Answer to Question #104999 in Chemistry for Riya

Question

Describe the process of sampling of soil.

Answer 1

Sowing or planting crops without prior soil analysis is a big mistake for users and land owners. The soil may contain elements and compounds, the presence of which is not compatible with the growth and activity of cultivated plants. Sampling for agrochemical analysis must be carried out taking into account the vertical structure, heterogeneity of the soil cover, topography and climate. The selection of mixed samples is best done in the spring, when fertilizers and crops have not yet been applied to the field. The second term for sampling is established after the harvest, when the main supply of available nutrients has already been consumed by plants, and the absence of crops does not interfere with the work. Most often, the “envelope” method is used to select mixed soil samples. It consists in the fact that samples are taken at each of the sections diagonally or along the "envelope" (four points in the corners and one in the center) at its five points. Soil samples are taken using a soil auger or probe. For sampling on dry and dusty soils, a soil probe is used, and on stony or frozen soils, a soil drill. There are also hydraulic or mechanical samplers for taking surface and depth samples. They greatly facilitate sampling, especially when taking a large number of samples from different sites. Tool surfaces must be free of corrosion and rust.

Sample preparation consists of stirring, grinding and reducing to a certain mass. To reduce the sample using the method of quartering. The crushed material is poured onto a sterile dense sheet of paper, mixed thoroughly, and roots, stones and other solid objects are discarded. Then the soil is distributed in place with an even thin layer (0.5 cm) in the form of a square, divided into four sectors, the contents of the two opposite sectors are discarded, and the other two are combined together and mixed again.

The soil is divided until about 300 g is left and sieved through a sieve of 1 mm diameter. After that, the soil is poured into a clean container with a ground stopper and numbered. Samples for analysis are taken from the obtained sample. If analysis is impossible immediately, then the soil can be stored in the refrigerator: slightly contaminated - at a temperature of 0 ° C for 72 hours, and very contaminated - 48 hours.The results of the analysis make it possible to determine the type and rate of fertilizers, the correct use of which leads to an increase in yield, level of profitability and thereby leads to a decrease in negative environmental impact.