| In order to clarify the damage mechanism of residual film to agriculture,and achieve the sustainable development of agriculture in residual film area.Through a combination of indoor infiltration test,pot test and field test,this study tried to study the soil moisture infiltration under different conditions(initial moisture content,dry bulk density and drip rate)in the presence of residual film,study the changes and consumption of soil moisture and nitrate nitrogen under the coexistence of residual film and crops and study the effects of residual film on crops growth(roots,stems,leaves and ears),yield and water use efficiency of summer maize and winter wheat.The main conclusions are as follows:(1)The mechanism of residual film on soil water infiltration under indoor conditions was investigated.When the infiltration depth was 40 cm,with the initial water content increasing,the one-dimensional and three-dimensional infiltration time and infiltration water volume decreased and the soil moisture content of 0-30 cm and the initial infiltration rate decreased in one-dimensional infiltration.Moreover,the irrigation uniformity increased in three-dimensional infiltration.As the dry bulk density increased,the infiltration time of one-dimensional and three-dimensional infiltration increased,and the infiltration water volume and irrigation uniformity in three-dimensional increased,and one-dimensional infiltration water volume,soil moisture content and initial infiltration rate decreased.With residual film amount increasing,the one-dimensional infiltration time and the initial aspect ratio of the three-dimensional infiltration increased.In one-dimensional infiltration,within the range of 0–200 kg/hm~2residual film the infiltration water volume increased with the increase of residual film amount.In the three-dimensional infiltration,the infiltration water volume in the range of 0-720 kg/hm~2residual film increased first and then decreased with the increase of residual film amount and440 kg/hm~2 residual film was the turning point.In the three-dimensional infiltration,the irrigation uniformity first increased and then decreased with the increase of the residual film amount,and reached a maximum value at the residual film amount of about 437 kg/hm~2.The one-dimensional infiltration time first increased and then decreased with the increase of the buried depth of the residual film.The water content of the 30–40 cm soil layer first decreased and then increased with the increase of the buried depth of the residual film.As the flow rate of the emitter increased,the amount of three-dimensional infiltration water and the uniformity of irrigation increased.The residual film amount and the drip rate in the three-dimensional infiltration had an interactive effect on the cumulative infiltration water volume and irrigation uniformity.(2)The effects of residual film on soil moisture,temperature and nitrate-nitrogen content in agricultural soils were clarified.The soil moisture content of summer maize increased with the increase of residual film,and the water consumption in deep soil decreased with the increase of residual film.In the early stage of winter wheat growth,the residual film reduced the soil moisture content and increased the water consumption in the shallow layer.In the later stage the residual film increased the soil moisture content in the deep layer and reduced the water consumption in the deep layer.Residual film prevented water infiltration.The residual film in shallow soil increased the water content of the shallow soil and reduced the water content of the deeper soil and the residual film in the deep soil increased the water content in the residual film zone and the upper soil.This effect enhanced with the increase of residual film amount.Ridge-furrow structure and film mulching weaken the influence of residual film on soil water storage,reduced the difference in water storage between residual film treatments,and delayed the time when the difference appeared.Residual film had no significant effect on soil temperature.In the summer maize season,ridging and mulching significantly increased the soil temperature on the ridge,but had no significant effect on the temperature in the furrow.In the winter wheat season,white film mulching ridges increased the soil temperature in the early stage and lowered the soil temperature in the later stage.Black film mulching ridges reduced the soil temperature,and the warming effect of straw mulching furrows was more significant under ridges mulched with black film than white film.Residual film in summer maize season increased soil nitrate nitrogen content and reduced nitrate nitrogen consumption.Nitrate nitrogen consumption occurred in the 0-100 cm soil layer in the flat planting pattern mode,and the nitrate nitrogen consumption mainly occurred in the 0-30 cm soil layer in the ridge-furrow mulching pattern.In the winter wheat season,the residual film increased the soil nitrate nitrogen content,reduced the nitrate nitrogen content at the maturity stage,increased the nitrate nitrogen consumption,and increased the nitrate nitrogen loss.(3)The effect of residual film on root growth and root conformation of summer maize and winter wheat was investigated.The residual film reduced the potential maximum root length of summer maize,delayed rooting,and shortened the root growth time.When the residual film amount was greater than90 kg/hm~2,the difference was significant.Root growth was more sensitive to the residual film at the seedling and maturity stages.Both the residual film and film mulching made the center of summer corn root length(the depth of 50%and 95%of the cumulative root length)moved upward,and the residual film amount greater than 90 kg/hm~2 had a significant difference.The ridge-furrow mulching with film and straw mulching lowered and residual film raised the center of winter wheat root length.The root length center of summer maize and winter wheat first decreased and then increased with the growth process,and the center was the lowest in the filling stage.Ridging and mulching increased root length and promoted early rooting.The double ridge and furrow full mulching mode was the most significant.Double-ridge furrow full mulching mainly increased the root length on the ridge,reduced the root mass and slowed down the growth in the later stage.(4)The effects of residual film on above-ground dry matter,yield and water use efficiency of summer maize and winter wheat were analyzed.Residual film reduced the dry matter of summer maize and winter wheat stems,leaves,ears dry matter,reduced yield and WUE.Compared with the control,each residual film treatment reduced the yield by 1.8%,13.1%,24.6%and 32.4%in two years,WUE decreased by 4.6%,13.3%,20.4%and 26.2%respectively,and the difference was significant when the residual film amount reached 180 kg/hm2.Single ridge-furrow mulching increased the dry matter of summer maize by 15.3%,and double ridges furrow full mulching increased dry matter in the early stage and reduced dry matter in the later stage,reducing yield by 9.4%.Both of them reduced the ET by 10.7%and 7.0%,and increased WUE by 18.5%and 5.9%.The residual film treatments reduced winter wheat yield by 1.6%,17.3%,27.2%and 32.2%,reduced ET by 1.8%,2.6%,4.9%and 8.1%respectively,and reduced WUE by 0.2%,15.5%,24.1%and 26.3%,respectively.When the residual film amount reached 180kg/hm2,the yield and WUE were significantly reduced,and when the residual membrane amount reached360kg/hm2,ET was significantly reduced.Plastic film mulching on ridges and straw mulching in furrows increased the aboveground dry matter,yield and WUE of winter wheat,and white film mulching on ridges had the best effect.Residual film reduced the number of ears in a single row,and ridging and mulching increased the number of ears in a single row.Planting methods and residual film affected the yield of wheat by affecting the number of ears in a single row.Covering ridges with white film and furrows without covering is a recommended planting mode in the summer maize-winter wheat rotation system in Guanzhong area. |
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