长期施肥潮土在玉米季施肥初期的有机碳矿化过程研究

摘要

In a 37-day laboratory incubation study soil organic C mineralization was determined in soil samples obtained from initial stage of maize growth in an 18 year long-term field experiment which was carried out to evaluate nutrition equilibrium in a fluvo-aquic soil under different fertilization treatments. During the incubation time, cumulative CO_2-C released from soil was positively correlated to soil organic carbon, total nitrogen and microbial activity, which with a general decrease order of OM>1/2OM+1/2NPK>NPK>NP>PK>CK>NK. Amodified first-order model best described C mineralization in the soil. Potentially mineralized C (C_0), easily mineralized C (C_1) and the initial potential rate of C mineralization (C_0k) were significantly different among the treatments with a general decline order of organic manure treatments>mineral fertilizer treatments>control, which were positively correlated to soil organic carbon, total nitrogen and microbial activity. Mineralization rate (k) and potentially mineralized C divided by organic C (C_0:Organic C) were not significantly different among treatments, which were not correlated to soil organic carbon, total nitrogen and microbial activity except k was negatively correlated to organic carbon. Consequently, we conferred that long-term application of both organic manure (OM or 1/2OM+1/2NPK) and mineral fertilizers (except NK) to soil could significantly increase the mineralization of soil organic carbon, reflecting the differences in soil properties, thus increase the availability of soil mineral nutrients to crops and soil organic carbon content.%以黄淮海平原长期定位试验地2007年玉米播种期土壤为研究对象,通过室内37天的培养实验并选择4个应用比较广泛的方程对土壤有机碳矿化过程进行拟合,其目的主要是为了比较研究长期不同施肥土壤在玉米季施肥初期有机碳矿化过程及主要矿化参数的差异,并评估矿化参数和主要土壤性质之间的相关关系.结果表明,37天培养期内各施肥处理土壤CO_2-C累积释放量与土壤有机碳、全氮含量和微生物活度均呈显著正相关,大小依次为OM＞1/2OM+1/2NPK＞NPK＞NP＞PK＞CK＞NK,有机碳矿化过程均呈曲线形式,与Jones(1984)改进的一级动力学方程拟合效果最好.拟合所得土壤潜在可矿化有机碳量(C_0)、易矿化有机碳量(C_1)和初始潜在矿化速率(C_0k)均表现出有机肥处理高于化肥处理,施肥处理高于不施肥处理(NK处理除外),与土壤有机碳、全氮和土壤微生物活度均呈显著正相关;有机碳矿化速率(k)和土壤潜在可矿化有机碳占土壤总有机碳的比例在处理间差异均不显著,除k与有机碳呈显著负相关外,其他与土壤性质均无显著相关性.因此,我们推测有机肥和化肥的平衡施用均能显著增强土壤有机碳的矿化作用,有利于土壤无机养分的释放,同时使部分有机碳在土壤中积累.