Study On Return-field Corn Straw Decomposition And Nutrient Release Characteristics Under Two Tillage Methods Of Rainfed Farmland In The Loess Plateau

As a carrier of substance, energy and nutrient, crop straw is a valuable and renewablenatural resources in agro-ecosystems. Using straw resources efficiently is closely linked with asereise of sustainable agricultural development problems in farmland and agriculturalproduction,such as soil fertility, soil conservation, environmental security and ecological balance.Straw return-field skill is not only an important conservation tillage technology,but also aneffective way to effectively use straw resources and economic-ecological sustainabledevelopment, which has been widely used in agricultural production. Starting from the stalkitself, under the special climatic conditions in the Loess Plateau, a typical dry farmland in thearea of corn stalks, exploring straw decomposing mechanism (decomposition characteristics andnutrient release characteristics) and the influencing factors deeply, can make contribute inpromoting the development of conservation tillage techniques. This thesis is on the basis of fieldtrials, using traditional tillage and traditional tillage with plastic, using buried bag method tostudy on the corn straw decomposition, nutrient release patterns, and the effect of differentreturn-field quality, return-field depth, straw decomposing, the main conclusions are as follows:1The corn straw decomposed value, decompoed ratio, decomposed rates of Conventionaltillage with plastic treatment were higher than conventional tillage treatment.2According to the characteristic of straw decomposed value, decompoed ratio, decomposedrates under different decaying periods in the field, the whole process of corn strawdecomposing were devided into two phases: fast decaying straw period (pre-90d), slowdecomposing period (90d after).3The straw decomposed value, decompoed ratio, decomposed rates increases with theincrease of the corn straw return-field quality; decomposing corn stalks plowing rate wassignificantly greater than the surface field covered treatment; adding decomposing agent canpromote corn stover decomposition. The promoting effect is different by different types ofdecomposing agent in early decomposing period, and the difference decreases latter.4Corn stover contains large amounts of nutrient elements such as C, N, P, K, each elementhas a characteristics: pre-release period which were released quickly (90d), the late slow releasecharacteristics. After decomposing270d, each nutrient elements release rate of corn stalksdecreasing order is below: total potassium (97.15%), total phosphorus (81.85%), total nitrogen(80.23%), total organic carbon (78.68%).5The straw return-field quality too less is not conducive to the release of organic carbon and total nitrogen. Increasing straw return-field quality can promote nutrient release. Strawplowing fields nutrient release rate is greater than straw mulching, which under conventionaltillage conditions the depth of field to handle the maximum nutrient release rate of20cm, underconventional tillage with mulch conditions the depth of field of nutrition10cm maximum release;decomposing agent can affect different levels of corn stover nutrient release, the effect ofdifferent farming methods promoted decay differences.