Qingying Meng

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 1: Configuration of Plough for Production of Large Soil Clods in Subsoil*

Abstract A method is proposed for soil improvement of salt-affected soils. Soil clods of desired size are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the plough configuration to produce soil clods with the proper size by brittle fracture was analysed in an indoor soil bin. The results showed that when brittle fracture (tensile failure) took place in the soil, a horizontal crack in the soil was produced at the tip of the plough blade, followed by an another upward crack toward the soil surface with the angle of about 40°. A short blade length (50 and 80 mm) and deep ploughing (150 and 200 mm) of the deep tillage plough generated unwanted huge soil clods of about 25 kg. In order to generate proper soil clods, the ideal rake angle should be 20°, and the ideal blade length was 130 mm.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils:—Part 2: Draught and Vertical Force Induced on Plough by Brittle Fracture—

Abstract A method is proposed for soil improvement of salt-affected soils. Large soil clods are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the draught and vertical force induced on this plough body by brittle fracture (not by shear failure) was analysed to get the large soil clods in an indoor soil bin with a soil with cement. The results showed that the normal mean peak draught was about 1 kN, and the downward vertical peak force was about 10 kN at 200 mm in the operating depth. When the blade length was short (50 mm or 80 mm) and huge soil clods were produced, the peak draught and vertical force increased to about 2 kN and 20 kN respectively. When the blade length was long (200 and 250 mm) and the operating depth was deep (150 and 200 mm), the peak draught increased abnormally to 4–5 kN. The peak vertical force also increased abnormally to 30–40 kN. The proper length of the plough blade was determined to be 130 mm because of the smallest draught and downward vertical force.

Improvement of Salt-affected Soils by Deep Tillage: Part 2: Large-scale Field Tests in a Sodic Soil (Solonetz) Region*

A deep tillage method was tested for soil improvement of salt-affected soils. Capillary rise of groundwater was cut off by the deep tillage, which made a coarse layer in the subsoil. This paper deals with large-scale field tests constructed by a four-stage subsoil plough in a sodic soil (solonetz) region. The results showed that the deep tillage down to the subsoil proved positive for the improvement of the solonetz soil. In the deeply tilled field, the grass height and density of cultivated natural pasture were much greater than those in the conventional (subsoiled) field. In the subsoiled field, the grasses were growing at the areas on the subsoiler channels, but their grass height was much shorter than in the deeply tilled field. At the undisturbed areas between the subsoiler channels, the grasses could not survive at all.

Three-stage Subsoil Interval Mixing Plough for Improvement of Planosol: Part 1: Draught and Moment*

To improve planosol soil conditions, a new Three-stage Subsoil Interval Mixing Plough (hereafter, TSIM-plough) was developed in 2010. The TSIM-plough resolved three problems encountered by the original Three-stage Subsoil Mixing Plough (hereafter, TSM-plough) developed in 1996. That is addition of an extra first plough body to the previous design TSM-plough. Firstly, its working width was increased from 460 mm to 920 mm with an extra first plough body installed. Secondly, its calculated draught moment caused on the tractor was reduced, thus allowing the tractor to running straight more easily. Thirdly, the ground trafficability increased with the improved layering of soft and hard subsoil solum, and tractors for harvesting no longer sank under wet field conditions even in the first year of operation.

Three-stage Subsoil Interval Mixing Plough for Improvement of Planosol: Part 2: Soil Improvement and Crop Yield*

Abstract To improve planosol soil conditions, a new Three-stage Subsoil Interval Mixing Plough (hereafter, TSIM-plough) was constructed in 2010. The TSIM-plough resolved three problems encountered by the original Three-stage Subsoil Mixing Plough (hereafter, TSM-plough) developed in 1996. In this paper, the improved soil penetration resistance (trafficability) and crop yields in the field operated with this TSIM-plough are discussed. The new plough produced greater soil penetration resistance, and so greater trafficability of vehicles. The difference of the soybean yield was small between the TSM-plough and the TSIM-plough, and so the usage of the TSIM-plough is preferred.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 3: Field Experiments*

Abstract A method is proposed for soil improvement of salt-affected soils to till down to about 600 mm in depth by a special plough. The goal is to cut off the capillary rise of the groundwater by creating a coarse layer of tilled subsoil. Earlier, a plough configuration to produce soil clods with the proper size in the subsoil was determined in an indoor soil bin. In this paper, we designed and tested prototypical plough bodies in field experiments. A plough blade length less than 130 mm produced large soil clods and a blade length more than 130 mm generated small ones. With any length, deeper operating depth caused larger soil clods to form. The proper specifications of the third and fourth plough bodies of the special plough are as follows: the plough blade length is 130 mm, the operating width is 300 mm, the operating depth is 200 mm and the cutting angle is 20°.