Effects of Vesicular Arbuscular Mycorrhizae and Applied Phosphorus through Targeted Yield Precision Model on Root Morphology, Productivity, and Nutrient Dynamics in Soybean in an Acid Alfisol

Abstract

A field experiment was conducted in a phosphorus (P)–deficient acidic Alfisol in northwestern Himalayas to study the effect of three vesicular arbuscular mycorrhizae (VAM) cultures [VAML, local VAM culture (Glomus mosseae) developed by CSK Himachal Pradesh Agricultural University, Palampur, India; VAMT, VAM culture (Glomus intraradices) developed by Centre for Mycorrhizal Research, The Energy and Resources Institute (TERI), New Delhi, India; and VAMI, VAM culture (Glomus mosseae) developed by Indian Agricultural Research Institute (IARI), New Delhi, India] on growth, productivity, and nutrient dynamics in rainfed soybean. Plant height, aboveground dry matter, root dry matter, total dry matter, root length, root weight density, Rhizobium root nodule count, root colonization, yield attributes, yield, and nutrient uptake of soybean increased consistently and significantly with increase in inorganic P levels from 25 to 75% of recommended P2O5 dose based on targeted yield precision model coupled with various VAM cultures. VAMT (Glomus intraradices) at each P level showed its superiority over VAMI and VAML. Sole application of any of the three VAM cultures produced similar growth and development parameters as well as grain yield (18.68 to 19.08 q ha−1) as produced through farmers’ practice (nitrogen at 20 kg ha−1), indicating that VAM has a vital role in root morphology and nutrient dynamics in a soil–plant system, though significantly greater productivity was obtained with 100% of the recommended P2O5 dose based on soil-test crop response (STCR) precision model without VAM inoculation. Targeted grain yield of soybean (25 q ha−1) was achievable with 75% of the recommended P2O5 dose applied with any of the three VAM fungi cultures without impairing soil fertility, thereby indicating that VAM fungi can save about 25% P fertilizer in soybean in P-deficient acidic Alfisols of northwestern Himalayas.