Effect of balanced fertilization on yield and quality of sunlight greenhouse cucumber and soil characteristics under continuous cropping

Multi-site experiment was conducted to study the effect of balanced fertilization on yield and nutrition quality of cucumber and characteristics of soils, which was then compared with custom application fertilizer in continuous cropping under sunlight greenhouse conditions. Balanced fertilization technique includes mathematical model and target yield method. The results show that balanced fertilization increases cucumber yield, saves investment and therefore enhances benefit and improves nutrient quality of sunlight greenhouse cucumber. At the same time, this technique obviously alleviates accumulation of soil nutrient and salinity. Mathematical fertilization model adapts to continuous cropping in sunlight greenhouse conditions for longer periods or higher soil nutrients, while balanced fertilization for target yield adapts to continuous cropping in sunlight greenhouse conditions for shorter periods and lower soil nutrients. Compared with custom fertilizer application, cucumber yield under balanced fertilization for target yield increases by 5.4%～30.8%, fertilizer investment reduces by 734～59 253 yuan·hm^-2, nitrate content in cucumber decreases by 20.8 ～145.3 mg·kg^-1, and vitamin C and soluble sugar content respectively increases by 0.2～2.5 mg·(100g)^-1 and 0.11 %～0.47 %. Compared with custom fertilizer application, cucumber yield under mathematical model fertilization increases by 7.6%～34.7%, fertilizer investment reduces by 944～59 463 yuan·hm^-2, nitrate content in cucumber decreases by 14.0～147.0 mg·kg^-1, vitamin C and soluble sugar content respectively increases by 0.4～3.5 mg·(100g)^-1 and 0.14 %～1.11 %. At harvest, soil nutrition and conductivity under balanced fertilization reduces. Soil salinity is in significant correlation with conductivity(R = 0.949 5) for sunlight greenhouse cucumber in Hebei Province. Soil conductivity can serve as an important indicator of soil salinity.