Combined application of biochar and farmyard manure reduces wheat crop eco-physiological performance in a tropical dryland agro-ecosystem

摘要

Combined application of biochar and organic fertilizer has been widely recommended for improving soil bio-physical properties. However, detailed exploration of combined application on crop eco-physiological performance is limited. In this study, we explored the agronomic and eco-physiological responses of wheat crop grown under different combinations of rice-husk ash (RHA/biochar), farmyard manure (FYM) and chemical fertilizers in a silty loam soil. Aboveground biomass varied significantly across the treatments and was found higher (11-31%) under chemical fertilizer-applied treatments, but lower (6%) under sole RHA-applied treatment as compared to control. Crop eco-physiological parameters varied significantly (at P<0.01) with the treatment and crop growth stages. Sole chemical fertilizer- and FYM-applied treatments showed better (5-26% higher), whereas sole RHA- and combined RHA+FYM-applied treatments showed poor (2-15% lower) photosynthetic rate as compared to control. Ear length was moderately correlated (r=0.53) with aboveground biomass and explained 27% of the variability in it. Transpiration rate, intercellular CO2 concentration and water-use efficiency (WUEp) were identified as the major determinants of photosynthetic rate during vegetative and maturity growth stages. WUEp along with transpiration rate was found to explain 94% of the variability in photosynthetic rate for overall dataset. The findings suggest that combined RHA+FYM amendment may limit crop agronomic and eco-physiological performance due to nutrient immobilization. Therefore, combined application of RHA+FYM with chemical fertilizer application at reduced rate can be suggested for improving crop eco-physiological and agronomic responses under the sustainable agriculture practices in silty loam soils of tropical dryland agro-ecosystems.