Evaluation of Soil and Water Conservation Practice on Soil phsico-chemical properties at Nejo, Western Wollega Zone, Oromia Regional State, Ethiopia

ABSTRACT

Land degradation is a pervasive problem that negatively influences agricultural productivity in Ethiopia as it cause depletion of soil organic matter. Therefore, implementation of soil and water conservation is believed to mitigate the impacts of soil erosion. An on-farm study was conducted in Arjo Gudetu kebele, Eastern Wollega of Oromia with the objective of evaluating soil and water conservation practices on soil physio chemical properties and productivity of crop lands. The study involves one factor: level soil bund (with and without) wasa main plot. The treatment (Treatment1=with bund splited in to 12 and Treatment2 = without splited in to 10) with randomized complete block design. Soil sample were collected at 0-50cm and 30-60cm soil depth and analyzed for selected physical and chemical properties. Yield and yield components of the crops were determined using a quadrant sampling technique 1*1m. The data was analyzed using general linear model procedures and to separate difference between mean LSD (5%) was used. On maize (Zea Mays L.) field, level soil bund increased the mean value of soil moisture contents at 0-30 cm and 30-60 cm soil depth, the grain yield increased by 26% and biomass increased by 22%. On sorghum (Sorghum bicolor L.) field the mean value of soil moisture content, days to flowering, maturity dates significantly affected and biomass was increased by 8.25%.

Keyword: Crop, Land degradation, Level soil bund, Soil erosion

CHAPTER ONE: INTRODUCTION

1.1. Background and Justification

Land degradation is serious problem in Ethiopia. The average annual rate of soil loss in the country is estimated to be 12 tons ha-[1] every years and it can be even higher 300 tons ha-[1] every years on steep slopes and in places where the vegetation cover is low (Abera, 2003). A recent study demonstrated that loss of plant nutrients with eroded sediments from the fragile ecosystems in western Ethiopia following the conversion to agricultural use resulted in a significant yield reduction with an immediate harm to the income of the farm due to the loss of N and P, respectively (Erkossa et al., 2015). This leads to low crop productivity and food insecurity in the area.

Considering the background problems enumerated above on soil erosion, proper soil and water conservation becomes imperative. One way of controlling the adverse effect of soil degradation is adopting the appropriate technology which prevents soil erosion. Soil conservation activities can change the physical conditions of the soil like soil structure, water holding capacity, soil bulk density, soil porosity and its workability (Erkossa, 2005; Gete, 2000). However, lack of evaluating the effects of SWC on the crop land down the process of adoption and replicating such structures. This study was conducted to establish empirical evidence regarding the productivity impact of level soil bund on maize and sorghum production by conserving water and plant nutrients.

1.2. Statement of the problem

In the study area soil erosion is a serious problem due to deforestation, continues cultivation of crops, over grazing, limitations of SWC practice, inadequate land cover by grass due to termite, poor soil infiltration capacity and high volumes of runoff. This leads to low crop productivity that cause food insecurity in the area. Recently there is an ongoing attempt by the agricultural extension system to introduce soil and water conservation measures like level soil bund, in filtration trench and area enclose to increase crop productivity in the area. Thus, it is important to conduct a research to assess how crop land productivity improved through application of Soil and water conservation practices like level soil bund on crop land and infiltration trenches and Rhodes grass re­seedling on grass lands at the study area.

1.3. Objective of the study

General objective

- To evaluate the effects of soil and water conservation measures on soil physio chemical proerties

The specific objectives are

- To evaluate the effects of level soil bund on selected soil physical properties
- To access the role level soil bund on soil chemical properties.

2. CHAPTER TWO: MATERIALS AND METHODS

2.1. Description of the study site

Ebba Waqayo PA is one of the Nejo district PA which locates close to Didessa River in Southwestern part of the Abbay River. The geographically location of the area is between 09010' N and 0 9000' N latitude and 36010' E and 6030' E, longitude.

The maps were removed by the editorial staff for copyright reasons

Maps of study area and sampling plots

The altitude of the study area from 1100 to 2300 m asl and comprises two agro-ecological zones: the low (51%) and middle altitude (49 %) (Erkossa etal, .2015). The mean annual rainfall varies from 1,200 to 2,000 mm and the minimum and maximum mean Temperatures are 18[0]c and 32[0]C respectively.

2.2. Experimental Design and Treatments

For study, Arjo Gudetu PA was selected. For experimental work 22 farmers' plots a quarter of a hectare each, were selected whereas, 12 plot with soil bund and 10 plots were without soil bund and the experimental protocol of two treatments which could be conducted as follows: Pure stand crop on a plot without soil bund (Treatment 1) and Pure stand crop on a plot with soil bund (Treatment 2).The treatments would be arranged in a randomized complete block design where soil conservation practice (level soil bund) taken as the main plot. The design of soil bunds in this study was to allow 0.60m depth and 0.675m wide with 2:1 side slope runoff water storage which was tied at every 3 meters interval in each bund.

2.3. Land preparation

The experimental plots were prepared by farmers by tilling two to three times. The selected plots as pure crop stand with soil bund were those having soil bund and done maintenance of the structure. Maize verities such as shone, limu and BH543 those familiarized to the area were planted at 80 cm x 40 cm spacing while sorghum was planted at 20 cm x 20 cm spacing. NPS fertilizer were applied (100 kgha-[1]) at planting and UREA were top-dressed (100 kgha-[1]) at about 35-40 days after planting on the maize crops and the sorghum were planted partially without fertilizers and under recommended ratio. Weeding was conduct by hand three times for all plots of maize and two times for sorghums.

2.4. Soil sampling and analysis

2.4.1. Soil physical analysis

2.4.1.1. Monitoring soil moisture

Soil samples were collected using a spiral auger at two depths (0-30, 30-60cm) for gravimetric moisture content determination. The samples were labeled and put into 22 mm plastic bags and transferred to Oromia agricultural research institute Nekemte soil Laboratory. The soil moisture content was determined by drying the soil to constant weight and measuring the soil sample mass after and before drying. The water mass was calculated as the difference between the wet and oven dry samples. This was done as follows: initially weighing the field samples (10g) using sensitive balance and drying the field samples at 105[0]c for 48 hours in the oven and weighing them again. The percentage of water held in the soil was calculated as the weight difference of the field and oven-dried soil was divided by weight of soil sample before oven dry, multiplied by 100 (Equ. 2)

Abbildung in dieser Leseprobe nicht enthalten

Where Mc =moister content

2.4.2. Analysis of Soil Chemical Properties

Soil samples were collected at harvesting stage for all plots at 0-30 cm using spiral Auger and then the selected chemical properties determined as follows: organic carbon using Walkely and Black method (Neilsan and Sommers,), total nitrogen using Kjeldahl digestion and distillation method (Bremner and Mulvaney, 1982),available phosphorous Bray II Method, Soil pH was determined at soil: water suspension ratio of 1:2 using a conventional glass electrode pH meter (Jackson,1973) and CEC was determined by Ammonium acetate Method at Ethiopian agricultural research institute of Debre Zeit agricultural research center.

2.5. Agronomic Data Collection

In order to evaluate the effect of level soil bund on crop land data for maize and sorghum yield and yield components were collected and analyzed separately. Days to 50% flowering and maturity, cobs per plant, seeds per cobs, thousand grain weights grain yield, dry biomass and harvesting index were measured and recorded either in due course of growth or harvest time for those crops samples from each experimental plot that were treated with and without level soil bund.

2.5.1. Vegetative Growth Parameter

Days to 50% flowering was recorded was taken as the time from the date of planting until half of the plant populations in the farm plot started to flower.

Days to maturity (DM) was recorded as the number of days after sowing to when 90% of the plants in a plot form black layer at the point of attachment of the kernel with the cob. Maize physiological maturity was recorded when the black layer at the seed base was observed. Sorghum physiological maturity was recorded as the appearance of a dark spot on the opposite side of the kernel from the embryo emerged.

2.5.2. Yield and Yield Components

Biomass: was calculated at harvesting stage by measuring the total biomass using spring balance from three randomly selected samples using a 1 m x 1 m quadrant at each plot. Then about 1 kg biomass of crops from each plot was taken to laboratory after making the average to calculate dry biomass.

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