温度对不同年限日光温室土壤氮素矿化特性的影响

【目的】日光温室作为具有我国特色的一种高强度的栽培方式,过量施肥问题突出。随着温室栽培在我国北方地区规模的不断扩大,由此带来的土壤退化和地下水污染问题值得关注。不少研究表明,随着日光温室栽培年限的增加,土壤有机质含量不断增加;且温室栽培中的土壤温度与露地存在很大差异,其土壤氮素矿化特性如何,尚缺乏研究。【方法】本研究以位于黄土高原南部陕西省杨凌示范区不同栽培年限的日光温室土壤为研究对象,采用室内好气培养法(84 d)测定不同培养温度(20℃和30℃)对不同年限温室(0 3年)土壤0—20 cm及20—40cm土层氮素矿化量,采用一级动力学方程拟合土壤氮素矿化曲线,根据土壤氮矿化势(N0)评价不同栽培年限温室土壤氮素矿化特性。【结果】1)随着日光温室栽培年限的增加,土壤有机质、全氮含量和氮素累积矿化量随之显著增加。2)30℃的土壤氮素累积矿化量高于20℃的矿化累积量;栽培年限长的日光温室矿化作用对温度的敏感程度高于年限短的温室。3)若温度和栽培年限同时增加,土壤氮素累积矿化量随之增加,说明温度和栽培年限对土壤氮素净矿化量有一定的交互作用,但差异不显著(P0.05)。4)日光温室栽培年限越长,土壤氮矿化势(N0)越大;与种植前相比,第2a、3a温室土壤氮矿化势增加了5.59和11.48倍。5)回归分析表明,0—20 cm土层土壤有机质含量每增加1 g/kg,20℃和30℃条件下土壤氮矿化势(No)分别增加2.70及3.18 mg/kg;土壤全氮含量每增加1g/kg,No分别增加37.28及43.12 mg/kg。【结论】日光温室土壤氮素矿化量随其栽培年限的增加显著增加;培养温度由20℃增加到30℃,土壤氮素矿化量也明显增加,日光温室栽培年限和温度对土壤氮矿化有一定的正交互效应。因此,在日光温室氮素管理中应考虑栽培年限和温度对土壤氮素矿化的影响,以采取针对性的氮素管理措施。

Effects of temperature on soil nitrogen mineralization in solar greenhouses with different cultivation years

【Objectives】 Vegetables cultivated in solar greenhouse are under a very intensive and unique production system in China. However, over-application of fertilizers is very common. As the development of this system in north China, it results in a series of problems, including the degradation of soil properties,groundwater pollution. Many studies found that the content of soil organic matter was increased as the age of solar greenhouse. Unlike open fields, soil temperature in solar greenhouse is higher, and could affect nitrogenmineralization from the greenhouse soils. However, there is few research to study this topic. 【Methods】 Soil samples (0-20 cm and 20-40 cm layers) were collected from greenhouses with different ages (0, 2, and 3 years) in Yangling, Shaanxi which locates at the south edge of Loess Plateau. The contents of soil organic matter and total nitrogen were analyzed. An incubation method (84 d) was used to study effects of different temperatures (20℃ and 30℃) on soil nitrogen mineralization in the solar greenhouses. The first order reaction model was used to fit curve of soil N mineralization, and nitrogen mineralization potential (N₀) was used to evaluate the soil N mineralization. 【Results】1) The contents of soil organic matter, total N, and the accumulative mineralized N in different greenhouses are increased with the increase of greenhouse ages. 2) The soil mineralized N amount at 30 ℃ is higher than that at 20 ℃. The response of the mineralized N to temperature in soil with long cultivating history is higher than that in soil with short cultivating history. 3) As the increases of soil temperature and the cultivating history, the soil mineralized N amount is increased, and the soil N₀ is also increased. There is a positive interaction between soil temperature and the cultivating history, however, the difference is not significant. 4) Compared to the soil before planting crops, the N₀ values of soils with 2 and 3 years history are increased by 5.59 and 11.48 times, respectively. 5) The regression analysis indicates that the N₀ values of soils at 20 ℃ and 30 ℃ are increased by 2.70 and 3.18 mg/kg when soil organic matter is increased by 1 g/kg, and when soil total N content is increased by 1 g/kg, the N₀ values of soils at 20 ℃ and 30 ℃ are increased by 37.28 and 43.12 mg/kg, respectively. 【Conclusions】With the increase of cultivation year, the N mineralization from the greenhouses is increased significantly. When soil temperature increases from 20 ℃ to 30 ℃, the soil N mineralization is also increased. The accumulation of mineralized N of longer cultivated soil responses remarkably to the temperature changes. We conclude that when making sound N fertilizer recommendation for vegetable crops in solar greenhouses, the effects of temperature and cultivating history on the N mineralization from soil needs to be considered.