Optimizing co-application of starter ammoniacal-N and K-containing fertilizers for barley in the seed-furrow

Abstract

It is unclear how seed-placed starter ammoniacal-N-and-K fertilizers influence barley (Hordeum vulgare L.) seed-crop emergence, and its early establishment, due to salt injury and potential ammonia production and toxicity within the soil profile under different placement rates. Keeping in this view, the study was undertaken to experiment the effects of different fertilizer types, and rates using three different soil types characterized by fine (G1), medium (G2), and coarse (G3) textures when simultaneously placed with barley seed and establish safe-starter fertilizer recommendation models. The fertilizers were applied at varying rates from 0 to 60 kg N ha−1 and 0 to 74 kg K ha−1 alongside barley seeding. Maximum predicted safe starter ammoniacal-N-fertilizer rates were as follows: urea = 15, 35 and 26 kg N ha−1 is safe for G1, G2 and G3 soils, respectively. DAP (Diammonium phosphate), 52 kg N ha−1 is safe for fine textures whilst 12 and 37 kg N ha−1 for medium and coarse textures. MAP (Monoammonium phosphate) is safely placed at 55, 11 and ≥60 kg N ha−1 for G1 – G3 soils. For MOP (Muriate of Potash) and SOP (Sulfate of Potash), 67 and ≥74 kg K ha−1 were ideal for improved barley emergence across all the soil types. Visual appearances including delayed seed emergence, leaf chlorosis, and stubby coleoptiles were observed at varying seed-placed N and K rates. Intricate relationships among various emergence parameters, root architecture, aboveground and root biomass, chlorophyll content, all showing significant interrelationships. Data indicate that cubic model could be used for predicting seed-safe rates for multiple fertilizer types.