Rational application of fertilizers and reduction of environmental risks in agriculture

Mineral fertilizers remain the main tool for increasing field productivity — they provide at least half of the yield increase. However, with an irrational approach, chemicalization turns into serious losses of active ingredients and environmental pollution. To avoid this, an agronomist needs to understand exactly how nutrients are lost during the production process and how to minimize these leaks.

• Yield increase due to fertilizers — at least 50 %
• Losses during logistics and application — 10–15 %
• Optimal granule size — 1,5–3 mm
• Maximum allowable concentration of nitrate nitrogen in feed — 0,25 %
• Dangerous potassium threshold in feed — over 3 %

Main causes of nutrient leaching and the impact of erosion

Environmental pollution with fertilizers occurs due to technological failures and planning errors. Nutrients are lost at all stages of handling fertilizers. The main factors of losses include inadequate transportation, storage, blending, and application, as well as violations of application rates and timing. The situation is aggravated by the low quality of the fertilizers themselves and the uncontrolled use of industrial or household waste.

Water and wind erosion of soil cause serious damage to fertilizer efficiency. Due to the washout and leaching of nutrients, farms annually fail to receive a significant portion of the harvest. The volume of these losses depends directly on the degree of soil erosion in a specific field.

Even after entering the soil, fertilizers are not fully utilized. The leaching of cations from the soil follows the pattern of NH4, and anions follow 3 4. Due to technological violations and the low quality of the fertilizers themselves, a hectare of arable land loses colossal amounts of active ingredients annually, and their actual uptake coefficient by plants remains low.

Application uniformity and product safety control

One of the main reasons for poor nutrient uptake is the uneven distribution of fertilizers across the field. With poor equipment calibration, some plants receive an excess of nutrients while others starve. This leads to patchy crops, uneven ripening rates, and reduced product quality. Moreover, the higher the concentration of the active ingredient in the fertilizer, the greater the yield losses will be due to its uneven distribution.

It is particularly difficult to distribute fertilizer blends prepared from components with different granule sizes evenly across the field. For high-quality operation of fertilizer drills and spreaders, it is optimal to use fertilizers with a granule size in the range of 1,5–3 mm. Such granules guarantee application accuracy and create better conditions for nutrient uptake by the root system.

Excessively high fertilizer application rates can lead to the contamination of surface and groundwater, the accumulation of nitrates, nitrites, sulfates, chlorides, and heavy metals in concentrations exceeding the maximum allowable levels (Table 254; Ionas V.A., Vildflush I.R., Kukresh S.P., 1998).

An excessive increase in nutrient concentration in water bodies causes increased plankton reproduction and the overgrowth of coastal flora, which gradually leads to a reduction in the water surface area, shallowing, siltation, and the death of aquatic organisms due to a deficit of dissolved oxygen in the water.

Table 254 – Maximum allowable concentration of harmful substances in natural waters, mg/l Substance* Domestic drinking water Fishery water bodies

 Ammonia 2,0 0,005 Aniline 0,1 0.0001 Boron 0,5 0,1 Copper 1,0 0,004 Molybdenum 0,25 0,0012 Urea 0,1 80 Arsenic 0,05 0,05 Nitrates 45 40 Nitrites 3,3 0,08 Sulfates 500 100 Chlorides 350 30 Cyclohexanol 0,5 0,001 Cyclohexanone 0,2 0,0005 Zinc 1,0 0,01 *Supplemented by A.H. Sheudzhen

The risk of environmental pollution largely depends on the type of fertilizer.