Study On Soil Water And Salt Distribution And Cotton Growth Characteristics Of Drip Irrigation With Film Under Magnetized Brackish Water

Xin jiang is short of fresh water resources and rich in brackish water resources,but brackish water irrigation can easily lead to soil salinization and limit crop growth.Using magnetized brackish water irrigation can effectively promote crop growth.In this paper,the effects of different irrigation amount and different gypsum application amount on soil water and salt migration and cotton growth characteristics under magnetized brackish water irrigation were studied in order to determine the best irrigation and gypsum application scheme.The main results are as follows:(1)Under the infiltration conditions of brackish water and magnetized brackish water,the accumulative infiltration amount and wetting front depth under different gypsum application rates at the early stage of infiltration had little difference.In the later stage of infiltration,the cumulative infiltration amount and wetting front depth decreased with the increase of gypsum application rate.Soil moisture content decreased with the increase of soil depth,and decreased with the increase of gypsum application rate at the same soil depth.(2)Under the condition of magnetized brackish water irrigation,with the increase of soil depth,the volume water content increased first and then decreased,and the soil water content increased with the increase of irrigation amount,and reached the maximum at boll stage.The variation trend of soil salt content in narrow row and wide row was the same,and the salt content reached the maximum at 30-40cm.Under different irrigation conditions of magnetized brackish water,plant height and stem diameter increased with time.Leaf area index increased first and then decreased with time.The biomass,the number of effective bolls per plant and yield increased with the increase of irrigation amount,while the weight per plant increased first and then decreased.With the increase of irrigation amount,the water use efficiency increased first and then decreased.The change of irrigation quantity is not sensitive to harvest index.(3)Under the condition of magnetized brackish water irrigation,the water content of narrow row and wide row increased first and then decreased under different gypsum application rates,and reached the maximum at 30-40cm.The water content decreased first and then increased with the increase of gypsum application rate,and then decreased with the increase of gypsum amount.The soil salt content in narrow row and wide row decreased first and then decreased with the increase of depth,and the salt content reached the maximum at 30-40cm.Under the condition of magnetized brackish water irrigation,the increasing range of plant height and stem diameter under different gypsum application rates was stable when gypsum application rate was 0.4kg/m2,the leaf area index increased first and then decreased with time,and the change trend of biomass was the same.The yield of cotton increased with the increase of gypsum application rate,and the difference of effective bolls per plant was small,while the weight per plant increased first and then decreased with the increase of gypsum application rate.Water use efficiency increased gradually with the increase of gypsum application rate and tended to be stable.The harvest index increased first and then decreased with the increase of gypsum application rate,but the range of change was small.The optimum amount of gypsum applied in this experiment is 0.4kg/m2.(4)Logistic model can better describe the variation of plant height and total biomass with time.By comparing the measured plant height and total biomass of different irrigation and gypsum rates with the fitting values of Logistic model,it was verified that the logistic model was consistent with the variation trend of plant height and total biomass with the growth period.