Economic analysis of organic inputs and biostimulants: Adoption and crop yield in South India

Biostimulants are increasingly promoted as sustainable alternatives to chemical inputs; however, their adoption among smallholders remains uneven. This study examines the socioeconomic, institutional, and infrastructure-related determinants of bio-stimulant adoption in a socioeconomically backward district of Tamil Nadu, India. Using primary survey data from 315 farmers, complemented by on-farm plot-level experiments, the study employs Probit, IV Probit, Biprobit, and structural equation modelling (SEM/GSEM) to address endogeneity and latent socioeconomic status (SES). SES is constructed using income, land size and livestock. Results indicate that adoption is positively associated with socioeconomic status and membership in farmer groups, but is significantly constrained by region-specific factors, groundwater scarcity, gender, and crop type. Experimental evidence complements these findings, showing yield gains from biostimulant application—particularly for groundnut and blackgram—though outcomes vary due to on-farm constraints such as water stress and pest incidence. Findings highlight that promoting biostimulant adoption requires more than demonstrating agronomic benefits; complementary investments in awareness, water management, market linkages, and institutional support are essential. The study contributes to evidence on sustainable input adoption in resource-constrained settings and offers policy insights for scaling bio-inputs in smallholder agriculture.