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研究长期免耕土壤微生物活性能及时准确反映免耕土壤质量的演变趋势,探求最佳免耕年限。通过野外调查和室内分析,调查了水旱轮作条件下,不同免耕年限土壤微生物量的变化,并采用主成分分析法对土壤微生物活性进行了综合评价。结果表明:①旱作和水作后,免耕土壤微生物量碳、氮均显著高于常规每年翻耕的耕作方式,微生物量磷则相反。随着免耕年限延长,旱作土壤微生物量碳、氮均呈逐渐降低的趋势;水作后,则呈先增加再降低的趋势;而微生物量磷在不同免耕年限间无显著差异。②主成分分析表明,旱作后免耕土壤微生物活性高于常规每年翻耕,水作后则相反。随着免耕年限延长,免耕土壤微生物活性呈先降低再增加的趋势,旱作后免耕7—8 a土壤微生物活性最低,水作后免耕5—6 a土壤微生物活性最低。
Studying the activity of long-term no-till soil microorganisms can accurately and accurately reflect the evolution trend of no-till soil quality and explore the best no-tillage time. Through field investigation and indoor analysis, the changes of soil microbial biomass under different tillage years were investigated under the conditions of runoff and waterlogging, and the soil microbial activities were comprehensively evaluated by principal component analysis. The results showed that: (1) The soil microbial biomass carbon and nitrogen in no-tillage soil were significantly higher than those in the conventional tillage system after dry cultivation and watering, respectively. Microbial biomass phosphorus was the opposite. With the prolongation of no-tillage, the soil microbial biomass carbon and nitrogen in dry land tended to decrease gradually, and then increased first and then decreased with the increase of dry land moisture. However, there was no significant difference in microbial biomass phosphorus between different tillage years. ② Principal component analysis showed that the activities of no-tillage soil after dry farming were higher than those of conventional tillage, while the water use was the opposite. With the prolongation of no-tillage, the microbial activities of no-tillage decreased first and then increased. The activities of soil microbes after tillage for 7-8 a were the lowest, while those for tillage 5-6 years after tillage were the lowest.