Journal of Agronomy and Field Innovations

Background: Soybean (Glycine max (L.) Merr.) is a highly important legume crop known for its protein, oil, and industrial utility. The structure of its root system plays a crucial role in acquiring water and nutrients, thereby affecting crop productivity. Humic acid, one of the components of humic substances found in soil, is increasingly considered a natural biostimulant that can alter root architecture and the functioning of the rhizosphere.
Objectives: The aim of this paper is to study the impact of soil-applied humic acids applied separately and in combination with recommended fertilization on the parameters of the soybean root architecture, physiological performance, nutrient uptake, and yield.
Methods: The present study was conducted in a field experiment using a randomized complete block design with 7 treatments (control, recommended dose of fertilizers, 4 doses of humic acid at different levels, and one combined treatment) replicated four times each. Root architecture was measured using WinRHIZO image analysis, physiological parameters were measured using SPAD chlorophyll meter and gas-exchange systems, nutrient concentrations were measured with the help of Kjeldahl digestion and ICP-OES, while yield components were calculated based on the physiological maturity of soybean.
Result: Humic acid application led to a notable rise in root length, root area as well as lateral roots number in relation to the control group. Furthermore, when combined with fertilizers, humic acid achieved the greatest improvement of root structure. Moreover, this treatment was not only followed by improvements in other roots-related, but also physiological processes.
Conclusion: The use of humic acid in soils has positive effects on root structure development of soybean plants and therefore enhances their physiological efficiency as well as yield.