基于玉米大豆轮作的黑土玉米农田酶活性对 不同耕层厚度的响应
黑土退化导致土壤耕层变薄，影响土壤生产力。本研究在重建不同厚度黑土层的定位模拟试验区开展免耕玉米大豆轮作试验，设置3个黑土耕层厚度，分别为10cm、20cm和30cm，重点研究了耕层厚度对玉米生育期内关键土壤酶活性的影响，并分析了乳熟期根际和非根际土壤的酶活性及其速效养分的差异。研究表明，不同生育期不同耕层厚度的玉米农田土壤脲酶活性变化差异不明显，而土壤蔗糖酶活性变化差异显著；且土壤磷酸酶活性在同一生长期不同耕层厚度差异明显，磷酸酶对耕层厚度的反应更为敏感。相同耕层厚度中不同土层深度间酶活性也有明显差异，0-10cm土层的酶活性高于20-30cm土层酶活性。乳熟期玉米根际土壤的脲酶 、蔗糖酶、磷酸酶均在10cm耕层厚度中活性最强；不同耕层厚度处理时，玉米农田土壤的根际土壤酶活性高于非根际土壤；30cm耕层厚度速效氮含量根际土显著高于非根际土壤，但有效磷含量无显著差异，而根际土的速效钾含量均低于非根际土。
英文摘要:
The degradation of Mollisols results in the thinning of topsoil which is a main factor affecting farmland productivity. With simulation experiment of different topsoil depths reconstruction under no-tillage maize-soybean rotation in Mollisols region, this study examined the effects of different topsoil depths on key soil enzyme activities in maize growing season, and compared the rhizosphere soil and bulk soil enzyme activities and available nutrients at milking stage. The depths of the simulated topsoil were 10cm, 20cm and 30cm. The results showed that there were no significant differences in soil urease activity among different topsoil depths. More significant changes of soil invertase activity were found in different growth stages. Soil phosphatase activity varied significantly with different topsoil depths at same growth stage, and invertase activity was more sensitive to the response of topsoil depth. The enzyme activity was also significantly different between different soil layer at the same depth, and higher enzyme activity was found in 0-10cm soil layer compared with that of 20-30cm soil layer. Rhizosphere soil at 10cm topsoil depth all had the strongest urease, invertase and phosphatase activities. The enzyme activity of rhizosphere soil was higher than that in bulk soil at different topsoil depths. Available nitrogen content of rhizoshere soil was significantly higher that of bulk soil at 30cm topsoil depth, and no differences were found between bulk soil and rhizoshere soil for available phosphorus. However, available potassium content of rhizoshere soil was lower than that of bulk soil.
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