Study On Stubble Decomposition Characteristics And Nutrient Release Laws Under Different Stubble-returned Mode In The Loess Plateau Dry Farmland

Crop stubble is a kind of important renewable organic resource, it plays an important role in enriching soil fertility, increasing crop yield and protecting ecological environment after stubble returning. It has become the most direct and effective utilization way. Based on typical dry farming stubbles like corn and wheat stubble in the loess plateau dry agricultural area, using the nylon mesh bags method, the concrete decomposition condition, nutrient releasing rules and the influence of different stubble species, tillage measures, additive amounts, stubble-returned depths and decomposing accelerators on stubble decomposition was studied in Gansu Agricultural University dry farming testing station located in Mazichuan Village, Lijiapu Town, Anding District, Dingxi City, Gansu Province. The research will provide theoretical basis for the rational utilization of stubble and scientific management of farmland nutrients, also offer technical support for the promotion of stubble returning in the region. The main results were as follows:1.In the fast decay period(100d), corn stalk decomposed faster than wheat stubble, the release of carbon, nitrogen, potassium of corn stubble was quicker than wheat stubble, while the phosphorus release ratio of two kinds of stubble were rarely different.2.Plastic film mulching can promote stubble decay.The nutrient releasing ratio increases over time, and varies among different nutrients.3.Stubble additive amount has no significant effects on quality loss ratio, while with the increase of stubble additive amount, the decomposing rate rises. The nutrient release ratios of stubble increase over time, and rarely differ under different additive amounts.4.Soil buried corn stubbles decomposed faster than surface buried ones, the nutrient release ratio of soil buried stubble is also bigger than cover returning ones. Stubble with returning depth of 10 cm decomposed fastest under conventional tillage(T), while under conventional tillage with plastic treatment(TP), with the increasing of stubble-returned depth, the early-stage stubble quality loss ratio and nutrient release ratio increased; the difference between stubble-returned depth of 10 cm and 20 cm is not obvious in the late stage of decomposition, the two stubble-returned depth have little influence on stubble decomposition.5.Under conventional tillage(T), the three kinds of decomposing accelerators can all promote the stubble decaying in the early stage; while under the conventional tillage with plastic treatment(TP), adding decomposing accelerators has no obvious effect on stubble decomposition.