Application of Organic Fertilizer in Substrate Cultivation

Substrate cultivation experiments,in which rape and amaranth were chosen in succession as experimental crops,have been carried out to study the effect of different rate of organic fertilizer on vegetable growth and nutrients uptake.Fermented pig manure was applied once as base fertilizer before rape sowing and no other fertilizer was applied any more during rape-amaranth growth period.The results showed that higher rate of organic fertilizer(70,90 kg/m~(3)) significantly inhibited rape growth,while treatment of lower rate of organic fertilizer(10 kg/m~(3)) reduced biomass of amaranth in succession.With increase of organic fertilizer rate the balance indexes,which is ratio of amount of supplied nutrient to amount of absorbed nutrient by plants,increased and nutrients use efficiency decreased.Use efficiency of nitrogen,phosphorus and potassium in organic fertilizer were 9.5%-34.5%,2.5%-7.1% and 24.4%46.6% respectively.Available nitrogen content in the substrate of all treatments was very low after amaranth harvest,while available phosphorus was accumulated significantly.The paper also discussed on possibility of organic fertilizer used once as base fertilizer without topdressing in long-term-vegetable-cultivation system.