不同土壤耕作方式下秸秆还田量对晚稻土壤养分与微生物的影响

在耕翻、少耕和免耕条件下研究了早稻秸秆还田量对晚稻土壤养分与微生物的影响,结果表明,①秸秆还田显著提高土壤有效磷和速效钾含量,对土壤碱解氮含量的提高体现在水稻生育后期;秸秆还田对土壤碱解氮和有效磷含量的提高效果在免耕条件下最好,而对速效钾含量的提高效果在少耕条件下最好;②不同耕作方式下宜实行不同秸秆还田量,就提高有效磷和速效钾含量而言,耕翻和少耕条件下宜实行全部秸秆还田,而免耕条件下宜实行2/3秸秆还田;③秸秆还田使土壤真菌和嫌气性细菌数量减少,放线菌和好气性细菌数量增加;耕翻使土壤真菌和嫌气性细菌数量减少,好气性细菌数量增加;④土壤耕作有利于晚稻生育前期与后期土壤微生物活度的提高,秸秆还田量对土壤微生物活度的影响在不同耕作方式下表现不同,耕翻条件下以2/3还田量处理的土壤微生物活度最高,而少免耕条件下1/3还田量处理最高.

Effects of straw return on soil nutrients and microorganisms in late rice under different soil tillage systems

The effects of returning early rice straw to the soil on soil nutrients and microorganisms in late rice under different tillage conditions, including normal tillage (deeply plowing and harrowing), minimum tillage (rotary tillage only) and no-tillage were studied. The main results showed that (1) contents of phosphorus and potassium in soil were improved significantly by straw return, while improvement of the available nitrogen was only observed in the late stage of rice cultivation. The effects of straw return on the available nitrogen and phosphorus were best under no-tillage conditions, while the content of potassium was best under the minimum tillage condition. (2) Different return straw percentages should be adopted under different tillage systems. To improve contents of phosphorus and potassium, 100% straw return should be adopted under normal tillage and minimum tillage conditions, while two thirds straw return should be adopted under the no-tillage condition. (3) Soil fungi and anaerobic bacteria decreased, while actinomycetes and aerobic bacteria increased after straw return. Tillage led to decrease of fungi and anaerobic bacteria and increase of aerobic bacteria. (4) Soil tillage improved the microbial activity in the early and late growth stages of late rice. The amount of straw returned affected microbial activity differently under different tillage systems, and it was highest in the treatment with 2/3 return straw under normal tillage conditions, while it was highest in the treatment with 1/3 return straw under minimum and no-tillage conditions.