Physico-mechanical Properties of Soil during the Treatment Period

Abstract

Results of research work on physical and mechanical properties of soil during its main cultivation are presented in this article. It is established that physical and mechanical properties of soil act as defining factors in design development of working elements and justification of operating modes of soil-cultivating machines. They mainly depend on the type and texture of soil.

Keywords: Polishing the soil; Two layers of plow; Up and down forms; Dumper of surface; Takyr soil- infertile hard soil.

Introduction

Research has established that the physical and mechanical properties of the soil are the determining factors in creating the design of working bodies and in justifying the operating modes of tillage machines. They mainly depend on the type and mechanical composition of the soil.One of the main factors influencing soil cultivation from the point of view of agricultural technology and energy, regardless of the type of mechanical composition, is the humidity, hardness and density of the soil of the cultivated horizon.The moisture content of the soil greatly influences its mechanical strength and, therefore, it’s processing. Soils with low moisture content have greater mechanical strength; during their cultivation, many blocks and large lumps are formed, therefore the traction resistance of soil-cultivating working bodies is of great importance. Due to its significant plasticity, wet soil crumbles and does not stick well to the surface of the working tool. The soil moisture and hardness were studied under typical conditions against the background of old arable land with long-standing irrigation, grown from cotton and alfalfa, while the soil moisture and hardness were determined using standard methods. The hardness of the soil was determined using a modern manual hardness tester (Dutch design), and various conical tips were used depending on the condition of the soil. The average error of the device reading does not exceed ± 8% [1]. From the data obtained [2-4], soil moisture and hardness largely depend on the agrotechnical background and horizon depth (Table 1).

Depending on the agrotechnical background and the predecessor, changes in humidity and soil moisture and hardness differ from each other in depth, for example, in a cotton field in the arable layer at a depth of 0-30 sm, soil moisture increases from 12.32 to 14.83%, while the soil hardness is 1.65 to 2.72 MPa, further, at a depth of 30-50 cm, soil moisture decreases to 10.05%, and soil hardness increases sharply to 6.25 MPa. In an alfalfa field, soil moisture in horizons of 0-50 cm ranges from 11.25 to 16.81%, while soil hardness at a depth of 0-30 cm increases from 2.18 to 3.27 MPa, and subsequently with increasing layer depth soil hardness increases to 5.65 MPa. During the period of main tillage, soil moisture ranges from 10.05 to 14.83%, instead of the optimal 17-18%, which increases soil hardness and requires additional energy costs for tillage.From this we can conclude that the depth of soil hardness largely depends on the predecessor and the number of agrotechnical tillage methods.In addition to the hardness of the soil, the development of plants, the yield of cotton and other agricultural crops is influenced by its density. The study of soil density in old cotton fields was carried out at a groundwater depth of 1.8-2.0 m.

The soils are meadow, irrigated for a long time, the mechanical composition is medium loamy, slightly saline.

Determination of soil density depending on the initial moisture content in various soil types is

Presented in Figure 1.
The data obtained show that in all the studied soils, the horizons (0-30 cm) have a satisfactory density in the range of 1.3-1.35 g/cm³, with increasing depth of cultivation of the horizons, the soil density increases.

It has been established that an increase in soil density in the underlying horizons undoubtedly has a negative effect on water permeability and the value of field moisture capacity of the soil, as well as on the yield of agricultural crops. The density of the soil also depends on their type and moisture content.

In desert-sandy soils, an increase in their density in the horizon of 20 cm and below indicates a low soil moisture content, which is related to coarse and difficult-to-cultivate soils.

It has been established that in the sub-arable horizon, where the soil density is usually too high, working tools should be used that prevent the formation of a compacted soil layer.

Changes in the mechanical strength of takyr and light soil gray soil for compression and rupture due to their moisture content were studied, the results of which are given in Table 2.

It should be noted that the tensile strength of light soil gray soil is significantly greater than that of takyr soil. The compression force also changes according to the same pattern. Light soil gray soil has a slightly higher compressive stress limit than takyr soil.

At the same moisture content, the compressive stress of the studied soils is 5-6 times higher than the tensile strength.

Thus, based on the data presented, we can come to the conclusion that these soils have very high mechanical strength at low humidity and their processing requires high energy consumption.

References