不同施氮量对桑园红壤耕层酶活性的影响

在广西红壤典型气候区研究施用氮肥对桑园土壤过氧化氢酶、脲酶、酸性磷酸酶和转化酶酶活性的影响,为广西红壤区桑园合理施氮和耕地保育提供科学依据。试验设置3个施氮量水平(N1:120.75 kg N/hm2,N2:172.5 kg N/hm2,N3:207 kg N/hm2),在冬季测定不同氮肥处理下耕层土壤酶活性,并与桑叶产量进行相关分析。结果表明,土壤脲酶和转化酶活性均随着施氮量的增加而增加,过氧化氢酶和酸性磷酸酶活性在中等施氮量(N2处理)下较大。土壤转化酶和脲酶活性呈显著的正相关关系、转化酶和磷酸酶活性呈显著的正相关关系,土壤脲酶、磷酸酶、转化酶活性与桑叶产量呈极显著相关。合理施用氮肥能提高桑园土壤转化酶、磷酸酶、脲酶活性,土壤脲酶和蔗糖酶活性可作为评价桑园土壤肥力质量的指标之一。

Effects of nitrogen fertilization on enzyme activities in suface layer of red soil under mulberry cultivation

Studying the effect of nitrogen fertilizer on soil enzymatic activities and Mulberry production is helpful for rational application of N fertilizer and preservation of cultivated lands in Guangxi. Four soil enzymes activities in surface layer of red soil were investigated by using a Mulberry field experiment with different N fertilization treatments in the representative climate zone of Guangxi province. There were three application levels for nitrogen fertilization, including 120.75 kg/hm² (N₁), 172.5 kg/hm²(N₂) and 207 kg/hm² (N₃). The soil enzymes activities were investigated in winter and their correlation with Mulberry leave yield was analyzed. The results showed that the urease and invertase activities were enhanced with increasing N application rate, while the maximal activities of acid-phosphatase and catalase occured under the moderate N application rate (N₂). Significant positive correlationsship was found between Mulberry leaf yield and activities of invertase, urease, and alkali-phosphatase. The invertase activity was closely correlated to the activities of alkali-phosphatase and urease.