Effect of foliar application of humic acid and vermicompost leachate on yield and quality of soybean in vertisols

Introduction

Soybean [Glycine max (L.) Merrill] is an important grain legume and oilseed crop, widely recognized for its high nutritional and industrial value. The seeds contain approximately 40-44 per cent protein and 20 per cent oil, making soybean an important source of both dietary protein and edible oil. Because of its nutritional quality, productivity and diverse industrial uses, the crop has considerable potential for expansion in India. As a leguminous crop, soybean can tolerate periods of moisture stress to some extent and also contributes to the improvement of soil fertility and productivity through biological nitrogen fixation. In India, soybean is cultivated over an area of 12.95 million ha, producing about 15.27 million tonnes, with an average productivity of 1179 kg ha⁻¹ (Anon., 2025) [1] . Nevertheless, soybean productivity and quality in India remain comparatively low, which may be attributed to inadequate crop management, particularly improper nutrient management. The limited recycling of organic wastes and the continued dependence on readily soluble N, P and K fertilizers, often without adequate use of organic matter or humic substances, may adversely affect soil health and create long-term environmental and ecological concerns. Humic acid is a complex organic substance containing different types of organic compounds and functional groups that can interact with several metallic ions, including Mg, Zn, Ca and Cu. It can be applied either directly to the soil or as a foliar spray. When incorporated into the soil, humic acid may improve soil structure, aeration and nutrient availability. Foliar application, on the other hand, can enhance nutrient absorption through the leaves and may contribute to improved membrane permeability and photosynthetic activity. Thus, humic acid has potential as a biostimulant for improving plant growth and nutrient utilization (Hudda et al., 2020) [2] .

Vermiwash is another organic biostimulant that is commonly applied as a foliar spray. It contains several essential nutrients, including N (0.29%), P (0.042%), K (0.143%), Ca (0.186%), Mg (0.11%), S (0.058%), Fe (0.466 ppm), Mn (0.406 ppm), Zn (0.11 ppm) and Cu (0.18 ppm). It is generally described as a transparent, pale-yellow to brown coloured liquid biofertilizer containing excretory materials and mucous secretions of earthworms along with soluble organic and micronutrient components. Because of its nutrient content and biological constituents, vermiwash has the potential to function as a supplementary biofertilizer and biostimulant for promoting crop growth, nutrient uptake and yield (Godara et al., 2020) [3] . ). Before the commencement of the experiment, a representative soil sample was collected from a depth of 0-30 cm to characterize the initial soil conditions of the experimental field. The collected soil was thoroughly mixed, and the required quantity was obtained by the quartering method and packed in polythene bags for laboratory analysis. The initial soil analysis indicated that the soil was slightly alkaline, with a pH of 7.78 and electrical conductivity of 0.12 dS m⁻¹. The soil contained 0.58 per cent organic carbon, while the available N, P, K and S were 147.10, 10.00, 302.00 and 10.01 kg ha⁻¹, respectively. The initial DTPA-extractable Fe, Mn, Zn and Cu contents were 4.62, 4.65, 0.60 and 0.68 ppm, respectively.

Material and methods

Results and discussion

Effect of foliar application of humic acid and vermicompost leachate on yield of soybean

Effect of foliar application of humic acid and vermicompost leachate on quality of soybean

Grain yield

The effect of foliar application of humic acid and vermicompost leachate on yield of soybean was studied in table no 14. The grain yield of soybean was observed to vary between 12.98 and 17.00 q ha⁻¹. The highest grain yield (17.00 q ha -1 ) was recorded in treatment recommended dose of fertilizers (RDF) along with foliar sprays of vermicompost leachate at 20 and 35 DAS followed by RDF with humic acid at 20 and 35 DAS (16.71 q ha -1

), RDF with vermicompost leachate at 20 DAS (14.82 q ha -1

), RDF with foliar spray of vermicompost leachate at 35 DAS (14.78 q ha -1

) and RDF combined with foliar spray of humic acid at 20 DAS (14.69 q ha -1

). This treatment was found statistically significant over the treatment absolute control (12.98 q ha -1

) and RDF (14.14 q ha -1 ). But it was recorded at par with the treatment RDF combined with foliar spray of humic acid at 20 DAS (14.69 q ha -1 ), RDF with humic acid at 20 and 35 DAS (16.71 q ha -1

), RDF with vermicompost leachate at 20 DAS (14.82 q ha -1

) and RDF with foliar spray of vermicompost leachate at 35 DAS (14.78 q ha -1

). The lowest grain yield (12.98 q ha -1 ) was recorded in absolute control. The increase in yield may be attributed to the beneficial effects of humic acid and vermicompost leachate in enhancing nutrient availability, improving physiological processes, and promoting better plant growth. Similar findings were reported by Kapase et al. (2014) [4] , who observed that the application of humic acid-based organic fertilizers significantly enhanced soybean yield. Supporting findings was given by Gaikwad et al. (2012) [5] , Deotale et al. (2017) [6] .

Straw yield

The effect of foliar application of humic acid and vermicompost leachate on straw yield of soybean was showed in table no 14. The straw yield of soybean was recorded in the range of 27.8 q ha -1 to 31.0 q ha -1

. The highest straw yield (31.0 q ha -1 ) was observed in treatment with RDF with foliar spray of vermicompost leachate at 20 and 35 DAS followed by RDF with humic acid at 20 and 35 DAS (30.7 q ha -1

), RDF with foliar spray of vermicompost leachate at 35 DAS (29.6 q ha -1

) and RDF with humic acid at 35 DAS (29.6 q ha -1

). This treatment was found statistically significant over the treatment absolute control (27.8 q ha -1

) and RDF with foliar spray of vermicompost leachate at 20 DAS (28.0 q ha -1

). This treatment was found statistically at par to the all the treatment of application except RDF + foliar spray of vermicompost leachate at 20 DAS (28.0 q ha -1

) and absolute control (27.8 q ha -1 ). The lowest straw yield (27.8 q ha -1 ) was recorded in the absolute control. Savita et al. (2018) [7] who attributed the increase in straw yield to improved growth parameters, enhanced activity of plant growth regulators, and higher dry matter accumulation in vegetative plant parts. Comparable findings were also reported by Kadam et al. (2008) [8] and Dandge et al. (2016) [9] .

Effect of foliar application of humic acid and vermicompost leachate on quality of soybean

The effect of foliar application of humic acid and vermicompost leachate on protein content in soybean was recorded in [10] stated that humic acid stimulates plant growth through the assimilation of major and minor nutrients, activation or inhibition of enzymes, changes in membrane permeability, and protein synthesis. Similar results reported by Thakur et al. (2013) [11] , Prasad et al. (2016) [12] , Ahmed et al. (2012) [13] and Kaya et al. (2005) [14] .

Table 1. Effect of foliar application of humic acid and vermicompost leachate on yield of Soybean:

Treatment No. Treatment Details Grain Yield (q ha -1 )

T [15] recorded that the application of RDF along with humic acid @ 15.0 kg ha -1 resulted in the highest oil yield (497 kg ha -1 ) compared with the other treatments. The increase in oil content may be attributed to the role of humic substances in improving nutrient availability and uptake, thereby enhancing plant growth and metabolic activities associated with oil synthesis. Similar findings were recorded by Moradi et al. (2017) [16] , Hendawy et al. (2015) [17] .

Conclusion

Based on the data generated during the investigation, it was concluded that the application of RDF + foliar spray of vermicompost leachate at 20 and 35 DAS recorded the highest grain and straw yields of soybean, followed by the application of RDF + foliar spray of humic acid at 20 and 35 DAS. The oil and protein content of soybean seeds was significantly influenced by the application of RDF + foliar spray of humic acid at 20 & 35 DAS which shows highest percentage and lowest was observed in absolute control.

Acknowledgement

AcknowledgementThe authors gratefully acknowledge the Department of Soil Science, Dr. Panjabrao Deshmukh Krishi Vidyapeeth (PDKV), Akola, for providing the necessary infrastructure and institutional support that facilitated the successful completion of this research work.

References

1. Anonymous. Ministry of agriculture, Govt. of India. 2025.
2. Hudda J, Godara A, Kukreja S. Effect of application of humic acid and vermiwash on the growth, quality and yield of plants: A review. International Journal of Current Microbiology and Applied Sciences. 2020;9(11):1277-1284.
3. Godara A, Hudda J, Kukreja S. Effect of application of humic acid and vermiwash on the growth, quality and yield of plants: A review. International Journal of Current Microbiology and Applied Sciences. 2020;9(11):1277-1284.
4. Kapase PV, Deotale RD, Sawant PP, Sahane AN, Banginwar AD. Effect of foliar sprays of humic acid through vermicompost wash and NAA on morpho-physiological parameters, yield and yield contributing parameters of chickpea. Journal of Soils and Crops. 2014;24(1):107-114.
5. Gaikwad SB, Deotale RD, Uke AP, Parihar LB. Influence of foliar sprays of humic acid through vermicompost wash on growth, yield and yield contributing parameters of maize. Journal of Soils and Crops. 2012;22(1):115-121.
6. Deotale RD, Chinmalwar Y, Kalamkar VB, Kamdi SR, Jaybhaye VR. Effect of foliar sprays of cow urine and NAA on chemical, biochemical parameters and yield of pigeonpea. Journal of Soils and Crops. 2017;27(2):159-164.
7. Savita SP, Girijesh GK, Dinesh Kumar M, Nagarajappa Adivappar A. Effect of humic substances on nutrient uptake and yield of soybean. International Journal of Chemical Studies. 2018;6(4):1565-1569.
8. Kadam SR, Amrutsagar VM, Patil SR, Bagwan IR. Effect of organic nitrogen sources and fulvic acid spray on growth and yield of soybean in Inceptisol. Asian Journal of Soil Science. 2008;3(2):214-216.
9. Dandge MS, Peshattiwar PD, Ingle YV, Mohod PV. Effect of different application method of humic acid on nodulation and seed yield of soybean. International Journal of Agricultural Science. 2016;12(2):339-343.
10. Yathish C, Fathima PS, Pushpa K, Krupashree R, Theerthana T. Effect of foliar application of calcium nitrate, boron and humic acid on growth, yield and economics of transplanted pigeonpea. International Journal of Current Microbiology and Applied Sciences. 2021;10(5):68-78.
11. Thakur H, Rekha KB, Babu SSN, Padmaja G. Effect of humic substances on growth and yield of sunflower (Helianthus annuus L.). Journal of Research ANGRAU. 2013;41(4):106-108.
12. Prasad U, Kumar S, Singh R, Singh V. Formulation of vermiwash and humic acid and its application on Allium cepa. Biosciences Biotechnology Research Asia. 2016;13(1):523-529.
13. Ahmed AM, Gad El-Hak SH, Moustafa YMM. Effect of foliar application with two antioxidants and humic acid on growth, yield and yield components of peas (Pisum sativum L.). Journal of Horticultural Science & Ornamental Plants. 2012;4(3):318328.
14. Kaya M, Atak M, Khawar KM, Çiftçi CY, Özcan S. Effect of presowing seed treatment with zinc and foliar spray of humic acids on yield of common bean (Phaseolus vulgaris L.). International Journal of Agriculture & Biology. 2005;7(6):875-878.
15. Kumar TS, Rekha KB, Babu SS, Madhavi A. Growth and Yield of Rainfed Sunflower (Helianthus annuus L.) as Influenced by Humic Acid under Nutrient Management Practices in Alfisols. Research Journal of Agricultural Sciences. 2016;7(3):544-547.
16. Moradi P, Pasari B, Fayyaz F. The effects of fulvic acid application on seed and oil yield of safflower cultivars. Journal of Central European Agriculture. 2017;18(3).
17. Hendawy SF, Hussein MS, El-Gohary AE, Ibrahim ME. Effect of foliar organic fertilization on the growth, yield and oil content of Mentha piperita var. citrata. Asian Journal of Agricultural Research. 2015;9(5):237-248.
18. Gomez KA, Gomez AA. Statistical Procedures for Agricultural Research (2 ed.). New York: John Wiley and Sons; 1984. How to cite this article: Patil C, Kanase NM, Bhoyar SM, Jadhao SD, Goud VV, Konde NM, et al. Effect of foliar application of humic acid and vermicompost leachate on yield and quality of soybean in vertisols. International Journal of Research in Agronomy. 2026;9(9):926-929. doi: https://www.doi.org/10.3354