Richard N. Onwonga

Influence of Selected Ecological Farming Practices on Soil Moisture Retention and Yield of Sorghum (Sorghum bicolor (L.) Moench) and Cassava (Manihot esculanta Crantz) in Semi-Arid Yatta Sub-County, Kenya

In this study, the influence of ecological farming practices on soil moisture and yield of cassava (Manihot esculanta Crantz) and sorghum (Sorghum bicolor (L.) Moench) was investigated. The study was conducted in semi-arid Katangi and Ikombe divisions of Yatta sub-county between October 2010 and August 2012. A randomised complete block design with a split plot arrangement was used. Main plots were three cropping systems: (i) Intercropping; (Dolichos [Lablab purpureus]/Cassava, Dolichos/Sorghum, Pigeon pea [Cajanus cajan (L.) Millsp.]/Sorghum, Pigeon pea/Cassava); (ii) Rotation; Dolichos-Cassava, Dolichos-Sorghum, Pigeon pea-Cassava, Pigeon pea-Sorghum and (iii) Monocrop (pure cassava and sorghum). Split plots were organic inputs; farm yard manure (FYM), compost and absolute control. Sorghum/pigeon pea intercrop+FYM treatment had high moisture levels during short rain season (SRS) of 2010 at Katangi (5.21%), SRS of 2011 at Ikombe (5.19%) and long rain season (LRS) of 2011 at both sites (5.83%, 12.30%). Grain yields were highest under sorghum/dolichos intercrop+ FYM during LRS of 2011 at Katangi (1.36 t ha-1) and Ikombe (1.48 t ha-1), and SRS of 2010 at Katangi (1.39 t ha-1) only. Cassava/dolichos intercrop recorded high soil moisture levels in both sites under sorghum/dolichos intercrop during SRS of 2010 (6.48%, 8.35%), LRS of 2011 (7.63%, 8.77%) and LRS of 2012 (6.41%, 3.65%) for Katangi and Ikombe, respectively. Tuber yields were higher under cassava/pigeon intercrop in Katangi (18.63 t ha-1) and Ikombe (28.73 t ha-1) during SRS of 2010 and LRS of 2011, and SRS of 2011 and LRS of 2012 at Katangi (20.86 t ha-1). Intercropping sorghum with dolichos and cassava with pigeon pea + FYM would be a viable strategy to boost crop yields in smallholder farming systems of Yatta sub-county.

Assessment of soil nutrient balances in organic based cassava (Manihot esculenta Crantz) and sorghum (Sorghum bicolor (L.) Moench) cropping systems of Yatta Subcounty, Kenya.

Long-term food production in developing countries is under threat due to soil nutrient mining resulting from unsustainable production practices. In this study, the sustainability of various cropping systems and organic input combinations were assessed through monitoring nutrient flows and balances at crop production level. The study was conducted in Katangi and Ikombe divisions of Kitui sub-county between October 2010 and August 2012. A randomised complete block design with a split plot arrangement was used. The main plots were three cropping systems: (i) Intercropping (Dolichos [Lablab Original Research Article American Journal of Experimental Agriculture, 4(12): 1557-1578, 2014 1558 purpureus]/Cassava, Dolichos/Sorghum, Pigeon pea [Cajanus cajan (L.) Millsp.]/Sorghum, Pigeon pea/Cassava); (ii) Rotation (Dolichos-Cassava, DolichosSorghum, Pigeon pea-Cassava, Pigeon pea-Sorghum); (iii) Monocrop (pure cassava and sorghum). The split plots were; farm yard manure (FYM), compost and control. All crops had above ground biomass incorporated after harvest in the same plot they were harvested from. Nutrient flows; nitrogen (N), phosphorus (P) and potassium (K), were monitored for four seasons; short rain season (SRS) of 2010, long rain season (LRS) of 2011, SRS of 2011 and LRS of 2012 using NUTMON toolbox. There were no significant differences in nutrient balances between the four seasons except in sorghum based cropping systems where N and P balances were significantly lower in the second year. Losses across the seasons occurred mainly through harvested products in both sorghum and cassava cropping systems while addition mainly occurred through biological N fixation and incorporation of crop residue. Negative NPK balances were found in cassava than sorghum-based cropping systems regardless of legumes used in both sites. Dolichos rotation with sorghum and compost applied resulted in positive N balances. Dolichos-cassava rotation with compost also had reduced N losses compared to when pigeon pea was used. P losses were less negative under pigeon pea-sorghum and pigeon pea-cassava rotation with FYM applied. Pigeon pea rotation with sorghum and FYM applied resulted in reduced K losses while with cassava the same cropping system was superior but with application of compost. The choice of legume and organic input for use would depend on environment farmer operates in. In N, P and K limited environments; dolichos rotation with compost application, pigeon pea rotation plus FYM and, pigeon pea-sorghum rotation plus FYM and pigeon pea-cassava rotation with compost applied would, respectively, be recommended as farming practices.

The Effect of Organic-Based Nutrient Management Strategies on Soil Nutrient Availability and Maize Performance in Njoro, Kenya

A field experiment based on the concept of organic nutrient management was conducted in Njoro, Kenya, to test the effect of improved legume fallows, crotalaria (CR), lablab (LB), garden pea (GP) and natural fallow (NF, as control) on available soil N and P and maize performance. The experimental design was a split plot fitted to a randomized complete block. The main plots were two cropping systems involving the improved legume fallows and NF preceding sole maize and maize–bean (M/B) intercrop. The sub-plots were two residue management types: residue incorporation and residue removal with farm yard manure (FYM) incorporated instead. Residue incorporation resulted in higher concentrations of N and P in soil than FYM in both cropping systems. Under sole maize, grain yield following LB was significantly higher than after CR, GP and NF. In the M/B intercrop, maize grain yield following LB was significantly higher than after GP and NF, with no significant differences in yields following CR and LB. Maize dry matter (DM) yields followed a similar trend. Overall, maize grain and DM yields were higher in sole maize cropping system than in M/B intercrop but an additional 0.5–0.6 kg ha–1 of bean grain yield was realized in the latter cropping system. The improved fallow legumes enhanced soil productivity, besides the seeds providing ancillary protein in diet locally, with resultant higher yields of the succeeding crop.

Intermediate Maturing Soybean Produce Multiple Benefits at 1:2 Maize:Soybean Planting Density

A study was conducted to identify the most suitable intercropping arrangement in smallholder farms in Western Kenya. Biomass and N (nitrogen)-accumulation, N2 fixation and grain yield of maize and soybeans grown as intercrops at three planting densities were assessed. The study was conducted in four seasons. Three soybean varieties, Namsoy 4m, SC Squire and TGx1987-18F, were used in the experiment. Maize: soybean planting densities 1:1 (D1), 1:2 (D2), 1:3 (D3) as well as sole soybean (SS) and sole maize (SM) were tested. Higher biomass, N-accumulation, and N-fixed in the order 3.8 Mg ha-1, 260 kg ha-1 and 161 kg ha-1 respectively, were recorded in D3 with long maturing variety TGx1987-18F. Conversely, higher soybean grain yield < 2.4 Mg ha-1 was achieved by intermediate maturing SC Squire in D3. The highest maize yield in the intercrop was obtained in D1. N balance calculations indicated that planting TGx1987-18F resulted in an addition of 6 to 67 kg N ha-1, while SC Squire and Namsoy 4 m removed 3 to 89 kg N ha-1 when soybean grain was removed from the field. The differences in N balances between the intercrops depended on the N-fixed and the amount of N in harvested soybean and maize grain. Greater land equivalent ratio < 1.75 were obtained with SC Squire and Namsoy 4m in D2. We concluded that intermediate maturing soybean have multiple benefits for farmers in Western Kenya at 1:2 maize: soybean planting density provided that the practice is accompanied with good soil and crop management practices.

Effect of Legume Integration and Phosphorus Use on Maize N and P Concentration and Grain Yield in Kabete - Kenya

Aims: Investigate effect of legume integration and phosphorus application on nitrogen (N) and phosphorous (P) concentration and yield of maize. Place and Duration of Study: The study was carried out in Kabete Field Station of the University of Nairobi during the long (LRS) and short rainy (SRS) seasons of 2012. Methodology: A split plot layout in a randomized complete block design (RCBD), with three replicates was used. The main plots were sole maize, intercropping (chickpea/maize; lupin/maize) and rotation systems (chickpea-maize; lupin-maize) systems. The sub plots were Minjingu rock phosphate (MPR) and triple superphosphate (TSP) fertilizers, applied at 60 kg P ha. Maize P and N concentrations were measured at seedling, mid-flowering and physiological maturity/harvest. Maize grain and dry matter (DM) yield were determined at physiological maturity. Results: During the LRS, significantly (P=0.05) higher maize P concentrations were recorded in Original Research Article Templer et al.; IJPSS, 19(2): 1-9, 2017; Article no.IJPSS.34972 2 chickpea/maize intercrop (C/M) with TSP at seedling; sole maize, chickpea/maize (C/M) and lupin/ maize (L/M) intercrops, with MPR and TSP at mid flowering and L/M intercrop with TSP at harvest. In the SRS at seedling and harvest stages, significantly higher values were recorded in the lupinmaize rotation (L-M) with MPR. At mid flowering, significantly higher P values were observed in L/M with MPR. During the LRS, N concentration in maize was significantly higher in L/M with TSP and L/M with MPR at seedling and mid flowering stages, respectively. At harvest L/M with TSP had significantly higher values. In the SRS, maize N concentration was significantly higher in L-M and chickpea-maize (C-M) rotation with MPR and sole maize with TSP at seedling; and L/M with MPR and TSP, at mid flowering and harvest, respectively. During the LRS, maize grain yields were significantly higher in L/M with TSP and MPR and C/M with MPR. In the SRS, significantly higher maize grain yields were recorded in L/M with TSP and L-M with MPR. DM yields in the LRS were significantly higher in L/M with TSP applied. In the SRS, DM yields were significantly higher in L/M with MPR, C/M with MPR, L-M with MPR and C-M with MPR. Conclusion: The integration of MPR or TSP and legumes increased maize N and P concentration and yields. The use of cost effective MPR in an intercropping system may be preferred by small holder farmers.

Effect of excessive and minimal soil moisture stress on agronomic performance of bush and climbing bean (Phaseolus vulgaris L.)

Abstract Water stress is a major crop production constraint for common bean (Phaseolus vulgaris L). The response of bush and climbing bean to excessive and minimal soil moisture at various plant growth stages was investigated under greenhouse for two growing periods; September–February 2016 and March–July 2016. The control consisted in watering with recommended rates for each plant growth stage. Two bean genotypes RWR2245 (bush bean) and MAC44 (climbing bean) were used for this study. The minimal soil moisture (drought stress) treatment consisted of withholding water supply, from the on-set of emergence, vegetative, flowering, pod setting and seed filling growth stages, up to the wilting point of plants. The excessive soil moisture (waterlogging stress) was achieved by saturating the soil on a daily basis for five successive days, starting from the on-set of the aforementioned plant growth stages. For each genotype, these treatments were replicated four times and arranged in a Completely Randomized Design. Drought stress accelerated the number of days to maturity whilst waterlogging stress tended to increase the number of days to maturity. Both stresses reduced the agronomic performance of both genotypes. However, pod setting and flowering were the most sensitive stages to drought stress and waterlogging stress, respectively.

Soil Fungal and Bacterial Populations in White Lupin ( Lupinus albus ) - Maize ( Zea mays L) Cropping System Amended With Minjingu Phosphate Rock

Aims: To determine fungal and bacterial populations under white lupin (Lupinus albus ) maize (Zea mays L) cropping system amended with Minjingu Phosphate Rock (MPR). Study Design: A randomized complete block design with four replicates was used. Treatments were; (i) control i.e. fallow (F) – maize (M) rotation with triple super phosphate fertilizer (TSP) applied (M TSP - F), (ii) fallow - maize rotation with MPR applied (M MPR - F), (iii) white lupin (L) – maize rotation with MPR applied (M MPR - L) and (iv) maize/white lupin intercrop with MPR applied (M/L MPR - F). Place and duration of study: The experiment was conducted in Njoro sub-County, Kenya during the long (LRS) and short rain seasons (SRS) of 2010 and 2011.

Influence of Amendments Added to Acid Soils on Biochemical Properties, Nitrogen Uptake and Hybrid Maize Yields in Nakuru County, Kenya

Aim: The current study investigated effect of soil amendments; lime (L), manure (FYM) and minjingu phosphate rock (PR) added to soils on soil microbial biomass carbon and nitrogen (SMB-C and SMB-N), available soil nitrogen (N), crop N uptake and grain yields of two maize hybrids (H513 and H614). Study Design: Two experiments, one for each maize hybrid as test crop, were laid out in a randomized complete block design with a 2 factorial arrangement. The factors each at two levels were L (0 and 3 t ha), PR (0 and 60 kg P ha) and FYM (0 and 5 t ha) giving a total of eight treatments; L, RP, FYM, L+RP, L+FYM, RP+FYM, L+RP+FYM and control (nothing applied). Methods: Soil and plant samples for the determination of SMB-C and SMB-N, available soil N, and crop N uptake were collected at maize seedling, tasseling and physiological Original Research Article Lelei et al.; IJPSS, Article no. IJPSS.2014.004 468 maturity. Place and Duration of the Study: The experiment was conducted in Molo district of Nakuru County, Kenya during the long rain seasons of 2009 and 2010. Results: SMB-C and N levels were higher in 2010 than 2009, with lower levels obtained at maize tasseling for both maize hybrids. Available soil N and crop N uptake were higher at maize seedling and declined towards maturity. Statistically significant (P<.05) increases in SMB-C and SMB-N and available soil N and uptake were obtained with the application of soil amendments over the control. In all treatments, H513 had lower N uptake than H614 at tasseling and maturity stages of maize growth and correspondingly higher available N in soil. Maize yields (t ha) were higher in 2010 than 2009 and in H614 than H513. The H614 yields were significantly higher (P<.05) in L+PR+FYM (3.9) and, L+PR+FYM (4.1) and L+PR (3.9) treatments in 2009 and 2010, respectively. For H513, yields were significantly higher in L+PR+FYM (2.1 and 2.4) and L+PR (1.9 and 2.1) treatments in 2009 and 2010, respectively. Conclusion: The L+PR+FYM treatment is a feasible acid soil amendment for its superiority in the measured soil and crop parameters. The H513 matured faster than H614 and because of this attribute, is a viable option in response to the diminishing rainfall amounts and unpredictable weather patterns experienced in the County.