Method for measuring soil bulk density

Abstract

The invention discloses a method for measuring the soil bulk density. The method comprises the following steps: collecting soil, placing the collected soil into a self-packaging bag and removing air in the self-packaging bag; when the inside of the sealing bag is in a negative pressure state, sealing the self-packaging bag; measuring the volumes of the sealed self-packaging bag and the soil in the sealed self-packaging bag; taking another empty self-packaging bag of which the size is identical with that of the self-packaging bag for accommodating the soil; removing the air in the empty self-sealing bag and measuring the volume of the empty self-packaging bag; sealing the soil in the bag and drying the soil to constant weight to obtain the weight of the soil; and then calculating the bulk density of the soil according to a formula. According to the method disclosed by the invention, the error of the volume of the soil with an irregular shape can be effectively reduced, and thus the test precision of the soil bulk density is improved. In addition, the method is suitable for measuring the bulk density of the soil under special environments (environmental complexity and soil body crushing) and is especially suitable for measuring the bulk density of the soil on discontinuous soil bodies and soil bodies in which more stones and plant root systems exist in the soil, the soil layer thickness is thinner or the soil structure is loose.

Description

technical field [0001] The invention relates to a method for measuring soil bulk density, which belongs to the technical field of measuring soil physical properties in agriculture and forestry. Background technique [0002] Soil bulk density refers to the dry weight of soil (including the volume of soil voids) in the natural state per unit volume. The size of soil bulk density reflects the level of soil structure, air permeability, water permeability and water retention capacity, which has important application significance in agricultural and forestry production. In agricultural and forestry research, especially when evaluating soil fertility and site quality, the measurement of soil bulk density is often involved. [0003] At present, there are ring-knife method for measuring soil bulk density (Guo Guoshuang. Talk about the determination of soil bulk density. Irrigation and Drainage, 1983, 2(2): 39-40; Liu Duosen, Li Weibo. Simple measurement method of soil bulk density a...

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Problems solved by technology

[0004] The above-mentioned ring knife method, soil drilling method and original soil pipe method are mainly used on soil with tight soil structure, no stones, no thick root system, and thick soil layer. The three methods cannot collect soil clods with complete shapes; and the ring knife method and the soil drilling method need to manually beat the soil, which often changes the compactness of the natural soil and causes the soil volume to deform; in addition, if the soil extraction process Encountering large stones or thick root systems in the soil will damage the ring cutter, soil drill and soil borrowing pipe

Although the digging method, the irregular cave method and the wax sealing method can overcome some of the shortcomings of the ring knife method, the soil drilling method and the original soil borrowing pipe method, it is difficult for the digging method to meet the soil with loose structure and many stones. Dig a standard cube or cuboid soil pit, so there will be errors in calculating the soil volume; in addition, when the digging method encounters mineral soil, the plastic bag filling method is used to measure the soil volume, but it is impossible to visually determine whether the lower part of the pit is full of water. Therefore, the measured soil volume will also be inaccurate.

The irregular cave method is similar to the digging method. It also uses the plastic bag filling method to calculate the soil volume. It also has the disadvantage of not being able to accurately measure the soil volume, and requires a special capacity level sampling device. Due to the inconvenient soil collection and measurement process, this method is obsolete

The wax sealing method is to wrap the collected soil with melted paraffin, put it into a beaker to calculate the volume of the soil, the measurement process is cumbersome, the calculation formula is complicated, and errors are prone to occur when used in the field, and for loose structures or stones More soils cannot be measured using the wax seal method, so this method is no longer used

The soil borrower for testing soil bulk density is similar to the principle of the ring knife method, and cannot be used on rocky or loose soil.

The use of water-filled soil bulk density testers is limited in the field, and there are special requirements for soil measurement, so it is difficult to popularize and use

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