Study On The Interaction Effect Between Straw Mulching And Rice Season Water And Nitrogen Management Under Diversified Cropping Pattern

In order to explore the mechanism of different straw return and paddy season water and nitrogen management in paddy field and paddy field to improve rice yield,fertilizer use efficiency and soil nutrients In this study,the super rice F You 498 was used as the material under different rotation patterns.Through the two-year positioning experiment in 2018-2019,different rotation patterns were set in 2018.Straw return and rice season nitrogen reduction and fertilization were applied to the growth and yield of rice.And the effects of soil nutrients,that is,wheat-rice,rape-rice and green cabbage-rice three previous crop rotations(stubble)covering and returning to the field,three different nitrogen application rates for the rice season(no nitrogen application),Conventional nitrogen application and precise nitrogen reduction),in 2019,the effects of straw rotation and water and nitrogen management on rice growth and development,yield and soil nutrients were set in different rotation patterns,that is,wheat-rice,rape-rice-rice and green cabbage-In the three different rotation modes of rice,the former crop straw(stubble)was covered and returned to the field,different water management(conventional submerged irrigation and alternating dry and wet irrigation)and different nitrogen application treatments(no nitrogen application,conventional nitrogen application and precise nitrogen reduction).The effects of the previous crop straw return and rice season water and nitrogen management on rice yield formation,root development,material accumulation,straw decay and N release rate,soil nutrients,and nitrogen absorption and utilization efficiency at different growth stages of rice were systematically studied under different rotation patterns.influences.In order to improve the theoretical and practical basis for the diversification of rice straw before rice cultivation and the efficient use of rice season nitrogen.The main findings are as follows:1.Effects of returning straw to field and water and nitrogen management in rice season on rice yield and component factorsIn the two-year positioning experiment,the yield of rice in the oil-rice rotation mode was the highest.The main reason for the first year was that the oil-rice rotation mode had the highest effective ears,while the wheat-rice rotation mode had a 16.44% lower effective ear than other rotation modes 17.05% is the main reason for the lowest yield of this rotation model,and the yield components of the precise nitrogen reduction treatment in the rice season have not been significantly reduced compared with other nitrogen application rates,which is the reason for its continued yield reduction.In the second year,the oil-rice rotation model had higher grains per panicle and seed setting rate to obtain the highest yield.Under the different irrigation conditions,except for the grains per panicle,the other yield components and yields were W1> W0.At the same time,the number of grains per ear was the highest under the precise nitrogen reduction treatment in the rice season,and the other yield components were not significantly different from other fertilization treatments,and the final yield was not significantly reduced compared with conventional nitrogen application.To sum up,under the two-year positioning experiment oil-rice rotation system,rapeseed straw returning to the field combined with dry-wet alternate irrigation and conventional nitrogen application yields the highest yield,but precise nitrogen reduction treatment can reduce the amount of nitrogen fertilizer applied and obtain a higher effective ear As well as the number of grains per ear,the yield is not significantly different from that of conventional nitrogen application.Considering the yield result and the goal of green energy-saving production,rape-stalk straw returning to the field with dry-wet alternation and precise nitrogen reduction treatment is the best match model in the oil-rice rotation mode.2.Effects of returning straw to field and water and nitrogen management in rice season on rice root structure and material accumulationThere was no significant difference in the cell ultrastructure of rice roots with straw returning under different rotation modes,but the cell structure of rice roots was affected by conventional nitrogen treatment under flood irrigation,alternating dry and wet non-nitrogen treatment and alternating dry and wet nitrogen application.Different degrees of damage,and the combination of dry and wet irrigation with precise nitrogen reduction and fertilization treatments have complete rice root cell structure,thin cell walls,and many organelles,which is conducive to cell material exchange and information exchange to promote rice growth and development.The two-year rice dry matter accumulation law and yield are similar,and the oil-rice rotation model has the highest dry matter accumulation in rice.Different rotation modes mainly affect the accumulation of dry matter in the first and middle stages of rice,and the amount of dry matter accumulation in rice under different water management is basically the same.The performance is W1> W0,in which the dry matter accumulation of each organ in the rice-oil rotation model at the jointing stage is higher by 9.6%-9.8% than that of W0 treatment.For the amount of nitrogen applied in the rice season,the amount of dry matter accumulated in the early stage of the precise nitrogen reduction in the first year of the rice decreased.As the positioning year increased,the precise nitrogen reduction in the second year increased the stem and leaf stems of the rice at the full ear and mature stage.Material accumulation.From the perspective of dry matter transport,the stem-sheath dry matter output rate and contribution rate of rice stem and sheath were the lowest in the first year of oil-rice rotation system,while the stem and leaf output rate and contribution rate were 2.24% ～ 20.1 higher than other rotation modes in the second year.%,Combined with alternating dry and wet irrigation and precise nitrogen reduction treatment can also significantly increase the dry matter contribution rate of the leaves,thereby coordinating the accumulation and translocation of rice aerial matter,maintaining a high dry matter output rate and contribution rate,and promoting dryness in the late flowering period The material was transported to the ears to obtain high yield.3.Effects of returning straw to field and water and nitrogen management in rice season on nitrogen absorption,translocation and utilization of riceThe nitrogen absorption law of rice in different rotation patterns is similar to that of dry matter.In the first year of the oil-rice rotation pattern,the nitrogen accumulation of rice vegetative organs is 1.6% ～ 49.8% higher than that of other rotation patterns,especially the nitrogen in the stem and leaf Absorption;while the precise reduction of nitrogen in the rice season reduces the nitrogen absorption of vegetative organs at different stages,especially at the jointing stage of rice.In the second year of the oil-rice rotation model,except for the nitrogen accumulation in the rice mature stage,the remaining periods were higher by 7.6% to 61.4% than other rotation models,while maintaining the highest stem and leaf nitrogen contribution rate,but may be due to straw Compared with wheat-rice rotation system,decomposition has no obvious advantages in nitrogen transport.Water and nitrogen can synergistically promote the accumulation and operation of nitrogen.Under the alternating dry and wet irrigation,the accumulation of nitrogen in different periods,especially in the early and middle stages of rice,is significantly higher than that of submerged irrigation.It can also significantly promote nitrogen transport and reduce nitrogen in vegetative organs.Element retention.Compared with the first year,the precise reduction of nitrogen in the rice season increased the nitrogen accumulation in the stem and leaf of the rice in the middle and late stages,and also significantly promoted nitrogen transport and redistribution,which was beneficial to the nitrogen accumulation in the ear of the mature stage.For fertilizer utilization,the physiological utilization rate and agronomic utilization rate of rice nitrogen fertilizer in the first year of vegetable-rice rotation mode are the highest,while in the second year,the rice paddy production efficiency,agronomic utilization rate of nitrogen fertilizer,and nitrogen fertilizer partial The highest productivity.Different water treatments also have a significant effect on rice fertilizer utilization.Alternating dry and wet irrigation improves most of the fertilizer utilization index of rice.This effect is most obvious in the vegetable-rice rotation system,and precise nitrogen reduction in the rice season saves nitrogen.In addition to the first-year vegetable-rice rotation system,the utilization efficiency of other fertilizer treatments is significantly improved compared to conventional nitrogen application.In summary,with the increase in positioning years,the oil-rice rotation model combined with alternating dry and wet irrigation can obtain higher nitrogen transport of stems and leaves.With the precise nitrogen reduction treatment,although the nitrogen absorption of mature period is slightly reduced,the difference is not Significantly,at the same time,it promotes the transfer of nitrogen in the stem and leaf of the rice at the full panicle stage,especially the retained nitrogen in the stem to the panicle,and due to the comprehensive regulation of water and nitrogen,it promotes nitrogen absorption,reduces nitrogen loss,and significantly improves the agronomic utilization rate of nitrogen fertilizer.And partial productivity of nitrogen fertilizer,improve nitrogen utilization efficiency.4.Effects of returning straw to field and water and nitrogen management in different seasons on the rate of straw decomposition and nitrogen releaseThe nutrient release rules of different types of straw returning to the field remained the same for two years,showing a fast-slow-slow trend.At the same time,the two-year straw decomposition rate and N release rate showed that the vegetable residues returned to the field(Pq)> wheat straw returned to the field(Px)> Returning rape straw to field(Py),especially the decomposition rate of residues in green vegetables is significantly higher than that of other straw returning fields,but the nitrogen of rape straw returning fields is more conducive to rice absorption.Under different water and fertilizer management in the rice season,the decomposition rate of different straws in the early stage was W0> W1,and in the middle and late stages was W1> W0,but the N release rate of straw(residue)in different periods was W1> W0.The release rate of straw in the early stage of precise nitrogen reduction was slightly reduced,but it was significantly accelerated in the middle and late stages.At the same time,the release rate of N was significantly improved at any time.It can be seen that different straws combined with alternating dry and wet irrigation and precise nitrogen reduction can effectively promote Especially in the middle and late stages of straw decomposition and N release.5.Effects of returning straw to field and water and nitrogen management in rice season on soil nitrogenAfter two years of straw returning to the field under different rotation patterns,the soil fertility under different rotation patterns showed an upward trend,and the effect of increasing total nitrogen was much higher than that of alkali-decomposed nitrogen.The first increase and the second increase in the first and second year of the law are Pq> Px> Py and Pq> Py> Px,respectively,and alkaline nitrogen decomposition is Pq> Px> Py and Px> Py> Pq,the first year and the first After two years of rice harvest,the soil total nitrogen and alkaline hydrolyzed nitrogen content increased by 9.6% ～ 22.3% and 3.5% ～ 5.9%,respectively,compared with before sowing.With the extension of the year,the return of rapeseed and wheat straw to the soil promoted the increase of soil alkaline nitrogen,which was more obvious,and the nutrient loss in the autumn vegetable field was serious.Alternate dry-wet irrigation has a better effect on promoting soil alkaline nitrogen decomposition.Under the oil-rice rotation system,the increase rate of soil alkaline nitrogen in the rapeseed straw returning field was W1 75% higher than that of W0,indicating that the rape straw returning to the field combined with the application of dry and wet alternate Irrigation can effectively promote the increase of soil alkaline nitrogen,and rape straw can be more easily converted into available nitrogen.Two years of nitrogen application treatments have significantly increased soil total nitrogen and alkali-decomposed nitrogen content,and conventional nitrogen application treatments are higher than precise nitrogen reduction treatments,but the difference between the two is not significant.Soil nutrients increase with the increase of nitrogen application,but the difference between conventional nitrogen application and precise nitrogen reduction treatment is not significant,and there is no significant yield reduction.Combined with the yield results and analysis of green energy saving targets,oil-rice rotation can be used for production Combined with alternating dry and wet irrigation and precise nitrogen reduction can significantly increase the soil alkaline nitrogen content(75%),promote the effective conversion of nitrogen,reduce nitrogen waste.