Effect of bentonite-humic acid application on the improvement of soil structure and maize yield in a sandy soil of a semi-arid region

Sandy soils have poor soil structure, low water retention and low crop productivity. A bentonite-humic acid (B-HA) mixture was applied at a single rate of 30 Mg ha(-1) to a sandy degraded soil of China for improving soil physical properties and hydric regime, and productivity of maize (Zea mays L.). Measurements of soil aggregate distribution, soil bulk density (BD), soil water storage (SWS), and yield of maize and associated water use efficiency (WUE) helped to evaluate the effect of the B-HA 1 to 7 years after B-HA application. The addition of B-HA increased soil health by improving soil structure thereby facilitating the rapid formation of macro-aggregates, decreasing soil BD and increasing SWS in the top 100 cm. B-HA addition also increased maize growth and grain yield and WUE by 50%, 5 years after B-HA application. Linear regression and Principal Component analysis indicated that three macro-aggregate fractions and SWS were highly correlated with maize biomass and grain yield. Improvement of soil structure and hydric regime significantly increased maize grain and biomass yield and WUE. The addition of B-HA to sandy soil appears to be an appropriate technology for rapidly reclaiming a degraded soil in large areas of sandy land in semi-arid regions of the world.