| Under the new situation,the main contradiction in our country's agriculture has been transformed from insufficient total volume to structural contradiction.Promoting the structural reform of the agricultural supply side,improving the quality and efficiency of the agricultural supply system,and scientifically and rationally adjusting the crop planting structure are the necessary content of the agricultural and rural economic development at present and in the coming period.Planting structure is a basic structure of agricultural production.Studying the evolution characteristics and influencing factors of the crop planting pattern can enrich the theoretical system of the optimization and adjustment of the plant structure and provide the basis for planting structure adjustment.The study attempts to analyze the variation of the number of main crops(rice,corn,soybean),spatial pattern evolution and structure ratio in Fujin City from two structures of reclamation and cultivated regions for the last 18 years,and analyze the internal planting conditions of planting preference,planting condition and developing advancement in the reclamation and cultivated regions,and the response of external factors such as crop market economy and national policy regulation.The main contents and conclusions are as follows:(1)Based on the classification of major crops in Fujin City from 2000 to 2017,using mathematical statistics methods,citation dynamics model,expansion intensity index,and relative change rate,the quantitative analysis of planting structure of food crops was found that,from 2000 to 2017,the planting area of rice in Fujin City was basically in the first place in the food crops in the region.It originated from large-scale drought-reducing water in the floodplain of Fujin City.Rice cultivation developed rapidly and continued the trend of expansion.The scale of rice in agricultural region expanded rapidly.Soybeans are in a weak position in the three major food crops and are mainly distributed in agricultural region.The small scale of soybean in reclamation region reflects the irrationality of soybean planting in the reclamation region.The proportion of corn planting in the three major food crops fluctuates by a large margin.This is mainly due to the continuous reduction of corn planting in reclamation region since 2005 and the large fluctuations in the scale of corn planting in the later period,losing their dominant position,and the sowing of planting area.(2)Using spatial analysis and landscape index method to analyze the spatial pattern of crop planting structure in Fujin City from 2000 to 2017,it was found that the rice planting center of gravity has always been located in the reclamation area and gradually moved closer to the boundary between the reclamation area and the agricultural area.The rice planting center of gravity has always been located in reclamation area,gradually moving closer to the boundary between reclamation region and agricultural region.The agricultural region is gradually expanding the scale of rice cultivation,from the original squatter area to the regional balance.The planting conditions of Fujin City rice were better than that of the agricultural region.The inter-action behavior of rice and other crops in reclamation region,and the regularity and stability of rice distribution were higher than those in agricultural region.However,the improvement extent in agricultural region was greater than that in reclamation region and the rice in reclamation region was quickly chased.Soybean planting center of gravity has always been located in agricultural region.The regularity and stability of soybean distribution in agricultural region are higher than that in reclamation region.The importance of soybean planting in reclamation region is low.The focus of corn planting has been in agricultural region.The willingness of intercropping between corn and other crops in Fujin City is from weak to strong and then to weak,and the emphasis on corn planting is weak to strong and then to weak.(3)Planting structure types in different periods were spatially superimposed,and transfer matrix was used to analyze the direction of crop planting structure adjustment.The reform of drought-water in reclamation region is an important indicator for the adjustment of the planting structure in the entire region,resulting in unstable soybean and corn planting areas in reclamation region.During the period from 2005 to 2015,large-scale reform of drought-water was conducted in reclamation region,and the scale of water changes in agricultural region during the period from 2000 to 2017 gradually increased but was weaker than that in reclamation region.Between 2005-2010,2010-2015,and 2015-2017,61.75%,42.21%,and 36.89% of the area of corn in reclamation region were changed to the area of rice.Soybeans and corn competed in agricultural region,and rice developed steadily.From 2000 to 2017,large-scale areas of soybean and corn were transformed into each other in agricultural region.The instability of soybeans in agricultural region was due to the competition of corn in agricultural region.From 2015 to 2017,the maize crop in agricultural region gave way to the expansion of soybean.In 2017,the proportion of rice,corn and soybean planted in reclamation region was 88%,7.4%,and 4.6%.The proportion of rice,corn and soybean planted in agricultural region was 45.7%,22.3%,and 32%.The proportion of rice,corn and soybean planted in the entire region was 62.7%,16.3%,and 21%.The scale of rice in reclamation region continued to develop into a single crop of rice in reclamation region.In agricultural region,from large scale to small of corn,the ratio of expanding soybeans to planting has gradually become more balanced.The expansion of rice in reclamation region should be controlled,the scale of rice in agricultural region should be stabilized,and the input of rice farming techniques in agricultural region should be increased;the scale of soybean in reclamation region should be expanded,the soybean area in agricultural region should be stabilized,and the soybean rotation system in reclamation region and agricultural area should be actively promoted;and the scale of corn in reclamation region should be stabilized to market It is oriented to actively regulate the corn scale in agricultural region.(4)Analysis on the influencing factors of crop planting structure change.The planting structure of food crops is affected by factors such as climate,agricultural technology,agricultural market economy,subsidy policies,and ownership systems.Climate warming has a positive effect on crop yields and planting areas in the Sanjiang Plain in which Fujin City is located.The planting area of high-yielding crops has been expanding,and soybeans in Fujin City have grown due to relatively high yields and rapid development of rice and corn and other economic crops.To some extent,it was ignored.The improvement of agricultural technology provides basic conditions for obtaining higher agricultural income and crop planting adjustments.A number of land consolidation projects in Heilongjiang Province have been implemented one after another,which is a direct cause of the expansion of cultivated land in Fujin City and the expansion of improvement of drought-water levels.In recent years,the price of rice has steadily increased,the profit of rice cultivation is higher,the rice scale in Fujin City has expanded rapidly,and the reclamation region has benefited from rice cultivation,and the enthusiasm for planting rice in agricultural region has also increased.The response of reclamation region and agricultural region to the adjustment of state subsidy policies is quite different.The maize in agricultural region has been actively adjusted due to the release and reform of the temporary corn storage and storage policies.The reclamation region has been focusing on rice expansion,which was unaffected by the price subsidies of soybean target and the reform of temporary corn storage and storage policies.The land property rights system has had an important impact on the choice of crops to be planted. |
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