Effect of tillage and mulch on soil and the growth and yield of cowpea grown in the arid tropics

To conserve soil, save petroleum, and to improve the physical environment, soils should be minimally tilled for crop production. Our understanding of the tillage effects on light textured soils of the arid tropics for crop production is limited. Studies were conducted from 1982 to 1984 to find out the effect of tillage and surface mulching of loamy sand soil on physical properties, growth, and yield of cowpea (Vigna unguiculata cv. FS‐68) grown in arid western Rajasthan, India. The results showed that reduced soil tillage (one disking with a disk harrow) for three years significantly increased the final organic matter content from 0.27 to 0.35%, decreased the moisture retention at ‐0.01 MPa from 11.0 to 10.6%, soil bulk density from 1.58 to 1.52 g cm−3, soil strength from 9.9 to 5.9 kg cm−2 and steady state infiltration rate from 15.6 cm h−1 to 10.8 cm h−1. There were, however, marginal differences between reduced and excessive tillage (three diskings). Under all the tillage conditions, mulching the inter row spaces with native weeds (6 t ha−1) increased the organic matter content by 10 to 25%, infiltration rate by 10 to 20%, moisture retention ( — 0.01 MPa) by 6.0 to 20.0%, and decreased the bulk density by 0.05 to 0.07 g cm−3, soil strength by 1.25 to 3.20 kg cm−2 and maximum temperature at 10 cm depth (during growth period) by 0.5 to 10°C. Tillage increased the grain yield (mean of 1983 and 1984) from 8.2 q ha−1 to 12.3 q ha−1. There was, however, no significant difference in yield obtained from reduced and excessive tillage treatments. Mulching significantly increased the grain yield from 50 to 150% with no tillage, 25 to 45% with reduced tillage and 25 to 40% with excessive tillage with lower water use and higher water use efficiency.