| The Loess Plateau,as an important grain production area in China,has been affected by insufficient rainfall and uneven spatial and temporal distribution of precipitation.The grain output is low and unstable.In order to improve the soil moisture status,plastic film and straw mulch planting techniques are widely used.In order to understand the impact of different mulching modes on farmland environment and further improve the mulching cultivation technology,this experiment set up a variety of mulching planting methods in the semi-arid area(Pengyang County,Ningxia)(S:flat straw covering;B:straw covering during leisure period Biodegradable film cover during growth period;D:full-film double furrow;P:common film mulch with flat cropping;R:ridge film furrow planting;CK:bare land flat cropping)),analysis of different cover planting methods for farmland soil moisture,temperature,respiration The main research results are as follows:(1)Impact of covering on soil moisture.In two years,the average soil water content of 0-200 cm soil layer of each treatment in0-60 D stage after sowing increased by 5.12%-29.60%compared with CK treatment;the increase of shallow soil water storage(0-60 cm)was greater than that of deep soil water storage(60-200 cm);by 60-160 D stage after sowing,the average soil water content of each treatment was 0-200 The average soil water content of cm soil layer increased by 3.29%-13.19%compared with CK treatment,which was significantly reduced.At this stage,there was no significant difference between the soil water storage of 0-60 cm soil layer and CK treatment.The soil water storage of deep soil,especially 120-200 cm soil layer,was significantly higher than CK treatment.Both mulching and straw mulching can significantly improve the ability of rainwater collection.In the 60-100 days after sowing in 2019,the rainfall is as high as 255.3 mm.The average soil moisture content of 0-200 cm soil layer of each covering treatment is 8.73%-23.76%higher than that of CK treatment,and 0.83%-15.64%higher in other stages.In the early growth stage,the biodegradation film mulching(b)showed similar water holding capacity to the common mulching film,but in the later stage,there was no significant difference between CK and soil water content.The water holding capacity showed as follows:plastic film autumn mulching(P)>straw autumn mulching(s)>full film double ridge furrow treatment(d)>Ridge Film furrow sowing treatment(R)>biodegradation film mulching treatment(b)(2)The effect of covering on soil temperature.The seasonal change of soil temperature during the growth period of each treatment showed a curve that fluctuated greatly in the early stage and tended to be gentle in the later stage.The mulching treatments(B,D,P,R)improved the soil thermal environment in which maize seedlings grew,and slowed the chilling stress in the early spring season.The average temperature of 0-25cm soil layer under each mulching treatment(B,D,P,R)at 0-100 d after sowing was 7.72%,12.36%,and 16.60,respectively,compared with the bare field flat treatment(CK)%And 1.69%.From 100 to 168 days after sowing,the increase rates were-0.46%,5.97%,7.10%,and 0.64%,respectively,and the temperature increase effect was much lower than that in the early fertility period.The soil cooling rate driven by straw mulch was 7.76%from 0 to 100 d after sowing,which was much larger than the later 1.43%.Compared with CK,the temperature increase of membrane treatment at night is greater than during the day,reducing the soil temperature difference between day and night by 0.77℃-2.46℃.The temperature of the soil covered by straw shows that the cooling rate at night is less than during the day.The temperature increase effect of the degradable biofilm in the early stage is similar to that of the ordinary mulch film,and there is no significant difference in the soil temperature between the CK treatment and the late growth stage.The effect of ridge film ditch sowing(R)is weak when the rainfall is high.The average temperature of the0-25 cm soil layer during the whole growth period is 3.19 ℃ and 2.81 ℃ lower than the other mulching treatments(B,D,P).And 3.80 ℃,no significant difference with CK treatment.We found that in terms of warming effect:P(20.26℃)>D(19.40℃)>B(18.61℃)>R(17.96℃)>CK(17.69℃)>S(16.67℃).(3)The effect of mulch on the growth and yield of spring cornThe plant height of spring maize under B,D,P and R treatments at 0-80 d after sowing increased significantly by 28.96%-109.09%,27.32%-81.82%,31.15%-143.18%and 20.16%-50.00 respectively compared with CK treatment.%.The dry matter quality per plant at0-120 d after sowing was significantly improved by 7.78%-744.08%,7.73%-679.59%,13.18%-1154.69%and 8.08%-329.39%,respectively,compared with CK treatment.The spring maize leaf area at 0-60 days after sowing was significantly increased by 14.88%-513.52%,7.78%-506.63%,16.09%-737.01%and 6.28%-500.04%compared with CK treatment.As the growth period progressed,the differences in plant height,dry matter quality per plant,and leaf area between treatments gradually decreased.Straw mulching resulted in lower soil temperature in early spring,which affected the early growth and development of crops.The dry matter quality of each plant in the S treatment was lower than that of the CK treatment in each stage of the two-year growth period.Significantly lower than CK treatment.In the end,the yield and water use efficiency were 28.56%and 36.50%lower than those of CK treatment,respectively.The plastic film mulching planting method improves the dissipative structure of the soil and shortens the growth cycle of spring maize in the early growth stage.The average grain yield of B,D,P and R treatments was 23.34%,22.65%,28.06%and 20.76%higher than that of CK treatment,respectively,and the water use efficiency was 8.82%,14.88%,11.60%and 10.72%higher than that of CK treatment.(4)Impact of coverage on soilemissions.S,B,D,P and R treatments increased total soil CO2 emissions during the growth period of farmland compared with CK treatments by 32.61%,34.13%,28.61%,51.70%and40.34%,respectively.The seasonal change of soil respiration is closely related to the growth period of crops,and the soil respiration under each mulching treatment(B,D,P,R)showed similar seasonal changes,which gradually decreased after reaching the peak of soil respiration CO2 emission rate 80 days after sowing..S and CK treatments gradually decreased after reaching the maximum value 100 days after sowing.Observing the daily changes in soil respiration,it was found that the peak of soil respiration rate for all treatments increased from 12:00(June 21)to 14:00(July 11)as the growth period progressed.The seasonal changes of soil respiration under the three treatments showed a single peak type,which reached a peak 80 days after sowing.The diurnal changes of heterotrophic respiration showed the same regularity as soil respiration.The main factor affecting the seasonal change of soil respiration is soil temperature.The exponential equation Rs=aeb T can better fit the relationship between the two,and each treatment has a significant positive correlation.Using the formula Q10=e10b to calculate the soil temperature sensitivity coefficient of each treatment,it was found that the soil Q10 of each mulch treatment(S,B,D,P,R)decreased to varying degrees compared with the CK treatment.Using the quadratic function Rs=ax2+bx+c to fit the relationship between soil respiration and soil moisture,it was found that all treatments showed a significant correlation.The quadratic function of fitting B,D,P,and R treatments was Next,the quadratic function of CK and B processing is opening downward.Due to the low output of S treatment,the carbon emission efficiency(CEE)is significantly lower than other treatments.Comprehensive consideration,biodegradable film mulch treatment(B),full-film double furrow treatment(D),flat-cultivation common mulch mulching treatment(P)and ridge-mulch furrow sowing treatment(R)can all improve compared to bare flat cropping(CK)Soil water and heat status and yield increase effect.The double furrow treatment(D)showed the best water use efficiency(WUE)and higher carbon emission efficiency(CEE). |
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