Granula metric soil analysis and its application to agronomic practices



Information here makes it possible to more thoroughly understand the question — how to find and analyze the soil for growing garlic, and what characteristics of growing on various types of difficult soils.

“…. Rumors about the attack on the Soviet Union denied any soil…

— Soil — thought Chonkin, — it depends.

If, for example loam is a coffin and if

dry sand, for the potato better not”

Vladimir Voinovich.

The life and extraordinary adventures of soldier Ivan Chonkin





The laboratory «AgroAnaliz» had been performing a variety of analyses of soil, irrigation water, vegetative plants and seedlings for ten years.


And if in the beginning of our journey we had to convince farmers of the need of soil investigation, at least most of the key indicators (salinity, pH and nutrient contents), but now the situation has changed dramatically.

Agronomists of large holdings, farms in practice understand how to plan the cultivation of any culture without first examining the field is an adventure, sometimes with very unfortunate consequences.

Some “got a taste” and in the last few years we are showered with applications for the determination of soil cobalt, selenium, and other “exotics”. In a market economy, to dissuade the client from unnecessary ordering as it is not accepted, but still, in our opinion, the practical value have only the data of tests that can be adequately interpreted in specific agronomic decisions.

And until then, until science can develop exact formulas for calculating the need for cobalt fertilizers for soils with varying supply of cobalt, a wiser solution would be the concentration of financial resources and staff time to conduct those analyses, which allow to calculate the rates of fertilizers, the correct selection of a disinfectant and to make many other, equally important agronomic decisions.

In this regard, it is necessary to talk about the very important but still not familiar to many agronomists, grain-size analysis of soil.

What is this analysis? As he carried out? Why it should be done and what technological solutions should take the agriculturist, depending on its results?

Our soil (if not to take into account of the contained moisture and air) consists of particles ranging in size from very coarse gravel to microscopically small. They are divided into factions:


Table 1. International classification of soil particles according to size

Classification Particle diameter (mm)
Gravel more 1
Coarse Sand  0,5-1,0
Medium-grained sand  0,25-0,5
Fine sand  0,1-0,25
Silt particles  0,002-0,05
Clay  < 0,002


That matter, what proportion of this soil consists of particles of silt, clay and sand, respectively, will depend on the most important water-physical properties, the potential water holding capacity, permeability, thermal conductivity…

It is based on the calculation of the ratio of these fractions specialists and carry the soil to the “loam”, “loam”, “sand”, from the conversation which always starts the section “site selection” in the feature any crops.

Below we consider a number of cases where without knowing the exact parameters of water-physical characteristics of soil it is impossible to make the right agronomic decisions.

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As all these elements to measure?

Way enough have been developed and widely used in world practice.

Laboratory professionals can easily find its detailed description in the relevant Standards, and to a wider audience, I will explain briefly:

Selected averaged soil samples from the fields, sift them through special sieves, pour water with a special solution of dispersant (to particles separated from each other), again passed through a sieve, pour the suspension in a measuring cylinder and after a certain period of time, select the slurry, which is dried and weighed in the balance of high precision.

In the end you get a result that looks like this: “this soil is composed of 22% sand, 18% clay and 60% silt”

And then these results are entered into a special computer program “Calculator of water-physical soil properties”



And get the values of such soil characteristics as moisture content of wilting, the lowest moisture content and maximum moisture content.


Recall briefly the essence of these indicators.



The least moisture capacity (LC) is ideal for plants the condition of the soil when all the pores are filled with air and the capillaries — water. Note on the soils of different mechanical composition of this index has different values (from 22% to 49% in this example)

The limit moisture capacity is a glut of soil moisture. And the pores and capillaries filled with water, plant roots suffer and eventually die from lack of air.

Humidity wilting is already an acute shortage of moisture in the soil, most of the capillaries have lost water, and plants are unable to obtain it from the soil, which leads to loss of turgor and significant loss of crops later.

These parameters are also quite different for different textured soils.

Know these indicators agronomist necessary. To carry out a glaze to prevent either one or the other extremes. So for example, knowing the size of the range between the lowest moisture capacity and wilting moisture to your soil you will be able to determine the optimal frequency of watering. Because soils with higher water-retaining ability can be watered less frequently.

But this knowledge is necessary and those who work in non-irrigated areas. Very often when planning sowing this or that crop agronomist must evaluate the reserves of productive moisture in the soil.

What is “productive moisture”? It is just the difference between the actual relative humidity of the soil today and the humidity wilting characteristic of this soil. And if the first indicator (relative humidity) is easy to determine by weighing dried soil in weighing bottles in a drying oven, the humidity wilting can be found only by conducting a particle size analysis of the soil and processing of the data calculation program.

But the results of this analysis, we can also classify our soil on mechanical composition.


Table 2 shows this classification of the soil and, using her agronomist could select the optimal areas for growing different crops more accurately and correctly than it does in the epigraph to this article, the hero of the novel, Voinovich.


Table 2. Classification of soils on their mechanical composition (by Kaczynski).

The content of physical clay ( particles smaller than 0.01 mm ), %
Soils of podzols type of soil formation Soils of the steppe type of soil formation Saline and highly alkaline soils Short name of the soil particle size distribution
0 – 5 0 – 5 0 – 5 Sand loose
5 – 10 5 – 10 5 – 10 The sand is connected
10 – 20 10 – 20 10 – 15 Sandy loam
20 – 30 20 – 30 15 – 20 Loam light
30 – 40 30 – 45 20 – 30 Loam average
40 – 50 45 – 60 30 – 40 Loam heavy
50 – 65 60 -75 40 – 50 Clay easy
65 – 80 75 – 85 50 – 65 Clay medium
> 80 > 85 > 65 Clay heavy

Separately with the extremes of sand and heavy clay soils.


Sandy soil


Our company has many years of experience in the region is rich in such soils is famous Oleshkivski Sands in the Kherson region Ukraine  – the largest sandy area in Europe is 220 thousand hectares (externally – a real desert with sand dunes, here called Kuchugury). Over the years we have learned a lot of new technology intensive production on these lands.





At first, the specifics of irrigation

 Sands are characterized by a very narrow range of available moisture after a heavy watering so the soil is in the state of maximum water holding capacity (saturation moisture, lack of air to roots), and then very quickly goes into a state of humidity wilting (critically low humidity causing a steady loss of turgor of a plant).

This is due to the high permeability and low moisture-holding capacity of such soils, and low capillarity.

So, to prevent either the first or the second extreme, to irrigate such soils often have and small irrigation norms.

Therefore, the optimal method of irrigation of sandy soils is drip irrigation, but it allows you effortlessly and labor costs to pour small doses, as often as necessary – at least daily though twice a day.

Low capillarity causes another technological solution for such soils are narrowing of rows between rows.

As you know, on the drip is taken to double rows with the placement of a drip tube in the narrow row

But if you have loam, the soil with high capillarity width of this “narrow” aisle can be 50-60 cm (for tomatoes, cabbage, peppers…), on the Sands it is better to make very narrow – 30-35 cm

Sometimes even have to lay some drip tube for every row (which leads to a dramatic increase in costs per hectare).

For the same reason and the pipe for watering must be chosen with more dense arrangement of droppers, not 30-33 cm as usual, but 20 or even 15 cm between droppers.


The second feature of farming in the Sands associated with mineral nutrition

 Sands humus, we grow a number of crops on a sandy soil with a humus content of less than 0.5%. And it is because of the low content of humus and mineral nutrition you need to be very careful because these soils have a low buffer capacity (the ability of soil to resist rapid changes in pH when introducing an acidic or alkaline fertilizer).

Work on the Sands close to the work of hydroponics – the slightest mistake not only in the total dose of any fertilizer, but in a single feeding, can create serious problems. At that time, as well hummus loam successfully able to “fix” small mistakes agronomists.

Therefore, no matter how much the grower got used to work successfully on the Sands, the task of improving Soil humus content should be among the priority. To residues, to occupy the field planting green manures between growing basic crops to apply fertilizer are the main methods of solving this problem. Although, unfortunately, they operate very slowly, because the sand still have to constantly deal with the leaching of the humus particles.

I would like to clarify the meaning of “organic fertilizer”. Often the concept of good organic fertilizer is associated with well-decomposed manure, humus which is five to eight years disintegrated to a fine powder. It’s not the best solution, as this humus mineralization of already went too far, and most of the organic matter is decomposed to inorganic compounds.

If the main task for us is not the replenishment of nutrients, and increase organic content in the soil, it is better to use half – rotted manure in which the particles are not already straw yellow and dark brown, but still remain separate and are clearly distinguishable as straws.

Fresh manure for these purposes would be even better, but it is a source of too many weed seeds and many pathogens, and the best solution to this problem – correct preparation of manure in manure storages with careful control of humidity and temperature “burning”.

A good organic fertilizer can be virtually any organic material that can be expensive to deliver in the field, straw, sunflower husk, waste from canneries, urban wipers swept away the fallen leaves, which are from the big cities in the autumn caravans of cars are taken to the landfill… just remember that the “raw organics” rotting in the soil, will strongly bind the nitrogen, and therefore simultaneously with the introduction of such materials is necessary to apply a precisely calculated dose of fertilizer (they are derived from the so-called “carbon-nitrogen ratios”).



Another problem of vegetable production in the sand – spring winds

 Not only that, it is too light, sandy soil, strong wind can blow the top layers of the seed (this is especially dangerous for varieties of crops which are sown to a depth of 2 — 3 cm), but even after the emergence of a new danger. A strong wind picks up the sand grains from the soil surface, and this air / sand mixture like sandpaper “is scabbing” the tender shoots of onions, carrots, sometimes tomatoes. Loss of shoots sometimes reaches 30 %. In order to prevent this, there is only one way to maintain the surface of the sandy soil always moist. Wet soil – soil is heavy, and the wind it is not so easy to rise.



But there is sand and very important (e.g., to growers) advantages

At first, sand the vegetables grow pure, it is possible to implement without pre-washing. This is especially important for potatoes and root crops.

Secondly, the sands are more technologically. Tillage, spraying fields can be any day, even after a very heavy rain, the sand dries very quickly and allows you to go on the field and the technology and people in practically all technological operations.

This is a quick drying sandy soils greatly facilitates the fight against diseases (as a prerequisite for the development of many diseases is high humidity).

Quick drying, Sands and facilitates weed control in wide row spacing, of course, with drip irrigation. Pouring only a narrow strip between the double rows, we leave wide aisles with no moisture and on sandy soil the weeds they can not grow, while the soil greater water holding capacity of one or two rains could be enough to weed successfully developed in the aisles, unless time does not destroy its crops.

Another advantage of the sands – they warm up much faster and hence allows early to sow, to plant seedlings, eventually get an earlier harvest.


Heavy clay

It is much harder to work on soils is related to opposite extremes – heavy clays. This type includes the soils with the content of physical clay and more than 65% (table 2).

Clay soils have low permeability, they may take a while to stagnate not only rainfall but also irrigation water, and plants usually suffer from a lack of air in the soil. The capillarity of these soils is also very low.

Simple and radical solution to this problem does not exist (the importation of sand for soil improvement in the real scale of the garden, but not in industrial fields) the only acceptable solution for the professional is the constant loosening of row spacing.

It is the cultivation, not cultivation. That is the working bodies of your tools must be pointed foot and do not the razor and chisels (chisel foot). Of course, if the soil treatment is also the task of removing the weeds, the cultivator can be combined working bodies of various types.


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In wide row widths it is necessary to cut and constantly “refresh” the slit with a depth of 40-50 cm.


And of course heavy clay has specific requirements for watering.

The beets and carrots water logging (which happens on clay after almost every rain) leads to the fact that roots will be formed in the form of short “barrels”, to ramify and to shorten.


On the potatoes when growing on heavy soils typical problem is the darkening of the core.

This defeat occurs due to lack of oxygen. If you encounter such a problem do not look for reasons or in mineral nutrition or protection. It’s a classic physiological lose, to avoid which only the maintenance of an adequate level of aeration of the soil (loosening and anti-water logging).

The hollow trunks of potatoes – a classic consequence of water stress. This lesion is more common on light sandy and sandy soils. You can cast on the field for the season, absolutely the right amount of water but if watering will be based on the principle of “if dried up then waterlogged!” such permanent water stress will lead to the formation of tubers inside the voids due to uneven growth of parenchyma cells.


The more intensive agriculture you are, the higher you set “bar” yield the more important proper site selection including soil.

However, in appearance ( as well as using all sorts of anecdotal methods “spit on the ground, squeeze it into a ball and roll out into a sausage…..”) you hardly distinguishable from heavy clay medium or heavy loam mild clay.


Therefore, granulometric analysis is necessary.

To measure is to know” is the motto of many experienced and successful agronomists. Let it be your motto.

After knowing all the important characteristics of your soil, you will be able to find effective ways to correct all of its flaws, or at least, the right choice of culture and processing methods to obtain high yields even in difficult soils.


Vadim Dudka, Director of the chain of laboratories “AgroAnaliz”

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