Design of variable screw pitch rib snapping roller and residue cutter for corn harvesters

The blocking between two snapping rollers will seriously constrict the harvesting efficiency for corn harvester.A variable screw pitch rib snapping roller was developed to solve this problem.The comparative experiment between fixed screw pitch rib snapping rollers and variable screw pitch rib snapping rollers illustrated that variable screw pitch ribs can avoid corn-stalk blocking effectively,and it can improve working efficiency by 56.7%.Conservation tillage with standing corn residue was testified that it had a strong control of soil wind erosion.In order to implement this mode of conservation tillage at a production scale,a cutter was developed in this study.Subsequently,two experiments were conducted,one was to test the cutting ratio(defined as the totally cut off stalk population divided by total stalk population),and the other one was to test standing-residue height.The experiment results showed that the mean cutting ratio increased significantly(p<0.05)along with increasing height of cutter-head above the ground(cutting height);the cutting ratio’s mean value increased significantly(p<0.05)along with the decreasing angle between the cutter-head and the ground(cutting angle).The average standing-residue height increased along with the increase of cutting height from 300 mm to 500 mm.The average standing-residue height increased significantly(p<0.05)along with the decrease of cutting angle from 15°to 0°.Therefore,the newly designed snapping roller can improve the harvesting efficiency and prolong the working life of the cutting table;and the cutter can promote the popularization of the conservation tillage with standing corn residue in Northeast China.

Effects of residue management and nitrogen fertilizer rates on accumulation of soil residual nitrate and wheat yield under no-tillage system in south-west of Iran

Conservation tillage,residue management and optimizing nitrogen(N)fertilization are important stra-tegies for soil and water conservation and sustainability of agricultural systems.In order to evaluate the effects of various residue management methods and N fertilizer rates on some soil quality indicators,accumulation of residual soil nitrate,and wheat yield under no till system,a split-plot experiment was arranged in a randomized complete block design with three replications.Main plots were three residue management methods,including retaining(R.M1),removing(R.M2)and shredding(R.M3)of corn res-idues.The subplots consisted of four N fertilizer rates,100(N1),150(N2),200(N3),and 250(N4)kg N ha^(-1) from urea source.The results showed that soil organic carbon and total N in R.M1 and R.M3 treatments increased at the depth of 0-15 cm as compared to R.M2.The maximum accumulation of soil nitrate was observed in R.M1 x N4 and R.M3 x N4 interactions at the soil depth of 60-cm.The results of this study showed that R.M1 x N3 and R.M3 x N3 interactions had a greater impact on wheat yield than the sole effect of R.M1 or R.M3.According to our findings,application of 200 kg N ha^(-1) in combination with R.M1 which had once less tractor passing for mechanical shredding than R.M3,can contribute effectively to improve soil quality indicators,control soil residual nitrate and subsequently produce more wheat grain yield in the south-west of Iran.