不同温度及化肥绿肥施用比例对果园土壤有机碳矿化的影响

Effects of temperature and green manure treatments on organic carbon mineralization in orchard soil

【目的】了解果园土壤有机碳矿化在不同温度下对不同绿肥施用量的响应关系,为构建果园生态系统的碳循环模型提供参数。【方法】采用室内培养模拟试验(培养期85d),在10、20、30℃等3个温度条件下,探讨化肥和绿肥不同比例(不施肥、100%氮肥、75%化学氮肥+25%绿肥、50%化学氮肥+50%绿肥、25%化学氮肥+75%绿肥、100%绿肥;各处理氮肥施用水平均为0.15gN/kg风干土)还园量对果园土壤有机碳矿化特征的影响。【结果】各施肥处理土壤有机碳矿化速率均表现为培养前期保持较高水平,之后快速下降,培养后期保持相对稳定的趋势;土壤有机碳矿化累积排放量为1439.4～4732.8mg/kg,全绿肥处理土壤CO2累积排放量最大;土壤有机碳矿化速率随温度升高而增长,不同的土壤绿肥还园处理土壤有机碳矿化的温度敏感性(Q10)不同,以不施肥处理土壤有机碳矿化的温度敏感性最低,25%氮肥+75%绿肥处理最高,各处理间差异显著(P<0.05)。【结论】10～30℃温度条件下,果园土壤有机碳矿化速率表现为培养前期高,之后快速下降,培养后期相对稳定的趋势。不同比例化肥和绿肥施用显著提高了果园土壤有机碳累计矿化量。氮肥、绿肥还田和温度的共同作用可使果园向大气中排放的CO2增加。

[Objective]This research aimed to understand the different responses of organic carbon mineralization to green manure fertilizers on orchard soil under different temperatures in order to provide parameters for constructing the or- chard ecosystem carbon cycle model. [Method]By the indoor culture simulation test （culturing period lasting for 85 d）, under the 3 temperature conditions of 10, 20, and 30℃, effects of different proportions of chemical nitrogen fertilizer and green manure （no fertilization, 100% nitrogen fertilizer, 75% chemical nitrogen fertilizer＋25% green manure, 50% chem- ical nitrogen fertilizer＋50% green manure, 25% chemical nitrogen fertilizer＋75% green manure, and 100% green manure; each nitrogen fertilizer application rate was 0.15 gN/kg in dry soil） were discussed and the influential characteristics of or- ganic carbon mineralization in orchard soil were studied. [ Result]The organic carbon mineralization rates in fertilization soil maintained higher levels during the beginning of the culturing period, but rapidly declined afterwards; during the late culturing period, the organic carbon mineralization rates remained relatively stable. The cumulative soil organic carbon mineralization emissions were 1439.4-4732.8 mg/kg, hence the cumulative emission of COz after the whole green manure soil treatment reached maximum. Soil organic carbon mineralization rate increased as the temperature rose, and the tem- perature sensitivity （Q^0） of different garden soil manure organic carbon mineralization also differed. The temperature sen- sitivity of soil organic carbon mineralization under the no fertilization treatment was at minimum, while sensitivity under the 25% chemical nitrogen fertilizer＋75% green manure treatment was at maximum. Difference between each treatment was distinctively significant. [ Conclusion]Different proportions of fertilizer and green manure application increased the temper- ature sensitivity in soil organic carbon mineralization; also, the combined action of nitrogen fertilizer, green manure, and temperature could cause increased CO2 emission from the orchard into the atmosphere.