Study On The Characteristics Of Crop Straw Maturity And Its Effect On Soil Carbon Transport And Wheat Nutrient Absorption

China’s crop straw resources are abundant and widely distributed,but the utilization level is low,and at the same time,more fertilizer is input into farmland.Therefore,it is very significance that improve the effective utilization of straw resources and promote the efficiency of material recycling.This experiment is conducted through three different ways:In a constant temperature incubator,a three-factor three-level orthogonal design is used to combine the three factors of temperature,straw length and straw type,to study the decomposition of straw and dynamic process of nutrient release.Among them,the setting temperature of wheat straw decomposition is 15℃,25℃and 35℃,the straw length is:powder,5cm and 10cm;the maize straw setting temperatureis 15℃,20℃and 25℃,the straw length is:powder,4cm and 8cm.By returning ¹³C-labeled maize straw to the field,the circulation and distribution of the straw after entering the soil can be tracked.Based on the cultivation and fertilization positioning tests began in 2010,nine treatments were set in the trial,namely:deep tillage+organic fertilizer（DTF）,shallow tillage+organic fertilizer（STF）,no tillage+organic fertilizer（NTF）,deep tillage（DT）,shallow tillage（ST）,no tillage（NT）,deep tillage nitrogen+reduction by 20%（DTR）,shallow tillage+reduces nitrogen by 20%（STR）,no tillage+reduces nitrogen by 20%（NTR）.In order to explore the effects of farming methods and fertilization modes on the soil fertility of farmland,and provide a theoretical basis for comprehensive management of nutrient resources and measures for improving soil fertility of farmland.The main conclusions of this study are as follows:1.Under the combined effect of temperature,straw length and straw decomposing agent,the decomposition characteristics of wheat straw and maize straw are different.At the same temperature,the smaller the straw volume and the better the degree of decomposition by adding straw decomposing agent.With the extension of the decay time,the higher the straw decomposition rate,the less the residual amount.After 100 days of decomposition,the surface morphology of wheat straw and maize straw were looser and the decomposition rate and decomposition rate were significantly higher than those of other treatments at35℃and 25℃,respectively.Wheat straw has the highest carbon and nitrogen nutrient release rates under A₃B₁C₃ treatment;the soil total phosphorus and available potassium contents were relatively higher under A₃B₂C₁ treatment.Under the treatment of A₃B₁C₃,the nitrogen nutrient release rate of maize straw was the highest,which was 83.25%.The content of available potassium in the soil under A₃B₃C₂ treatment was significantly higher than that in other treatments.2.The ¹³C content of wheat rhizosphere soil and non-rhizosphere soil changes with the growth period.As the growth period progressed,the ¹³C content of non-rhizosphere soil gradually decreases,and the ¹³C content in the rhizosphere soil is the lowest at the jointing stage,and slightly increasesat the maturity stage.The ¹³C distribution rate in wheat rhizosphere soil and non-rhizosphere soil showed that the ¹³C distribution rate in non-rhizosphere soil decreased（96.03%-94.74%）,while the ¹³C distribution rate in rhizosphere soil increased（3.97%-5.26%）.The soil nutrient content also behaves differently under different treatment.On the whole,the total carbon content of the soil under W₂treatment was significantly higher than that of the other treatments;while the total nitrogen and total phosphorus contents in the soil under W₁treatment remained at a high level throughout the growth period of wheat.3.Soil nutrient content and wheat yield are different under different tillage and fertilization modes.The changes of soil total carbon and total phosphorus content are consistent,and they gradually decrease as the growth period progresses and the soil layer deepens.The total nitrogen content shows a trend of first decreasing,then increasing,and then decreasing throughout the growth period.On the whole,STF treatment can increase the total carbon and total nitrogen contents of the 0-60cm soil layer,and the total phosphorus content of soil is highest under DTF treatment.DTF treatment can increase the number of spikelets and spikelets per wheat.The yield of wheat treated with organic fertilizer is higher,of which DTF treatment has the highest yield(11412.33 kg·hm^-2),followed by STF and NTF treatment,respectively it is11121.68 kg·hm^-2,10468.72 kg·hm^-2.