| Subsoiling tillage,as one of the key technologies of conservation tillage,is widely applied in most areas of China because of its soil condition improvement and yield increasing effects.However,high resistance and high energy cost of subsoiling work are important issues to be solved urgently.The problem of how to take energy saving,yield increasing and soil loose into consideration,and the problem of determining the appropriate subsoiling interval time have not been systematically studied.Therefore,maize root-soil composite simulation model was developed by using EDM.According to EDEM simulation and field experiments,subsoiler key structural parameters,subsoiling depth and working speed were optimized.A linear weighted math model was developed based on the indexes of fuel consumption,soil condition improvement and yield increase rate.The comprehensive effect of chisel-shape subsoiler(CS),arrowhead-shape subsoiler(AS)and wing-shape subsoiler(WS)were tested by this analysis model.The main result are as follow:(1)Maize root-soil composite simulation model was developed by using EDM.According to cutting simulation experiments of maize root and root-soil composite model,the key parameters of root-soil composition were determined,which was consisted of root particle shear module,critical stress,bonded disk radius,coefficient of static friction and bonding stiffness and critical stress between root and soil.According calibration experiment and regression analysis under the condition of light loam soil in Zhuozhou Hebei province,it was calculated that the optimum value of root particle shear module,critical stress,bonded disk radius,coefficient of static friction and bonding stiffness and critical stress between root and soil were 6.293 Mpa,1.034 Mpa and 3.013mm,0.7,90 MN/m3 and 90 Mpa.Field subsoiling experiment showed that the error of subsoiling resistance between simulation experiment and field experiment was within 10%,the root-soil composite model could accurately simulate the actual in the field soil condition.(2)According to EDEM simulation and field experiments,subsoiler key structural parameters.The results indicated that,in clay loam condition,the relatively best subsoiler was chisel-shape subsoiler(CS)when it’s penetrating angle a was 21°.In light loam condition,the relatively best subsoiler was arrowhead-shape subsoiler(CS)when its penetrating angle a was 21°.In clay loam condition,the traction resistance for wing-shape subsoiler(WS)was greater than those for CS and AS by 54.4%and 25.6%,respectively(P<0.01).When the penetrating angle a was 21°,the traction resistance was lower than those by 8.3%and 17.6%(P<0.05)when its penetrating angle a was 18°and 24°.In light loam condition,he the traction resistance for CS was lower than those for AS and WS by 146.6%and 27.0%,respectively(P<0.01).When the penetrating angle a was 180 and 24°,the traction resistance was higher than it by 25.0%and 18.0%(P<0.05)when the penetrate angle was 21°.The subsoiler type with the smallest tillage specific resistance was the CS in clay loam condition,and AS in light loam condition.(3)The subsoiling depth and working speed were optimized.The changing rule of critical depth and the specific resistance of subsoiling varying with the depth and width ratio of buried components were cleared.It was indicated,in clay and light loam condition,the relatively suitable subsoiling depth is 400 mm,and relatively suitable speed was 3 km/h.When the subsoiling depth was 500 mm,in clay loam condition,in the ditch profile of CS and AS subsoiler,the critical depth could appear,and its depth range was 350～400mm.In light loam condition,the ditch profile of the CS presented a vertical groove and rat hole,the critical depth could be found in 250～300 mm depth in the ditch profile of AS subsoiler.The tillage resistance of the CS and AS increased with the subsoiling depth,while the tillage specific resistance decreased then increased,and it was lowest when the subsoiling depth was 400mm.(4)A linear weighted math model was developed based on the indexes of fuel consumption,soil condition improvement and yield increase rate to analyze the comprehensive effect of different subsoilers.The result showed,in clay loam and light loam condition,the relatively suitable subsoiler was CS subsoiler and AS subsoiler,respectively.Subsoiler tine shape had significant impact on fuel consumption.The monitoring results of subsoiling effect in 3 consecutive years indicated that,the soil loosening effect decreased year by year after subsoiling.In the third year of subsoiling work,the loosening effect mainly disappeared.Therefore,it was advisable to conduct subsoiling work once every 2 years. |
PDF Full Text Request