Agricultural researchers evaluating novel crop management strategies have demonstrated that supplementing standard fertilizer protocols with an organic acid-based biostimulant can significantly enhance soybean productivity under open field conditions. In a randomized complete block field experiment conducted during the 2024 Kharif growing season at the Agricultural Research Station in Kasbe Digraj, Maharashtra, India, agronomists evaluated the commercial biostimulant EliArmor applied in combination with the regional general recommended dose of fertilizer. Cultivated on the adaptable regional soybean cultivar Phule Sangam, also designated KDS-726, the combined treatment delivered notable agronomic gains over standard fertilization practices alone. Specifically, applying the biostimulant at an application concentration of 2000 parts per million alongside the recommended fertilizer baseline elevated soybean grain yield to 25.89 quintals per hectare. This represented a 15.1 percent grain yield expansion compared to plots receiving standard fertilization without the biostimulant, which produced 22.50 quintals per hectare, alongside corresponding improvements in stover biomass, nutrient assimilation efficiency, and physical seed quality attributes.

The study addresses critical agronomic pressures surrounding soybean, Glycine max, which represents an indispensable oilseed and plant protein staple within international agricultural systems. Global soybean output reached approximately 395 million metric tons during the 2023 to 2024 season, anchored by major production hubs across South America, particularly Brazil, and the United States. Global demand climbed to an estimated 386 million metric tons over that identical timeframe, driven by the expanding manufacturing of livestock feed, bio-based industrial fuels, and plant-derived protein goods for direct human consumption, with China alone responsible for importing 108 million metric tons annually. Because expanding arable land faces clear ecological boundaries, agronomic research increasingly targets biostimulant substances to enhance biological yield potential and stress resilience without relying exclusively on heightened synthetic fertilizer inputs. Non-microbial biostimulants, including defined organic acids, do not directly supply crop nutrients themselves but rather stimulate endogenous plant physiological processes, facilitate nutrient transport across root membranes, and optimize mineral absorption from surrounding soil environments.

Low-molecular-weight organic acids have emerged as an important subset of biostimulant chemistry due to their capacity to alter rhizosphere mineral dynamics through coordination chemistry and ligand exchange mechanisms. Organic compounds such as citric acid and succinic acid can naturally chelate essential micronutrient cations like iron and zinc while simultaneously displacing bound phosphate molecules from calcium, aluminum, and iron mineral surfaces. In neutral to alkaline soils, applied phosphorus frequently becomes immobilized into insoluble calcium phosphate complexes, limiting root accessibility despite substantial total soil phosphorus reserves. Exogenous additions of organic acid formulations can solubilize these bound fractions, effectively increasing the pool of plant-available Olsen phosphorus and assisting ion mobility within root zones. Despite these demonstrated geochemical mechanisms in controlled pot and field settings, commercial biostimulant mixtures containing multiple organic acids have remained poorly documented under real-world Kharif field environments in western India when applied as an add-on to regional general recommended fertilizer doses.

The experimental field site at the Agricultural Research Station in Kasbe Digraj, operating under Mahatma Phule Krishi Vidyapeeth in the Miraj Taluka of Sangli District, provided specific edaphic conditions characteristic of the region. Baseline chemical analysis determined that the experimental soil was distinctly alkaline, registering a pH of 8.13 based on a standard 1 to 2.5 soil-to-water suspension, and non-saline, showing an electrical conductivity of 0.35 deciSiemens per meter. The native soil organic carbon was recorded in the medium range at 0.55 percent. Soil nutrient availability testing revealed that initial available nitrogen was deficient at 165.30 kilograms per hectare, while available phosphorus was moderate at 14.53 kilograms per hectare, and available potassium was notably high at 456.00 kilograms per hectare. These chemical baselines established an agronomic environment where alkaline conditions promoted phosphate fixation and restricted micronutrient solubility, providing an ideal test bed to observe whether organic acid additions could improve nutrient acquisition in field-grown crops.

The evaluated test product, EliArmor, manufactured and supplied by Zero Gravity Solutions, Incorporated, was characterized as a water-soluble liquid organic-acid mixture possessing an acidic pH of 4.28. Quantitative formulation analysis confirmed that the biostimulant contained 8.05 percent citric acid by weight, 5.74 percent benzoic acid by weight, and 4.24 percent succinic acid by weight, accompanied by 0.65 percent elemental silicon. The product also contained 36.31 percent total organic carbon and 62.60 percent total organic matter. To evaluate the agronomic response across different treatment intensities, the liquid product was prepared as aqueous dilutions at concentrations of 666 parts per million, 1000 parts per million, and 2000 parts per million, representing field delivery rates equivalent to 3000, 4500, and 9000 milliliters per hectare, respectively. These dilutions were tested without any supplementary chemical surfactants to evaluate the direct efficacy of the acid formulation.

The trial utilized a randomized complete block design comprising five distinct experimental treatments replicated across four blocks to ensure statistical rigor. Individual gross experimental plots measured 4.50 meters by 3.60 meters accommodating ten crop rows, while central net harvest plots measured 3.60 meters by 3.40 meters spanning six rows, maintaining plant spacing at 45 centimeters between rows and 10 centimeters within rows. Treatment one served as an absolute control receiving neither fertilizer nor biostimulant. Treatment two received the general recommended dose of fertilizer, consisting of 50 kilograms of nitrogen, 75 kilograms of phosphorus pentoxide, and 45 kilograms of potassium oxide per hectare, combined with 10 metric tons per hectare of farmyard manure. Treatments three, four, and five received this full fertilizer baseline augmented with EliArmor at 666, 1000, and 2000 parts per million, respectively. The biostimulant protocol comprised three foliar knapsack sprays delivered to run-off at 500 liters per hectare paired simultaneously with three targeted root-zone soil drenches at 1000 liters per hectare applied at 21, 35, and 55 days after sowing.

Systematic crop assessments revealed that the highest biostimulant rate produced substantial gains in biological and economic yields over unfertilized and fertilizer-only baselines. Grain yield reached only 16.04 quintals per hectare in the absolute control, whereas applying the recommended fertilizer alone elevated yield to 22.50 quintals per hectare, representing a 40.27 percent fertilizer response. Integrating EliArmor at 666, 1000, and 2000 parts per million produced grain yields of 24.91, 24.73, and 25.89 quintals per hectare, reflecting yield increases over the unfertilized control of 55.29 percent, 54.15 percent, and 61.48 percent, respectively. Relative to the standard fertilizer baseline, these treatments achieved yield increases of 10.71 percent, 9.91 percent, and 15.07 percent. Aboveground stover biomass similarly expanded from 18.43 quintals per hectare in the control to 28.66 quintals in the fertilizer baseline, ultimately reaching 31.21 quintals per hectare under the 2000 parts per million biostimulant treatment. Despite these marked biomass increases, the crop harvest index remained steady within a narrow band of 44.0 to 46.5 percent, demonstrating balanced partitioning between vegetative biomass and harvested seed.

Total macronutrient uptake, determined by summing elemental accumulation across harvested grain and stover tissues, responded strongly to the combined fertilizer and biostimulant treatments. Total nitrogen uptake was 76.53 kilograms per hectare in the absolute control, expanding to 113.66 kilograms under fertilizer alone, and reaching 125.02, 124.61, and 130.44 kilograms per hectare under 666, 1000, and 2000 parts per million biostimulant applications, an increase of 14.76 percent for the highest concentration over fertilizer alone. Total phosphorus uptake exhibited a particularly pronounced relative response, rising from 8.39 kilograms per hectare in the control to 12.46 kilograms under recommended fertilizer, and climbing further to 13.54, 13.53, and 14.86 kilograms per hectare under increasing biostimulant concentrations, representing a 19.26 percent gain at 2000 parts per million over fertilizer alone. Potassium uptake followed a comparable upward trend, increasing from 33.76 kilograms per hectare in control plots to 54.82 kilograms with fertilizer, and reaching 60.16 kilograms per hectare at the 2000 parts per million rate, reflecting higher nutrient removal driven primarily by expanded total crop biomass.

Micronutrient assimilation in both grain and stover fractions demonstrated substantial enhancements, aligning with the expected metal-chelating capabilities of low-molecular-weight organic acids in alkaline soils. Total iron uptake rose from 950.94 grams per hectare in the absolute control to 1460.3 grams per hectare under recommended fertilizer, reaching 1617.6, 1592.5, and 1728.3 grams per hectare across the 666, 1000, and 2000 parts per million treatments. Total zinc uptake grew from 362.68 grams per hectare in the control to 575.6 grams with fertilizer alone, escalating to 675.8, 652.3, and 739.3 grams per hectare under the respective biostimulant additions, an overall gain of 103.85 percent over the unfertilized control. Manganese accumulation peaked at 763.6 grams per hectare under the 666 parts per million treatment compared to 638.3 grams in the fertilizer baseline, while copper uptake reached its highest level of 358.9 grams per hectare at 666 parts per million relative to 336.8 grams in fertilizer-only plots, confirming enhanced trace metal absorption across all supplemented treatments.

Evaluation of seed quality metrics and vegetative architecture indicated specific physiological responses to biostimulant supplementation. Crude protein content in harvested grain, determined through Kjeldahl total nitrogen analysis, increased from 31.33 percent in the absolute control to 33.34 percent under fertilizer alone, peaking at 34.63 percent under the 1000 parts per million treatment before recording 34.26 percent at 2000 parts per million. Seed test weight, measured as the mass of one hundred mature seeds, rose from 16.19 grams in the control to 17.23 grams with fertilizer, achieving its highest value of 17.56 grams under the 2000 parts per million biostimulant dose. Seed oil concentration remained statistically unaffected across fertilized treatments, measuring between 18.96 and 19.12 percent. Morphological measurements taken at 70 days after sowing showed that plant height increased significantly to 88.75 centimeters under the 2000 parts per million treatment compared to 83.95 centimeters with fertilizer alone. Pods per plant reached 86.52 at the highest rate, significantly surpassing the 78.10 pods recorded under fertilizer alone, whereas primary branching counts did not differ significantly between fertilizer alone and biostimulant treatments.

Visual phytotoxicity monitoring conducted before each application and five days following each spraying event revealed a uniform score of zero across all monitored plots, indicating that repeated foliar contact and soil drenching caused no foliar chlorosis, necrosis, scorch, epinasty, or stunting. However, the trial authors emphasize significant limitations inherent to the experimental scope that prevent immediate broad generalization. The study was conducted at a single research station across one Kharif season, meaning environmental interactions with varying soil textures, rainfall patterns, and alternate cultivars remain uncharacterized. Furthermore, because foliar spraying and soil drenching were applied concurrently at each intervention interval, the experimental design cannot isolate whether the observed yield and nutrient uptake gains derived from leaf absorption, root rhizosphere modifications, or their combined synergy. The authors also noted that the six-application schedule requires intensive labor, disease incidence was unrecorded, and internal physiological mechanisms such as enzyme kinetics, photosynthesis rates, and gene expression were not measured directly, underscoring the necessity of multi-location trials and formal cost-benefit assessments prior to commercial deployment.

Subject of Research: Agronomic evaluation of an organic acid biostimulant on soybean yield and nutrient uptake under field conditions

Article Title: Influence of an organic acid-based biostimulant on soybean growth, yield and nutrient uptake under field conditions

Article References: Kharat, K. R., Boro, H. H., Kale, S. D., & Pottathil, R. (2026). Influence of an organic acid-based biostimulant on soybean growth, yield and nutrient uptake under field conditions. Discover Plants, 3(1), Article 521. https://doi.org/10.1007/s44372-026-01010-3

Image Credits: AI Generated

DOI: 10.1007/s44372-026-01010-3

Keywords: soybean research, crop science, organic acid biostimulant, nutrient uptake, field agronomy, plant nutrition, sustainable agriculture, Kharif season, Influence, organic, acid-based, biostimulant