Soil amelioration by deep ploughing of different machineries and its effect on promoting crop growth and yield

Abstract: For many years, farmers adopt a traditional cultivation method (turning, rotating, hallowing, pressing) to grow crops in China. However, improper mechanization, the nonstandard deep tillage or illogical methods of rotary tillage and subsoiling result in soil compaction, loss of soil and the plow pan formation. Consequently, the depth of tillage is shallowing, the ability of moisture conservation is weakening, and surface runoff is increasing. Improper soil tillage methods deteriorate soil quality, affect the roots to penetrate lower soil layer, limit the potential of soil production and restrain the development of modern agriculture. How to improve the production capacity of tillage soil through mechanization becomes a valuable research project, from which a better soil tillage method needs to be developed in order to improve soil properties. However, a completed technological system for subsoiling was not yet built to achieve such goal. To improve soil tillage, field experiments (block-tillage comparison) were conducted to study the effect of deep tillage mechanically on the growth of sugar beet and soybean with the help of self-developed deep pine plough (ES-210, tillage depth 40 cm) and the subsoil tillage plough (tillage depth 20 cm). Deep pine plough was used to move subsoil (20-30 cm) up to the soil layer (10-20 cm) to form a hole. At the same time, some upper soil fell in the hole becoming fertilizer grooves. These grooves allowed deep growing of roots, conserving water and promoting fertilizer use by plants. The wide head of the plow (subsoil tillage plough) can break the plow-pan to subsoil layer down to 35-40 cm deep. A comparison test was carried out with the conventional tillage (stubble chopping). Results showed that the cultivation measures improved the physical quality of the soil. Compared with the conventional tillage treatment, the solid phase ratio respectively decreased by 1.6%-3.3% and 2.8%-4.5% with deep loosening and subsoil tillage treatments. In the meanwhile, liquid phase and vapor phase increased, resulting rationalization of three phase ratio of soil. At the same time, plough pans were broken and hardness of the soil layer was reduced. For the soil depth of 20-35 cm, this was more obvious. Simultaneously, soil available water of top soil increased by 1.1%-1.2% and 0.9% for deep loosening and subsoil tillage, respectively. The irreducible water (ineffective water) decreased by 0.4%-1.1% and 0.5%-0.9%, respectively for the two tillage treatments. Compared with the conventional tillage treatment, deep loosening and subsoil tillage treatments promoted root growth and facilitated the accumulation of plant dry matter. The root growth increased by 5.1% and 2.9% of sugar beet, 11.5% and 13.2% of soybean for deep loosening and subsoiling, respectively.Dry matter accumulation increased by 2.3%-4.1% and 3.1%-4.8% of sugar beet, 7.8%-10.0% and 10.4%-13.6% of soybean, respectively for two deep tillage treatments. Mechanized soil improvement technology both increased crop production and farmers' income. For those deep loosening and subsoiling treatments, sugar beets yield increased by 8.5% and 12.6%, and soybean yield increased by 5.0% and 6.1%, respectively. Compared with the conventional tillage treatment, deep loosening and subsoil tillage increased the income by 1003.3 and 1454.4 yuan/hm2, and profit ratio was subsoil tillage > deep loosening > conventional tillage. Hence, two kinds of tillage measures improved the soil structure of arable layer, enlarged compatibilizing effect, improved root growth environment and crop yields. The research results provided the technical support for the future of farming machinery research. It provided scientific evidence to expand this technology.