关中灌区夏季休闲效果评价

Effects of summer fallow in Guanzhong irrigation area

试验研究夏季休闲对陕西省关中地区中等肥力的红油土壤蓄水、硝态氮(NO_3^--N)累积及其对后季作物的影响。结果表明,休闲蓄水作用主要取决于降水量,降水少,休闲效果突出。与蓄水效果不同,休闲显著增加土壤剖面中NO_3^--N累积量,其在土壤剖面中的分布与降水量有关,降水少的1993年有96.8％的NO_3^--N累积在0～80cm土层,3.2％的NO_3^--N累积在80～120cm土层;而降水多的1992年有57.1％的NO_3^--N累积在0～80cm土层,42.9％的NO_3^--N累积在80～120cm土层。休闲后作物产量和吸N量显著高于连作作物。从全轮作周期看,连作3季的作物总籽粒和干物质与休闲后2季差异不显著,休闲反而增加NO_3^--N淋失和反硝化。

Field trials were carried out to study the effects of summer fallow on water storage and NO3--N accumulation in soil profile and the follow crops. The results showed that the storage ef-fect of water in the period of summer fallow was related to the precipitation. The NO3--N accumu-lated in the soil profile increased significantly during the period of summer fallow,and the distribu-tion of accumulative NO3--N changed with the amount of precipitation during fallow period: 96.8% of NO3--N was accumulated in the 0-80cm soil layer and 3.2% in the 80-120cm soil lay-er in 1993 with lower precipitation,but 57.1% in the 0-80cm soil layer and 42.9% in the 80-120cm soil layer in 1992 with higher precipitation. After fallow,the crop yield and N uptake were significantly higher than that of the crop in succession. In the total cycle of crop rotation,the total grain and above-ground yields of three crops without fallow were almost the same as that of two crops after fallow.