Greenhouse gas emissions (methane and nitrous oxide) and water use in a water-saving ground cover rice production System (GCRPS) in North China, Beijing
Rice production in China is restricted due to limited water resources, especially in northern China. Therefore, a water-saving cropping system, the Ground Cover Rice Production System (GCRPS), in which the soil is no longer submerged, was compared to the traditional lowland rice production system with respect to water consumption and its effect on greenhouse gas emissions (CH4 and N2O). Methane and nitrous oxide were surveyed by portable closed chambers. The experiment was carried out in the years 2001 and 2002 on a field northwest of Beijing. This site, with its rather light soil texture and low ground water table, represented one of the more extreme rice production environments. The high water consumption in the paddy rice could be reduced by 67 % to 47 % on average through the GCRPS. Likewise, the low water use efficiency of the paddy rice could be slightly improved in GCRPS with plastic mulch, but in the GCRPS control without mulch application, water savings were offset by a strong yield decline. A complete water balance was derived from field data by the application of the eco-physiological crop model Oryza2000 in combination with the soil-water balance model PADDY. To evaluate the impact of the GCRPS as compared to paddy rice on global warming, nitrous oxide and methane fluxes were transferred to CO2 equivalents according to the IPCC. From the GCRPS, the cumulative CO2 equivalent flux was almost identical in the two years. On the contrary, in the paddy rice, a large increase was observed in 2002, which was mainly due to the 12-fold increase of nitrous oxide flux. For the year 2002, the comparison showed that cumulative CO2 equivalent fluxes in the GCRPS and paddy rice were in a similar range of about 175 and 141 g CO2 m-2, respectively.
Use and reproduction:
No CC License (german copyright law applies)