Effects Of Integrated Nutrient Management On Nitrogen Utilization,Yield And Quality Of Rice-Rape Rotation

Rice and rape are the main grain and oil crops in China,and their production is directly related to china’s grain and oil security.Domestic and foreign scholars have done a lot of researches on how to obtain high yield of rice and rape from breeding,cultivation,fertilization and other aspects,but these work are mainly concentrated on the research of single technology,and little research on integrated nutrient management technology.The combination of rational fertilization and soil cultivation technology is an important guarantee for achieving high yield and high efficiency of crops.In recent years,excessive application or improper use of nitrogen fertilizer in rice-oilseed rape rotation in the upper reaches of the Yangtze River has led to a decrease in the utilization rate of nitrogen fertilizer,a serious loss of active nitrogen,and an increasingly prominent environmental problem.Low soil organic matter and certain soil nutrient deficiencies limit the increase of crop yield potential.At the same time,the adoption rate of integrated nutrient management techniques by farmers is low.Based on this paper,the rice-rape rotation in the southwest region was used as the test crop system.The effects of different measures of integrated nutrient management（addition of silicon fertilizer in rice,application of boron fertilizer in rape,use of bio-organic fertilizer and straw returing to field）on nitrogen assimilation and absorption,crop yield and soil fertility of paddy soil were studied systematically.The physiological characteristics of nitrogen,nutrient absorption and transport characteristics,and the yield and quality of crops in different growth stages of rice and rapeseed under different measures of integrated nutrient management were clarified.At the same time,reasonable nutrient management measures were proposed through nutrient balance,which to further enrich and supplements the nutrient regulation mechanism of rice-rape rotation,and achieves the goal of increasing crop yield and efficiency,and provides technical support for ecological security in the upper reaches of the Yangtze River.The main findings are as follows:Compared with no nitrogen treatment（CK）,the integrated nutrient management measures can significantly increase the content of soluble protein,free amino acid and chlorophyll of rice functional leaves and the enzymes activities of nitrogen metabolism.The contents of soluble protein,free amino acid and chlorophyll in rice-rape were higher than those in late growth stage,and rice was the highest in jointing stage,and rape was the highest in seedling stage or bud stage.In general,the contents of soluble protein,free amino acid and chlorophyll of Z4 treatment were the best,and they were different degrees of improved compared with FFP treatment.Z4 treatment significantly increased the NR activity in the early growth stage of rice,and Z3 and Z4 treatment significantly increased the NR activity of rape during the whole growth period.The integrated nutrient management measures are not very effective in improving the GS activity during the whole growth period of rice and rape.There were significant or extremely significant relationship between soluble protein,free amino acid,chlorophyll,NR activity,GS activity and N concentration in functional leaves of rice and rape.The integrated nutrient management measures promoted the accumulation of dry matter in rice and rape.During the whole growth period,the dry matter accumulation of rice and rape showed an increasing trend.In general,Z4 treatment of dry matter accumulation is better than FFP treatment,laying a material foundation for high crop yield.Compared with CK,integrated nutrient management measures can significantly increase crop grain nitrogen content.Nitrogen accumulation in the mature stage of rice and rape season was optimized by Z4.The NPP and NAE of rice showed a trend of Z4>Z3>Z2>Z1>FFP;The NPP and NAE of rape showed a trend of Z4>Z3>FFP>Z2>Z1;Among them,Z3 and Z4 treatments have achieved the purpose of nitrogen fertilizer efficiency.The integrated nutrient management measures can significantly increase the translocation and translocation efficiency of nitrogen,phosphorus and potassium in the rice and rape nutritional period to reproductive period,reduce the accumulation of nutrients in the stems,and increase the transport of nutrients into the grains.Compared with CK,integrated nutrient management has different degrees of increase in rice and rape yield and yield components.Both rice and rape yields were best treatment with Z4.Among them,the rice yield of Z4 treatment reached 8636.50kg.hm^-2,which was significantly increased by 763.00 kg.hm^-22 compared with FFP treatment.The rape yield of with Z4 treatment reached 2742.62 kg.hm^-2,which was not significantly different from FFP treatment.The regression equation of crop yield component showed that rice yield was mainly affected by the effective panicles and the number of grains per panicle,while rape yield was mainly affected by the number of siliques per plant and the number of seed per pod.Integrated nutrient management measures can improve crop quality.Compared with FFP,Z3 and Z4 treatments increased the content of crude protein and amylose in rice grains to different degrees.Z4 treatment had a significant effect on the oil content of rapeseed.Compared with CK,FFP treatment and integrated nutrient management measures significantly increased the total nitrogen content of soil tillage after rice harvest,and the increase range was 48.08%-52.88%.After the rape was received,the soil total nitrogen content of the Z4 treatment was significantly higher than rest treatment.Z3and Z4 treatments effectively improved the nitrogen supply in the middle and late seasons of rice,and Z4 treatment also effectively increased the nitrogen supply in the middle and late stages of rape.Compared with FFP treatment,integrated nutrient management measures can significantly increase soil microbial biomass nitrogen content in rice by 65.29%-106.14%.The effect of integrated nutrient management measures of rape on soil microbial biomass nitrogen is:Z3>Z4>Z2>Z1>FFP.Compared with CK,integrated nutrient management measures have improved soil available nutrients（alkaline nitrogen,available phosphorus,and available potassium）after rice and rape are received.But there was no significant difference in soil pH.Compared with FFP treatment,soil organic matter in integrated nutrient management measures has been improved to varying degrees.In the rice-rape rotation,the soil nitrogen is deficient in the rice season,both FFP treatment and integrated nutrient management measures had nitrogen surplus in rape.Except for the Z3 and Z4treatment in the rice,the rest treatment were surplus with phosphorus.All treatments of potassium have serious deficits in the two season crops.