LIQUID COMPLEX FERTILIZERS AND MICROBIOLOGICAL: CONDITIONS OF COMPATIBILITY

LIQUID COMPLEX FERTILIZERS AND MICROBIOLOGICAL: CONDITIONS OF COMPATIBILITY

In Ukraine, as in the rest of the world, there is a growing problem of increasing cost of mineral fertilizers, leading to a search for alternative methods to boost crop yields. Among these methods, the use of biological products can significantly enhance the efficiency of mineral fertilizer usage in agriculture during economic and ecological crises. This approach helps reduce the agrochemical load on agroecosystems and improves soil health. However, when considering the economic viability of technological measures, farmers prefer using liquid complex mineral fertilizers (LCF) combined with microbiological products in a single tank mix. Nevertheless, the behavior of live microorganisms in contact with high-concentration nutrient salt solutions remains poorly understood. Currently, no scientific source clearly substantiates the conditions and possibilities of combining biological, chemical, and microbial products in a single tank mix for use in agricultural ecosystems. Therefore, while working with farmers, agronomists from BTU rely on the results of years of research conducted by BTU scientists.

What signs indicate the incompatibility of a microbial products and liquid mineral fertilizer?

Precipitate has formed and this mixture is technically impossible to be applied
Microorganisms die when mixed with mineral substances, and the expected effect of using this tank mix is lost.

Reasons for incompatibility
Modern farmers try to use as little water as possible or avoid it when preparing tank mixes. Reducing the hectare rate of the tank mix volume is an additional lever for lowering technological process costs. However, the concentration of mineral salts is not always safe for microorganisms in the bioproduct.Normal functioning is possible for most microbes with a salt concentration of 0.9% in the solution. Increasing the concentration to 1-2% inhibits microorganisms' vital processes, while reproduction stops at concentrations of 6-8%. Salts' aggressiveness toward microorganisms also depends on other conditions in the environment. The negative impact increases when the pH decreases (increased acidity) and the temperature of the solution rises.Available LCFs on the Ukrainian market have a density of 1.24–1.31 g/cm³, meaning the salt concentration in such solutions can reach 20-30%. Therefore, when mixing fertilizers and microbial products without adding water, there is a high chance of decreasing the activity of the living component in the bioproduct. Not all microorganisms, of course, have the same sensitivity to salt solution concentrations. The most resistant are those organisms capable of spore formation. For example, Bacillus subtilis and Bacillus licheniformis can survive not even in 6-8% solutions (typically harmful for most bacteria), they also tolerate concentrations up to 10-12%. However, the key term here is "survive" rather than "live and propagate".

What happens when biologicals are mixed with LCF?
When transporting biological products to the field, the temperature rises to 20°C or even higher. Upon opening the packaging, microorganisms are exposed to oxygen and become metabolically active. The next step involves preparing the tank mix, which often requires mixing components without adding water. The recently activated microorganisms encounter a salt concentration that is too high for their survival. As a result, some organisms become inactivated while others attempt to develop protection.The main protective functions of microorganisms in high salt concentrations include:Increasing the synthesis of biologically active substances, osmoprotectants, and the formation of hygroscopic mucous capsules around the microbial cell;Fixing potassium ions, which promote moisture accumulation around the microorganism's protective capsule;Breaking down internal storage polysaccharides into water (metabolic water);Spore formation.The precipitation formation results from microorganisms attempting to protect themselves in a concentrated salt solution.

How can the effectiveness of a tank mix be ensured?
We recommend the following sequence of actions: Carefully review the manufacturer's recommendations on the compatibility of specific microbial products with nutrient salt solutions exceeding 25%. Consider adding water to the tank mix, as the optimal ratio for microbes is 1:1 between water and LCF. Increasing the water volume will reduce the risks of precipitation formation and microorganism activity. Reduction of water volume or not adding it at all, on the other hand, will increase risks. To prevent inevitable economic losses caused by precipitation when mixing large volumes of tank mix components in the field, a preliminary rapid analysis of the tank mix is essential. This can be done by testing it in smaller volumes while keeping the component ratio same. To ensure the survival of the specific microbial component in the tank mix, it is necessary to pre-model such mixes and consult with relevant laboratories that can determine the extent of microorganism survival in specific mixtures. Please note that the analysis process may take up to 14 days.Based on years of research experience, BTU specialists have developed an algorithm to study the compatibility of components in tank mixtures. They are prepared to carry out this research for you and advise on the compatible use of microbial products with liquid mineral fertilizers.

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