Soil water storage, yield, water productivity and transpiration efficiency of soybeans (Glyxine max L.Merr) as affected by soil surface management in Ile-Ife, Nigeria

Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used. In this study, conventional (NC) and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-Ife, Nigeria. The conservation practices are: Tied ridge (TR), Soil bund (BD), Mulch (ML), Mulch plus Soil bund (MLBD), Tied ridge plus Mulch (TRML), Tied ridge plus Soil bund (TRBD). The practices were arranged in Randomised Complete Block Design with four replicates. Seasonal rainfall was 539 and 761 mm in 2011 and 2012, respectively. Seasonal soil water storage (SWS) ranged from 485 mm for NC to 517 mm for TRML in the two seasons. ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC. ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9 oC compared with NC, TR and TRML. Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons. Grain yield increased by 41.7% and 44.3% for BD and MLBD, respectively compared with NC. Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC. Similarly, it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC. These findings demonstrate that when there are fluctuations in rainfall, in-situ water conservation practices improve SWS, land, and water productivity and transpiration efficiency of Soybeans.