup and Ghosh 1979) due to continuous inorganic fertilizer application. Manure application is also reported to increase or decrease in pH of tire system. Sarkar (1998) reported an increase in pH over 5 years in a maize - wheat system at Ranchi. Sharma et al. (1998) also reported an increase in pH through FYM application in Palampur, India. Swarup and Ghosh (1979) reported a slight decrease of 0.06 in pH due to organic matter addition.

The results of chemical and physical analysis of soils amended with organics in horticultural crops indicated that apart from ameliorating the poor physical properties of the compacted soil, additions of the composted organic amendments significantly increased soil pH, organic carbon content and the available supplies of phosphate and Mg in the soil (Wein and Allen 1997). Singh and Chauhan (2002) recorded relatively high accumulation of organic carbon, on FYM application in soil.

Sharma et al. (1997) have reported moderating effect of FYM on soil pH. Often there is an initial increase in pH over the first one or two months of the residue decomposition followed by a decline to above or below the initial pH level (Asghar and Kanehiro 1980). Similarly there was improvement in the soil pH towards neutrality after the application of vermicompost in the soil growing Chinaaster (Nethra et al. 1999). An increase in pH on application of organic manures has also been reported by (Hoyt and Turner 1975; Hue et al. 1986; lyamuremye and Dick 1996; Noble et al. 1996; Wong et al. 1999).

Electrical conductivity of the soil extract indicates concentration of soluble salts in the soil solution. EC values less than 1 indicate that these soils are free from hazard of soluble salts as prescribed by Gupta and Gupta (1987). Pattanayak et al. (2001), Yaduvanshi (2001) and Smiciklas et al. (2002) also observed a decrease in soil pH after the use of organic materials. According to Hussain et al. (2001) a significant decrease in EC and pH was observed for gypsum, H2SO4 and FYM combination. Among the possible reasons may be the improvement in porosity and hydraulic conductivity, which resulted in enhancing the leaching of salts. Okwuagwu et al. (2003) inferred that during microbial decomposition of incorporated organic manure, organic acid may have been released, which neutralized the alkalinity of the organic manure thereby reducing the pH of the soil which is favorable for a good crop production. Somani & Totawat (1996) observed a similar result in their work on organic amendments in alkaline soils.

Sanwar et al. (2008) opined that the production of organic acids (amino acid, glycine, cystein and humic acid) during mineralization (aminization and ammonification) of organic materials by heterotrophs and nitrification by autotrophs would have caused this decrease in soil pH. The pH of the soil is a result of the soil soluble ions. The number of ions decides the pH value. An exponential decrease of EC in soil solution with the increasing value of ultrasonic velocity was noted by Deshpande and Thakre (2010). Similarly according to Paive et al. (2011), soil pH was decreased under FYM application.

In an experiment performed by sleutel et al. (2005) it was noticed that manure and fertilizer application can increase the amount of OC present in free POM, occluded POM and mineral associated OM at the time scale of several decades. Differences in the relative increases of the OC present in different soil fractions lead to a shift in the relative distribution of the bulk soil OC in these fractions. Based on fractionation results of two long-term arable field experiments, it can be concluded from this study that at the time scale of decades manure and fertilizer application result in relatively more labile OC present in the soil compared to an unfertilized control treatment. A consequence of the measurability of these changes at this time scale is that it may be possible to use such experimental data for the development and calibration of SOC models with conceptual OC pools which correspond to existing physical fractions. The theoretical model suggested by Six et al. (2002), used in this study, may qualify as such a model. However, chemical fractionation of the silt + clay associated OC by a simple hydrolysis technique seems to be unable to separate an inert SOC pool, which is virtually unaffected by management, and alternative techniques will be needed here.

A study was conducted by Li et.al. 2011 in China to determine the influence of poultry litter (PL) and livestock manure (LM) from intensive farming on soil physical and biological indicators of soil quality. Results showed that PL and LM amendment increased soil macropore and mesopore volumes and decreased soil micropore volumes. Tensile strength in PL and LM treatment were lower than those in CF, while soil aggregate wet stability index were greater than those in CF. Compared with CF treat­ment, the microbial biomass C and N contents (+89%, +74%), soil basal respiration rate (+49%) and soil microbial quotient (+45%) in PL and LM treatment were significantly greater. Significant linear correlations were found be­tween soil organic carbon and most soil physical and biological properties (P < 0.01). The results suggested that modern intensive farm manures can be alternate chemical fertilizers as a main fertilizer to improve soil physical and biological indicators in a rice-wheat system.

A laboratory experiment was conducted by Roy and Kashem (2014) in which incubation for 60 days was carried out to observe the changes of soil pH, electrical conductivity (EC), soil organic carbon (SOC), and potassium chloride extractable nitrogen (NH4+ N) in a soil to which three animal manures viz. cow dung (CD), chicken manure (CM) and a combination of CD and CM had been applied at a rate of 10 t ha−[1]. The effects of manures varied with manure type and incubation period. Soil pH slightly increased with the incubation period up to 30 days there after it declined with time significantly (p < 0.05). There was a significant (p < 0.05) increase in EC as days of incubation increased. Organic carbon contents of manure treated soils reached its peak at 15 days of incubation and decreased thereafter with time. The content of NH4+ increased significantly (p < 0.05) as incubation period increased in control and cow dung amended soils whereas there was no significant difference in NH4+ contents when either chicken manure alone or cow dung and chicken manure mixed in combination. After 60 days of incubation, the highest amount of NH4+ was found in cow dung plus chicken manure treated soil followed by chicken manure treatment.

Ahmad and Rahman (1991) observed in an experiment with Dhaincha (Sesbania aculeata) 40 t ha-[1] and well decomposed cowdung (60 t ha-[1] and 80-60-40 kg ha-[1]NPK treatment which resulted in a subsequent crop, significantly higher grain yield over control was obtained from plots received organic matter in previous crop season. Relatively higher level of exchangeable K, total N and CEC and improvement in soil physical properties such as decrease in bulk density and increase in moisture retention of field capacity were brought about by application of dhaincha. Jaur et al. (1973) reported all the treatments appreciably increased organic N content of soil. Dhaincha (S. aculeata) released the maximum amount of inorganic N and available S. All treatment improved CEC of the soil.

The presence of organic matter (OM) distinguishes the soil from a mass of rock particles and allows it to become a living system. Soil organic matter (SOM) serves as a soil conditioner, nutrient reservoir, substrate for microbial activity, preserver of the environment, and major determinant for sustaining and increasing agricultural productivity in the long run. Long term experiments are fundamental in constructing and validating models such as Rothamsted carbon Turnover model to simulate the turnover of soil organic matter Jenkinson et. al. 1987). Under humid tropical Indian conditions, where breakdown of organic matter is much more compared to that under temperate climates, application of organic matter had to be in larger quantity to have significant build up in SOM as was found out by Gupta et al. (1996), where yearly applications of 45 t ha-[1] manure increased the SOC level from an initial value of 0.47% in 1967 to 1.8% in 1995.

Sharma et al. (1995) also reported a 50% increase in SOM over 25 years due to addition of 35 kg ha-[1] FYM in Himachal Pradesh, India. Several other researchers have observed similar SOC increases and substantial residual effects as a result of manure additions (Mathers and Stewart 1974; Meek et al. 1982; Kanazawa et al. 1988; Sommerfeldt et al. 1988). The FYM is very effective in maintaining levels of soil organic matter because it degrades slowly as outlined by Nand Ram (2000). According to (Prakash et al. 2001) FYM treated plots showed higher organic carbon compared to other treatments. At Dhanwad, Patil (2002) reported that application of crop residues + RDF + FYM @ 7.5 t ha-[1] recorded significantly higher organic carbon (0.43 %) available N (239 kg ha-[1]), P (31.55 kg ha-[1]) and K (370 kg ha-[1]) as compared to control and RDF.

Shirani et al. (2002) reported manure application @ 30 and 60 Mg ha-[1] increased OM by threefold and fivefold. As expected, the concentration of total organic matter increased as the rate of application of organic manure increased (Barzegar et al. 2002). Sustaining soil organic carbon (SOC) is of primary importance in terms of cycling plant nutrients and improving the soil physical, chemical and biological properties (Lal, 1997). A decrease in SOC leads to a decrease in soil structural stability (Castro Filho et. al. 2002).

Farmyard manure enhances the soil organic carbon level, which has direct and indirect effect on soil physical properties (Lado et al. 2004). Binitha (2006) confirmed that fertilizer application coupled with addition of organic amendments like FYM, coir pith etc. resulted in significant increase in soil organic carbon, available nitrogen, available phosphorus and exchangeable potassium. According to Saha et al. (2010) the continuous application of balanced nutrition through lime, FYM, and microbial inoculants induced substantial buildup of SOC (68.58%), of the soil over NPK fertilizer. Similar results were obtained by Mubarak et al. (2009).

Khan et al. (2010) inferred that the increase in organic matter was 29.9% and 16.3% with FYM @ 40 Mg ha-[1] and 20 Mg ha-[1] respectively. The addition of organic matter in the form of FYM might be the reason for higher content of organic carbon in surface layers (Bande et al. 2010). Saha et al. (2010) observed a close relationship between soil aggregation and organic matter status of the soil. The greatest SOC content was recorded under the treatment 100% NPK + lime + bio fertilizer + FYM (T10), which was 68.58% greater than the control plot. Similarly Palve et al. (2011) concluded that organic carbon decreased under treatments where FYM application was not done.

Budhar et al. (1991) studied the effect of S. rostrata and P on Ganua glabra (P. pinnata) green manures on chemical properties of rice soil cv. Rice IR 60. They found that in post-harvest soil N and K content were highest after application of S. rostrata and P content was highest after P. pinnata. Ahmad et al. (1991) observed significant increase in soil organic carbon and total N by use of organic sources (cowpea or sunn-hemp) of nitrogen over 2 years to rice crop in rice-wheat sequence was observed after harvest of first rice crop upto 3rd year following for one year.

Kolar et al. (1993) reported that incorporation of Vigna unguiculata and Sesbania aculeata before the transplanting of rice increased organic carbon content of the soil. Joshi et al. (1994) observed that the green manuring with Sesbania aculeata in rice crop increased hydraulic conductivity of soil by 1.7 cm day-[1] as compared to NPK fertilizer alone with rice-wheat system.

Singh (1994) a five year study on integrated nitrogen management revealed that organic C and available P and K contents were significantly increased by Sesbania aculeata than manure incorporation.

Brar et al. (2001) found that nutrient uptake increased significantly from FYM 0-20 t ha-[1] Thus total N uptake increased from 55.5 kg ha-[1] in 0 t ha of FYM and 99.3 kg ha in 20 t ha-[1] of FYM. Singh et al. (2002) evidenced that application of P increased the uptake of P and N. This shows synergistic relationship between the two nutrients which is evidence of improvement of soil physical properties after groundnut crop. Highest uptake of NPK was recorded in the kernel, haulm and hull of groundnut, when combined application of organic manures was done in the trial conducted by Badole et al. (2003).

Investigations of Okwuagwu et al. (2003) revealed that available P in the treated plots was very high as a result of residual effect with cattle manure + NPK. Anilkumar and Thakur (2004) found that the available NPK content was higher when 10 tonnes of FYM was applied. The addition of FYM is considered as the best source of nitrogen which is being proved from the results of incubation study and most effective in increasing the plant height was reported by Sharma and Dayal (2005).

Kumar and Gowda (2010) the highest available Nitrogen was recorded in recommended FYM applied plot which had 47.2% higher available N over the treatment. Moreover the available phosphorus in the soil showed a gradual increase due to application of different sources and levels of organic manures. The available K ranged from 253.64 kg ha-[1] to 534.86 kg ha-[1]. The magnitude of uptake of nutrients was due to the fact that FYM or vermicompost increases the fertilizer use efficiency to a considerable extent (Mohan Kumar et al. 2011).

Ayuba et al. (2005) reported that higher organic matter was recorded in soil receiving combined application of organic manure as poultry manure and cow dung over a control. Ganapathi et al. (2008) reported that application of FYM alone increased the soil organic carbon significantly over soils applying with only chemical fertilizer under finger - millet crop production.

Pareek and Yadav (2011) found that increased the organic carbon content in soil significantly over control, which could be attributed to direct incorporation of organic FYM @ 12 t ha-[1] or poultry manure @ 5 t ha-[1] or vermicompost @ 4 t ha-[1]. The application of organic manure can minimize the negative effect of continuous application of inorganic fertilizer to finger millet by helps to maintain soil C levels and which minimizes N losses from the cropping system while increasing the sustainability of the system (Rao et al. 2012; Hemalatha and Chellamuthu, 2013).

Ganapathi et al. (2008) reported that application of FYM alone increased the soil available N, P and K status significantly over the soils applied with only chemical fertilizer under finger millet crop production.

Yadhuvanshi et al. (1985) reported that continuous application of NPK fertilizers and FYM would increase the exchangeable calcium and magnesium contents in the soil. They also reported that the continuous use of only chemical fertilizer would cause depletion in Ca and Mg contents of soil due to release of higher levels of exchangeable H+ and Al[3]+ ions. Higher levels of NPK would also cause higher crop production and hence depletion in contents of basis cations. Higher Mg in continuous FYM applied plots than N, P and K alone applied plot was observed.

Available sulphur content of the soil was found to be highest in treatment supplying N as ammonium sulphate and lowest in control (Lal and Mathur 1992). Gajanana et al. (2005) reported that the continuous 25 years application of FYM @ 10 t ha-[1] increased soil exchangeable Ca, Mg and available significantly compared to plots receiving control and receiving recommended NPK alone.

Ganapathi et al. (2008) reported that application of FYM alone increased the soil exchangeable Ca and Mg status significantly in comparison to soils applied with only chemical fertilizer under finger millet crop production.

Patil (2015) reported that organic farming farms recorded higher in exchangeable Ca, Mg and available S as compared to inorganic farming farms and also indicated that a exchangeable calcium was significant positive correlation with soil pH(r=0.260*), CEC (r=0.481***), available phosphorous (r=0.227*), exchangeable Mg (r= 0.836**), available sulphur (r=0.289*) and per cent silt(r=0.225*) and significantly negative correlation with per cent silt (r=-0.448**), similarly exchangeable magnesium was significant positive correlation with CEC (r=0.495***), exchangeable Ca (r=0.836**), available sulphur (r=0.290*) and per cent silt (r=0.335*) and significant negatively correlation with soil organic carbon r=0.380**) and available nitrogen (r= 0.387**).

Parylak et al. (2000) noticed in two years after organic fertilizer application into soil the content of copper increased by 14.6 per cent, zinc by 13.8 per cent and manganese by 7.8 per cent on average, as compared to soil fertilized with mineral fertilizers only.

Kumar and Qureshi (2012) observed that use of organic manures i.e. FYM (10 t ha-[1]), sulphitized pressmud (10 t ha-[1]), in-situ green manuring as Sesbania aculeate, wheat residue (2.5 t ha-[1]) decreased soil pH and their combined use with fertilizers was significantly reflected in the build-up of available NPK, organic carbon and DTPA– extractable micronutrients status in soil.

Behera and Shukla (2013) reported that organic carbon content in surface soil was positively correlated with DTPA-Zn (r = 0.833**) and DTPA-Cu (r = 0.899**) which explains that the complexing agents generated by organic matter promote the availability of these nutrients in soil and DTPA-extractable Zn and Cu did not reveal any significant relationship with soil pH.

Bhavitha (2013) noticed that available Zn had a positive and significant correlation with clay, pH and highly significant correlation with organic carbon content of the soil. Further noticed that available Cu was found to have significant and positive correlation with the organic carbon status of the soil, but very poor correlation with soil factors like pH and clay content.

Dhaliwal et al. (2013) concluded that the incorporation of different manures like FYM, green manure, poultry manure in soil before rice transplantation resulted in significantly higher content of the DTPA and total Zn in the soil which may be ascribed to the higher release of Zn through decomposition of organic manures. The increase in DTPA-extractable and total Zn may be attributed to chelating action of organic compounds released during decomposition of manures.

2.3 Effect of organics on biochemical changes

Microbial biomass in soil is the living component of soil organic matter and is included as a precursor to more stable fractions of organic matter in many models of organic matter formation (Parton et al. 1987). Because as much as 95% of the total soil organic matter is nonliving and, therefore, relatively resistant to change, decades may be required to notice any perceptible change in SOM. Microbial biomass has a turnover time of l year (Paul 1984) and therefore responds rapidly to conditions that eventually alter soil organic matter levels. Thus the size of microbial biomass might indicate degradation or aggradations of soil organic matter (Powlson et al. 1987; Sparling 1992).

The amount of microbial biomass although comprise a small portion of soil organic matter, yet reflects the total organic matter content within the living microbial component. Dinesh et al. (2000) found that soils amended with organic manures consistently registered significantly greater microbial biomass and biomass C compared to the unamended soil. Yan et al. (1998) found that soil microbial biomass C increased greatly after application of organic manures. Similar results were reported by several which showed increase in microbial biomass C after organic manures were applied. Also the applications of sewage sludge and cattle manures significantly increased soil organic carbon and microbial biomass carbon.

Liang et al. (2005) reported that the incorporation of organic amendments to soil stimulated dehydrogenase activity because the added material may contain intra and extracellular and may also stimulate microbial activity in the soil. Sriramachandrasekharan et al. (1997) observed that green manures have potentials to maintain higher dehydrogenase activity over farmyard manure, coir pith compost and paddy straw.

Jagadeesh (2000) reported that application of FYM along with recommended fertilizers recorded highest activities of dehydrogenese activity than all other treatments. The addition of organic manures caused significant differences in dehydrogenase (oxidoreductase) activity in submerged vertisol planted with rice. Among the organic manures, FYM @ 10 tonnes ha-[1] recorded significantly higher activity of dehydrogenase (Srinivas and Saroja 2002).

Stronger dehydrogenase activity was observed in compost applied plots due to higher organic matter content and further noticed that higher levels of organic C stimulate microbial activity and dehydrogenase synthesis (Wlodarczyk et al. 2002). The rotation of legumes with cereals increased stabilization of dehydrogenase activity (Praveen Kumar et al. 2007).

Large proportion of the phosphorus in soil exists in organic form (50-80 % of total P). The cycling of organic P has a large effect on P availability and long term ecosystem productivity. The organic fraction of soil P has received relatively little attention, because of its complex nature. In order to become available to plants, P compounds must be hydrolyzed by phosphatase, which are of plant and microbial origin. Phosphatase produced by microorganism and plant roots have a major role in the hydrolysis of soil organic P thereby releasing inorganic P for plant uptake.

Colvan et al. (2001) observed that plots receiving FYM had the highest extractable P values and the greatest enzymes activities. Mc Callister et al. (2002) reported that phosphatase activity although related to P availability is not a straight forward measurement of P status.

Fox and Comerford (2002) examined the phosphatase activity in the rhizosphere of slash pine grown spodosols and observed significant Renella et al. (2006) studied the phosphomonoesterase production and persistence during plant mineral decomposition in soils with various pH. Both acid and alkaline phosphomonoesterase were produced in greater amounts during plant residue decomposition. They concluded that the alkaline phosphatase activity by six to fifteen times and acid phosphatase activity increased by two to ten times.

2.4 Effect of organics on growth parameters

Premi and Kalia (2003) reported that green manured plots with dhaincha (S. aculeata), alongwith 25% recommended N gave equivalent grain and higher straw yield to recommended N, indicating that 90 kg N (from chemical sources) ha-[1] can be saved under this treatment. Dhaincha + 25% recommended N also enhanced milling %, head rice recovery, amylase content and minimized gelatinization temperature.

Danesh et al. (2004) reported from Bhadra command (Karnataka, India) to evaluate S. aculeata intercropping for in situ manuring in drum seeded rice. Treatments were: incorporation of dhaincha at 30 and 40 DAS between paddy rows (Mt, M2 and M3, respectively; Nitrogen at 50, 75 and 100% (120 kg ha-[1] of recommended rate (S1t S2 and S3, respectively). The mean no. of grains per panicle, mean grain weight per panicle, mean panicle length, mean 1000 grain weight, mean grain yield, mean straw yield, mean panicle per m[2] and mean dhaincha biomass were highest with Mi and S3 treatments.

Singh (2006) reported from Agra, U.P. on rice-wheat cropping system that 3 organic manures at 10 t ha-[1] viz., FYM, dhaincha (S. cannabina) and cut rice straw were added to 50 and 100% of recommended dose of NPK fertilizers. The green manure dhaincha applied with 100% of recommended dose of NPK fertilizer gave the maximum yield of rice as well as wheat crop. The total uptake N, P, K and Zn by both crops were increased significantly with application of fertilizer or their combined use with organic manures. Among the organic manures, the overall performance of green manures was best followed by FYM and cut straw. Application of FYM and cut rice straw as well as green manuring in rice and wheat significantly improved the available NPK and Zn status of soil.

Surekha (2007) conducted a field experiment during wet and dry season at Hyderabad to study N-release patter from these organic sources of different C/N ratio and lignin content and their effect on rice productivity (Oryza sativa). The 3 organic sources were: paddy straw with C/N ratio 61.5 and lignin content 6.3%; green gram (Phasaolus sureus) with C/N ratio 19.5 and lignin content 8.7%; dhaincha (S. aculeata) with C/N ratio 13.1 and lignin content 5.8%. There were used in different combination alongwith inorganic fertilizers. The grain yield was significantly higher in the treatment that received organics in place of inorganic fertilizers alone due to increase in the productive tillers (panicles) in llnd and 3rd year by 7-23%. The residual effect of organic added in wet season significantly increased grain yield in 2 and 3rd year in all treatments that received organics compared with inorganic fertilizers alone. Thus, organics with moderate C/N ratio and lignin content released N slowly and gradually for longer periods and led to higher productivity in rice-rice system.

Surekha et al. (2008) reported from KAU, Kerala, India that in a field experiment to study influence of different organics on productivity and nitrogen use efficiency in irrigated rice. 3 organic sources (paddy straw, green gram and dhaincha) were used in different combination alongwith chemical fertilizers. Though the green manure, green gram could only resulted significant yield, increase by (13%) over inorganic fertilizers in 1st year, all 3 organics resulted significant grain yield increase over fertilizers alone (by 17- 41%) from second year onwards. Nitrogen uptake and nitrogen harvest index, that is partitioning of N to grain were also substantially improved by organic sources. The nitrogen use efficiency as measured by different indices, viz., agronomic efficiency, physiological efficiency, internal efficiency, recover efficiency and partial factor productivity could be increased when a part (1/3rd) of N was supplemented through organics.

Binitha (2006) outlined that the levels of FYM had significant influence on dry matter productivity at all stages of the crop was confirmed by Barik and Mukherjee (1995). Decomposition of added materials depends on its chemical constitutes and physical and biochemical conditions in the surrounding environment (Subba Rao, 1988).

In an experiment conducted by Jigmee et al. (2015), the difference in yield between different levels of CMT was statistically significant. The increase in the total yield resulting from application of the chicken manure tea may be attributed to the presence of readily available form of nutrient i.e. ammonia and nitrate (Gross et al. 2008) and also to its property to enhanced soil aggregation, soil aeration and water holding capacity, offers good environmental conditions for the root system of broccoli plants. This better availability of soil nutrients and favorable soil condition resulted in healthy plants with large vegetative growth, which lead to higher yield and head diameter. The highest yield was obtained from inorganic fertilizer with the yield of 12.12 t ha-[1] and the least from control with yield of 9.29 t ha-[1] respectively. The positive dose-response pattern of the CMT applications suggests that there is good potential to further optimize this soil amendment. Also, an economic analysis of the costs and benefits of the high performing organic treatments would be valuable. The link between head compactness measurement and an increase in nitrogen was observed here, and this has been reported elsewhere (Wojciechowska, 2005).

A study on the effect of poultry and cattle manures on the growth and yield of okra (Abelmoschus esculentus L.) was carried out by Attigah et.al. (2013) in the transitional zone of Ghana in 2008 and 2009 in a randomized complete block design experiment with three replicates. The treatments were; 350 kg NPK ha-[1], 8t Poultry Manure ha-[1], 12t Cow dung Manure ha-[1], 175 kg NPK + 4t Poultry Manure ha-[1], 175 kg NPK + 6t Cow dung Manure ha-[1] and No treatment of manure (control). The combined treatments of 175 kg NPK + 4t Poultry Manure ha-[1] and 175 kg NPK + 6t Cow dung Manure ha-[1] produced higher levels of the growth and yield parameters than the rest of the treatments in both seasons. The 175 kg NPK + 4t Poultry Manure ha-[1] recorded the highest figures of the parameters which were not significantly (P=0.05) different from the figures of the 175 kg NPK + 6t Cow dung Manure ha-[1] treatment. The combined treatments were found to be economically profitable. The treatment combination of 175 kg NPK + 4t Poultry Manure ha-[1] was more superior in the areas assessed.

Though a lot of work has been carried out in field of integrated and chemical farming system in combination with organic practices across the world, but the work in field of fully organic farming system needs to be promoted, as the literature so far reflects that the research carried out in the field of organic cultivation, has not been worked out in a fully sustainable way, right from a combination of organic seed selection to final stage. The research work carried out by the researchers showed that there is a lack of organic protocol, right from the correct combination of seed treatment, raising of seedlings, and various field protocols.

CHAPTER 3

MATERIALS AND METHODS

The present investigation entitled “Studies on impact of organic manures on soil quality in Okra-Dhaincha-Broccoli sequence” was conducted at Organic Farming Research Centre of SKUAST -Jammu during 2016-17 and 2017-18. The details of materials and methods employed for determination of different parameters of the aforesaid study have been described in this chapter under following sub heads:

3. Experimental Site

3.1. L ocation

Geographically the experimental site is located at 32°39'35.5"N latitude and 74°47'35.0"E longitude at an elevation of 332 meters above the mean sea level in site the Shivalik foothill plains of North-Western Himalayas.

3.2. Climate

The weather data for the crop season was recorded at the Agro-meteorological observatory located very close to the experimental site at the Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu. The minimum to maximum temperature during the crop growing season ranged from 13.0 to 42.9 ºC and 1.0 to 37.20 ºC, respectively in year 2016-2017 and minimum to maximum temperature ranged from 22.4 to 39.8 ºC and 0.4 to 30.1ºC, respectively in crop season 2017-18. The mean daily relative humidity ranged from 36 to 98 per cent and 37 to 100 per cent in the year 2016-17 and 2017-18, respectively. The mean daily rainfall ranged between 0 to 128.0 mm in 2016-17 and 0 to 134.0 mm during 2017-18. Total rainfall received during 2016-17 was 916.0 mm whereas 1,007 .0 mm of rainfall was received during the succeeding year i.e. 2017-18, which was 91.0 mm more than the previous year.

3.3. Soil Characteristics

Surface soil sampling from 0-15 cm depth was done randomly from four spots of the field prior to start of experiment. The soil samples collection were mixed together to form respective composite sample. After harvesting of crop, treatment wise soil sampling was done. The composite soil sample so obtained was air dried, grinded and passed through 2 mm sieve and was analyzed for different physico-chemical and biological properties. The analyzed values (0-15cm) for different soil parameters viz., physico-chemical and biological properties have been given in the table 1. The technique adopted for the soil sampling was two step procedure of random sampling as given by Peterson and Calvin, 1965.

Table 1. Soil physico-chemical properties of experimental site

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The data recorded in respect of physico-chemical properties of the soil of the experimental site revealed that the soil of the experimental field was sandy clay loam in texture, slightly alkaline in reaction, medium in organic carbon, low in Available N, medium in Available P and Available K, low in Available S, Available Zn and high in Available Cu, Mn and Fe.

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