潮棕壤免耕农田土壤酶活性的动态变化

研究了潮棕壤免耕和常规耕作农田土壤蔗糖酶、脲酶和酸性磷酸酶活性在玉米不同生育时期和不同土层深度的动态变化.结果表明，免耕可显著提高表层(0～10 cm)土壤酶活性，其蔗糖酶活性在玉米拔节期、大喇叭口期和成熟期显著高于常规耕作，脲酶活性在拔节期和孕穗期显著高于常规耕作，酸性磷酸酶活性在孕穗期和成熟期显著高于常规耕作(P＜0.05)；在10～20cm土层，免耕土壤蔗糖酶活性在苗期、拔节期和大喇叭口期与常规耕作差异显著，脲酶活性除孕穗期外均显著高于常规耕作(P＜0.05)；在20～30 cm土层，免耕土壤蔗糖酶活性在玉米各生育期均显著低于常规耕作，土壤脲酶活性在苗期、酸性磷酸酶活性在成熟期与常规耕作差异显著(P＜0.05).随土层深度的增加，免耕农田土壤酶活性总体呈下降趋势；常规耕作农田土壤蔗糖酶和酸性磷酸酶活性总体呈上升趋势，而脲酶活性呈下降趋势.

Dynamics of aquic brown soil enzyme activities under no-tillage

This paper studied the effects of no-tillage on the dynamics of invertase, urease and acid phosphatase activities in an aquic brown soil during maize growing season. The results showed that in 0 - 10 cm soil layer, the invertase activity at jointing, trumpet-shaped and ripening stages, urease activity at jointing and booting stages, and acid phosphatase activity at booting and ripening stages were significantly higher under no-tillage (NT) than under conventional tillage (CT). In 10 - 20 cm soil layer, the invertase activity at seedling, jointing and trumpet-shaped stages was significantly different between NT and CT, and the urease activity during whole growing season except at booting stage was significantly higher under NT than under CT. In 20 - 30 cm soil layer, the invertase activity during maize growing season was significantly lower under NT than under CT, and urease activity at seedling stage and acid phosphate activity at ripening stage were significantly different between these two treatments. Under NT, there was a decreasing trend of soil enzyme activities with increasing soil depth; while under CT, soil invertase and acid phosphatase activities increased, but urease activity decreased with increasing soil depth.