| Rice is the main food crop in China,which has a long history and a wide planting area.By the end of 2018,China’s rice planting area and output have reached 4.8 million hectares and 28.59 million tons respectively.Chongqing is located in the southwest of China.It is one of the six major rice areas in China.Its planting area is stable at 700000 hectares throughout the year,with an annual output of about 5.2 million tons.At present,there are many problems in rice planting in our city,such as large amount of fertilizer,unreasonable proportion of fertilizer and extensive way of fertilizer application.In order to pursue the output value of rice,farmers often have the phenomenon of excessive fertilization,which results in the accumulation of nitrogen and phosphorus in the paddy soil and the increase of the risk of nutrient loss.Nutrient loss will not only affect crop quality,surface runoff will also cause eutrophication of water,ammonia volatilization will also aggravate greenhouse effect and other problems.The above problems are disadvantageous to the city’s economy and ecological environment.Therefore,on the basis of ensuring the food security of our city,we should carry out scientific weight-loss,reduce nutrient input,improve nutrient utilization efficiency and achieve environmentally friendly fertilization without reducing rice yield.In view of the problems of large amount of fertilizer and low efficiency of fertilizer application in rice production in Chongqing,based on the investigation results of soil fertility level and farmers’ fertilizer application in Chongqing region,the recommended amount of N,P and K was determined according to the target yield method,and the effect of balanced fertilization formula on rice growth character,output value and comprehensive utilization rate of fertilizer was explored by field test verification method Demonstration,new business subjects and modern vocational farmer training were carried out to realize the popularization and application of rice area.The experiment and verification of Rice Fertilization Formula Based on Chongqing’s basic soil fertility were studied,and a large area of popularization and application was carriedout.The main research results are as follows:1.In order to control the total amount of nutrients in a specific area,a large formula fertilizer design was carried out.According to the basic soil fertility level of rice in various regions of Chongqing,more than 408 soil samples of rice field in Chongqing were collected in 2018 by the combination of sampling method and multi-access sampling to determine the nutrient content.The results showed that according to the regional characteristics of soil nutrients,the rice production area of our city was divided into three areas,namely southeast,northeast and West Chongqing.The soil nutrient status of each area is as follows: Southeast Chongqing Area > West Chongqing Area > middle and Northeast Chongqing area.According to the level of soil P and K and the situation of nutrient abundance and deficiency,the soil zoning of Chongqing area is summarized,which is the rice area of Western Chongqing,the rice area of Southern Chongqing and the rice area of Northeast Chongqing.According to the current situation of soil nutrients and the target yield method of rice,the recommended amount of N,P and K in each region of our city was determined.2.In order to verify the best application amount of NPK in three areas of our city,the effect of reduced fertilization on the growth and yield of rice was studied by plot experiment.The optimum amount of N,P and K for rice in the three areas were n 131kg/ ha,p2o548 kg / HA and K2 O 72kg / HA in the northeast of Chongqing,n 131 kg / ha,p2o542 kg / HA and K2 O 63kg / HA in the West and south of Chongqing.The yield of optimized treatment was 7.65%,5.2% and 12.2% higher than that of farmers.The indexes of leaf area index,SPAD value and dry matter accumulation of rice plants showed the same trend,that is,the indexes of optimized fertilization treatment were higher than those of farmers’ habit treatment,SPAD of rice differentiation stage was5.2% higher than that of farmers’ habit treatment,1000 grain weight of rice under optimized fertilization treatment was 30.7% higher than that of farmers’ habit treatment,and leaf area index was significantly different from that of farmers’ habit fertilization.3.in order to make clear the feasibility of reducing the amount of fertilizer and explore its impact on the output value of rice,and provide a theoretical basis for the formulation of a suitable fertilization program for "weight loss and efficiency" of rice.The yield of rice was measured at the mature stage of rice.The results showed that the yield of rice increased by 10.1%,14.0% and 12.4% respectively in the south of Chongqing,5.2% in the west of Chongqing,and 11.0% and 4.3% in the northeast of Chongqing.The 1000 grain weight of optimized fertilization treatment was 30.7%higher than that of farmers’ habit treatment,and the optimized fertilization treatment had a positive impact on rice yield.Combined with the response of rice output value after reduced fertilization,it is recommended to continue to use the optimized fertilization treatment scheme in the rice production area of Northeast Chongqing to meet the high yield of rice;in the rice production area of West Chongqing and South Chongqing,it can continue to lose 20% weight on the basis of optimized fertilization treatment.4.In order to explore the ability of optimizing fertilization to supply nutrients to rice and to avoid the risk of nutrient loss.The changes of nitrogen and phosphorus content in the surface water of the paddy field were measured after fertilization,and the basic properties of the cultivated soil were measured before fertilization and after rice ripening.The results showed that the concentration of ammonia nitrogen and total nitrogen in the field water increased significantly on the next day after the application of base fertilizer,and the total nitrogen reached the maximum peak value.However,with the passage of time,the nitrogen concentration in the field water decreased rapidly and steadily in the week after fertilization.Under the condition of farmers’ habit of fertilization,the total nitrogen of the surface water of the plot is the highest at different times,and the risk of nitrogen runoff is high.The highest peak content of total nitrogen in the surface water of optimized fertilization treatment was 50% ~ 75% lower than that of farmers’ habitual fertilization treatment.And the content of alkali hydrolyzed nitrogen in opt soil was always higher than that of FFP.Therefore,optimized fertilization can reduce the risk of nutrient loss,and the ability of continuous nitrogen supply of OPT is significantly higher than that of FFP.5.In order to explore the potential of optimizing fertilization cost saving and efficiency increasing,this paper analyzed the comprehensive efficiency of fertilizer and economic angle,collected rice plants,and measured the nutrient content.By analyzing the effect of optimized fertilization on fertilizer efficiency,it is found that the nitrogen utilization rate,agronomic utilization rate and partial productivity of OPT are higher than those of FFP.In the demonstration and extension experiments of 10 districts and counties,the nitrogen utilization rate and partial production rate of OPT are 8.9% ~35.5% and 3.18% ~ 45.18% higher than those of farmers,and the income after deducting fertilizer cost The income increased by 5.23% ~ 12.66% compared with the farmers’ habitual fertilization.However,on the basis of optimized fertilization treatment,the nitrogen increased by 20%,and the three nitrogen efficiency indexes decreased.Therefore,optimizing fertilization can not only reduce costs and increase economicbenefits,but also improve the efficiency of fertilizer utilization.6.In order to explore the promotion ability of the large formula fertilization scheme,according to the soil fertilization ability and the characteristics of rice fertilizer demand,the recommended fertilization amount in Chongqing rice area was formulated.In terms of rice special fertilizer products and supporting technical scheme and comprehensive technical mode of reduced fertilization,a complete set of nutrient management technology for rice whole process nutrition package in Chongqing was formed.In conclusion(1)on the basis of farmers’ habits,the weight loss of 20% of rice yield in three regions of Chongqing increased by 4.3% ~ 14.0%,and the utilization rate of nitrogen increased by 8.9% ~ 35.5%.Rice weight loss can achieve the purpose of increasing efficiency.2.The optimized fertilization treatment has stronger physiological activity than the farmers’ habitual fertilization treatment,which significantly increases the leaf area and SPAD index of rice,leading to the obvious enhancement of leaf photosynthesis and good accumulation of grains.In addition,the optimized fertilization can reduce the runoff loss of nitrogen and the risk of pollution.(3)The comprehensive technology model of reducing fertilization in three rice planting areas of Chongqing was established and applied in a large scale.The research has very important theoretical and practical value. |
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