| The Yellow River Diversion irrigation area in Ningxia is an important part of the largescale water conservancy project in the Yellow River basin,and also the agricultural production area with the longest history and the most perfect irrigation system in northwest China.The planting structure in the region is single,the water resources for agriculture are scarce,and the utilization rate of water and fertilizer resources is low.Therefore,it is necessary to optimize the planting mode to comprehensively improve the efficiency of water and nutrient use,thereby ensuring food yield.Maize and soybeans are conventional crops in the region,and the grass-bean intercropping pattern is widely used due to its ecological niche differences and competitive complementarity in resource utilization.However,a single planting structure over a long period of time can easily lead to a decline in soil fertility,which adversely affects crop yields.Crop rotation can reduce the accumulation of soil pests and achieve the purpose of balancing soil nutrients and cultivating fertility.The combination of strip intercropping and rotational cropping,and rotation on the basis of strip intercropping,can effectively solve the problems caused by long-term cropping.The strip rotation mode is very mature in southwest China,and whether it is suitable for irrigation areas still needs further research to determine.Therefore,this study conducted a 3-year field positioning experiment in Tongxin County from2019 to 2021.Set up four planting modes of maize and soybean strip intercropping(IMS),maize and soybean strip rotation(RMS),maize monocropping(MM),and soybean monocropping(SS),and analyzed the agronomic correlation traits of maize and soybean marginal and midstream rows under different planting modes,crop water and nitrogen utilization and their yield.The main results obtained are as follows:(1)The maize ‖ soybean system was beneficial to the growth and development of the dominant crop maize and inhibited the growth of the inferior crop soybean,but the inhibition of the RMS treatment was relieved to a certain extent than that of the IMS treatment.Compared with single-cropping maize,IMS and RMS treatments significantly decreased maize plant height by 5.83% and 11.72%,and maize stalk diameter and dry matter accumulation increased significantly by 8.85%-9.14% and 19.46%-19.49% compared with mono-crop maize;IMS and RMS Compared with single crop,the treatment significantly increased soybean plant height by 27.91% and 16.28%,and the soybean stem diameter and dry matter accumulation decreased compared with single crop.IMS and RMS treatments decreased by 24.83%-19.53% and 10.72%～11.24%;The growth advantage of RMS treatment was significantly higher than that of IMS treatment,and the side rows of the same treatment were more affected.(2)The maize ‖ soybean system had obvious intercropping water advantage in the 0-100 cm soil layer,and the intercropping water equivalent ratio was greater than 1 under both IMS and RMS treatments.Compared with MM,the IMS and RMS treatments increased the soil water content of the dominant crop corn belt and achieved efficient water use,and decreased the soil water content of the inferior crop soybean compared with SS.The RMS treatment alleviated the water use disadvantage of the IMS treatment.Compared with single-cropping maize,the IMS and RMS treatments decreased soil water consumption by 5.04% and 5.51%,and the average soil water content and water use efficiency increased significantly by 7.87%-23.9% and 19.85%-43%.The treatment was significantly higher than that of the IMS treatment,and the water use efficiency advantage of the same treatment was obvious.The IMS and RMS treatments significantly increased the soil water consumption of soybean by 4.42% and 5.34%,and the average soil water content and water use efficiency decreased by 6.34%-54.4% and5.1%-39.89%,respectively.Soil water use efficiency of soybean strip RMS treatment was significantly higher than that of IMS treatment,and soybean side row was more affected in the same treatment.(3)The maize ‖ soybean system was favorable for the uptake and transport of nitrogen by stems,leaves and grain organs of the dominant crop maize,however,the nitrogen accumulation and nitrogen transport of the inferior crop soybean were inhibited under the IMS and RMS treatments.The nitrogen uptake and transport capacity of maize in RMS treatment was significantly higher than that in MM and IMS treatments.Compared with single-cropping maize,the nitrogen accumulation in the RMS treatment increased significantly by 40.34%,and the nitrogen transport amount and grain nitrogen transport rate in maize were both RMS>IMS>MM treatment.Compared with soybean monoculture,nitrogen accumulation and nitrogen transport decreased by 35.88% and 33.32% in IMS and RMS treatments,respectively.IMS and RMS treatments reduced soybean nitrogen transfer and promoted nitrogen transfer to grains.The IMS treatment had better nitrogen transfer rate in the middle row,while the RMS treatment had more obvious advantages in the side row.(4)The maize ‖ soybean system has the advantage of intercropping land and promotes the yield increase of the dominant crop corn belt.However,this system is not conducive to the yield formation of the inferior crop soybean,and RMS treatment can alleviate the negative effect of continuous intercropping on soybean yield reduction.Compared with single-cropping maize,the number of corn per ear and 100-kernel weight under IMS and RMS treatments increased by 8.56%-5.34% and 15.82%-9.04%,respectively.The yield advantage of side row corn is obvious.Compared with single-cropping soybean,the effective pod number,grain number per plant,pod number per plant and 100-grain weight of IMS treatment were seriously reduced,resulting in a significant decrease of 55.81% in IMS soybean yield compared with monoculture,while RMS treatment decreased by 37.88%,and was significantly lower than that of IMS treatment,the yield of side row soybean was greatly affected.Above all,the maize-soybean band rotation mode(RMS)promotes plant growth and development and rationally distributes water and nitrogen resources,which can make up for the negative effects of continuous single cropping and intercropping on soybean yield while ensuring increased corn yield. |
PDF Full Text Request