免耕对黑土蚯蚓数量和土壤密度的影响

以自2001年秋在吉林省德惠市中层黑土上进行的耕作定位试验小区为研究对象,对比免耕和常规耕作对东北黑土蚯蚓数量和土壤密度的影响.试验设计为裂区随机区组设计(免耕和常规秋翻两个处理),4个区组,种植作物为玉米和大豆.在玉米6叶期和8月末或9月初两次测定蚯蚓数量,土壤密度秋收后测定.采用SAS软件对2004～2006年的蚯蚓数量和土壤密度进行方差分析.试验结果表明,耕作方式、作物类型和采样时间对蚯蚓数量的影响较大,均达显著差异(P《0.05).免耕处理的蚯蚓数量是秋翻处理蚯蚓数量的2.4倍,种植大豆的蚯蚓数量是种植玉米蚯蚓数量的1.6倍,第1次的蚯蚓数量是第2次蚯蚓数量的1.9倍.耕作方式和作物类型对土壤密度没有显著影响.虽然免耕处理使5cm～10cm的土壤密度略有增加,但免耕的土壤密度与秋翻的土壤密度相比,并无显著差异.因此,同常规秋翻相比,免耕明显增加土壤中的蚯蚓数量,而且不会引起土壤的板结.

Impacts of No-tillage on Earthworm and Soil bulk Density in Black Soil in Northeast China

The tillage experiment trials were established in Dehui County,Jilin Province in 2001.The impacts of no-tillage(NT) and moldboard plow(MP) on the number of earthworms and soil bulk density of a black soil in Northeast China were studied.The tillage experiment was arranged in a randomized complete block design with four replicates.Each tillage plot was split into sub-plots with different corn-soybean rotations.Earthworm was counted two times when the corn has six leaves and in late August or early September.The data of earthworms and soil bulk density from 2004 to 2006 was analyzed using SAS.The results showed that the differences of earthworms under tillage,crop and time were significant.The results showed that the number of earthworms under NT,soybean and the first time were respectively 2.4,1.6 and 1.9 times as many as those under MP,corn and the second time.There were no significant differences of soil bulk density between tillage treatments and crops.NT increased bulk density of soil layer of 5 cm-10cm,but there was no significant differences between NT and MP.Studies showed that NT compared to MP could increase the number of earthworms and could not result in the soil becoming hard.