ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

The furrow sowing with whole plastic-film mulching on double ridges had been widely used in the arid region of northwest China, because it could resist drought and increase production. So the mechanical plowing and filming on seedbed was an inevitable trend in farming. For further study of the improved working performance of operation machine for tillagefertilization and sprayingfilming on double ridges, the Box-Behnken experimental design with four factors and three levels was performed, parameters such as operation machine speed, soil elevator speed, lateral flow angle of covering unit and straight flow angle of covering unit were selected as independent variables, which would influence mechanical damage rate of daylighting mulch. The mathematical model was established, then the effects of various parameters and their interactions were analyzed as well. The test results showed that effects order of four parameters on mechanical damage rate of daylighting mulch were as follows: soil elevator speed, operation machine speed, lateral flow angle of soil covering unit and straight flow angle of soil covering unit. The optimal working parameters were combined operation machine speed of 0.67m/s, soil elevator speed of 070m/s, lateral flow angle of soil covering unit of 75° and straight flow angle of soil covering unit of 48°. Confirmatory tests showed that the average value of mechanical damage rate of daylighting mulch was 0.216%, which compared with the optimization before, had dropped significantly, and also avoided mechanical damage of daylighting mulch under this condition.