PHD-Department of Agricultural Sciences and Technology

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Browsing PHD-Department of Agricultural Sciences and Technology by Author "Njeru, Peterson Newton Muchiri"

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    Impact of Water Harvesting and Soil Fertility Management Technologies on Intercropping Sorghum and Cowpea Production in Embu and Kirinyaga Counties, Kenya
    (Kenyatta University, 2025-11) Njeru, Peterson Newton Muchiri
    Climate change coupled with poor soil fertility, shrinking natural resource base, ineffective markets, institutional weaknesses, and inadequate policies are the key drivers to sub-optimal agricultural productivity. Sorghum (Sorghum bicolor (L.) Moench) and cowpea (Vigna unguiculata L.) production continue to experience intransigent production problems. This study was carried out in Mbeere South and Kirinyaga West Sub-Counties classified as semi-arid lands and Medium to high potential areas with declining potential (MHPDP), respectively. This research aimed to determine the effect of soil water harvesting and integrated soil fertility amendment practices on: - i) Sorghum and cowpea yields, ii) Soil chemical properties and soil water content at different soil depths, iii) Farmers evaluation criteria for ranking and evaluation of treatments, and iv) The cost benefit returns during LR 2011, 2012 and LR 2012. The study involved experimentation approach and farmers’ evaluation of the study treatments in the scale of good, fair and poor using a structured questionnaire. The treatments were arranged in a 3 x 2 x 6 factorial structure. The main factors were three water harvesting (i.e., Tied ridging, Contour Furrows and Farmer Practice), two cropping patterns (Mono-cropping and Inter-cropping) and 6 soil fertility management options (Control, 40 kg P ha-1 + 40 kg N ha-1, 40 kg P ha-1 + 20 kg N ha-1, 40 kg P ha-1 + 40 kg N ha-1 + Manure 5 t ha-1, 40 kg P ha-1 + 20 kg N ha-1 + Manure 2.5 t ha-1 and manure 5 t ha-1 laid out in a partially balanced incomplete block design (PBIBD), replicated thrice. Soil moisture was measured at soil depth of 100 cm at 10 cm intervals using Diviner 2000 at fortnight interval of 2 weeks after planting. Soil samples were also collected and a composite sub-sample derived at a depth of 0-20 cm for soil elements analysis for each treatment at the beginning and end of experiment. Sorghum and cowpea productivity was measured at physiological maturity, and cost of production data was collected during the experimentation period to determine cost benefit return. Data were analyzed using ANOVA and significant means separated using Least Significant Difference (LSD) at 95% Confidence Interval. There were significant effects (p=0.051, p=0.001 and p=0.0314) of soil water harvesting techniques, cropping patterns and soil fertility amendment options on sorghum height during the SR 2011 respectively, and significant (p=0.0001) during the LR 2012. However, soil fertility amendment practices had significant effect (p=0.0003, p=0.0001 and p=0.0001) on sorghum grain yields during the LR 2011, LR 2012 and SR 2011, respectively. There was also a significant interaction effect (p=0.0047) and (p=0.0047) on cowpea productivity during the SR 2011 and LR 2012 seasons, respectively. Soil pH, N, total C and available P increased significantly (t-test, p<0.05) in manure treatments except in the “controls” at the end of experiment. Soil water content measurements was a significantly higher at initial stages of 2 WAP, 4 WAP and 6 WAP intervals in relation to the late stages of the season. On farmers treatment evaluation, biophysical sorghum grain yields (t/ha) and farmers treatment evaluation had a significant positive correlation (r>0.5, p<0.0001) on individual treatments. However, there was a significant relationship where farmers evaluation and ranking of treatments highly depended on his/her gender and education level (Pearson Χ2>15.4, p<0.0001). The treatments of the study showed significant effect (p<0.0001) on net benefit, benefit cost ratio and return to labour were significantly. This study demonstrated that soil water harvesting techniques, cropping patterns and integrated soil fertility amendment practices have positive influence on sorghum and cowpea productivity in Central Kenya Highlands and is cost-effective.