Optimization of fertilizer application to increase agricultural production efficiency

Every ton of fertilizer that is not assimilated by plants represents direct financial losses for the farm. Rational use of mineral nutrition begins at the stage of transportation and storage, where it is necessary to completely eliminate any leakage. In the field itself, the agronomist's main guidelines should be technological discipline and a balance of nutrients. Exceeding scientifically-based rates will not yield any harvest increase, but will lead to the contamination of soil and groundwater.

Distribution accuracy: from warehouse to field

When working with centrifugal spreaders (fertilizer application machinery), it is important to strictly observe the distance between equipment passes and to select the optimal working width. This guarantees uniform distribution of granules across the field area and their complete assimilation by plants. In aerial application, significant losses are inevitable due to wind drift of fertilizers onto roads and shelterbelts. To minimize this damage, the agronomic service must ensure precise ground signaling and strict quality control of flights.

Technologies for increasing the efficiency of nitrogen nutrition

Nitrogen fertilizers pose the greatest environmental risk due to their mobility. To increase nitrogen efficiency, it is necessary to strictly link top dressing with the physiological needs of crops during specific phases of the growing season. Fractional fertilizer application in small doses produces good results. At the same time, it is extremely important to incorporate granules into the soil immediately after the spreaders have passed.

• Incorporation depth after spreading — 8–10 cm
• Ammonium nitrogen retention period — 1–1.5 months
• Application frequency with inhibitors — 1 time

Local application method allows for a significant increase in nitrogen return. With this method, the fertilizer is not mixed with the soil but is placed in pockets at a certain distance from seeds or roots. High nitrogen concentration in the pocket temporarily suppresses the activity of nitrifying bacteria and reduces nitrate leaching from the root zone. As a result, seedlings develop uniformly, overall crop productivity increases, and nitrogen application rates can be reduced without compromising the harvest.

As an alternative to fractional top dressing, chemical nitrification inhibitors are used. The preparations temporarily block the oxidation of ammonium to nitrites, which allows the number of field operations to be reduced from two or three to one. An even more radical solution is the replacement of traditional forms — ammonium sulfate, ammonium nitrate, and urea — with ultra-concentrated, slow-release fertilizers. They gradually release nitrogen as the plant growth progresses due to their special composition (urea condensation with aldehydes) or polymer and sulfur coatings on the granules.

Balanced plant nutrition and prevention of nitrogen losses

The efficiency of nitrogen fertilizers directly depends on the presence of associated elements. Microelements actively participate in the reduction of nitrates and help plants assimilate nitrogen. In addition, they slow down urea hydrolysis and curb the activity of nitrifying microorganisms in the soil, acting as natural nitrification inhibitors. Plant growth regulators, which activate internal metabolism and nitrogen uptake, also help to increase the efficiency of nitrogen nutrition.

To reduce nitrate accumulation in soil and groundwater, it is necessary to expand the acreage of grain legumes and make more active use of biological nitrogen. In the future, genetic engineering methods may be used to enhance nitrogen fixation in plants. Losses from nitrate leaching are minimized through scientifically-based crop rotation, including crops with deep root systems capable of extracting nutrients from lower soil horizons.

Losses of other macronutrients can also be controlled. Phosphorus export is reduced using anti-erosion measures, correct agrotechnics, and wastewater treatment. Potassium leaching is regulated by the timing and application methods in combination with anti-erosion soil tillage. When using organic fertilizers, it is important to observe production technology, maintain sanitary protection zones, and properly dispose of manure. Working with micro-fertilizers also requires strict compliance with the rules:

• Apply optimal rates strictly within the appropriate timeframes.
• Choose the most effective method of application.
• Use chelated forms of micronutrients.
• Ensure uniform distribution across the field area.

Ecological Agrochemistry: From the First Machines to Biosphere Control

Ecological agrochemistry studies the cycle of substances in agroecosystems at all levels — from molecular to biospheric. It investigates the chemical interaction of plants with the soil and the external environment. The need for this science arose with the growth of anthropogenic pressure on the planet.

Until the 18th century, humans lived in harmony with nature, as per capita energy consumption remained minimal. The turning point came in 1705 with the invention of the first atmospheric steam-powered water-lifting machine. Later, in 1796, thermal energy was converted into mechanical energy for the first time using a steam engine.

In the 19th century, agriculture took a step forward: the range of crops expanded, tools improved, and the transition to a crop rotation farming system began. At the same time, agronomic chemistry originated as an independent science. The starting point was 1840, when the fundamental work "Chemistry in Its Application to Agriculture and Physiology" was published. The theory of mineral nutrition of plants described therein paved the way for the widespread adoption of mineral fertilizers. The development of science fostered a belief in human unlimited possibilities, which was also reflected in the literature of the late century: "The Time Machine" was published in 1895, "The Invisible Man" in 1897, and "The War of the Worlds" in 1898.

The first quarter of the 20th century was a triumph of scientific progress. The theory of relativity linked mass, time, and energy together; quantum mechanics made it possible to understand that the microworld is governed by laws different from those of the macroworld. Equally striking were the successes of quantum mechanics, one of the main branches of quantum theory. Quantum mechanics first allowed for the description of atomic spectra and the understanding of their structure, the establishment of the nature of chemical bonds, and the explanation of the periodic table of elements. During these same years, two important events related to energy occurred. First, in 1939, O. Hahn and F. Strassmann recorded the processes of nuclear fission for the first time. Later, in 1942, an atomic reactor was created under the guidance of an Italian physicist. The period 1945–1965 is characterized by a culmination of optimistic views on science and technology. Scientists commanded deep respect and were considered heralds of a new surge in the standard of living. Many were seriously convinced that in the foreseeable future there would be no place for physical labor and that a fully automated paradise would arrive.

G. Stent (1965) in his book "The Coming of the Golden Age: A View of the End of Progress" suggested that an unlimited source of energy – the atom – would give people power previously attributed to gods. However, there are no miracles in nature: a thesis is followed by an antithesis. The antithesis was A. Toffler's book (1970) "Future Shock". The second half of the 20th century did not bring the imagined triumph to humanity. The development of civilization and the latest achievements of science and technology, along with grandiose successes, caused the emergence of a number of serious problems, among which ecological safety has come to the fore today.

Given the current state of mankind's technical equipment, productive forces and production relations in the global community, the growth of the Earth's population, increasing urbanization, and the spread of the consumer society stereotype, the scale of natural resource extraction, the degree of environmental impact, and its pollution have become dangerous for humanity itself. There is a change in the historically established habitat to which humans have been genetically adapted over long years of evolution.

The ecological problems that humans encountered at the turn of the century are a consequence of the increased volume of waste from industrial enterprises and chemical plants discharged into the environment, and the irrational use of chemical plant protection productsplant protection products and fertilizers. The content of many chemical elements and the presence of their various forms in the soils of agricultural lands have come to depend on management methods. Moreover, technogenic pollution is capturing ever new territories. In this regard, a new branch of agrochemistry has developed intensively, studying the complex impact of agrochemical agents on the biosphere and their ecological functions under anthropogenic influence on agroecosystems or during technogenic pollution — ecological agrochemistry.

Under modern conditions, Academician B.A. Yagodin (2002) identified the following tasks of ecological agrochemistry:

– to organize the application of chemical elements to the soil, determined by precise calculations that allow for maximizing their use by plants, increasing plant productivity, reducing nutrient losses and environmental pollution, as well as improving the soil itself and increasing its soil fertility;

– provide recommendations for optimizing the circulation of chemical elements in agricultural lands and natural biocenoses, contributing to the continuous improvement of the environment;

– develop methods for determining the parameters of plant nutrition when adding certain chemical elements to the medium and converting others into unavailable forms, with the aim of obtaining agricultural products with a specified elemental composition, taking into account the law on genetically determined utilization coefficients of nutrients entering the organism;

– study the regulatory functions of trace elements and their role in the realization of adaptive properties of plants, the mechanisms of element uptake by plants, and their influence on cell membrane permeability as a critical factor in shaping plant biomass quality;

• Organize continuous, territorially developed monitoring of the content of all elements in fertilizers, soil, air, irrigation and drinking water, plants, and animals. Ensure the further acquisition of knowledge regarding the elemental composition of the human diet, taking into account heredity, place of residence, and the age-related characteristics of people;
• Study the causal relationships between changes in the external environment and phenomena arising in plants, in order to respond in a timely manner to any undesirable changes in biochemical and physiological processes in plants that lead to a degradation in product quality. Record emerging shifts in the intensity of individual biochemical reactions and physiological processes, as well as changes in a range of metabolic processes and, consequently, changes in the quantity and quality of the product obtained from a given crop;
• Carry out the determination of optimum elemental composition for various agricultural, medicinal, and introduced plants in biogeochemical provinces, and organize the territorial placement of cultivated plants in accordance with the biogeochemical zoning map and available resources of element content;
• Identify artificial flows of elements caused by the movement of seed material and food products across the territories of countries and continents, evaluate their scale and compare them with the capacity of natural biogeochemical element migrations, and assess the influence of industry and other human economic and domestic activities on changes in the elemental composition of agricultural objects in regions, subregions, and provinces;
• Regulate, using the natural ecological setting, the targeted adjustment of the elemental composition of agricultural products to optimal values.

L.A. Lebedeva and I.L. Edemskaya (2005) recommend approaching the design of a fertilizer system from the perspective of ecological agrochemistry. They demonstrated that a scientifically grounded fertilizer system solves three integrated tasks:

• Creating optimal conditions for plant nutrition with the aim of realizing the genetic potential of the grown crop in terms of quantity and quality of the obtained product;
• Increasing the agronomic and economic return on investment when using agrochemical agents for the purpose of reproducing soil fertility and obtaining high crop yields;
• Realizing the ecological functions of agrochemical agents in specific agroecosystems.

Taking into account the current state of the environment, Academician V.G. Mineev (2004) established, concretized, and formulated the ecological functions of agrochemistry:

Ensuring an optimal circulation of biogenic elements in the agroecosystem with an active balance.

By regulating the biological cycle of substances and creating their active balance and content in soils and plants, agrochemistry performs an important ecological function, since a disturbance in the balance of biogenic elements in the soil–plant system leads to the deterioration of the chemical composition of soils, natural waters, and plants, which in turn negatively affects the nutritional value of products and can lead to various functional diseases in humans and animals. Maintaining a positive balance and an active biological cycle of nutrients in agriculture is the foundation of high agroecosystem productivity.

Reproduction of soil fertility, improvement of soil properties and humus status. 1052

These tasks are successfully solved through the implementation of a high culture of farming, which provides for the complex use of agrochemical agents – organic and mineral fertilizers, and chemical soil amendment.

It is precisely a scientifically grounded system of using agrochemical agents that allows for the avoidance of decreased biological activity and the deterioration of the physicochemical and chemical properties of soils, as well as the prevention of its dehumification. Without fertilizers, it is impossible to achieve expanded reproduction of soil fertility – a necessary condition for ensuring the growth of yields. With the realization of the potential productivity of regionalized crop cultivars, more favorable conditions for environmental conservation are created.

Optimization of cultivated plant nutrition with biogenic macro- and microelements. Optimization of conditions for aerial and mineral plant nutrition strengthens the activity of physiological barriers that limit the uptake of chemical elements and toxic substances not required for biosynthesis into plants. This, in turn, allows for the production of ecologically safe food for humans and animals. Balanced provision of nutrients to plants increases the plant organism's resistance to adverse environmental factors and enhances resilience to diseases and pests.

Reduction of negative consequences from global and local technogenic pollution of agroecosystems with heavy metals and other toxic elements. This vital ecological function of agrochemistry is achieved through the following methods:

• Inactivation of mobile forms of heavy metals in the root zone of the soil by reducing soil acidity;
• Application of organic fertilizers;
• Application of optimal rates and ratios of macro- and micronutrients for growth and development.

Fulfillment of this ecological function of agrochemistry allows for the production of environmentally safe food.

Improvement of the radioecological situation in the agroecosystem. Factors for the immobilization of radioactive elements in the soil and the reduction of their uptake by plants include:

• Liming of acidic soils;
• Application of organic fertilizers;
• Application of rational rates of phosphorus and potassium fertilizers.

Creation of optimal cultural agrolandscapes for various natural regions in accordance with their specialization. By purposefully changing the chemical composition of soil, plants, and groundwater, a cultural landscape is created that differs qualitatively from the natural one. Knowing the optimal parameters of the chemical composition of agrolandscape elements, it is possible to significantly improve it through the scientifically grounded application of agrochemical agents. This is the essence of one of the important ecological functions of agrochemistry.

Fertilizers and chemical ameliorants are an important link in the system of anti-erosion measures. A scientifically grounded system of fertilizer application, by creating optimal conditions for the growth and development of the plant root system, improves the physical properties of the soil, which in aggregate contributes to its better protection against erosion and reduces nutrient losses.

Increasing the biological activity of the soil and improving its microbiocenosis structure. Fertilizers have a significant impact on the biological activity and structure of soil microbiocenosis, and their effect can be direct or indirect, through changes in the living conditions of plants and soil biota. Fertilizers directly influence the processes of associative and symbiotic nitrogen fixation.

Optimization of mineral nutrition of plants increases disease resistance. The phytoprotective effect depends on the types and forms of fertilizers.

• Phosphorus fertilizers sharply reduce the incidence of brown rust and root rot in cereal crops.
• The aggressiveness of the snow mold pathogen in winter rye is weakened by antagonists (bacteria, fungi, actinomycetes), the development of which is enhanced by the use of fertilizers.

Fertilizers contribute not only to the realization of the genotype of a specific crop in terms of productivity, but also to improving the quality of the resulting produce.

And in this, as V.G. Mineev (2004) emphasizes, it is difficult to overestimate the fundamental and applied significance of agrochemistry as a science that occupies an active position in providing the planet's constantly growing population with high-quality food products.

The complex implementation of the above-mentioned ecological functions of agrochemistry is the task of a rational system of fertilization and chemical soil amelioration.