Effect of micro-catchment rainwater harvesting on water and nutrient use efficiency in farmland under different simulated rainfall conditions

In order to determine the optimum method for increasing the productivity and the ranges of rainfalls applicable for the plastic-covered furrow and ridge farming practice for rainwater concentration (RC), the experiment simulated different rainfalls to examine the effects of RC on the efficiency of farmland fertilizer utilization of corn plants in 2006-2007 (summer corn and spring corn were planted as the indicators in 2006 and 2007, respectively). The results showed that with the rainfalls ranging within 230-440 mm, RC practice could enhance the grain yield, water use efficiency (WUE) and nutrient use efficiency (NUE). In 2006, compared to conventional flat (CF) practice, the grain yield, WUE, NUEN, NUEP and NUEK under RC increased by 75.4%, 73.3%, 56.0%, 44.4% and 106.8%, respectively, at the rainfall of 230mm, and by 36.7%, 40.2%, 22.8%, 18.1% and 35.5% at the rainfall of 340mm, respectively. At the rainfall of 440mm, however, no significant difference was observed between RC and CF. In 2007, the grain yield, WUE, NUEN, NUEP and NUEK under RC were 82.8%, 77.4%, 64.0%, 52.2% and 123.9% higher, respectively, at the rainfall of 230mm than those of CF, and 43.4%, 43.1%, 30.4%, 21.8% and 41.2% higher, respectively, at the rainfall of 340mm than those of CF, while at the rainfall of 440mm, the grain yield, WUE and NUEN were 11.2%, 9.5% and 10.1% higher, respectively, under RC than under CF. Therefore, It is concluded that the RC farming practice could increase grain yield and improve WUE and NUE in farmland during the corn growing seasons with rainfall ranging 230-440 mm. It is also found that especially under lower rainfall, the practice had more obvious effect on the improvement of WUE and NUE and the increase of grain yield.