Optimizing nutrient management strategies to achieve higher productivity, greater nutrient use efficiency in eggplant and maintenance of soil health

Failure of management practices to achieve a better balance between nutrient supply and nutrient demand by eggplant (Solanum melongena L.) is a major cause of low productivity. Most of the published studies lack sufficient information on the role of best management practices in achieving greater nutrient use efficiencies vis-a-vis nutrient balance in relation to crop demand and nutrient supplying capacity of the soil. Therefore, this study investigated the effects of the application of synthetic fertilizers alone and a combination of synthetic fertilizers with farmyard manure (FYM) on fruit yield, nutrient availability, nutrient use efficiency, and nutrient balance in an eggplant over 4 years (2018-21). Application of 100%-recommended dose of fertilizer (100%-RDF) along with FYM (100%-RDF+FYM) increased fruit yield by 47% (72 t ha-1) than the application of 100%-RDF (49 t ha-1) alone. The increase in soil organic (SOC) stocks over the control (7.3 Mg ha-1) of the experiment was greatest in 100%-RDF+FYM (9.9 Mg ha-1) and lowest in the 100%-RDF (8.8 Mg ha-1) treatment. This was consistent with a maximum increase in availability of nitrogen (137 kg ha-1), phosphorus (40 kg ha-1), and potassium (193 kg ha-1) in soil. The maximum SOC and available nutrients in 100%-RDF+FYM resulted in enhanced agronomic efficiency and nutrient recovery of N, P, and K. Apparent N and P balance (except 100%-RDF) were positive in all fertilization treatments. While the apparent potassium balance was negative in all treatments. The 100%-RDF+FYM could be a sustainable fertilizer management practice to maintain soil health and improve eggplant productivity.