Decomposition Characteristics Of Cotton Stalk Under Different Rates

Stalk returning is an important measure to the sustainable development of agriculture.Exploring the characteristics of stalk decomposition and nutrient release can provide a scientific basis for evaluating soil quality and fertility.This experiment in Hubei area focused on cotton stalks which is based on cotton-wheat crop rotation mode,including zero stalk returning(ZS),half stalk returning(HS)and all stalk returning(AS),was carried out to explore the cotton stalk decomposition and its nutrient release,and the effect on soil nutrient level and wheat production.The main results are as follow:1.The different amounts cotton stalk decomposition behaved “quicker-slower”.The cotton stalk decomposition rate in HS and AS treatments was the fastest during the 0-20 d,and then the decomposition rate decreased gradually.After 170 days,the decay rates of HS and AS were 73.4% and 66.8% in 2018-2019,77.6% and 60.4% in 2019-2020,respectively.2.After 170 days,the cumulative release rates of soluble sugar,lignin and cellulose were 79.80%-81.38%,65.5%-69.0% and 58.3%-60.7%,respectively.After 70 d,soluble sugar,cellulose and lignin cumulative release amount at this time could account for more than 50% of the total release amount.3.The model of nutrient release was directly release.After the cotton stalk decomposed for 170 d,83.1%-83.9% of stalk K had been released compared with 74.3%-80.5% of stalk P,66.5%-74.4% of stalk N.4.During the decomposition period,the N,P and K release rule of cotton stalk different parts was fast at first and then slow.After 170 days decomposition,there was no significant difference in the release rate of each nutrient among different treatments.After170 d N release rate: cotton shell > cotton stem > branch > cotton root,P release rate:branch > cotton stem(cotton shell)> cotton root,K release rate: cotton shell > branch >cotton stem(cotton root),and the nutrient release rates decreased in the order K > P >N.5.After cotton stalk was returned to the field,soil organic matter,total N,total P,total K,alkali-hydrolysed N,available P,and available K increased by 25.5%-35.6%,33.3%-39.3%,8.3%-12.5%,6.2%-45.1%,39.8%-48.4%,18.4%-25.4%,12.5%-25.2%,respectively,compared with the treatment without stalk.6.Cotton stalk returning to field increased winter wheat yields,and the effect of all returning was more significant than half returning.Compared with the treatment without stalk returning,stalk returning increased panicles per unit area of wheat,and it increased with the increase of the amount of stalk returning.The cotton stalk returned to the field can basically decompose(70%)during the winter crop growth period.Stalk returning to the field is beneficial to improve the soil nutrient and increase the yield of winter crop(wheat),and it is appropriate to return the all amount of stalk to the field.