Effects Of Different Tillage Patterns And Straw Returning On Crop Growth Characteristics And Soil Physical And Chemical Properties In A Rice-rape Double Cropping System

To explore the effects of different tillage patterns and straw returning on crop growth characteristics and soil physical and chemical properties,Field experiments were conducted using hybrid rice cultivar Neiwuyou 5399 and hybrid rape cultivar Youyan 817 as the materials in 2016 and 2017 in Suiyang County,Guizhou Province.Treatments were arranged in split-plot design with straw returning（A）as main plots and tillage patterns（B）as subplots.JH（straw returning）,JL（no straw returning）formed the main plot and SF（conventional-tillage in rice season）,SX（rotary-tillage in rice season）,YF（conventional-tillage in rape season）,YM（no-tillage in rape season）formed the subplots.The group characteristics of rice and rape and the physical and chemical properties were studied.The test results show that:1.The effects of different tillage patterns and straw returning on the growth characteristics of hybrid rice.The effects of tillage patterns and straw returning on the yield of rice did not reach significant difference,but no matter straw returning or no straw returning,the yield of SF treatment was greater than that of SX treatment,among them:JH SF（11698.42 kg/hm²）>JH SX（11636.90 kg/hm²）.JL SF（11624.64 kg/hm²）>JL SX（11475.11 kg/hm²）,JH SF>JH SX>JL SF>JL SX,It shows that conventional-tillage has certain effect on improving rice yield;Under the same tillage patterns（conventional-tillage or rotary-tillage）,the yield of JH treatment was greater than that of JL treatment,among them:SF JH（11698.42 kg/hm²）>SF JL（11624.64 kg/hm²）,SX JH（11636.90 kg/hm²）>SX JL（11475.11 kg/hm²）,SF JH>SX JH>SF JL>SX JL,it shows that straw returning has a positive effect on crop yield of rice.Under straw returning,effective spikes and grains per spike of SF treatment were higher than that of SX treatment;under no straw returning,grains per spike,setting rate and1000 grain weight of SF treatment were higher than that of SX treatment,finally,the actual yield of rice of SF treatment is greater than that of SX treatment;It can be seen from the tillage method that effective spikes,grains per spike,setting rate and1000 grain weight of SF treatment were greater than that of SX treatment;in the early stage of rice growth,no matter whether straw returned to field,the net assimilation rate of SF treatment was greater than that of SX treatment;In the late growth stage of rice,no matter whether straw returned to field,the crop growth rate of SF treatment was greater than that of SX treatment;with the growth and development of rice,the accumulation of dry matter in rice increased gradually,under straw returning,the dry matter accumulation of SF treatment was greater than that of SX treatment at jointing stage,heading stage and mature stage;under no straw returning,the dry matter accumulation of SF treatment was greater than that of SX treatment at mature stage.Under straw returning,the matter delivery rate of stems and sheathes,matter conversion rate of stems and sheathes、matter apparent delivery rate of stems and leaves and matter apparent delivery amount of stems and leave of SF treatment were greater than those of SX treatment;with the growth and development of rice,the nutrient absorption（N,P,K）of rice also increased gradually,and reached the maximum in maturity.the difference of the nutrient absorption（N,P,K）between the different tillage patterns and straw returning to the rice was not significant at the different growth stages of the rice（early growth stage,middle growth stage and late growth stage）.2.The effects of different tillage patterns and straw returning on the growth characteristics of hybrid rape.No matter straw returning or no straw returning,the yield of YF treatment was greater than that of YM treatment:JH YF（3725.03 kg/hm²）>JH YM（3358.37kg/hm²）,JL YF（3522.77 kg/hm²）>JL YM（2484..23 kg/hm²）,under no straw returning,the yield of YF treatment（3522.77 kg/hm²）was significantly greater than that of YM treatment（2484.23 kg/hm²）,it shows that conventional-tillage has certain effect on improving rape yield.Under the same tillage patterns（conventional-tillage or no-tillage）,the yield of JH treatment was greater than that of JL treatment,YF JH（3725.03 kg/hm²）>YF JL（3522.77 kg/hm²）,YM JH（3358.37 kg/hm²）>YM JL（2484.23 kg/hm²）,the yield of YM JH treatment（3358.37 kg/hm²）was significantly greater than that of YM JL treatment（2484.23 kg/hm²）.It shows that straw returning has certain effect on improving rape yield.No matter straw returning or no straw returning,pod number per plant,seed number per pod and 1000 grain weight of YF treatment were higher than that of YM treatment;under the same tillage patterns（conventional-tillage or no-tillage）,seed number per pod of JH treatment was greater than that of JL treatment,the seed number per pod of YF JH treatment（16.73）was greater than that of YF JL treatment（14.55）.No matter straw returning or no straw returning,in each period of rape,leaf area index、dry matter accumulation、nitrogen absorption、phosphorus absorption and potassium absorption of YF treatment was greater than that of YM treatment.With the growth and development of rape,the amount of nutrient uptake（N,P and K）reached the maximum,no matter straw returning or no straw returning,in each period of rape,the amount of nitrogen absorption,phosphorus absorption and potassium absorption of YF treatment was greater than that of YM treatment.No matter straw returning or no straw returning,the yield of YF treatment was greater than that of YM treatment,In this experiment,the comprehensive benefits of 4kinds of rape cultivation mode are as follows:JH YF>JL YF>JH YM>JH YM>JL YM.It is necessary to point out that in the actual production of agricultural production,the labor cost is constantly improving,and local can combine the actual practice of choosing reasonable tillage patterns with the straw returning to carry out rape production.On the one hand,it can save resources,reduce the cost and reduce the consumption.On the other hand,it can also promote the high quality and high yield of rape,and achieve the double benefits of increasing production and increasing income.3.The effects of different tillage patterns and straw returning on soil physical properties.From the average value of the bulk density of the 3 soil layers,no matter straw returning or no straw returning,on the average of 0-21cm soil layer,the bulk density of SF treatment was less than that of SX treatment,it shows that tillage has certain effect on reducing soil bulk density,and short term straw returning is not effective;in the 0-7cm soil layer and the 14-21cm soil layer,under the straw returning,the soil total porosity and capillary porosity of SF treatment were significantly higher than those of SX treatment,however,there was no significant difference between SF treatment and SX treatment,when straw was removed from field,it shows that straw returning can reduce soil bulk density and soil porosity.There was no significant difference in aeration porosity between the 3 soil layers under different tillage patterns and straw returning,however,under straw returning,soil aeration and porosity of tillage treatments were greater than that of rotary tillage,it shows that tillage has some effect on improving soil aeration porosity,but short term straw returning has little effect on soil aeration porosity,when the straw was removed from the field,the water holding capacity of the 3 soil layers was significantly greater than that of the rotary tillage treatment,indicating that the short-term straw returning to the soil has a small influence on the water holding capacity of the soil,and the tillage method had a great influence on the soil water holding capacity.4.The effects of different tillage patterns and straw returning on soil chemical properties.This study showed that there was no significant difference in soil available phosphorus,available nitrogen,total nitrogen,available potassium,CEC,exchaneable Mg²⁺and exchaneable Ca²⁺in 0-7cm soil layer,7-14cm soil layer and14-21cm soil layer.In this study,in the 0-7cm soil and 7-14cm soil layer,no matter whether the straw returned to the field,the soil organic matter content of the tillage treatment was significantly greater than that of the rotary tillage treatment,under the two tillage methods,the organic matter of 0-21cm soil layer treated by straw returning was larger than that of straw,but not significant;in the 0-7cm soil layer,no matter whether the straw was returned to the field,the total phosphorus in the soil treated by plowing was greater than that in rotary tillage;in the 3 soil layers,no matter whether the straw was returned to the field,the total nitrogen content of the tilled soil was greater than that of the rotary tillage treatment,and the total nitrogen of the 0-7cm soil layer and the 7-14cm soil layer was significantly greater than that of the rotary tillage treatment when the straw was removed from the field;in the 0-7cm soil layer,no matter whether the straw was returned to the field,the total potassium content in the soil treated by tillage was greater than that in the rotary tillage treatment;in the7-14cm soil layer,no matter whether the straw was returned to the field,the soil available nitrogen content of the tillage treatment was higher than that of the rotary tillage treatment;in the 14-21cm soil layer,no matter whether the straw was returned to the field,the available phosphorus content in the soil treated by plowing was larger than that in the rotary tillage;in 14-21cm soil layer,under the same tillage way,soil available potassium in straw returning field was significantly larger than that in straw field.