Organic matter in agrocenosis
Summary
The following nutrients are required for plant growth
- Carbon dioxide
- Water
- Mineral elements:
- Macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S)
- Trace elements: iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), chlorine (Cl)
In natural ecosystems, plant nutrition is carried out due to the circulation of organic matter: fallen plants and leaves, falling into the soil, decompose, becoming food for microflora. During decomposition, organic matter breaks down into water, carbon dioxide and minerals.
Also, during the life of microbes in the soil, mineral elements retained in the soil absorbing complex are additionally dissolved (see the section "Dynamic fertility").
In the process of agriculture, the natural cycle of organic matter is disrupted due to regular harvesting. As a result, there is not enough organic matter in the soil, which leads to a deficiency of all nutrients: carbon dioxide and mineral elements in dissolved form.
Modern agricultural practice solves the problem of removing organic matter by applying high doses of mineral fertilizers (in Russia - about 400 kg per hectare, in Europe - up to 1000 kg per hectare). This partially compensates for the lack of mineral elements, but leads to pollution of water bodies and salinization of the soil (see the section "Mineral fertilizers").
However, this does not solve the problem of CO2 deficiency. In greenhouses, this problem can be solved by spraying carbon dioxide, but in open fields this approach is not applicable, which leads to a decrease in yields.
In addition to mineral fertilizers, organic fertilizers are used in agriculture. The most common application of manure to the soil. However, manure cannot be applied fresh due to the danger of soil contamination with parasites and infections. For disinfection, manure is brought in rotted, which is why most of the organic matter has time to decompose into water and carbon dioxide / methane even before it is added to the soil.
At the moment, RosOMU has completed research on the artificial disinfection of manure with its subsequent introduction into the soil in a non-decomposed form. If there are enough bacteria in the soil, the introduction of undecomposed organic matter will be sufficient for:
- the appearance of the required amount of minerals as a result of the activity of the soil microflora;
- releasing large amounts of carbon dioxide from the soil.
Additional dissolution of small doses of minerals in organic fertilizer (as a result of which an organo-mineral fertilizer, OMU is obtained) allows to accelerate the effect of fertilization safely for the soil while maintaining a long-term effect from an increase in the content of organic matter in the soil.
A further way of developing WMD may be the addition of a complex of bacteria to the fertilizer, which will allow restoring the soil microflora in case of its disturbance and increasing the efficiency of organic fertilization.
The cycle of organic matter
The main cycle for fertility is the cycle of organic matter. But which organic matter is more important to us?
Organic matter is in two energy states:
- humus
- undecomposed organic residues (hereinafter - organic matter).
Humus is a product of deep decay of organic matter. Energetically, it is almost inert, there are no carbohydrates and proteins in it, and microbes hardly eat it. All the energy for microbes and worms - for circulation - for fertility - for growing food - for the economy - is conserved in "fresh" organic matter: plant residues and animal feces.
This is almost all the summer energy of the Sun, assimilated in this area. In middle latitudes - up to 400 kcal / sq. m per year, in the tropics - 5 times more.
About twentieth of it is fixed in humus substances. And all the rest of the energy is used as food for microbes that cannot absorb solar energy directly. At the same time, microbes, feeding on organic matter, release nutrients from it that are necessary for plants. Thus, the decay of organic matter provides nutrition for new plants. The decay is hundreds of times faster than humus mineralization: 90% of plant residues rot in one summer.
In the process of agriculture, we withdraw biomass from the natural circulation, which leads to a violation of the circulation and, as a result, to a violation of soil fertility.
In the current practice, fertility is restored with the help of chemical fertilizers, which only harm the soil.
Humus
The humus concept emerged at the end of the 18th century, and was made popular by the German agronomist Albrecht Thaer (1752–1828) in 1800. “Humus (from the Latin humus - earth, soil) is humus, an organic, usually dark-colored part of the soil, formed as a result of the biochemical transformation of plant and animal remains.
At the beginning of the nineteenth century Thayer saw and showed everyone: the plants are always the more luxuriant and developed, the more humus is found in the soil. Since then, we almost do not distinguish between humus and other organic matter - humus, compost and manure.
In the 20th century, many studies have shown that humus is the result, not the cause, of fertility. In general, this is a balancing physical and buffer-exchange environment.
The biochemical activity of humus is very low, it hardly decomposes by microbes. Therefore, it accumulates in the soil, and, moreover, creates deposits of peat or coal. It practically does not participate in the organic cycle and does not directly affect the harvest. Peat and brown coal are pure humus, up to 60-90% humic acids, but they are not suitable for farming. Humus can accumulate food reserves, but it does not give them away.
- U. Mishina conducted additional research on the nutritional value of humus. In several experiments with barley, she carefully selected all plant debris from the soil. The resulting negative effect on the yield could not be eliminated either with mineral fertilizers or the addition of humic substances.
It is known from the history of agriculture in the USSR: Ukrainian chernozems with 4-6% humus yielded higher yields than those of the forest-steppe Volga region with 10-15% humus. At the same time, on the Vladimir loams, in the fields of N.A. Kulinskiy, in a biological crop rotation with straw incorporation, grain yields do not fall below 55 c / ha. And in the Kuban, where there is almost three times more humus, half of the grain is harvested.
Mineral fertilizers
In Europe, up to 1000 kg of mineral fertilizers are applied per hectare. The reason for using fertilizers is simple: Plants need available, dissolved minerals. However, there are a lot of them in the soil. In chernozems, the content of minerals reaches 100 t / ha. But they are packed in a soil absorbing complex (AUC). Therefore, during intensive farming, mineral salts are actively added to the soil, which leads to an increase in yield, but also to a drop in the natural fertility of the soil.
The introduction of mineral fertilizers causes significant harm to the environment:
- only 30% -40% of fertilizers are absorbed by plants
- 30% -35% goes to groundwater and reservoirs, causing severe damage to the environment
- 30% -35% accumulates in the soil, resulting in increased soil acidity.
As a result, long-term application of large doses of mineral fertilizers reduces the natural fertility of the soil and leads to the withdrawal of land plots from land use.
In addition, non-renewable sources are used as sources of potash and phosphate fertilizers, and current farming practices are not sustainable in the long term.
In addition, the introduction of mineral fertilizers does not help to compensate for the lack of another key nutrient for the plant - carbon dioxide. Plants consume hundreds of times more CO2 than minerals; its deficiency is also harmful for them, and the addition also increases the yield. At the same time, decomposing organic matter in the soil acts as a key source of carbon dioxide in the natural environment.
Undecomposed organic matter
Only 10% of crop production is grown for human consumption, and 90% is used for animal feed. In natural biocenoses, all organic matter is plant, and in agrocenoses, more than half of all organic matter is manure and dung. This brings its own part of the difficulty. Although the return of organic matter to the field is extremely important, our fields almost never receive it.
At the same time, to maintain fertility, it is not enough just to apply mineral fertilizers. Mineral elements make up 3-4% of the total crop biomass. And 97% is organic, built from carbon dioxide and water. There are hundreds of times more mineral elements in the soil than is introduced. But the carbon dioxide in the air is 20-50 times less than the plants need.
Under natural conditions, the source of carbon dioxide is decomposing organic matter: in the first summer, 3/4 of the organic matter decomposes into CO2 and water. At the same time, in the upper soil layer, the concentration of CO2 increases by 500-1000 times. Carbon for the crop is supplied mainly by the soil.
Minerals are supplied to plants in parallel and in proportion to carbon. It has been experimentally proven that the PPK minerals pass into solution the more the more organic matter decomposes - they are freed by microbes that consume organic matter, and carbonic acid, into which soil carbon dioxide partially passes.
In other words, it is not “nutrients” that need to be returned in accordance with the balance of biomass removal, but organic biomass. "Liebig's barrel" would be correct if carbon in the form of CO2 was in its rightful first place in the list of nutrients.
The return of organic matter is a necessary and sufficient condition for sustainable agriculture. All natural biomes demonstrate this for millions of years: they are absolutely stable. Agrocenoses also show this. Each ton of organic matter adds 3 tons of crop biomass, that is, doubles the conservation of solar energy. Accordingly, the energy consumption for agricultural machinery is halved, and the profitability of agriculture doubles.
And vice versa: there is no organic matter in the soil - dynamic fertility is not used - mineral substances are not used - photosynthesis is not in demand - energy is not stored in the harvest.
Now 20-30% of the plant biomass returns to the soil - mainly roots and crop residues, which is not enough to maintain fertility. To maintain fertility, it is necessary to return to the soil all manure, feces, and all plant waste. For a grain yield of 25 c / ha, plants need about 100 kg of macro- and microelements and about 1000 kg of dry organic matter to obtain CO2 and microbial service. At the same time, mineral nutrition is provided in the cheapest and safest way - through the effect of microbial decomposition of organic matter on the AEC and soil rocks.
At the moment, it is widely believed that it is impossible to return fresh organic matter to the soil - it is "alienated irreversibly" during the harvesting process. However, plant biomass does not disappear - almost all of it remains in the form of manure, sewage and industrial waste, which do not return back to the soil of agricultural land.
This leads to the fact that the excessive use of mineral fertilizers, together with the neutralization of their harm, now costs three times more than the organization of a permanent return of organic matter.
Dynamic fertility
Agricultural science operates with two types of fertility. Fertility potential is the likely productivity of a soil based on nutrient and humus content. Effective fertility is real productivity that you have received in practice. Neither one nor the other explains what is the essence of fertility, and how to increase it. The approach itself is wrong. Fertility is not a set of parameters. It's a process.
Decomposition of organic matter by an order of magnitude increases microbial activity and the release of CO2. Carbohydrates - feed for nitrogen fixers - dramatically increase nitrogen fixation. In fact, organic matter regulates nitrogen exchange with the atmosphere. The decomposition of organic matter activates the microbial transfer of potassium and phosphorus into solution. There is also a synthesis of biologically active substances and protective substances. At the same time, organic matter optimizes the water-physical properties of the soil. The harvest is not driven by potential fertility, but by a real-time process. Plant life provides a synergistic interaction of microbes, AUC and organics - dynamic fertility.
Dynamic fertility is the biological transformation of the energy of old organic matter into new biomass. The more manure and straw is decomposed directly in the field, the more energy will be given to fertility, and the more energy from the Sun will be stored in the crop.
Despite the huge sums and large-scale projects, dynamic fertility in the Union of Artists has never been scientifically reproduced. As a compromise result, composts, “biohumuses” and humate fertilizers are introduced into the soil, which does not lead to the desired effect.
Both humus and mineral salts - as well as other factors: organic matter itself, individual microbes, biologically active substances, gases and water - are associated with fertility, can increase it, but are not its cause. The main reason for fertility is the decomposition of organic matter.
Nitrogen
Nitrogen enters plants from plant residues or from the air. In both cases, with the help of bacteria. Some bacteria convert organic nitrogen into simple compounds - ammonia and nitrates.
Others - most of them - fix air nitrogen in organic matter. Many of them are in symbiosis, helping each other. And practically all nitrogen fixers, even legume nodule bacteria, feed on carbohydrates and without fiber, lignin or sugars, they will not fix nitrogen. Nitrogen fixation is entirely dependent on the presence of organic matter.
If all organic matter returned to our fields, nitrogen fixers would receive more than 60 million tons of carbohydrates and bind more than 12 million tons of nitrogen. If manure had not been composted, there would still be about 6 million tons of nitrogen left in it. Every year we lose 18 million tons of free and useful nitrogen just to artificially produce 8 million tons of harmful nitrogen fertilizers.
Carbon dioxide
Photosynthesis is the use of CO2 to build organics. The main component in the crop substance (up to 80%) is carbon dioxide. But there is an order of magnitude less CO2 in the air than plants absorb.
For example, beets absorb about 300 kg / ha of CO2 per day, while in a five-meter layer of air it contains only 28 kg. CO2 for high yields is supplied by the soil. And its only source is organic matter of the past year. Oxidized by bacteria, 1 kg of carbohydrates gives about 2 kg of CO2.
Mineral elements
When the balance is imbalanced, mineral elements often antagonize and block the absorption of each other. Therefore, for plants, not only availability is important, but also a balanced nutritional composition. And the best balance of elements is in the bodies of the plants themselves. The return of all organic matter not only mobilizes minerals from the AUC, but also brings in sufficient doses of elements itself.
Substances from the cycle do not go anywhere - there are always enough of them on the planet. We only need energy - to use these substances over and over again. Fertility is the realization of the symbiosis of plants and microbes in the cyclic process of the cycle of substances.