Soil appraisal is an assessment of the condition of a site for its fertility. At the end of this procedure, experts develop recommendations on how to farm the farmers. During the valuation, among other things, the zoning of the study area is carried out with the definition of relatively homogeneous zones in terms of fertility.
What is made for
Soil scoring is a procedure in which specialists usually solve the following tasks:
compare and group the soils of the district, republic, region, etc .;
the most favorable lands for cultivating agricultural crops are identified;
evaluate the result of economic activities of agricultural producers;
identify unused reserves.
Also, experts determine the need for certain measures aimed at increasing productivity. In addition, one of the main goals of soil appraisal is, of course, the introduction of new methods of farming.
Preparatory Activities
Land appraisal is made, of course, after a thorough study. Soil analysis is performed using:
Validation is also carried out taking into account data on long-term average productivity of the main agricultural crops grown in the region (at least 5-10 years).
Main stages
Soil scoring is a procedure in which specialists:
The final stage of the appraisal is always the development of practical recommendations for agricultural producers.
How is the statistical processing of data
This stage of valuation in most cases includes the following steps:
A reference plot is selected, the most productive, according to many years of statistics.
Land characteristics of the selected site are evaluated in points, the sum of which should be equal to 100 (sometimes 50). When carrying out such a procedure, for example, such properties of the soil of the reference area as pH, percentage of humus content, the amount of exchange bases, etc. can be taken into account.
Each of the diagnostic features of other areas of the district is scored in relation to the standard using special formulas.
Signs are revealed that indicate the deviation of soils from typicality. For example, in the taiga zone, such characteristics of the earth as the degree of bareness, stonyness, flushing, in the steppes, the presence of readily soluble salts, solonetzic acidity, etc., can be assessed. For each specific sign of deviation of the soil from typicality in a given natural zone, there is a correction factor taken into account when assessing the site.
The overall average score of soil bonitet is determined.
As indicators of soil appraisal, both properties acquired in the process of cultivation can be taken, as well as natural ones. During this procedure, among other things, the plots that are most suitable for the cultivation of certain crops are identified.
What formulas can be used in mathematical analysis?
When performing soil assessment and assessment of soils in relation to the standard of various kinds, indicators are expressed by the following formula:
B - the assessment point itself, Pf - the actual value of the indicator, Pe - the value of this indicator on the reference area.
The average bonitet score of the studied soil is determined using the following formula:
∑B is the sum of certain average scores of the estimated indicators (humus, pH, etc.), n is the number of indicators taken into account, K is the correction factor for the deviation of the soil from typicality for any characteristic.
How are rating scales developed?
After carrying out a mathematical analysis when performing land scoring and economic soil assessment, specialists begin to systematize the collected data. In this case, two scales are compiled in points:
The score of the second scale is determined as follows:
Using a soil map, several farms of the region are selected where land with certain properties, for which yield calculation is carried out, occupies 70-80% of the area.
Based on the reported data, the average productivity of the main crops for 5-10 years is calculated. Next, take the highest yield on soil with certain properties for 100 points.
At the next stage of soil appraisal and economic assessment of soils, specialists verify the correctness of their conclusions by comparing the points of the first scale with the data of the second. The discrepancy in indicators should not exceed 10%. If the scores do not match significantly, a reanalysis is made using other diagnostic indicators of the soil.
Third stage
After the scales are compiled, specialists determine the weighted average grade point using the following formula:
B0 = (BI1P1 + BI2P2 + ... + BINPn) / P, where:
- P - soil area of each type;
- BI - score for each variety of soil;
- P is the total area of the study area.
The systematization of the results depending on the magnitude of the points is what the analytical stage of soil scoring usually ends with. Land valuation, as you might have noticed, is a rather complicated procedure. After it will be carried out, experts begin to develop recommendations for the use of land in the study region.
Regression equation
Such an equation, in fact, is a mathematical model of the soil productivity of a particular region. It is used when using multivariate and correlation analysis in valuation. The regression equation looks like this:
Y = a + B1X1 + B2X2 + ... + BnXn, where:
B1, B2 ..., Bn - productivity gain coefficients, X1, X2 ..., Xn - indicators of factors that have the greatest influence on it, and - free member, Y - normal productivity.
Indicators taken into account when combining soils in groups
The distribution of land during the scoring may take into account the following factors:
belonging to one climatic province and mountain district;
degree of proximity in terms of basic physical and chemical properties, morphological structure, composition, stock of nutrients;
features of the relief in the conditions of which the soil cover was formed;
features of soil properties that reduce its fertility, complicate its use and determine the need for various kinds of reclamation enterprises.
What physical properties of the earth can determine its quality
The degree of soil fertility, among other things, may depend on factors such as:
the percentage of humus;
thickness of the humus horizon;
the percentage of sludge;
clay percentage;
gross reserves of humus, nitrogen, potassium and phosphorus;
particle size distribution ;
amount of absorbed bases.
Also, the acidity of the soil has a significant impact on the productivity of crops grown in a particular area.
Land classification
At present, there are a total of 7 main categories of soils, including 37 classes:
land suitable for arable land;
hayfields;
pastures;
unsuitable for growing agricultural crops;
lands potentially suitable for farming after land reclamation;
unsuitable for agricultural land;
disturbed.
Arable land
The soil in areas belonging to this category is characterized by a high degree of moisture and air exchange. Such a land always contains enough nutrients to grow various kinds of crops.
The category of arable land, in turn, includes several classes. These include drained watersheds and mild slopes:
light loamy and loamy carbonate;
non-carbonate;
sandy and sandy with increased influence of light rocks;
with increased influence of heavy rocks, clayey;
with increased influence of boulder-pebble deposits.
Also in this category are weakly drained, shortly moistened lands of the same type. In addition, slightly erosive gentle slopes are considered suitable for arable land:
on loose rocks, including slightly washed away;
loamy and clayey sloping slopes, including washed-out ones;
on dense rocks, including washed away.
A separate class of land suitable for arable land is, of course, cultivated soil.
Hayfields
First of all, floodplain meadow lands fall into this category:
clay and loamy;
sandy and sandy.
Relative to hayfields and non-floodplain areas with the same types of soil.
Pastures
Such sites are mainly used for grazing cattle, small cattle and horses. The pasture category includes, for example, solonetzic land and:
automorphic;
hemihydromorphic;
fused hydromorphic.
Also for pastures can be used plots:
waterlogged;
very stony and gravelly;
soddy sands.
What lands are considered unsuitable for growing agricultural crops
This category, in turn, includes:
riding bogs;
stony placers;
pebbles.
Crops are not cultivated on gravelly deposits and on some other types of soils.
Land for improvement
After carrying out various land reclamation measures, peat bogs, for example, may become suitable for growing agricultural crops:
Also in this category are:
Land unsuitable for farming
This category of land includes primarily:
rocks and placers;
glaciers.
Of course, snow-covered areas, as well as the bottom of various reservoirs, are considered unsuitable for farming.
What are the estimated signs taken into account when scoring soils most often
Thus, soil scoring is a modern procedure, the theoretical basis of which is the relationship between:
These relationships were once established by the Russian scientist V.V. Dokuchaev. He himself for the first time formulated the very concept of “soil appraisal”. The name of this researcher was subsequently named the Russian Soil Institute.
According to the draft provisional guidelines for soil appraisal developed by the specialists of this institution in collaboration with scientists from Rosgiprozem, it is recommended to take into account the following assessment factors for those areas in which agriculture is provided with moisture (taiga and burozemno-forest):
pH of salt extract;
humus content in arable soil;
hydrolytic acidity;
the content of mobile phosphorus;
soil texture;
the amount of absorbed bases;
degree of saturation with bases.
For mountain and foothill areas, forest-steppe zones, areas of depleted and insufficiently provided with moisture:
humus content in the arable layer;
base absorption capacity;
degree of saturation with bases;
soil solution reaction;
mechanical composition.
For irrigated areas:
In accordance with the characteristics of the soil in this particular area, the list of diagnostic features taken into account can be specified.
Existing soil scoring methods
Such a procedure can be carried out, for example, by the following methods:
Tyumentsevskaya. In this case, mainly the percentage of humus in the soil is taken into account.
Burlakovskaya. Using this technique, soil properties and spring wheat yield are taken as the basis.
When conducting research on land, among other things, PEI, the value of the soil and environmental index, can be taken into account. This method of soil scoring was developed by I. I. Karmanov from the Soil Institute.