Evaluation Research On Index System In Reasonable Arable Layer And Tillage Technology Of Maize Cropland In Typical Brown Soil

Brown soil is the main soil type for high-yield maize cultivation in Liaoning province.In recent years,many structural and functional barriers of brown soi have appeared due to the reuse and light maintenance of farmland management measures and continuous rolling of small agricultural machinery.The unreasonable soil structure has led to low crop yield,yield stability and decline of resource utilization efficiency,which are not conducive to sustainable development of agriculture.This study was carried out in the typical brown soil cropland in northeast China from 2015 to 2016,and the soil quality index was evaluated to determine:（1）the soil quality of reasonable arable layer;（2）qualitative and quantitative of evaluation indicators of reasonable arable layer;（3）explored the suitable tillage technology of brown soil in northeast China from the perspective of soil quality.Our results indicated that:1.The soil quality assessment was applied to the establishment of a reasonable arable layer.The soil quality of brown soil in the study area was quantified by calculating the soil quality index（SQI）.The average SQI in the study area was 0.54（2015）and 0.51（2016）,both of which were of medium level.According to the clustering analysis of yield（Y）,yield stability（CVy）and resource utilization efficiency（PFP）,the range of high Y were 9.11¹0.03 t hm-2（2015）,11.76¹2.61 t hm-2（2016）,respectively;the range of high CVy were 10.24%²0.42%（2015,2016）;the range of high PFP were 34.12⁴3.53 kg kg^-1（2015）,49.94%⁵4.65%（2016）,respectively.The regression equation of SQI,Y,CVy and PFP were used to obtain the appropriate range of SQI in the reasonable areable layer,which were 0.58⁰.68（2015）and 0.52⁰.69（2016）.2.Minimum data set index（MDS）screened by Pearson correlation and principal component analysis.SQI calculated by combining with membership function had significant correlation with Y,CVy and PFP,which are the main concerns of constructing reasonable areable layer.This indicated that the MDS index could be used as a reasonable areable layer evaluation index.The evaluation index（MDS）of reasonable areable layer in 2015 included TK of plough layer,SC、AP、TN of plough pan,SMC and MWD of subsoil layer.The evaluation index（MDS）of reasonable areable layer in 2016 included AK、BD of plough layer,AK of plough pan、SOM and AP of subsoil layer.3.The appropriate interval of evaluation indexes was determined by regression fitting of each evaluation index with SQI and combining with the appropriate SQI suitable interval of areable layer.In 2015,the suitable ranges of TK（plough layer）,SC（plough pan）,AP（plough pan）,TN（plough pan）,SMC（subsoil layer）and MWD（subsoil layer）were 22.16²4.06 g kg^-1,1051.08¹617.70 Kpa,6.01⁸.67 mg kg^-1,986.90¹052.13 mg kg^-1,37.51%³8.87% and 0.14⁰.17 mm,respectively.In 2016,the suitable ranges of AK（plough layer）,BD（plough layer）,AK（plough pan）,SOM（subsoil layer）and AP（subsoil layer）were 186.67²25.34 mg kg^-1 、1.28¹.39 g cm^-3、105.06¹29.22 mg kg^-1、10.82¹2.97 g kg^-1、0.30⁰.71 mg kg^-1,respectively.4.The soil quality evaluation system under different tillage techniques was established,and the tillage techniques were preliminarily screened by combining the appropriate SQI range of reasonable areable layer.In different years,there are many treatments that meet the appropriate range of SQI in the reasonable areable layer,indicating that the existing experimental design had a positive impact on maintaining soil quality and ensuring the normal function of soil.Among the treatments that met the SQI value of reasonable areable layer in 2015,there were T₂S₂L₁（0.71）,T₁S₁L₁（0.69）,T₂S₁L₁（0.69）,T₁S₁L₂（0.65）、T₁S₂L₁（0.58）;In 2016,the treatments that met the SQI value of the reasonable areable layer were T₂S₁L₁（0.68）,T₂S₂L₁（0.61）,T₂S₁L2（0.61）,T₁S₂L₁（0.53）,and T₁S₁L₂（0.53）.5.Through the comprehensive analysis of effects of different tillage techniques on SQI and yield in different precipitation years,it was concluded that high SQI and yield could be obtained by straw strip returning to the field（plowing and rotatry plowing）.T₁S₁L₁ was beneficial to obtain higher yield in dry years（2015）,while T₂S₁L₁ was more beneficial to obtain higher SQI in rainy years（2016）.They were the main tillage technologies suitable for maize cropland in the typical brown soil.