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本文比较常耕和免耕法对土壤微生物和生物学活性的影响。结果表明,连续免耕6—7年的砂壤土中微生物的数量较集中分布于上表层,常耕处理则相对均匀地分布于经常翻动的土层中。0—7cm表层土壤中微生物的优势种群在两种耕法中有一定差异,特别是霉菌。免耕处理0—7cm土壤培养1天的呼吸活性是常耕处理的2.1倍,尿酶活性是常耕处理的1.6倍。但随着土层的加深,免耕处理的呼吸活性、尿酶活性下降很快,至7—14cm处分别下降56%、71%。培养40天时0—7cm土壤无机氮释放量免耕和常耕处理分别为48.1、34.5mgN/kg,而7—14cm土层则分别为21.5、29.1mgN/kg。不加碳源只加入硫铵培养3天土壤中无机氮的减少在10%左右,免耕上表层0—7cm土壤减少较多,反映土壤微生物对无机氮的固定作用。长期免耕使具有高生物学活性的土层变得浅薄,而常耕处理则较为深厚。
This article compares the effect of no-tillage and no-tillage on soil micro-organism and biological activity. The results showed that the number of microbes in sandy loam from 6 to 7 years of continuous tillage was more concentrated on the upper surface than that of normal tillage. 0-7cm The dominant species of microorganisms in surface soils differ in their tillage practices, especially in molds. The respiration activity of 0-7cm soil-no-tillage cultivation for one day was 2.1 times of that of the conventional tillage treatment and that of urease activity was 1.6 times of the normal tillage treatment. However, with the deepening of soil layer, the respiration activity and the urease activity of no-tillage decreased rapidly, decreasing by 56% and 71% respectively at 7-14cm. At 40 days, the release of inorganic nitrogen in 0-7cm soil was 48.1 and 34.5mgN / kg, respectively, while that in 7-14cm soil layer was 21.5 and 29.1mgN / kg, respectively. Without carbon source, ammonium sulfate was only reduced by about 10% in 3 days after adding ammonium sulfate, while 0-7cm in no-tillage decreased more soil, which reflected the fixation effect of soil microorganism on inorganic nitrogen. Long-term non-tillage made the soil layer with high biological activity shallow, while the permanent tillage treatment was more deep.