Biofertilizer pellets as a strategy to enhance soil nutrient dynamics and microbial populations in mulberry (Morus indica L.) cultivation

Organic pelleted fertilizers are vital for enhancing soil health and increasing microbial populations in mulberry (Morus indica L.) cultivation. They supply essential nutrients, improve soil structure, promote microbial activity and contributing to sustainable sericulture. This study evaluated the impact of pelleted biofertilizers on soil quality through a factorial pot experiment in a greenhouse using a randomized complete block design. Treatments included combinations of Orgafol, biofertilizers (Azospirillum, phosphobacteria, arbuscular mycorrhizal fungi-AMF) and growth promoters. Soil pH, electrical conductivity (EC), available N, P, K and culturable microbial populations were measured 90 days after planting. Orgafol + Azospirillum + AMF (T10) produced the highest EC (0.62 dS m-1) and the lowest pH (6.48), whereas Orgafol alone maintained the highest pH (6.67). Nitrogen was maximised by Orgafol + naphthaleneacetic acid (NAA) + Azospirillum + AMF, phosphorus by Orgafol + phosphobacteria (13.32 kg ha-1) and potassium by Orgafol + NAA + Azospirillum (228.98 kg ha-1). Biofertilizer pellets markedly increased total microbial counts, peaking in Orgafol + NAA + Azospirillum + AMF + phosphobacteria (T9). PCA (principal component analysis)identified two principal components accounting for 73.27 % of the total variance. PC1 was strongly correlated with microbial counts and negatively with pH, while PC2 was associated with EC, phosphorus and potassium levels. Treatments T9 and T10 ranked highest in PC1 and T6 dominated PC2, highlighting their effectiveness in enhancing soil fertility. The study demonstrates that tailored pelleted biofertilizer blends can rapidly improve physicochemical properties and biological activity of mulberry soils, offering a scalable strategy for more sustainable and productive sericulture.