摘要
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。
The objective of this study was to determine the effect of zero tillage on soil microorganisms and biological activity. The field experiment was conducted on a sandy loam soil, which had been cultivated for many years, in Yangzhou, Jiangsu Province. After 6 years of the adoption of zero tillage on the soil (wheat and rice rotation), 0-28 cm soils were sampled to determine microflora and biological activity so as to make a comparison between zero tillage (ZT) and conventional tillage (CT). Results indicated that microbes in 0—7 on, soil were more concentrated in ZT than in CT. Systemetic studies showed that more so-called allochthonous flora such as Rhizopus, Mucor and Gram negative rods were observed in the 0—7cm soil of zero tillage than in that of conventional tillage, indicating the changes of biological environment of the soil. Respiration and urease activities of 0—7 cm soil for ZT were 2.1 (incubated for 1 day) and 1.6 (incubated for 12 hs) times as high as those for CT respectively. However, as soil went deeper, respiration and urease activities of ZT treatment decreased more dramatically than those of CT treatment. Inorganic N releases of 0—7 cm soil for ZT and CT upon 40 days incubation were 41.8 and 34.5 mgN/kg respectively, bur those in the 7—14cm layer, 21.5 and 29.1 mgN/kg respectively. N immobilization of the soil was around 10%. Surface layer of ZT treatment showed the greatest potential for N immobilization. Long-term ZT practice made the surface soil rather thin although more active as compared to the CT practice.
出处
《土壤学报》
CAS
CSCD
北大核心
1992年第4期370-376,共7页
Acta Pedologica Sinica
关键词
微生物
免耕
生物活性
Soil Microorganisms, Zero Tillage, Biochemical activity, N mineralization, N immobilization
