不同施氮量对茶园土壤有机碳矿化特征的影响
Effect of Nitrogen Fertilization on Organic Carbon Mineralization in Soils at Tea Plantations
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摘要: 通过室内模拟试验研究不同施氮水平对两种茶园土壤 (黄壤和红壤) 有机碳矿化特征的影响。试验设置4个氮水平处理, N0、N1、N2、N3, 含氮量分别为0、100、200、400mg·kg-1。结果表明, 培养结束后2种土壤在N0处理下的有机碳累计矿化量分别为586.58mg·kg-1和298.84mg·kg-1, 黄壤有机碳矿化量显著高于红壤, 但有机碳矿化比率和矿化常数k值则显著低于红壤。2种土壤在氮输入后的有机碳矿化速率和累积矿化量都显著高于N0处理, 表明氮输入对有机碳矿化具有促进作用。随着氮输入量的增大, 有机碳累积矿化量有增加趋势, 增幅分别为20.90%91.88%和48.52%113.88%, 氮输入对低肥力的红壤促进作用更明显。一级动力学方程较好地描述了2种茶园土壤有机碳的矿化累积动态, 施氮显著增加了易矿化有机碳量 (C1) , 其中矿化常数k值和初始潜在矿化速率 (Cok) 均随施氮量的增加而增加, 而半衰期 (T1/2) 均随施氮量的增加而降低, 这说明短期氮肥施用能加速有机碳周转, 有利于土壤碳氮转化和提高土壤的供氮能力。Abstract: A laboratory incubation experiment was conducted to study the effect of the varied nitrogen (N) inputs, i.e., 0mg·kg-1 (N0) , 100mg·kg-1 (N1) , 200mg·kg-1 (N2) and 400mg·kg-1 (N3) , on the organic carbon mineralization (OCM) in the yellow and red soils at tea plantations.The results indicated that under N0 the cumulative OCM of the yellow soil was 586.58mg·kg-1, which was significantly higher than that of the red soil (298.84mg·kg-1) .But, the rate and constant kof mineralization were significantly lower for the yellow soil than those for the red soil.Increasing exogenous N resulted in the increase of the cumulative OCM in the yellow and red soils by 20.90%-91.88% and 48.52%-113.88%, respectively.The first-order kinetics equation appeared to adequately describe the dynamics of OCM in the soils.N fertilization made the easily mineralizable organic carbon (C1) in soil increased significantly with an exponentially increased k, raised the initial potential mineralization rate (Cok) , and lowered the half-life.The results suggested that a short term N treatment could promote the OCM turnover, which was conducive to the carbon/N transformation and fertility improvement of the soil.