Effects Of Mulching On Soil Moisture And Temperature For Potato In Arid Areas Of China

Dryland agriculture plays an important role in China's agricultural production.Potato is one of the main crops in arid areas of China.However,water shortage and uneven precipitation distribution are the main factors restricting dryland agricultural production.In order to optimize the allocation of water resources and improve crop yield,researchers have put forward a variety of drought-resistant cultivation techniques.Straw strip mulch planting technique is a drought-resistant and moisture-preservation cultivation technique with partial coverage of whole corn straw.The preliminary study shows that the technology can improve the soil thermal-moisture environment of potato and increase the yield.But the research on the mechanism of yield increase is relatively scarce.In order to further explore the mechanism of yield differences and esponse of soil thermal-moisture of potato on covering materials,mulching methods,earth-up methods and variety types in arid area of China.The four field experiments were conducted in Tongwei county pingxiang town of Gansu province during 2015-2016.Determination of temperature of 0-25cm soil layer,moisture content of 0-200cm soil layer,photosynthetic index,yield and yield components of potato in the whole growth period.The experiment is handled as follows:Cover and earth-up experiment set three kinds of covering methods?plastic film cover,maize straw strip mulching on flat planting,maize straw strip mulching on furrow and ridge planting?,three kinds of earth-up methods?heap of earth-up,furrow of earth-up,planting and earth-up of filling furrow?,and uncovered flat planting as a contrast.Straw strip mulching and variety experiment were two varieties in early and late maturing,four kinds of covering methods?Big ridge black film mulch planting,Maize straw strip mulching on flat planting,Maize straw strip mulching on furrow and ridge planting,Maize straw wholed mulching on flat planting?,and uncovered flat planting as a contrast.Mulching and tillage experiment was comprised four different treatments:residual film direct seeding?T1?,small ridge mulching straw and big ridge removed film of no rotary tillage?T2?,small ridge mulching straw and big ridge removed film of rotary tillage?T3?,and big ridge black film mulch planting?ck?as a contrast.Straw strip mulching and density experiment set two varieties in early and late maturing,4 kinds of density?45000,52500,60000and 67500 plants/hm²?.The results as follow:1.Whether normal precipitation year or inclined to drought year,the yield maize straw strip mulching on banded flat covering is close to the plastic film coverage,they are obviously better than the uncovered flat planting.The scop of increasing yield on maize straw strip mulching and plastic film coverage were inconsistent in two growing seasons.The yield of maize straw strip mulching was best in normal precipitation year,the yield was average higher 12.3%than ck.However,the yield of plastic film coverage was best in inclined to drought year,the yield was average higher 69.6%than ck.Compared with ck,plastic film mulching during the whole growth period significantly increased the temperature 1.2 degrees of 0-25cm soil layer on average.Straw mulching?flat and furrow?reduced the temperature of 0-25cm soil layer,and the maximum flat planting mulching reduction was 0.8 degrees below ck.The plastic film mulching increased the plot temperature of 10cm soil layer at more than 10 degrees in the whole growth period compared with the open field.Straw mulching reduced the plot temperature of 10cm soil layer in the whole growth period,which was greater than 10 degrees.Among them,the decrease of the flat planting mulching is the greatest.In late growth stage,plastic film mulching has obvious effect of increasing temperature,and from flowering to flowering stage straw mulching has the largest temperature drop.During the whole growth period,straw mulching and plastic mulching in 0-200cm soil layer had double effects on increasing soil moisture and reducing soil moisture.The ratio of soil moisture to straw mulching and plastic film mulching was 67.5%and 52.5%respectively.The soil moisture state of straw strip mulching on flat planting is generally better than that of plastic film and ck.The average is 0.64 and 1.03 percentage points higher than that of plastic film and open field.2.Whether normal precipitation year or inclined to drought year,the yield maize straw strip mulching on flat planting was more than three kinds of earth-up methods.And there is no significant difference between the ways of earth-up.The production of three kinds of earth-up methods shows:in normal precipitation year plating with earth-up is not as good as that in the open area,but in the drought years are better than ck.Straw flat and different soil filling methods reduced the temperature of 0-25cm soil layer compared with the open field,and the largest decrease?average than 1.55 degrees below ck?was in ditching and sowing soil in banded horizontal operation.And there is no significant difference between the ways of earth-up.In the whole growth period,the soil moisture content of 0-200cm was significantly different,and the planting and earth-up of filling furrow was the best?0.92 percentage points higher than ck?.And there is no significant difference between banded flat covering and planting and earth-up of filling furrow.3.Straw mulching and plastic film mulching significantly increased the yield of early and late maturing varieties than ck,and the yield-increasing effect was better than that of the inclined to drought year.In the 2 growing seasons,the growth effect of plastic film mulching was more than that of early maturing varieties?50.7%?,and the straw banded flat covering and precocious varieties?52%?were larger than those of late maturing varieties?33.4%?.The warming effect of plastic film mulching and the cooling effect of banded flat covering were all late maturing varieties?1.62degrees and 1.13 degrees Celsius?were larger than those of early maturing varieties?1.39 degrees,1.01 degrees Celsius?.Plastic film mulching and straw mulching at the whole growth stage of0-200cm had no significant difference in soil moisture content between early and late maturing varieties.And the early maturing varieties in drought years are better than those of late maturing varieties.Compared with late maturing varieties,Early maturing varieties reduced water consumption during the whole growth period.4.Compared with the big ridge black film mulch planting?ck?,residual film direct seeding?T1?,small ridge mulching straw and big ridge removed film of no rotary tillage?T2?and small ridge mulching straw and big ridge removed film of rotary tillage?T3?decreased the yield of potato,and the largest decline was T2?22.93%lower than ck?.And the main reason for reducing production is to reduce the weight of single potato.There was no significant difference in yield among T1,T2 and T3.Compared with ck,T1,T2 and T3 decreased the soil temperature of 0-25cm in the whole growth period,and the largest decrease was T3?ck lower than 1.12 degrees?.Soil moisture content of T3 in 0-200cm soil layer at growth stage is similar to ck,but significantly better than T1 and T2.5.The yield of potato was significantly affected by planting density.The yield of early and late maturing varieties was 60,000 plants/hm² in the 2 growing seasons,the highest being25485.75kg/hm² and 28834.35kg/hm² respectively.From the analysis of yield components,whether normal precipitation year or inclined to drought year,the yield of late-maturing varieties were determined by weight of single tuber,the number of potato tuber was less.The early-maturing varieties in normal precipitation year are mainly determined by the density,and the partial drought year is mainly determined by the number of potato tuber.From the perspective of vegetative growth,the yield difference was mainly caused by biomass and straw yield,and the harvest index was relatively stable,and the effect on yield was small.6.Covering materials,mulching methods and earth-up methods has a significant effect on potato yield.From the analysis of yield components,the yield of potato were mainly determined by weight of single tuber,the number of potato tuber was less.Single potato weight was achieved by increasing the quantity ratio and quality ratio of more than tuber of 150g and reducing the ratio of quality and quantity of tuber of under 50g.From the perspective of vegetative growth,the yield difference was mainly caused by biomass and straw yield,and the harvest index was relatively stable,and have less impact on production.From the analysis of hydrothermal environment,increasing the average temperature in the whole stages and soil moisture in growth later stage is conducive to yield of the potato in normal precipitation year,decrease the temperature in tuber initation stage and increase soil moisture in growth later stage is conducive to yield of the potato in inclined to drought year.7.Cover crops can adjust the proportion of water use in the crop stage.Compared with ck,plastic film mulching obviously increased the water consumption ratio from seedling stage to tuber expansion stage.And straw mulching decreased the water consumption and its rate from sowing to seedling stage,and increased the water consumption and its rate of starch accumulation period to harvest period.The effect of each treatment on the water content of the plant in the growth period was not consistent,and the water content of plant on coverage planting was lower than the conventional planting,and the scop of decreased on water content of the plant in film mulching was more than straw mulching.8.Coverage and density had significant effects on plant height,dry weight,stem and leaf dry weight of early and late maturing potatoes.Plant height,stem and leaf dry weight and plastic film mulching were higher than that of straw mulch and open field?ck?at the early stage of growth.In the late growth stage,straw mulching was close to or even surpassed plastic film mulching.The dry weight of single plant potato with plastic mulching is better than that of straw mulching and open field?ck?.Compared with plastic film mulching and ck,Straw banded flat covering significantly increased the net photosynthetic rate?16.46%higher than ck?,decreased stomatal conductance?1.59%lower than ck?and intercellular CO₂ concentration?2.69%lower than ck?in the growth middle later stage.