半干旱区旱地不同覆盖种植方式玉米田的土壤水分和产量效应

Effects of mulching methods on soil water dynamics and corn yield of rain-fed cropland in the semiarid area of China

为探讨半干旱区旱地不同种植方式玉米(Zea mays)田的土壤水分动态特征,测定了全膜双垄沟播(PMF)、全沙覆盖(SM)和裸地(CK)3种不同处理0–200cm土壤水分季节变化、垂直变化及年际变化。结果表明:PMF明显改善玉米拔节前0–200cm土壤的水分条件,有利于玉米前期生长;随着玉米生育进程的推进,3种处理的耗水量依次为:PMF﹥SM﹥CK,而土壤贮水量表现为CK﹥SM﹥PMF;在相同降雨条件下,PMF处理0–200cm土壤水分降雨入渗补给深度最大,SM次之,CK最小。随着种植年限增加,PMF的耗水量和耗水深度增加,两年种植期间耗水深度从20–120cm向120–200cm推移;连续种植两年后,3种处理40–120cm土壤含水量下降至9.0%以下,其中PMF下降最快(7.9%),土壤含水量接近萎蔫系数7.2%,玉米只能靠当年降水生长,如种植年限继续增加,土壤极有可能形成干层。3种处理之间耗水量、产量、水分利用效率都存在显著差异,PMF最高,SM次之,CK最低。因此,在半干旱区采用全膜双垄沟播种植玉米可显著提高产量,但连续种植可导致土壤贮水量显著降低,对农田可持续生产能力造成不利影响。

Aims A new drought-resistance farming technology of double ridges and furrows mulched with plastic film and furrow planting （PMF） is widely applied on rain-fed agriculture in the middle and eastern part of Gansu Province,China, to increase crop yield and water use efficiency. However, its impacts on seasonal and annual soil water dynamics are not well understood. Our objectives were to （a） investigate seasonal and annual changes in soil wa-ter content, corn yield and water use efficiency of different mulching methods and （b） evaluate the ecological impact of PMF on rain-fed cropland in semi-arid areas. Methods We studied three treatments： PMF, whole field surface sand mulching and flat planting （SM） and un-covered and flat planting （CK）. Using oven-drying and neutron-probe methods, we observed soil water in the 0–200 cm layer from 2009 to 2010. Important findings PMF could improve soil water storage in the 0–200 cm layer significantly before corn jointing and improve corn development in the early growth period. With corn growth, there was a significant difference in water consumption among the three treatments in the sequence PMF SM CK. Conversely, the se-quence of change of soil water storage was CK SM PMF. Under the same precipitation, soil water restoration depth of PMF was deepest and CK was shallowest （in the 0–200 cm soil layer）. The quantity and depth of soil water consumption increased with increases of corn planting years in PMF treatment, e.g., depth of water con-sumption deepened from 20–120 cm to 120–200 cm from 2009 to 2010. After two years of continuous cropping of corn, soil water content in the 40–120 cm layer was 9.0% in all three treatments, the soil water content of PMF treatment decreased to 7.9% （which is close to the wilting coefficient of 7.2%） and corn development de-pended on rainfall in the growing season.This indicates that continuous corn cropping with PMF would result in a dry soil layer in semiarid areas. Water consumption, corn yield and water use efficiency were highest in PMF treatment, but lowest in CK in both years. Therefore, PMF could improve corn yield significantly,but continuous cropping may result in significant reduction of soil water storage and was disadvantageous to sustainable development capacity of cropland.