Design of corn high-stubble cutter and experiments of stubble retaining effects

Abstract: In order to improve the productivity of land and protect the cultivated land environment in a ridge area of Northeast China, one mode of conservation tillage with high stubble for corn is currently emerging. This new conservation tillage aims to retain a certain height of stalk standing in the field, while using the other part of the stalk in other ways. The standing part of the stalk is sufficient to recover the field's fertility and also helps to avoid environmental pollution. Meanwhile, the other part of the stalk can feed livestock during the winter or be used as fuel in rural areas. One can see that this method has many advantages. Unfortunately, the existing corn harvesters can't realize this mode of conservation tillage. In order to mass-produce this mode of high-stubble conservation tillage, harvesters which can automatically retain high stubble are developed.Horizontal corn harvesters have some advantages, such as low grain breakage rate and impurity, and this practice is used widely all over the world. Adding the cutter to an existing two-row corn harvester is the main designing idea of this paper. Additionally, since different corn varieties and complex working conditions have different requirements, cutting height and cutting angle should be adjustable. Finally, the results of two experiments are presented. The first experiment was to vary the cutter head's height and the cutter angle, while measuring the cutting ratio (defined as the ratio between cut stalks to total stalks, expressed as a percentage). The second experiment tested the relationship between the stubble height (output parameter) and the cutter head's height above the ground (input variable) as well as the cutter angle (input variable). Some relations among cutter head's height, cutter angle, cutting ratio and resulting stubble height were presented; and these relations can be used to adjust cutter head's height to create a desired stubble height.We came to the conclusion that with the increasing of cutter head's height, cutting rate increases, and the cutting ratio's mean value increases from 90.16% to 95.43%. In the range of 0 to 15° of cutting angle, with the increasing of the angle between the cutter head and the ground, the cutting ratio's mean value increases from 90.17% to 95.42%. While varying the cutter head's height, the mean value of stubble height increases from 307 to 363 mm, it is to say that the average stubble height increases along with the elevation of cutter head's height. Similarly, while varying the angle between the cutter head and the ground, the mean value of stubble height increases from 329 to 341 mm. Broadly speaking, the average stubble height increases along with the increase of the angle between the cutter head and the ground. In conclusion, the cutter designed in this paper can help to realize the high-stubble conservation tillage in conjunction with existing horizontal corn harvesters, which has profound influence on promoting the high-stubble conservation tillage in ridge areas of Northeast China.