接种蚯蚓对秸秆还田土壤碳、氮动态和作物产量的影响

通过为期 2年的小区 (2 .8m× 1.0m)试验 ,研究了旱作水稻 小麦轮作条件下接种蚯蚓对施用玉米秸秆 (第一季用量 15 0 0g·m-2 ,以后各季为 75 0g·m-2 )农田土壤碳、氮动态和作物产量的影响 .结果表明 ,接种 10条·m-2 或 2 0条·m-2 环毛蚓 (Pheretimasp .)对土壤有机碳和全氮含量无显著影响 ,蚯蚓活动未造成土壤C库的衰减 ,土壤碳、氮基本维持平衡 .接种蚯蚓处理土壤N的矿化作用增强 ,矿质N含量提高 ,NO3 - N含量增加 ,而且稻季比麦季增加更为明显 .接种蚯蚓在稻、麦季均能提高微生物量碳、氮含量 ,蚯蚓具有扩大土壤微生物量N库和促进有机N矿化的双重作用 .这种作用在有效C源供应丰富的作物生长发育旺盛期更为明显 .接种蚯蚓对旱作水稻和小麦有一定的增产作用 ,其中水稻的增产幅度达 9.3% ,小麦为 5 .1% .接种蚯蚓后土壤容重明显降低 ,孔隙度显著增加 .蚯蚓在保持土壤C库平衡的同时 ,对于促进秸秆有机肥N素养分的再循环和作物生产力的提高具有重要的生态学意义 .

Effect of earthworm inoculation on soil carbon and nitrogen dynamics and on crop yield with application of corn residues

This study was carried out in the Experimental Station of Nanjing Agricultural University, which is in a subtropical monsoon region characterized by a warm-wet spring and a hot-dry summer. The annual average temperature, precipitation and evaporation are 15.6 degrees C, 1010 mm and 1560 mm, respectively. In 1999, the experimental plots (2.8 m x 1.0 m x 0.6 m) were established by concrete frame. Soil in the plots was orthic aquisols collected from Rugao County, Jiangsu Province. Crop rotation was upland rice and winter wheat. At the beginning of the first crop (rice) season, earthworms (Pheretima sp.) were inoculated at a density of 10.m-2 and 20.m-2, respectively, in the plots with an application of corn residues at the rate of 1500 g.m-2(750 g.m-2 in the following seasons). The responses of soil carbon and nitrogen and crop yield to earthworm activity were investigated from 1999 to 2001. The results showed that earthworms had no significant influences on total soil carbon and nitrogen content, which implied that there was no depletion of soil carbon and nitrogen pools in the presence of earthworms. The maintenance of soil carbon might be explained by low assimilation efficiency of organic matter by earthworms, and by the compensation of carbon returning from plant production enhancement. Soil mineral nitrogen, soil microbial biomass carbon and microbial biomass nitrogen were increased, and nitrogen mineralization was strengthened by earthworm activities, which was more obvious at jointing/booting and heading stages. In comparison with no-worm treatments, the yield of rice wheat increased by 9.3% and 5.1%, respectively, in the treatments inoculated with earthworms. It was concluded that earthworm was very important in promoting nitrogen recycling of crop residues and plant productivity, and in keeping the balance of soil carbon pool as well.