Effects Of Agricultural Mulch Planting Measures On Soil Preferential Flow Characteristics In Fields

At present,plastic film mulching planting technology is widely used in agricultural production,which affects soil environment and effectively improves crop yield to a certain extent.In this study,the pepper fields with and without film（CK）mulching were taken as the research object.The field dyeing experiment and soil column water infiltration experiment were combined.The spatial development and movement process characteristics of soil preferential flow in the field and the factors of soil preferential flow formation were analyzed by using image analysis,computational fluid dynamics simulation and principal component analysis.Reveal the effect of agricultural film mulching planting measures on soil preferential flow in the field.It provides some theoretical support for further elucidating the effect of agricultural film mulching measures on soil moisture conservation and crop quality and yield increase.（1）In the 0-50 cm soil space,the staining patterns of pepper fields under film mulching cultivation measures were mainly banded and agglomerated.The soil profile staining of pepper field under no mulching cultivation was mostly finger-shaped and highly differentiated.The soil profile staining of pepper field under no mulching cultivation measures was mostly finger-shaped and highly differentiated.The average surface area density(0.086 cm^-1)of the vertical profile of the pepper soil under the film mulching cultivation measure(0.086 cm^-1)was 0.54 times that under the non-film mulching cultivation measure(0.16 cm^-1)（P<0.05）,and the concentrated distribution area of staining was relatively small.The average peak value and total staining area ratio of pepper fields under film mulching cultivation measures were 0.37 and 0.72times higher than those without film mulching cultivation measures,respectively,with significant differences（P<0.05）.The preferential flow evaluation index（0.36）of pepper field under film mulching cultivation measures was smaller than that under no film mulching cultivation measures（0.42）,and the development degree of soil preferential flow under film mulching cultivation measures was relatively weak.（2）The average outflow time（16 min 53 s）of the undisturbed soil column in the pepper field under the film-covered planting measure was 5 min 8 s later than that without the film-covered planting measure（11 min 45 s）,and the average mass flow rate of the pepper field under the film-covered planting measure(0.15 g·s^-1)was 0.45times that without the film-covered planting measure(0.33 g·s^-1)（P<0.05）.The average peak flow velocity and the average flow velocity after stable outflow in each layer of pepper field without film mulching were 2.61 times（P<0.05）and 4.52 times（P<0.05）higher than those under film mulching.Under the same water supply conditions,the soil preferential flow phenomenon in pepper field occurred earlier under no film mulching planting measures,and the preferential flow velocity was larger and the movement change was more intense.The water flow movement below 20 cm soil depth was mainly vertical,and the soil water holding capacity was relatively weak.（3）In the 0-50 cm soil space,the average saturated hydraulic conductivity(0.033mm·s^-1)of pepper field under plastic film mulching was 0.5 times that under no plastic film mulching(0.066 mm·s^-1),and the bulk density was relatively large.The contents of organic carbon,total nitrogen and total phosphorus in pepper soil under plastic film mulching were 2.07,1.05 and 1.12 times higher than those without plastic film mulching,respectively.Under the two different film mulching cultivation measures,soil total nitrogen,total phosphorus and saturated hydraulic conductivity are the soil environmental factors that directly affect the formation of soil preferential flow,and the influence degree of non-film mulching cultivation measures is greater than that of film mulching cultivation measures.