The results of a three-year study on efficiency of new microbial preparations under different conditions of mineral nutrition of spring wheat are presented. Seed inoculation with bio-preparations elevates grain weight by 21–39% against a PK background, whereas an increment from V417 bio-preparation comes to 39% as compared with the background, from strain V167—to 30%, and from standard strain Ch-13—to 21%. The yield increases by 46% with N45 and by 58% with N90 against an NPK background. No significant yield increments were observed with bio-preparations against an NPK background. Bio-preparations based on strains Ch-13, V167, and V417 produced a positive effect on the studied parameters: economic value coefficient (Cecon), productive tillering, spike length, weight of 1000 seeds, nitrogen and phosphorus accumulation in grain, payback from nitrogen fertilizer via increased grain yield, and the quantity of grain produced per 1 kg of consumed N. Preparation based on endophytic strain V417 was the most effective. As a result of the increased grain yield and straw weight with the use of nitrogen fertilizer and bio-preparations, the removal of nitrogen, phosphorus, and potassium rose bringing about a negative balance of nutrient elements. In the experiment, the product based on endophytic strain V417 was the most efficient.
Nyambose et al. (Mon,) studied this question.