Vegetable Residues Resource and Effect of Waste Vegetable Retun to Field at Plateau
|Keywords||Quantity and nutrient resources of vegetable waste return vegetable waste tofield directly Nutrient release Nitrogen mineralization in soil Decomposing cycle Nitrogen lossin soil Yield effect|
The disposal of vegetable waste in the process of vegetable planting is a problem. Our research is based on vegetable waste cycle agriculture and main object is reduce the use of fertilizer. Laboratory incubation experiment and field experiment of vegetables waste of plateau summer vegetable were conducted in Lanzhou City in order to understand the decomposition cycle of vegetable waste and nutrients change in soil and fertilizer reduction after applied vegetable waste, provide a basis theory for vegetable waste return to field. The results showed as follows:(1) Large amounts of waste leaves was produced through vegetable growing, and waste leaves not only waste resources, but also pollute the environment as which contain nitrogen, phosphorus, and other nutrients, especially potassium. Vegetable waste return field become possible, because of farmland leisure during vegetable harvested in October until early April next year.(2) The result of decomposition experiment from mid-September to mid-March show that celery decompose more rapidly than cauliflower waste. The decomposition pattern which was characterized by using an exponential regression equation fit well except for H3(R2=0.49-0.71), and predict the half of celery and cauliflower waste dry matter decomposed need31-57and6-12days. Luckily, we noticed that logarithmic equation is better than the exponential equation.(3) Comparing with CK, soil fertility increased significantly when vegetable waste is added. Soil organic matter, total nitrogen, available phosphorus and potassium were1.28to1.39times,1.20to1.46times,1.36to1.82times,2.60-1.81times higher than the CK, respectively. pH decreased significantly.The result showed that the net accumulated nitrogen mineralization in amended soil under inorganic nitrogen supply level was4-5times higher than the CK, moreover, the net accumulated N mineralization under N1level was significantly higher than under other nitrogen levels. Net accumulated nitrogen mineralization in amended soil with wasted cabbage leaves was3-5times higher than the CK, and the net accumulated nitrogen mineralization under B2treatment was significantly higher than that under Bland B3treatments. No significant interactive effect was found (.P=0.275) between the inorganic nitrogen level and the addition of wasted cabbage leaves by statistical analysis. The addition of wasted cabbage leaves influence nitrogen mineralization in amended soil was the dominated factor(Eta2=0.16), while the inorganic nitrogen supply level was the secondary (Eta2=0.07). In the early period(0-20d) of incubation the net accumulated nitrogen mineralization gradually increased under B1treatment, and then maintained a steady tendency in the later period of incubation. But nitrogen mineralization, immobilization and re-mineralization occurred in the early period of incubation (30d) and the net accumulated nitrogen mineralization increased gradually in the later period of incubation under B2and B3treatments. The result showed nitrogen mineralization mainly occurred in the first30days of incubation according to mineralization rate after wasted cabbage leaves added. In addition, during the period of incubation, a first-order kinetics equation of net accumulated nitrogen mineralization in amended soil fits well with the extension of incubation days (R2=0.62-0.89).(4) Available N in lower layer and different fields decreased and vegetable yield kept steady after applying half P(600kg-ha-1) and no K(375kg-ha-1) compare with tradition and farmyard manure reduced when incorporate vegetable waste.(5) In summary, Vegetable waste return field not only making use of waste leaves efficiently, but also increasing the soil nutrient content, moreover, that can reduce environmental pollution based on the above analysis.