| The problems of low fertility,low resource utilization rate and low yield of crops in the red soil dryland in China,have caused the productive potential not to be fully played and excavated.Farmland intercropping has the characteristics of making full use of natural resources and increasing crop yield by a large margin,which plays an important role in agricultural production.In order to explore the physiological and ecological effects of intercropping model and the corresponding characteristics of crops in red soil dryland,In2016 and 2017,two years of field experiments were conducted in the Science and Technology Park of Jiangxi Agricultural University,three cotton intercropping patterns were designed,cotton intercropping soybean,cotton intercropping maize and cotton intercropping sweet potato,which were compared with cotton monoculture,soybean monoculture,maize monoculture and sweet potato monoculture.The effects of intercropping patterns on cotton growth,yield,fiber quality,microclimate and photosynthetic characteristics,soil physical and chemical properties,biological characters and economic benefits were analyzed.In order to explore the characteristics of efficient utilization of resources and productivity of maize and soybean intercropping under in red soil dryland,A field experiment was carried out in Red Soil Research Institute of Jiangxi province in 2017,Compared with maize and soybean monoculture patterns,this paper analyzed five maize and soybean belts with different row spacing.The effects of maize and soybean banded intercropping on resource utilization and soil environment under different row spacing were analyzed.In order to improve the resource utilization efficiency,multiple cropping index and land productivity of red soil dryland,the high efficient planting pattern and key technology which was suitable for the development of red soil dryland were selected,so as to develop green,high yielding and efficient dryland agricultural production provides scientific theoretical basis.The main conclusions were as follows.（1）Cotton intercropping could promote the increase of height and node of first boll branches;promoting the growth of cotton plant height,boll branch layer and leaf number,dry matter per plant,chlorophyll content and leaf area index;the yield of cotton could be improved by increasing the number of bolls in particular to improving the proportion of the peaches;the quality of cotton fibers can be improved by decreasing the micronaire and increasing the specific strength.The comprehensive analysis shows that the intercropping advantage of the treatment of cotton intercropping sweet potato was more obvious.（2）Compared with cotton monoculture,cotton intercropping could increase the seasonal utilization ratio by 21.3%～43.6%,the photosynthetic radiation by 32.4%～44.0%,the effective accumulated temperature by 28.6%～62.4%,and the precipitation by49.1%～52.5%;It also could improve the light transmittance of cotton,which was beneficial to the photosynthesis of cotton.The light requirement of dwarf crops was weak.The diurnal variation trend of air relative humidity in each model was"U"curve.Cotton intercropping patterns could improve the air humidity in the model compared with cotton monoculture.The air humidity of soybean monoculture and maize monoculture was higher than that of cotton monoculture,but the air humidity of sweet potato monoculture was lower than that of cotton monoculture pattern.The lowest value of air humidity in cotton intercropping sweet potato was 17.8%higher than that in cotton monoculture at the flowering and boll stage of cotton;In the flocculating period,each intercropping pattern had advantages in improving air humidity.The lowest value of air humidity in the three pattern was higher than that in cotton monoculture by 8.5%～30.0%.The trend of the daily change of air temperature in each model showed a tendency to increase first and then decrease.Cotton intercropping pattern could lower the air temperature than the corresponding monoculture pattern,the air temperature of cotton monoculture and other intercropping crops monoculture were different.In the flowering and bolling period,the air temperature in the cotton intercropping maize and cotton intercropping sweet potato was lower than that of cotton monoculture 2.1℃and 3.4℃respectively;the air temperature of the three intercropping patterns were 1.1～1.7℃lower than cotton monoculture at the stage of sprouting.In soybean monoculture,maize monoculture and sweet potato monoculture,the phenomenon of"photosynthetic midday break"appeared.The phenomenon of"photosynthetic midday depression"of soybean and sweet potato under intercropping pattern was obviously improved.The changes of net photosynthetic rate,stomatal conductance and transpiration rate are consistent:soybean monoculture pattern>cotton intercropping soybean pattern,sweet potato monoculture pattern>cotton intercropping pattern,maize monoculture model<cotton intercropping maize model,but the manifestation of the concentration of intercellular CO2 was the opposite.Therefore,cotton intercropping patterns could effectively increase air humidity,reducing air temperature and light intensity in different degree,and avoid high temperature stress and diurnal temperature difference;the photosynthetic effect of soybean and maize in cotton intercropping pattern was lower than that in the corresponding monoculture model,and cotton intercropping sweet potato pattern improved photosynthetic effect compared with sweet potato monoculture.（3）When the temperature was lower at 8 o’clock,the soil temperature of cotton intercropping patterns could be increased than that of monoculture;the soil temperature was lowered to avoid high temperature stress at 14 o’clock;keeping warm and increasing the moisture,avoiding the injury of low temperature injury when the outside temperature reduced at 20 o’clock.The intercropping pattern of cotton can regulate soil temperature more effectively than cotton monoculture,the diurnal range of soil temperature and soil depth can be fitted to quadratic polynomial form.Fitting polynomial regression formula,the correlation coefficient was above 0.99,the advantages of“cotton intercropping soybean”and“cotton intercropping sweet potato”were more prominent.The soil moisture content of cotton intercropping pattern and cotton monoculture was the lowest in boll-opening stage,cotton intercropping patterns could increase soil moisture content of cotton at each growing period compared with cotton monoculture,and“cotton intercropping soybean”was better before flourishing bolling stage,“cotton intercropping sweet potato”was better in the later stage,and the soil moisture content of each intercropping pattern was lower than that of crop monoculture patterns.Compared with cotton monoculture,cotton intercropping pattern could improve soil physical characteristics by reducing soil bulk density,increasing soil total porosity and capillary porosity.Cotton intercropping sweet potato pattern could reduce soil bulk density,the reduction amplitude by 5.5%,and the soil capillary porosity was increased,the increased range by 5.3%compared with cotton monoculture.The patterns of“cotton intercropping soybean”and“cotton intercropping sweet potato”could significantly increase total soil porosity by 12.2%and 13.0%respectively.Overall,“cotton intercropping sweet potato”was better.（4）Cotton intercropping pattern could increase soil nutrient content compared with cotton monoculture.The results showed that cotton intercropping could increase the content of soil alkaline nitrogen,organic matter and total nitrogen in 2016,the soil organic matter,total phosphorus,available phosphorus and available potassium content were increased significantly in 2017,and the superiority of“cotton intercropping soybean”and“cotton intercropping sweet potato”were obvious.Cotton intercropping and monoculture could promote the accumulation of soil total organic carbon,active dissolved organic carbon,organic carbon and soil microbial biomass carbon;The soil carbon pool index and soil carbon pool management index,and the pattern of“cotton intercropping with sweet potato”was better.SOC,AOC,DOC,SMBC and CPMI were positively correlated with available phosphorus and total phosphorus,and AOC and SMBC were positively correlated with available phosphorus.Therefore,paying attention to the rational application of phosphate fertilizer on developing of cotton production on red soil dryland.Compared with cotton monoculture,cotton intercropping pattern could effectively increase the number of bacteria,fungi,actinomycetes,nitrogen-fixing bacteria and the total number of microbes in soil,and could effectively increase the activities of catalase,urease and invertase in soil;but the intercropping patterns were higher than that of soybean,maize and sweet potato monoculture.（5）The soil moisture content of cotton intercropping patterns and the effect value of nutrient index were mostly negative,the nutrient consumption of intercropping pattern was generally higher than that of monoculture pattern,the competition between cotton and intercropping crops in water and nutrient was stronger.Therefore,the competition between crops for water and fertilizer could be alleviated by proper fertilization and irrigation of intercropping pattern.The photosynthetic effects of cotton intercropping pattern were all negative,indicating that the photosynthetic rate of soybean,maize and sweet potato in cotton intercropping patterns were lower than that of soybean monoculture,maize monoculture and sweet potato monoculture.The decrease of cotton intercropping sweet potato was larger than that of sweet potato monoculture.The land equivalent ratio of each intercropping pattern was more than 1,and the relative competitiveness of intercropping was more than 0,which indicated that the land use efficiency of intercropping pattern was higher than that of monoculture pattern,and the cotton competitiveness of intercropping pattern was stronger than that of intercropping crops.Using the fuzzy membership function method in fuzzy mathematics,the soil fertility in different planting patterns were comprehensively evaluated.The results were as follows:cotton monoculture pattern<soybean monoculture pattern<cotton intercropping soybean pattern,cotton monoculture<cotton intercropping maize<maize monoculture,cotton monoculture<sweet potato monoculture<cotton intercropping sweet potato,among them,the comprehensive fertility of cotton intercropping soybean,cotton intercropping sweet potato patterns were higher than that of cotton monoculture and corresponding soybean and sweet potato monoculture pattern,it was concluded that cotton intercropping soybean and sweet potato could improve soil fertility to some extent.The grey correlation degree method was used to evaluate the comprehensive benefits of cotton intercropping patterns and corresponding monoculture pattern,including economic benefit,ecological benefit and social benefit.It was concluded that the cotton intercropping sweet potato pattern had the highest weighted correlation degree and the best performance.It was an optimal pattern for considering the economic,ecological and social benefits of the red soil dryland,which had positive significance for the planting structure design and optimization of the red soil dryland.（6）Maize and soybean intercropping had advantages in increasing soil p H value,organic matter content,alkaline nitrogen,available phosphorus and total nutrient content.The seasonal utilization ratio,the utilization rate of light and heat water resources and the soil water content could be increased.Utilization efficiency of light,heat and water of maize and soybean in intercropping were significantly lower than those of the corresponding monoculture,and utilization efficiency the light,heat and water of each intercropping were lower than that of maize monoculture,but significantly higher than that of soybean monoculture,the intercropping could improve the utilization efficiency of nitrogen,phosphorus and potassium of soybean and maize,but had no obvious advantage in increasing the nitrogen utilization efficiency of maize.The intercropping of maize and soybean can improve the land equivalent ratio,land productivity per unit price and economic benefit.Maize-soybean intercropping（bandwidth 2.8 m,row ratio 2:4,maize plant spacing 11.9 cm,soybean plant spacing 9.5 cm）was a better model for spreading in red soil dryland. |
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