日光温室土壤养分平衡及其累积特性

为探讨栽培年限对日光温室土壤养分平衡状况及其动态累积特性的影响,以黄土高原南部陕西杨凌的13个日光温室为研究对象,连续4 a监测其养分投入量、蔬菜产量、土壤养分含量等变化,以评价温室栽培系统养分平衡状况及土壤养分的累积特性.结果表明:温室土壤每年N、P2O5、K2O的平均投入量分别为18.04、15.65和17.79 kg/km2,其中来自有机肥的N、P2O5、K2O分别占各养分投入总量的64%、58%、53%,氮、磷、钾投入过量问题突出;表层土壤w(有机质)、w(TN)、w(矿质氮)、w(速效磷)和w(速效钾)均随栽培年限的延长而不断增加;与建棚时相比,栽培第1年和第2年温室土壤各养分含量增幅迅速,第3年和第4年养分累积速度相对减慢.随着温室栽培年限的延长,土壤剖面硝态氮累积量显著增加;虽然研究区井水中ρ(NO3--N)平均值低于GB 5749—2006《生活饮用水卫生标准》标准,但随着温室栽培年限的延长,硝酸盐向深层土壤淋溶及进入地下水的风险值得关注.

Nutrient Balance and Accumulation in Soils of Solar Greenhouses

Abstract: To understand the changes of nutrient balances and accumulations in soil of solar greenhouses, 13 solar greenhouses in the southern part of the Loess Plateau, Yangling, China were investigated over four consecutive years from 2009 to 2013. The results showed that the average annual input rates of nitrogen (N), phosphorus (P₂O₅) and potassium (K₂O) fertilizers in manure and inorganic fertilizer forms were 18.04,5.65 and 17.79 kg/km², respectively. Nutrient inputs from manure accounted for 64% of total N input, 58% of the total P input and 53% of total K input. The over-application of N, P and K nutrients in the greenhouse was very common. As the greenhouse age increased, organic matter, total nitrogen and available P and K accumulation in the topsoil (0-20 cm) significantly increased. The increasing rates were significant during the first and second years, then leveled off from the third to the fourth year. Nitrate-N and electrical conductivity (EC) also increased with greenhouse ages. The nitrate-N content in soil profiles showed clear leaching down during the first 2-4 years. Although the average concentration of nitrate-N in well water in the solar greenhouse region was lower than the recommended level of nitrate-N in the drinking water, great attention should be paid to the nitrate leaching risk due to the over-accumulation of nitrate in soil profiles as the solar greenhouses age.