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Journal of Environment and Earth Science www.iiste.org

ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) DOI: 10.7176/JEES
Vol.9, No.5, 2019

Effects of Soil and Water Conservation on Selected Soil

Physicochemical Properties and Its Implication on Soil
Productivity in Ethiopia. A Review
Leta Hailu
Jimma Agricultural Research Center, PO box 192, Jimma, Ethiopia

Abstract
Soil erosion and land degradation have been a severe problem in the Ethiopian highlands due to dense population,
high livestock density and intensive crop production in the area. Soil and water conservation practice is one the
mechanism used to reduce soil and associated nutrient loss; thus, reduce the risk of production. Efforts were
started through soil and water conservation strategy at a large scale on farmland since the mid-1970 and 1980’s.
However, its effectiveness depends on specific site conditions. Therefore, reviewing the effects and implication
of the soil and water conservation practices on selected soil physicochemical properties and soil productivity is
essential. The study conducted in various part of the country showed that the implemented soil bund reduced
annual runoff and soil loss at different rates. Soil and water conservation have improved the soil
physicochemical properties on conserved cropland (BD, SMC, infiltration rate, clay content, pH, CEC, av. K, av.
P, SOC and TN) than in the adjacent cropland without soil and water conservation measures. In contrast, the
constructed soil and water conservation has shown no significant variations as compared to adjacent cropland in
a study conducted at Dawuro zone, Southern Ethiopia. Soil and water conservation, reduce the removal of fertile
topsoil and improves soil moisture, which favors crop growth as a result grain yield of the crops were increased
at various rates based on agro ecology, crop type and local management practices. In general, the effect of
constructed soil and water conservation had clearly showed positive impact on selected soil physicochemical
properties and crop yields. Therefore, maintenance of the existing soil and water conservation structures is
highly recommended to sustain its benefit, productivity and production; hence, improve the livelihood of the
community.
Keywords: land degradation, soil and water conservation, soil properties, soil productivity.
DOI: 10.7176/JEES/9-5-02
Publication date:May 31st 2019

1. Introduction
Agriculture contributes substantial role in the Ethiopian economy (MoFED 2010). It creates employment
opportunity for about 83-85 percent for the community and contributes 43-50 percent for growth and domestic
products (GDP) and 90 percent of the total foreign exchange earnings. It also provides about 70 percent of the
raw materials for different industries in the country to realize the agricultural-development-led industrialization
strategy. Furthermore, the role of gender in agricultural system is critical, women contributes as much as 70
percent of on-farm labor (Awulachew et al. 2006, MoARD 2010). `
The majority of the population of the country is inhabited in a rural highland area where heavily depends on
subsistence farming with no or low management of farmland that exacerbate soil erosion and land degradation.
Small holder farmers are predominantly responsible for producing about 90 percent of the agricultural
production (Awulachew et al. 2006 Gebreyesus & Kirubel 2009; MoARD 2010; Birhanu 2014). Nevertheless,
much of the land is degraded in sub-Saharan Africa, particularly in Ethiopia, where poor farmers highly depend
on land for their livelihood improvements (Nkonya et al. 2008).
Soil erosion and land degradation have been increasing in Ethiopian highlands due to the existence of arable
land (90 %), high human population (90%) and livestock density (60%) which resulted in natural resources
degradation (Hurni et al. 2010; Darley 2015). This is a noticeable environmental concern that results in declining
agricultural productivity, food insecurity and rural poverty (MoARD 2010; Gashaw et al. 2014; Kirui 2016).
Moreover, the loss of soil has dramatically reduces land productivity and biodiversity; and also disturbs
downstream water quality through sedimentation and eutrophication. Thus, it affects ecosystem health and
service that many people depend on for their livelihood (Darley 2015).
Soil erosion is predominant on arable land, in which the average annual soil loss is estimated to be 12
t/ha/year. It ranges up to 300 t/ha/year on steep slope fields and low vegetative cover area (Demeke 2003). This
loss of soil from arable land is associated with the loss of nutrients and soil moisture that affects food production
and worsens poverty. That contributes to the inability of investing in natural resource conservation and hinders
sustainable development of the agricultural sector (Kirui 2016). Consequently, adoption of soil and water
conservation is necessary to limit the soil loss to a tolerable level (11 tons ha-1yr-1) (Morgan 2005; Tulu 2011).
Soil and water conservation practice is a mechanism of reducing the soil loss and risk of production that has

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Journal of Environment and Earth Science www.iiste.org
ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) DOI: 10.7176/JEES
Vol.9, No.5, 2019

been adopted by the farmers (Kato et al. 2011). Its practice was dated back to mid-1970s and 1980s at large scale
on farmland (Aklilu 2006). Accordingly, the adopted soil and water conservation was capable of improving soil
physicochemical properties and enhances soil productive capacity (Bekele et al. 2016; Adimassu et al. 2017;
Fisseha & Alemayehu 2018). The effectiveness of soil and water conservation is depends on specific site
conditions, which is depending on soil depth, topography and local climate of the area (Kato et al. 2011).
Therefore, soil and water conservation interventions were undertaken in different parts of the country and
reviewing its effects on selected soil physicochemical properties and its implication on soil productivity is
essential.

2. Over View of Soil Erosion and Land Degradation in Ethiopia

Soil erosion is a destructive process altering and changing the topsoil layer and soil carbon stocks through
selective removal of fertile top soil along the slope (Olson et al. 2016). In Ethiopia, soil erosion is one of a
serious problem challenging the agricultural sector and economic development (Hurni et al. 2016). It is severe in
general and particularly in the highland areas where land highly degraded and exacerbates the prevailing of food
insecurity in the country (Belayneh et al. 2017).
The various studies conducted in the country point out that the loss of soil due soil erosion is at large rate.
For instance the study conducted in May Zegzeg catchment in Tigray highlands showed that the average rate of
soil loss was about 14·8 t ha−1 yr−1 (Nyssen et al. 2008). Likewise, in Koga River the average annual soil loss
rate was 30.2 t ha−1 yr−1which ranges from 12.1 t ha−1 yr−1 to 456.2 t ha−1 yr−1 for the outlet and the steep slope
area of the watershed, respectively (Molla & Sisheber 2017). Similarly, in the north western highlands of
Ethiopia, in the Geleda watershed of the Blue Nile basin, the soil loss in the steep areas of the watershed extends
up to 237 t ha−1 year−1 (Gashaw et al. 2017). This indicates that erosion rates exceeds tolerable levels and affects
the productive capacity of the soil system (Guerra et al. 2017). Besides, the loss of soil also results in loss of
water, nutrients, soil organic matter, and soil biota (Pimentel & Burgess 2013). These all indicate soil erosion
exceed the generation of new topsoil which leads to decline in soil productivity, low agricultural yield; that need
adoption of integrated soil and water conservation to reverse the problem. Thus, soil erosion control is being
important under every type of land use (Morgan 2005; Kumar & Pani 2013).

3. Soil and Water Conservation and Its Adoption in Ethiopia

Soil and water conservation is a key method in reversing land degradation in the country. To reduce soil erosion
and land degradation, various soil and water conservation measures have been adopted throughout the country
(Wolka et al. 2009). The indigenous agricultural system in Konso zone is characterized by stone-based terraces
and well integrated Agroforestry practices. It has existed for at least four hundred years. The strength of the
system is expressing culture and its institutions that contribute to this kind of agriculture (Beshah 2003)
The survey result reveals that there are various indigenous and adopted soil conservation practices in
Darimu and Chewaka Woredas of Illu Ababora Zone. Among these, fallowing, manure, contour plowing, crop
rotation and waterways are indigenous soil conservation practices and terracing, soil bund, fayna juu, grass strip,
chomo grass and elephant grass are some of the adopted soil conservation practices in the area (Belayneh et al.
2017).
In Ethiopia, adoption of large scale soil and water conservation techniques on farm lands was dated back in
the early 1970’s (Wolka et al. 2009). For instance soil bunds were introduced in Wolaita zone to conserve both
soil and water in an experimental catchment in the early 1980s, which have shown moisture and nutrient
conservation effects (Beshah 2003). Introduction of soil and water conservation technology strongly reduces
runoff production and soil loss. Stone bunds building lead to soil loss reduction of 58 to 66% in rangeland while
the reduction rate ranges from 43 to 50% in cropland at May Leiba catchment in central Tigray, northern
Ethiopia (Taye et al. 2013).
Indigenous soil conservation techniques alone became less efficient when compared to modern technologies
of conservation measures. Modern methods of soil and water conservation were unsustainable due to unpopular
top-down policies and lack of community participation that leads past efforts of the modern intervention
programs to being ineffective. Hence, to cope up with the problems, indigenous techniques of soil and water
conservation needs improvement and the modern ones also needs adaptation to the environment and involving
the community at all levels is vital (Osman et al. 2000).

4. Effectiveness of Soil and Water Conservation

Soil and water conservation measures interventions take various forms throughout the country to reduce soil
erosion and land degradation problem based on agro-ecology of the area (Ademe et al. 2016). According to
Nyssen et al. (2007), the constructed stone bund was trapped 76% of the total soil loss in the study conducted in
northern Ethiopia. Similarly, the study conducted in Jawe-gumbura watershed had reported a 28% annual runoff
and 47% soil loss reduction. These are therefore used as evidence for effectiveness of soil bund in reducing of

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Journal of Environment and Earth Science www.iiste.org
ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) DOI: 10.7176/JEES
Vol.9, No.5, 2019

runoff and soil losses. Consequently, soil bund has reduced losses of soil nutrients and organic carbon associated
with conserved soil. On the other hand, construction of soil bunds takes out cultivable area out of production by
8.6 percent as compared to control, which is needed to compensate by integrating with biological conservation
and increasing yield obtained from conserved land (Adimassu et al. 2017).
The farmers have several criteria to select soil and water conservation practices. The economic benefit is the
one given top priority to choose the structure. Therefore, strengthening participatory planning with farmers and
developing best future alternatives that provide with immediate benefit along with the long term benefit obtained
from soil and water conservation investment is required (Adimassu et al. 2013).

4.1 Soil and Water Conservation Impacts on Selected Soil Physicochemical Properties
Soil and water conservation practice improves the soil properties through reducing runoff velocity, because in
the absence of soil and water conservation, the soil is washed-out down the slope by erosion. Along with the loss
of soil, it results in loss of water, nutrients, soil organic matter and soil biota. This severely harms the proper
functioning of the soil system (Pimentel & Burgess 2013). Soil erosion lowers base saturation and soil organic
carbon (SOC) contents; as a result, it decreases the soil pH. The pH of the soil influences the availability of
phosphorus, which is low for non-conserved agricultural land (Amare et al. 2013; Bekele et al. 2016).
The study conducted in different parts of the country points out that cropland with soil and water
conservation practice showed significant variation in soil physicochemical properties (Bekele et al. 2016; Ademe
et al. 2017; Fisseha & Alemayehu 2018). Similarly, Ademe et al. (2016), indicates that soil and water
conservation improves the soil properties on conserved cropland (pH, K+, available P, SOC, TN, CEC and clay
content) than in the adjacent crop land that is without soil and water conservation measures. This indicates the
positive impacts of soil and water conservation practices in improving the nutrient status of the cropland. In
contrast to this, Wolka et al. (2011) reported that the constructed soil bund had not affected most of the tested
soil properties in cropland with soil and water conservation as compared to the non-conserved one. This might
be due to past erosion and land use practice of the site.
Table 1. Summary of soil and water conservation effects on selected soil physicochemical properties

Av.-P=Available phosphorus; Av.K=Available potassium; ARS=Amahara regional state; BD=Bulk density;

CEC= Cation exchange capacity; K=Potassium; N=Nitrogen; ORS=Oromia regional state; P=phosphorus;
pH=hydrogen ion concentration; SMC=Soil moisture content; SOC=Soil organic carbon; SNNPRS=Southern
nations, nationalities’ peoples regional state; TN=Total nitrogen.

4.2 Effect of Soil and Water Conservation on Soil Productivity and Crop Yield
In Ethiopia, a range of policies, strategies and institutional arrangements has been adopted to improve
agricultural production; however, the sector still suffers with the detrimental effects of soil degradation which
undermines potential soil productivity and requires enormous costs for reversing the degradation (Amsalu 2015).
Soil erosion an impact on soil productivity; most likely caused by deterioration in soil physical properties. In an
eroded landscape the physical and chemical properties of the soils are changed (Arriage & Lowery 2003). Soil

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Journal of Environment and Earth Science www.iiste.org
ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) DOI: 10.7176/JEES
Vol.9, No.5, 2019

degradation affects water availability, nutrient reserves and crop growth; thus, it leads to yield loss (Kumar &
Pani 2013).
Inappropriate soil management intensifies the effect of erosion on soil productivity; thus, considering
appropriate soil management for effective erosion control and maintaining soil productivity is crucial (Den
Biggelaar et al. 2004). Soil and water conservation reduces the removal of fertile topsoil and improves soil
moisture that favors crop growth; hence, increase crop residue input, which builds up soil organic carbon stock
and plant nutrients on conserved cropland. Soil organic matter improves soil aggregate, which influence total
porosity of the soil that negatively affects soil bulk density (Amare et al. 2013; Bekele et al. 2016; Oldfield et al.
2018). Low bulk density indicates a favourable condition for a better root growth, improved aeration, and
increased infiltration, which improves the productive capacity of the agricultural land (Gupta 2010).
Soil bunds of different ages were able to improve soil properties that affect crop yield on conserved
farmland, in northern Ethiopia. The croplands with soil bund had improved the crop yield from 0.584 to 0.65 t ha
-1
which compensates the financial cost expends for building bunds (Nyssen et al. 2007). Likewise, the soil bund
constructed at Absela site of Awi administrative Zone located in the Blue Nile Basin had improved yield of the
crop as compared to non-conserved adjacent cropland. The average yield obtained from accumulation zone had
increased crop grain yield by 29.8% as compared to loss zone; this might be due to accumulation of soil organic
matter and fertile topsoil above the bunds in the deposition zone of the bund (Gebreselassie et al. 2009).
Furthermore, the use of soil bund had increased soil moisture content under plot with contour bund. On
average 24.6% of yield increment was reported. This point out the contribution of the soil and water
conservation in conserving the soil productivity that enhances crop yield under the conserved plot of cropland
than non-conserved adjacent plot of cropland (Erkossa et al. 2018). Therefore, this implies that soil bund reduce
runoff velocity and hence soil erosion. Accordingly, the practice maintains the productive capacity of the soil. To
sustain the above mentioned effects of the practice, it requires regular maintenance and awareness creation to
fully engaging the farmers in the practice from planning to execute of the conservation measures according to
specific agro ecology of the site.

5. Conclusion
This paper attempts to review the effect of soil and water conservation on soil physicochemical properties in
focus to its implication on soil productivity in Ethiopia. Even though, the agricultural sector substantially
contributes to the economy, it is threatened by soil erosion and affected by the loss of the soil productivity. As
described above, soil erosion and land degradation affect the soil productive capacity and proper functioning of
the soil by deteriorating physical, chemical and biological properties of the soil which leads to yield losses.
However, most of the studies identified and compared in this review suggested that the implementation of
structural soil and water conservation reduced runoff and soil losses. This reduces the loss of associated nutrients
and soil organic carbon that improves the soil physicochemical properties and productive capacity of the
agricultural land. Thus, enhances the soil productive capacity and crop yield in conserved cropland than
croplands without soil and water conservation. To sum-up, structural soil and water conservation intervention
had profound effect on soil physicochemical property improvement in different part of the country that able to
improve soil productive capacity and crop yield.

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