Effect of Tillage and Millet Residue Mulch Rates on Water Use Efficiency of Cowpea [vigna Unguiculata (l.) Walp] in Maiduguri, Nigeria

A field experiment was conducted at the University of Maiduguri Teaching and Research Farm to determine the effect of tillage and millet crop residue mulch rates on water use efficiency of cowpea [Vigna unguiculata (L.) Walp]. Eight treatment combinations of 2-factor factorial experiment were laid out in randomized complete block design with no-till and tilled plots as factor A and residue rates (0, 2, 4, 6tha-1 ) as factor B. A composite soil sample was collected from surface (0 – 15cm) and subsurface (15 – 30cm), a week before the commencement of the experiment for routine soil physico-chemical properties of the site following standard procedures. Soil moisture storage within 0 – 180cm depth was monitored at planting, 3, 6 and 9 weeks after planting (WAP) at depth of 20cm interval. Water use and water use efficiency (WUE) were determined alongside with yield parameters. The result showed a significant (p < 0.05) difference due to effect of treatments on WUE. All the yield parameters were significantly (p < 0.05) affected by treatments with the highest mean values under NTR2 for grain yield, NTR3 for chaff and total dry matter (TDM). Grain yield and yield components were higher under no-till as the residue amount increased. Water use efficiency (WUE) was higher in no-till and increased with increasing amount of applied residue compared to tilled plots. The highest value of grain yield WUE of 5.27kgmm1 was recorded under NTR1 while chaff yield had 1.22kgmm-1 and TDM WUE was 18.09kgmm-1 respectively under NTR3. Generally, No-till and higher rates of 4 and 6tha-1 of residue rates is recommended for optimum water use efficiency and performance of cowpea in the study area.