Study On Yield,Resource Utilization Efficiency And Environmental Cost Of Different Planting Patterns In The Middle Reaches Of Yangtze River

Influenced by climate change and new production conditions,the planting area of early rice in the middle reaches of the Yangtze River decreases year by year,and the demand of maize in southern rice-growing areas increases gradually due to the advantages of labor-saving,high efficiency and high yield.In recent years,new planting modes,such as spring maize-late season rice,double-cropping maize and middle season maize-winter cole,have emerged in the middle and lower reaches of the Yangtze River.However,with the emergence of new planting modes,the lag of relevant cultivation research on the modes and can not guide the development of production and new planting modes.The formation of annual yield,the distribution and utilization characteristics of resources,and the environmental costs of different planting modes are still unclear.Therefore,on the basis of the traditional double cropping rice and middle season rice-winter cole pattern in this area,new cropping patterns,such as spring maize-late season rice,double cropping maize and middle season maize-winter cole,were constructed by replacing Resources-efficient crops.The annual yield formation,light,temperature,water use efficiency,environmental costs（soil physical and chemical properties and greenhouse gas emissions）of different cropping patterns were systematically studied.The main results are as follows:1.The annual yield and dry matter accumulation of maize-maize,maize-rice and maize-cole in maize cropping model were significantly higher than those in traditional rice cropping model,and the yield of maize in single season was significantly higher than that of rice and cole.Annual yield of spring maize-late season rice and double-cropping maize was 25.3%-26.3%and 23.7%-37.4%higher than that of double-cropping rice,respectively,and middle season maize-winter cole was 9.3%higher than that of middle season rice-winter cole after sowing date advanced.The effects of maize,rice and cole on the later crop were compared between the maize cropping model and the non-maize cropping model.The yield of late rice season in maize cropping was 12.1%-14.6%higher than that in non-maize cropping,and that of maize cropping-cole season was 15.2%higher than that in non-maize cropping,Analysis of yield components showed that the number of effective panicles in maize cropping-late rice season was 8.3%-10.7%higher than that in non-maize cropping,and the number of siliques per plant and 1000-grain weight in maize cropping-cole season were 30.5%and 9.4%higher than that in non-maize cropping.The dry matter accumulation of double cropping maize and spring maize-late rice after anthesis was 168.3%and 102.7%higher than that of double cropping rice,respectively,and the annual net assimilation rate was 132.1%and 102.7%higher than that of double cropping rice,respectively;The annual leaf area attenuation rate was as follows:double cropping rice>spring maize-late season rice>double cropping maize,middle season rice cole>middle season maize cole.The increase of decreasing rate of leaf area after anthesis led to the decrease of photosynthetic potential after anthesis.2.Comparing the resource efficiency of different planting modes,it shows that the annual resource utilization efficiency of double-cropping maize and spring maize-late season rice modes are significantly higher than that of double-cropping rice modes,and the resource utilization efficiency of middle maize season is significantly higher than that of middle rice season,and the maize cropping modes both show higher economic benefits.Compared with the traditional double cropping rice model,the annual solar radiation production efficiency of double cropping maize and spring maize-late season rice increased by 29.3%-45.0%and 22.0%-22.5%,respectively,annual accumulated temperature production efficiency increased by 40.0%-53.0%and 24.8%-25.2%,respectively,annual water use efficiency increased by 63.3%-119.8%and 24.4%-42.6%,respectively;Compared with the traditional rice-cole model,the solar radiation production efficiency,accumulated temperature production efficiency and water use efficiency of middle maize season increased by 23.8%,25.4%and 70.6%,respectively.The annual economic benefits of double-cropping maize and spring maize-late season rice models were higher than those of rice cropping models.The annual economic benefits of double-cropping maize:26500 yuan/hm²,spring maize-late season rice:24032 yuan/hm²,middle season maize-winter cole:16115 yuan/hm²,middle season rice-winter cole:14932yuan/hm²,double-cropping rice:12695 yuan/hm²,respectively,and the economic benefits in maize cropping-late rice season was 30.7%higher than that in non-maize cropping,the economic benefit in maize cropping-cole season was 39.4%higher than that in non-maize cropping.3.Analysis of environmental costs of different cropping modes showed that the global warming potential and intensity of greenhouse gas emissions of double cropping maize and spring maize-late season rice modes were significantly reduced.Cole cropping modes showed significant soil improvement characteristics,cole planting could improve soil organic matter and nutrient intensity;In the maize cropping model,reasonable soil tillage in maize rotation due to water and drought has a significant effect on improving soil bulk density in rice field.Double-cropping Maize model significantly reduces the global warming potential and intensity of greenhouse gas emissions.The intensity of greenhouse gas emissions of spring maize-late season rice model was significantly lower than that of double-cropping rice model,and the global warming potential and intensity of greenhouse gas emissions of middle season maize-winter cole model were 13.7%and 24.3%lower than that of middle season rice-winter cole model,respectively.The N₂O emission of each model was mainly concentrated in maize season and cole season,of which double-cropping maize was the lowest and middle season maize-winter cole was the highest;CH₄emission of each model was mainly concentrated in rice season,of which middle season maize-winter cole was the lowest and double-cropping rice was the highest.Rotary tillage of planting rice resulted in the increase of soil bulk density in 0-20 cm soil layer;Rotary tillage of planting maize reduced soil bulk density in 0-20 cm soil layer,and soil bulk density in 20-40 cm soil layer had a downward trend;No-tillage of planting cole was a reasonable cultivation mode suitable for cole cropping model.Available nutrients content increased significantly in 0-20 cm soil layer of double cropping maize model,the pH value decreased by 0.73.Available phosphorus content increased in 0-20 cm soil layer of spring maize-late rice model and summer maize-cole model,available potassium content decreased,and the pH value decreased by 0.12 and 0.36,respectively.In summary,the different planting patterns in the middle and lower reaches of the Yangtze River（Hubei region）were comprehensively analyzed from the yield,resource utilization efficiency and environmental costs.The double-cropping maize and spring maize-late season rice models showed greater advantages.From the perspective of single-crop yield and resource utilization efficiency,the maize season also showed greater advantages than the rice season and cole season.Under the change of climate and production conditions,Maize in the middle reaches of the Yangtze River has certain development potential.Maize cropping pattern can be used as an effective supplementary cropping pattern for rice and cole cropping patterns.