Effect of Tillage Method and Mulch on Soil Moisture Retention, Crop Growth, Nodulation and Yield of Green Gram in Semi-arid Kenya

Abstract

Agricultural productivity in arid and semi-arid areas has continued declining due to low unreliable rainfall, declining soil fertility, and poor agronomic practices. This study was conducted with the aim of contributing towards enhanced green gram productivity in the ASALs through use of conservation tillage methods and mulch application. The experiment had three replicates in a split-split plot arrangement where a randomized complete block design (RCBD) was used. Zero tillage (ZT), conventional tillage (CT) and furrow-ridge (FR) were the three main tillage systems that composed the main plots. The split plots were no mulch (0 t ha-1 (control) and mulched 3 t ha-1), while in the split-split plots contained variety N26 and KS20 of green gram. Data collected for percentage (%) emergence, days to 50% flowering, 75% maturity, plant height, number of primary branches, nodules and their dry weight, root and shoot biomass, number of pods plant, number of seeds per pod, grain weight and harvest index. Soil moisture content was determined by collecting soil samples at 0-30 cm depth at (vegetative, flowering and maturity) growth stages. The data were subjected to general analysis of variance using GenStat 15th statistical package. Means were separated using Fisher’s least significant difference (LSD) at 5 % probability level. According to the findings, tillage method together with mulch had significant effect on crop phenology, growth parameters, yield and its components. Furrow-ridge performed better than zero tillage and conventional tillage. Variety KS20 had more nodules than N26 under furrow-ridge mulched with mulch. Variety N26 under the same treatment had more branches, higher height, yield in both experiment sites. Tillage method and mulch significantly affected moisture content at every stage of green gram growth. Significant higher soil moisture was recorded in furrow- ridge, then no tillage with lowest recorded in conventional tillage. Mulched furrow-ridge as well as zero tillage were the better techniques with increased yield of green gram and also the most efficient techniques for soil moisture conservation in Katumani and Mwea. High water use efficiency was recorded under furrow-ridge mulched with 3 t ha-1 residues of plants compared to mulched conventional tillage plots and zero tillage and those without mulch. It is suggested that combination of furrow-ridge with mulch application can potentially increase green gram growth, nodulation and yields in arid and semi-arid environments. This study therefore recommends this practice to be incorporated into smallholder farming systems to increase resilience against drought