Soil nutrient content and nutrient balances in newly-built solar greenhouses in northern China

摘要

Soil nutrient content and nutrient balances in newly-built solar greenhouses in the southern part of China’s Loess Plateau were investigated over two consecutive years. Farmers applied manure and inorganic fertilizers at average annual rates of 1,907 kg N ha−1, 1,601 kg P2O5 ha−1 and 1,742 kg K2O ha−1. Manure accounted for 65 % of the total N input, 57 % of the total P input and 55 % of the total K input. The average annual nutrient surpluses were 1,374 kg N ha−1, 1,468 kg P2O5 ha−1 and 881 kg K2O ha−1. Soil organic matter, total N, available P, available K and electrical conductivity (EC) increased significantly across time in the topsoil (0–20 cm depth), but not in the subsoil (20–100 cm depth). The nitrate–N concentrations (mg N kg−1) of the 0–100 cm depth increased by 163–336 % over 2 years. The average accumulation of nitrate–N (kg N ha−1) of the 0–100 cm depth increased by 241 % and leveled out at 511 kg N ha−1; and it was 1,015 kg N ha−1 in the 0–200 cm depth. In conclusion, over-fertilization led to large nutrient surpluses in the soil of newly-built greenhouses.