Water and nitrogen use efficiency of lowland rice in ground covering rice production system in south China

Field experiment was conducted to test the effect of ground covering rice production system (GCRPS) on rice yield, nitrogen use efficiency (NUE), and water utilization coefficient. Cultivating lowland rice variety in upland condition by using of plastic film (T1), paper film (T2), or rice straw mulching (T3) to cover the ground resulted in similar yield as for paddy rice (T5), but the yield was significantly greater than that of upland rice cultivation system without mulching (T4). Water utilization coefficient of mulching treatments (T1, T2, and T3) increased from 178% to 219% compared to T5. About 69% irrigation water was saved when shifting lowland paddy rice into GCRPS. The nitrogen (N) nutrition state in flag leaf (FL) and 3rd leaf backward (LBW) showed no statistical difference between T1 and T5. However, N content of FL and 3rd LBW of T1 was significantly greater than that of T4. The amount of N uptake, NUpE and NUE of T1, T2, and T3 was remarkably greater than those of T4. Increment of nitrogen fertilizer utilization efficiency (INfUE) increased 12.1%, 12.5%, and 8.7% in treatments of T1, T2, and T3, respectively. Therefore, cultivating lowland rice variety with mulching treatment not only increased water coefficient, but increased NfUE significantly under upland condition as well.