SOIL MOISTURE CONSERVATION, CROPPING SYSTEMS AND SOIL FERTILITY EFFECTS ON SOIL AND MAIZE PERFORMANCE IN MACHAKOS COUNTY, KENYA
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Date
2019-05
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Abstract
The main causes of food insecurity in semi–arid parts of Kenya are low soil
fertility, low and unreliable rainfall. These two causes are the main challenges facing
small-scale farmers in food production especially in semi-arid areas of the country.
To overcome these challenges, soil and water management technologies especially
those in soil and water conservation need to be embraced. The aim of the study was
to determine the effect of tied ridges, fertilizers and cropping systems on soil
properties (moisture, pH and organic carbon), growth and yield parameters of maize;
and to identify the most cost effective water and soil management technology. This
study was carried out in four seasons at Katumani in Machakos County. The
experiment was a 2 x 4 x 2 factorial, laid out in a randomized complete block design
(RCBD). The treatments were: tied ridging, flat bed planting, farm yard manure 0
t/ha, farm yard manure 5 t/ha, nitrogen fertilizer 20 kg/ha, farm yard manure 5 t/ha +
nitrogen fertilizer 20 kg/ha, maize mono crop and maize cowpea intercrop. Data
collected included soil moisture content, soil pH, total organic carbon, growth
parameters and maize yield. The results showed that, treatments with flat bed
planting in maize mono crop significantly increased soil moisture content at 0–20cm
depth as compared to tied ridging in maize cowpeas intercrop during short rains
2015. Application of farm yard manure at 5 t/ha increased soil moisture content at 2
and 4 weeks after planting. The soil moisture content ranged from 6.30% to 23.80%.
During the short rains 2015, maize mono crop significantly increased vegetative
growth in comparison to maize cowpeas intercrop. Treatment with flat bed and 20
kg N/ha in maize mono crop had the highest mean for vegetative growth. However,
during the long rains 2016, treatment with tied ridging and 20 kg N/ha in maize
mono crop registered the highest mean for vegetative growth. During the short rains
2015, treatments with maize mono crop significantly increased grain yield with a
range of 1.35 t/ha 3.59 t/ha. Flat bed planting with farm yard manure 5 t/ha in maize
cowpea intercrop significantly increased the grain yield by 165.93%. The harvest
index during the short rains 2015 ranged between 0.35 and 0.48. Treatments with
maize mono crop significantly increased gross benefit, net profit, gross margin and
cost benefit ratio during short rains 2015 and long rains 2016. Application of farm
yard manure 5 t/ha + 20 kg N/ha had the highest variable cost. The cost benefit ratio
was positive during the short rains 2015 with a range of 1.47–2.98. The yield
differences among the four seasons could have been as a result of
variations/distribution in rainfall amount, soil moisture content and soil fertility as
induced by the treatments. Flat bed planting increased the yields during the short
rains 2015 when the amount of rainfall was high whereas tied ridging resulted in
improved yields during short rains 2014, long rains 2015 and 2016 when rainfall
amount was low. For the farmers to maximize yields and profits in the study area,
adoption of flat bed planting with farm yard manure 5 t/ha and maize cowpeas
intercrop during the seasons of high rainfall could be appropriate treatment
combination according to the findings of this study. However, during seasons with
low rainfall, tied ridging with 20 kg N/ha and maize mono crop could be
recommended for adoption. Also, variations in seasonal rainfall should be
considered when integrating different soil and water management practices because
the effectiveness of different technologies vary with the seasons. Farmers in
Machakos County may have to consider use of supplementary irrigation during the
dry spells to increase soil moisture.