The Effects of Mulched with Dripping on Carbon and Water Dynamics by Cotton in Northwest China

The mulch was widely practiced in cotton (Gossypium hirsutum L.) cropland in northwest China. Quantifying carbon and water flux was significant for maintaining the sustainable cotton production under the declining in available water in arid regions. In this study, the ecosystem exchange (NEE) and evapotranspiration (ET) of cotton was during 2009-2010 in Wulanwusu, North Xinjiang. The LAI reached to the maximum value of 7.3 m2 m-2 and 8.8 m2 m-2 around 80-90 days after planting. Although, the total precipitation account for 25-26% of the sum evapotranspiration (ET), the dripping irrigation supplied the water shortages and mulch restrained soil evaporation. Thus, the monthly total ET was more relayed on the irrigation than on the precipitation, and showed the supplement water was more important to oasis cotton. The NEP of cotton ranged from 454.23 gC m-2 y-1 to 526.31 gC m-2 y-1 during 2009-2010. The mulch made the water use efficiency (WUE) was 0.89 kgC m-3 y-1 and 1.11 kgC m-3 y-1, which was similar to that of crop in semi-humid regions of North Plane China. The results showed that mulch with dripping could maintain higher WUE and saving water in arid regions which had deficit irrigation.