Use of PGPR (GROUNDFIX®) to Improve Soil Health

Nowadays, the integral indicators of soil health in agrocenoses are the crop yield and the quality of raw material. In order to achieve efficient use of soil in the field, it is necessary to understand its physical, chemical and biological properties. It is essential to consider the possibilities of improving of the soil health and plant nutrition using different types of biofertilizers, especially of microbial origin. The standard indicators included in the agrochemical certificate describe various physical and chemical properties: humus content, granulometric composition, soil density, productive moisture, acidity, salinity degree, content of mobile or hydrolyzed nutrients – N, P, K, and microelements as well as different contaminants - mobile forms of cadmium, lead, pesticide residues, etc. For the microbial analysis, it is suggested to evaluate biological indicators by the number of microorganisms and the ratio of certain physiological groups. Principle of soil condition assessment according to the research conducted includes main groups of microorganisms: oligotrophs, pedotrophs, microorganisms that use different nitrogen compounds (mineral – organic), nitrogen-fixing bacteria; different groups of fungi: saprotrophs or pathogens.

The results of conducted experiments showed that before and after application of a complex of PGPR (Groundfix®) at a rate 1 l/ha, the soil indicators had a tendency to improve. The content of mobile phosphorus compounds increased by 49.3% and potassium increased by 55.8% respectively. This efficiency was achieved due to the microorganisms that contribute to the release of phosphorus and potassium from hard-to-reach compounds. Statistical data analysis showed that humus content and hydrolyzed nitrogen dependent were high during both the first soil sampling in May and the next one in August (204.4 mg/kg and 207.2 mg/kg). This stability was provided by the high number of microorganisms that transform organic compounds contributing to both the destruction of light organic matter of plant residues and the synthesis of humus substances. According to the results of the soil analysis, the bacteria could affect the acidity of the soil. Another important fact to discover was increase in the diversity of saprophytic fungi from two to five genera, including fungi genus Trichoderma, counting 15% from the total number of fungi. These changes could be explained by the activation of the indigenous agronomically valuable microbiota in the soil. Therefore, application of the product Groundfix affected the number of microorganisms of certain physiological groups. The ratio between these groups showed that in the soil there is a predominance of synthesis over destruction processes. The number of Azotobacter bacteria increased by 2.4 times, which confirms the high level of soil fertility.

Contrary to what has often been assumed, the efficacy of PGPR bacteria usage in soil health improvement has confirmed by multiple analyses and statistical data. Our finding indicate that this complex of bacteria not only activate other beneficial groups of organisms but also make P and K more available for plants uptake. As a result, farmers get more rich harvest on their fertile soil.