The laws of farming are the laws that describe the interaction of the factors of plant life and determine the optimal conditions for their growth and development in order to obtain the maximum yield.
The laws of farming are based on the results of a large number of studies and experiments, their processing and analysis and lay the theoretical and practical foundations of crop production. Correct application of agrotechnical, soil-reclamation and other methods, improvement of farming culture and effective regulation of soil fertility and crop yields are based on scientific understanding and practical use of the laws of farming.
- The Law of Equivalence and Irreplaceability of Plant Life Factors
- Law of the minimum
- The law of minimum, optimum, maximum
- The law of combined action of plant life factors
- The law of return
- The law of cropping succession or The law of crop rotation
- Other Laws of Farming
- The practice of applying the laws of farming
The Law of Equivalence and Irreplaceability of Plant Life Factors
All factors of plant life are equal and irreplaceable.
The provision of all life factors, both cosmic and terrestrial, is necessary for plant growth and development, regardless of the amount of the factor. The absence of one factor, even the smallest one, leads to a drastic reduction in yield and death of the plant.
No one factor is substituted for another. For example, a lack of potassium cannot be replaced by an excess of phosphorus, and a lack of light cannot be replaced by heat, etc.
It is only possible to get the highest possible yields if all the factors of life are constantly supplied in sufficient quantities. However, in practice, the law of equivalence and indispensability of factors is relative because of the different costs of providing plants with life factors. It is connected with the possibility of creating such conditions, both in material and technical respect, and by the soil and natural-climatic conditions in a particular area.
The law of equivalence and irreplaceability of plant life factors provides the material basis for farming: in order to obtain consistently high yields, it is necessary to strive to fully provide plants with all the factors.
Law of the minimum
The growth and development of a plant is determined by a factor that is at a minimum.
Also called the law of the limiting factor or Liebig’s law. Karl Sprengel first formulated the law of the minimum in 1828. It was later developed and popularized by Justus von Liebig in his 1840 book Chemistry in Application to Agriculture and Physiology, using minerals as an example. According to his observations, yield growth is directly related to an increase in the amount of that factor which is at a minimum, or:
Y = AX,
where Y is the yield; A is the proportionality factor for a particular factor; X is the stress of the factor.
The discovery of the law of minimum allowed in the second half of the XIX century to significantly increase the yield of crops traditionally cultivated in Central Europe through the application of mineral fertilizers on low fertile soils.
Traditionally, a “Dobeneck’s barrel” or “Libich’s barrel” is used to visually describe the law of the minimum. The boards forming the side surface denote different factors of plant life. The height of these planks equals the amount of a particular factor. The less a plant is provided with a particular factor, the lower the height of the plank, which is what determines the actual yield, even though the other factors may be the maximum that provides the potential yield of the crop.
If the height of the smallest plank is increased by adding the appropriate factor, the actual yield will be determined by the other plank, which will be at the minimum.
Despite the obviousness and simplicity of the law, subsequent studies have established a number of refinements. J. Liebich recognized a decreasing effect with each increase in a single factor. A. Mayer proved: the law of the minimum should be accepted taking into account the totality of factors, not only nutrients. E. Wolny, expanded the effect of the law and found that the quality of the crop is affected by a set of factors.
The law of minimum, optimum, maximum
Maximum development of a plant is possible under the optimal supply of life factors.
In the course of a number of experiments this law was subjected to verification and refinement, as a result of which it did not find its confirmation.
The law of minimum, optimum, maximum was proposed as a result of a number of studies, the most famous of which is the experience of Gelrigel. He grew barley in glass vessels filled with the same fertile soil. All plant growth conditions were the same, except for soil moisture, which was determined by full moisture capacity of 100%. In 8 vessels the moisture content was 5, 10, 20, 30, 40, 60, 80 and 100%. At the end of the experiment the yield was distributed as follows:
|Soil moisture, % of full moisture capacity|
|Yield, kg dry matter per vessel|
The maximum barley yield in the Gelrigel experiments occurred at a soil moisture content of 60% of the full moisture capacity. Minimum as well as maximum moisture did not provide a yield. If we express the difference in the yield gain per each successive moisture gradation referred to the moisture unit, we get a progressive decrease in the yield gain from successive increases in moisture, while the other factors remain unchanged. This law is called Thünen’s law.
W.R. Williams analyzed the Gelrigel experience and showed the private nature of the resulting regularity. He found that Gelrigel’s experience violates the condition of the only logical difference, which is the most important requirement of agronomic experience. Different soil moisture does not create the same nutritional conditions for plants. Moisture is inextricably linked with redox conditions in the soil and, therefore, significantly affects soil biochemical processes.
Thus, Gelrigel’s experience is essentially unreliable, and his conclusions are erroneous. This is confirmed by the data of E. Volny’s experiment. Under the same conditions as in the experiment of Gelrigel, except for the fertilizer not recoverable in anaerobiosis conditions, the results obtained are shown in the table.
|Soil moisture, % of full moisture capacity|
|Yield, g dry matter / vessel|
|Difference between subsequent and previous values, g dry matter/vessel|
|Difference per moisture gradation (%), g dry matter/vessel|
Experiments of E. Volny showed a completely different nature of the yield dependence on soil moisture compared to the Gelrigel curve: increasing moisture content causes a progressive increase in the yield increase per unit moisture content, rather than a decrease.
According to V.R. Williams, E. Volney’s experiment also had methodological flaws. Subsequently, E. Volny set a multifactorial experiment on spring rye plants, growing them in three rows of glass vessels with four vessels in each row.
Each row had three vessels with moisture content of 20, 40, and 60% of full moisture capacity and with unfertilized soil; the fourth vessel in each row had fertilized soil with moisture content of 60%. Illumination of each row was different (weak, medium, strong). The results are shown in the table and in the figure.
|Indicator||Yield, g dry matter / vessel|
|At soil moisture, % of full moisture capacity|
Yield growth in vessels with unfertilized soil with increasing moisture content echoed the results of the Gelrigel experiment. The addition of fertilizer resulted in a dramatic increase in yield in vessels with soil moisture of 60%. However, the addition of the light factor to the experiment dramatically increased the efficiency of the fertilizer. If we summarize the yield of the variants with fertilizer at different illumination, it appears that the interaction of all factors will give a significant increase in yield, increasing as new plant life factors are added to the system. These findings also refute Thünen’s law.
The law of combined action of plant life factors
All plant life factors interact in the process of plant growth and development, i.e. they act combined.
Liebscher and Lundegaard showed that the more other factors of plant life are in the optimum, the more intensive is the effect of the factor in the minimum. Lundegaard also established a negative effect on the development of plants of the combination of factors in the minimum, calling it “interference” of factors
Relying on the law of combined action of plant life factors, a number of researchers have attempted to establish a mathematical dependence of yield on life factors. The greatest success in this was achieved by E. Mitchenlich.
E. Mitchenlich attempted to find a mathematical relationship of yield increase to soil fertilization. He found that the yield increase was proportional to the difference between the maximum possible yield and the actual yield obtained and depended on each factor and its intensity. E. Mitcherlich by experiment determined the coefficients of utilization of individual nutrients: for nitrogen N – 0.2, phosphorus P2O5 – 0.6, potassium K2O – 0.4, magnesium Mg – 2.0 per 1 mm of precipitation.
Subsequent studies have shown that E. Mitchenlich’s dependence is not universal because of the complexity of the biological processes of crop creation. In addition, Trenel soon showed that it was mathematically incorrect.
Despite the complexities of mathematical expression of this law, it is important in the practice of farming. W.R. Williams pointed out that it is only possible to achieve maximum yields by simultaneously influencing the entire complex of plant life factors, which is a single organic whole, the elements of which are inextricably linked to each other. Influence on one of the factors of life entails the necessity to influence all the others.
The law of return
Substance and energy alienated from the soil with the crop must be compensated (returned to the soil) with a certain degree of excess.
First discovered by J. Liebig. D.N. Pryanishnikov and K.A. Timiryazev considered the law of return one of the greatest for science.
Farming by its nature as a branch of production is material: a crop is created from material constituents – energy and substances consumed by plants from the soil. Soil is also the environment in which plants grow and mediate their supply of the factors of life.
The systematic alienation of the yield from the fields without the return of the energy and substances used by plants, the soil loses its fertility. If the removal of energy and substances is compensated for, soil fertility is maintained; if this removal is compensated for with some excess, fertility is reproduced.
The law of return is the scientific basis of soil fertility reproduction. It can be considered as a special case of physical law of conservation of matter and energy.
The law of cropping succession or The law of crop rotation
The alternation in time and space of cultivated plants that differ from each other in biochemical, biological, agronomic and other properties.
The law of crop rotation is the scientific basis of the “principle of crop rotation” or proper crop rotation. Its basis is the law of unity and mutual influence of plants and environmental conditions.
Professor M.G. Pavlov already in 1838 recognized the law of crop rotation as a law of nature:
“Any agrotechnical measure is more effective in crop rotation than in monoculture.”
Other Laws of Farming
There are a number of other laws in agriculture: the law of autotrophic green plants, based on the theory of photosynthesis and mineral nutrition of plants; the law of entry, movement and transformation of minerals in plants, etc.
The erroneous interpretation of the results of some studies, in which only one factor was changed while the others remained constant, led to the formulation of the “law of decreasing soil fertility” or the law of Thurgo-Maltus, or the law of diminishing returns. It consists in the fact that each additional investment of money and labor in the land is accompanied not by a corresponding, but by a decreasing increase in the yield.
V.I. Lenin criticized these conclusions
“… “The ‘law of diminishing soil fertility’ is not at all applicable to those cases in which technology progresses, in which modes of production are transformed; it has only a very relative and conditional application to those cases in which technology remains unchanged.”
Lenin V.I. Poli. sobranie. vol. 5. p. 102.
Later on, the complete invalidity of “the law of decreasing soil fertility” was established by experiments with simultaneous influence on all factors of plant life. So in experiments with changing of three factors at the same time: light, nutrients and moisture of soil, it was shown that at full satisfaction of plants with these factors yield was continuously increasing.
This yield increase is limited only by the biological nature of the plant, as well as by the level of development of science and technology. F. Engels came to the directly opposite “law of decreasing soil fertility” conclusion:
“The productive power at the disposal of mankind is infinite. The productivity of the earth can be infinitely increased by the application of capital, labor, and science.”
Experiments of W. R. Williams, E. Volney and other scientists showed similar results: the optimal supply of light, moisture and nutrients to plants allows to increase the yield several times with significantly lower consumption of nutrients and moisture to create a unit of production. These findings allowed the successful introduction and use of intensive cultivation technologies, based on all the laws of agriculture, taking into account local soil and climatic conditions and features of the species, varieties of crops.
The practice of applying the laws of farming
The developed farming systems are based on the laws of farming. Modern trends of adaptive-landscape farming systems are based on the use of land resources of a particular agro-ecological group, focused on economically profitable production of high quality products in accordance with market needs, ensuring the stability of the agrolandscape and the constant reproduction of soil fertility. The development of farming systems is inextricably linked with the development of new technologies, one of the main requirements for which is adaptability to natural conditions, forms of management, different levels of intensification of production, etc.
The methodology of building technology is based on the laws of farming. For example, guided by the law of minimum, determine and eliminate the limiting factors of productivity, taking into account the soil and climatic conditions, specialization and level of intensification of production. Intensification of production changes the importance of certain factors: with the elimination of the deficit of some increases the role of others. The return of nutrients alienated with crops, according to the law of return, should be compensated with an excess, for constant expanded reproduction of fertility.
Non-observance or violation of the laws of farming in agricultural practice leads not only to failure to obtain the expected, but also to negative results with unreasonable economic costs. For example, unreasonable land reclamation, intensive technology, chemicalization, reform of the agroindustrial complex. Without taking into account the complex of mutual and systemic relationships, factors and techniques that seemed reasonable, necessary, environmentally justified, eventually led to negative consequences of the functioning of agricultural production.
High yields are provided by combinations of certain factors of plant life at each stage of development. Only with the complex action of all conditions of life is it possible to fully use each of them, which in practice is rare. More often, the factor in the minimum determines the formation of yield in specific soil and climatic conditions. For example, in the Non-Black Soil Zone it is nutrients, in arid areas – water.
Each agronomic method, as a rule, to create favorable conditions for growth and development of plants affects 1-2 factors of life. Therefore, only a complex of measures makes it possible to regulate all conditions of plant life. Obviously, the most important of these agronomic methods will be the one that affects the factor that is in the minimum.
In addition to the soil and climatic characteristics of the zone or locality, the development of a set of agronomic measures should take into account the phases of plant development. Methods should provide an increase in organic and mineral matter in the soil, increasing its fertility and improving its structure and structure.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.