Eurasian Journal of Soil Science

Abstract

This study investigated the effects of foliar-applied humic acid-based fertilizers on potato (Solanum tuberosum L.) yield, tuber quality, and nutrient uptake efficiency under irrigated conditions in Western Kazakhstan. A three-year field experiment (2021–2023) was conducted using the Silvana potato variety, a medium-early cultivar with high yield potential. The randomized complete block design included five treatments: (1) Control (no fertilizers), (2) Reasil Micro Hydro Mix, (3) Reasil Micro Hydro Mix + Reasil Forte Carb-Nitrogen-Humic, (4) Potassium Humate, and (5) Potassium Humate + Reasil Forte Carb-Nitrogen-Humic. All fertilizers were applied as foliar sprays at three critical growth stages: stem formation, bud appearance, and tuber formation. The humic acid-based fertilizers used in the study were produced by LLC "Life Force Group". Potassium Humate is an 80% alkaline extract of humic and fulvic acids from leonardite. Reasil Micro Hydro Mix contains various essential micronutrients, including N, Mg, B, Fe, Zn, and amino acids. Reasil Forte Carb-Nitrogen-Humic is rich in N (20%, including 18% amide-N) and also contains humic acids (6.2%), hydroxycarboxylic acids (6.2%), and amino acids (6%). Results showed that foliar humic acid application significantly increased potato yield and improved tuber quality. The highest average marketable yield (28.79 t/ha) was obtained with Potassium Humate + Reasil Forte Carb-Nitrogen-Humic, reflecting a 20% increase over the control. Starch content was also highest in this treatment (16.9%), while vitamin C content was better maintained in treated plots under stress conditions. Additionally, nitrate accumulation in tubers was reduced, improving food safety. Nutrient uptake efficiency was significantly enhanced by humic acid-based foliar treatments. The Potassium Humate + Reasil Forte Carb-Nitrogen-Humic treatment recorded the highest N, P, and K absorption levels, confirming the role of foliar humic applications in optimizing nutrient translocation. These findings demonstrate that humic acid-based foliar fertilization is an effective strategy for increasing potato productivity while reducing reliance on conventional fertilizers. These findings highlight the potential of foliar-applied humic substances as a sustainable alternative to conventional fertilization, particularly in semi-arid agricultural systems.

Keywords

Foliar fertilization, humic substances, potato yield, nutrient uptake, starch content, sustainable agriculture.

References

<p>Akladious, S.A., Mohamed, H.I., 2018. Ameliorative effects of calcium nitrate and humic acid on the growth, yield component and biochemical attribute of pepper (Capsicum annuum) plants grown under salt stress. <em>Scientia Horticulturae</em> 236: 244&ndash;250.</p>

<p>Akram, M.S., Ashraf, M., Akram, N.A., 2009. Effectiveness of potassium sulfate in mitigating salt-induced adverse effects on different physio-biochemical attributes in sun fl ower ( <em>Helianthus annuus </em>L.). <em>Flora - Morphology, Distribution, Functional Ecology of Plants</em> 204(6): 471&ndash;483.</p>

<p>Alimkhanov, Y., Yeleshev, R., Yertayeva, B., Aitbayeva, A., 2021. Responses of potato (Solanum tuberosum L.) varieties to NPK fertilization on tuber yield in the Southeast of Kazakhstan. <em>Eurasian Journal of Soil Science</em> 10(4): 285-289.</p>

<p>Bayat, H., Shafie, F., Aminifard, M.H., Daghighi, S., 2021. Comparative effects of humic and fulvic acids as biostimulants on growth, antioxidant activity and nutrient content of yarrow (Achillea millefolium L.). <em>Scientia Horticulturae</em> 279: 109912.</p>

<p>Budanov,&nbsp;N.,&nbsp;Aitbayev,&nbsp;Т.,&nbsp;Buribayeva,&nbsp;L.,&nbsp;Zhylkibayev,&nbsp;A.,&nbsp;Yertayeva,&nbsp;Z.,&nbsp;2023. Impact of different organic fertilizers on soil available nutrient contents, potato yield, tuber nitrate contents . <em>Eurasian Journal of Soil Science</em> 12(3): 215-221.</p>

<p>Butler, T.J., Muir, J.P., 2006. Dairy manure compost improves soil and increases tall wheatgrass yield. <em>Agronomy Journal </em>98(4): 1090&ndash;1096.</p>

<p>Chen, X.G., Kou, M., Tang, Z.H., Zhang, A.J., Li, H.M., Wei, M., 2017. Responses of root physiological characteristics and yield of sweet potato to humic acid urea fertilizer. <em>PLoS ONE</em> 12: e0189715.</p>

<p>Chen, Y., Clapp, C.E., Magen, H., 2004. Mechanism of plant growth stimulation by humic substances: The role of organo-iron complex. <em>Soil Science and Plant Nutrition</em> 50: 1089-1095.</p>

<p>de Moura, O.V.T., Berbara, R.L.L., de Oliveira Torchia, D.F., Da Silva, H.F.O., van Tol de Castro, T.A., Tavares, O.C.H., Rodrigues, N.F., Zonta, E., Santos, L.A., Garc&iacute;a, A.C., 2023. Humic foliar application as sustainable technology for improving the growth, yield, and abiotic stress protection of agricultural crops. A review. <em>Journal of the Saudi Society of Agricultural Sciences</em> 22(8): 493-513.</p>

<p>Jindo, K., Canellas, L.P., Albacete, A., Figueiredo dos Santos, L., Frinhani Rocha, R.L., Carvalho Baia, D., Oliveira Aguiar Canellas, N., Goron, T.L., Olivares, F.L., 2020. Interaction between humic substances and plant hormones for phosphorous acquisition.&nbsp;Agronomy&nbsp;<em>10 (5):</em> 640.</p>

<p>Jones, Jr. J.B., 2001. Laboratory Guide for Conducting Soil Tests and Plant Analysis. CRC Press, 384p.</p>

<p>Kalra, Y.P., 1998. Handbook of Reference Methods for Plant Analysis. CRC Press, 320p.</p>

<p>Kanai, S., Moghaieb, R.E., El-Shemy, H.A., Panigrahi, R., Mohapatra, P.K., Ito, J., Nguyen, N.T., Saneoka, H., Fujita, K., 2011. Potassium deficiency affects water status and photosynthetic rate of the vegetative sink in green house tomato prior to its effects on source activity. <em>Plant Science</em> 180(2): 368-374.</p>

<p>Li, C., Yao, W., Wang, J., Wang, J., Ai, Y., Ma, H., Zhang, Y., 2019. A novel effect of glycine on the growth and starch biosynthesis of storage root in sweetpotato (Ipomoea batatas Lam.). Plant Physiology and Biochemistry 144: 395-403.</p>

<p>Li, X., Li, D., Lu, Q., Wang, D., Ren, X., Lv, L., Ahmed, T., Yan, J., Li, B., 2022. Effects of different organic fertilizers on sweet potato growth and rhizosphere soil properties in newly reclaimed land. <em>Agronomy </em>12(7): 1649.</p>

<p>Li, Y., Fang, F., Wei, J., Wu, X., Cui, R., Li, G., Zheng, F., Tan, D., 2019. Humic acid fertilizer improved soil properties and soil microbial diversity of continuous cropping peanut: A three-year experiment. <em>Scientific Reports</em> 9: 12014.</p>

<p>Liu, Z.X., Chen, X.M., Jing, Y., Li, Q.X., Zhang, J.B., Huang, Q.R., 2014. Effects of biochar amendment on rapeseed and sweet potato yields and water stable aggregate in upland red soil. <em>Catena </em>123: 45&ndash;51.</p>

<p>Loebenstein, G., Manadilova, A., 2003. Potatoes in the Central Asian Republics. In: Virus and virus-like diseases of major crops in developing countries. Loebenstein, G., Thottappilly, G. (Eds.). Springer. pp.195-222.</p>

<p>Lumactud, R.A., Gorim, L.Y., Thilakarathna, M.S., 2022. Impacts of humic-based products on the microbial community structure and functions toward sustainable agriculture. <em>Frontiers in Sustainable Food Systems</em> 6: 977121.</p>

<p>Mora, V., Bacaicoa, E., Zamarreno, A.M., Aguirre, E., Garnica, M., Fuentes, M., Garcia-Mina, J.M., 2010. Action of humic acid on promotion of cucumber shoot growth involves nitrate-related changes associated with the root-to-shoot distribution of cytokinins, polyamines and mineral nutrients. <em>Journal of Plant Physiology</em> 167: 633-642.</p>

<p>Mukhametov, A., Ansabayeva, A., Efimov, O., Kamerova, A., 2024. Influence of crop rotation, the treatment of crop residues, and the application of nitrogen fertilizers on soil properties and maize yield. <em>Soil Science Society of America Journal</em> 88(6): 2227&ndash;2237.</p>

<p>Muminova, S., Tastanbekova, G., Kashkarov, A., Azhimetova, G., Balgabaev, A., 2022. Effect of foliar mineral fertilizer and plant growth regulator application on seed yield and yield components of soybean (Glycine max) cultivars. <em>Eurasian Journal of Soil Science</em> 11(4): 322-328.</p>

<p>Nardi, S., Pizzeghelloa, D., Muscolob, A., Vianelloc, A., 2002. Physiological effects of humic substances on higher plants. <em>Soil Biology and Biochemistry</em> 34(11): 1527-2536.</p>

<p>Nikbakht, A., Kafi, M., Babalar, M., Xia, Y.P., Luo, A., Etemadi, N.A., 2008. Effect of humic acid on plant growth, nutrient uptake, and postharvest life of gerbera. <em>Journal of Plant Nutrition</em> 31(12): 2155&ndash;2167.</p>

<p>Rathor, P., Upadhyay, P., Ullah, A., Gorim, L.Y., Thilakarathna, M.S., 2024. Humic acid improves wheat growth by modulating auxin and cytokinin biosynthesis pathways,&nbsp;<em>AoB PLANTS</em> 16(2): plae018.</p>

<p>Santi, M.A., Somboon, S., Thip-Amat, S., Sukitprapanon, T.S., Lawongsa, P.,&nbsp; 2024. Effects of humic acid application on bacterial diversity under maize cultivation. <em>Agrosystems, Geosciences &amp; Environment</em> 7(3): e20547.</p>

<p>Singh, Y.V., 2024. Standard Methods for Soil, Water and Plant Analysis. CRC Press, 324p.</p>

<p>Suh, H.Y., Yoo, K.S., Suh, S.G., 2014. Tuber growth and quality of potato (Solanum tuberosum L.) as affected by foliar or soil application of fulvic and humic acids. <em>Horticulture, Environment, and Biotechnology</em> 55 (3): 183&ndash;189.</p>

<p>Tang, C., Li, Y., Song, J., Antonietti, M., Yang, F., 2021. Artificial humic substances improve microbial activity for binding CO2. <em>iScience</em> 24(6): 102647.</p>

<p>Tastanbekova, G., Tokbergenova, Z., Sharipova, D., Jantassova, A., Surimbayeva, K., Azhimetova, G., Zhylkibayev, A., 2024. Enhanced tomato (Solanum lycopersicum L.) yield and soil biological properties through integrated use of soil, compost, and foliar fertilization under greenhouse conditions. <em>Eurasian Journal of Soil Science</em> 13(4): 366 - 375.</p>

<p>Tiessen, A., Hendriks, J.H.M., Stitt, M., Branscheid, A., Gibon, Y., Farré, E.M., Geigenberger, P., 2002. Starch synthesis in potato tubers ıs regulated by post-translational redox modification of ADP-Glucose Pyrophosphorylase : A novel regulatory mechanism linking starch synthesis to the sucrose supply.&nbsp;The Plant Cell 14(9): 2191&ndash;2213.&nbsp;</p>

<p>Verlinden, G., Pycke, B., Mertens, J., Debersaques, F., Verheyen, K., Baert, G., Bries, J., Haesaert, G., 2009. Application of humic substances results in consistent increases in crop yield and nutrient uptake. <em>Journal of Plant Nutrition</em> 32(9): 1407&ndash;1426.</p>

<p>Xiong, Q., Wang, S., Lu, X., Xu, Y., Zhang, L., Chen, X., Xu, G., Tian, D., Zhang, L., Jing, J., Ye, X., 2023. The effective combination of humic acid phosphate fertilizer regulating the form transformation of phosphorus and the chemical and microbial mechanism of ıts phosphorus availability. <em>Agronomy </em>13(6): 1581.</p>

<p>Zhao, W.R., Li, J.Y., Jiang, J., Lu, H.L., Hong, Z.N., Qian, W., Xu, R.K., Deng, K.Y., Guan, P., 2020. The mechanisms underlying the reduction in aluminum toxicity and improvements in the yield of sweet potato (Ipomoea batatas L.) After organic and inorganic amendment of an acidic ultisol. <em>Agriculture, Ecosystems &amp; Environment </em>288: 106716.</p>

<p>Zhou, L., Monreal, C.M., Xu, S.T., McLaughlin, N.B., Zhang, H.Y., Hao, G.C., Liu, J.H., 2019. Effect of bentonite-humic acid application on the improvement of soil structure and maize yield in a sandy soil of a semi-arid region. <em>Geoderma</em> 338: 269&ndash;280.</p>

Abstract

This study investigated the effects of foliar-applied humic acid-based fertilizers on potato (Solanum tuberosum L.) yield, tuber quality, and nutrient uptake efficiency under irrigated conditions in Western Kazakhstan. A three-year field experiment (2021–2023) was conducted using the Silvana potato variety, a medium-early cultivar with high yield potential. The randomized complete block design included five treatments: (1) Control (no fertilizers), (2) Reasil Micro Hydro Mix, (3) Reasil Micro Hydro Mix + Reasil Forte Carb-Nitrogen-Humic, (4) Potassium Humate, and (5) Potassium Humate + Reasil Forte Carb-Nitrogen-Humic. All fertilizers were applied as foliar sprays at three critical growth stages: stem formation, bud appearance, and tuber formation. The humic acid-based fertilizers used in the study were produced by LLC "Life Force Group". Potassium Humate is an 80% alkaline extract of humic and fulvic acids from leonardite. Reasil Micro Hydro Mix contains various essential micronutrients, including N, Mg, B, Fe, Zn, and amino acids. Reasil Forte Carb-Nitrogen-Humic is rich in N (20%, including 18% amide-N) and also contains humic acids (6.2%), hydroxycarboxylic acids (6.2%), and amino acids (6%). Results showed that foliar humic acid application significantly increased potato yield and improved tuber quality. The highest average marketable yield (28.79 t/ha) was obtained with Potassium Humate + Reasil Forte Carb-Nitrogen-Humic, reflecting a 20% increase over the control. Starch content was also highest in this treatment (16.9%), while vitamin C content was better maintained in treated plots under stress conditions. Additionally, nitrate accumulation in tubers was reduced, improving food safety. Nutrient uptake efficiency was significantly enhanced by humic acid-based foliar treatments. The Potassium Humate + Reasil Forte Carb-Nitrogen-Humic treatment recorded the highest N, P, and K absorption levels, confirming the role of foliar humic applications in optimizing nutrient translocation. These findings demonstrate that humic acid-based foliar fertilization is an effective strategy for increasing potato productivity while reducing reliance on conventional fertilizers. These findings highlight the potential of foliar-applied humic substances as a sustainable alternative to conventional fertilization, particularly in semi-arid agricultural systems.

Keywords: Foliar fertilization, humic substances, potato yield, nutrient uptake, starch content, sustainable agriculture.

References

Akladious, S.A., Mohamed, H.I., 2018. Ameliorative effects of calcium nitrate and humic acid on the growth, yield component and biochemical attribute of pepper (Capsicum annuum) plants grown under salt stress. Scientia Horticulturae 236: 244–250.

Akram, M.S., Ashraf, M., Akram, N.A., 2009. Effectiveness of potassium sulfate in mitigating salt-induced adverse effects on different physio-biochemical attributes in sun fl ower ( Helianthus annuus L.). Flora - Morphology, Distribution, Functional Ecology of Plants 204(6): 471–483.

Alimkhanov, Y., Yeleshev, R., Yertayeva, B., Aitbayeva, A., 2021. Responses of potato (Solanum tuberosum L.) varieties to NPK fertilization on tuber yield in the Southeast of Kazakhstan. Eurasian Journal of Soil Science 10(4): 285-289.

Bayat, H., Shafie, F., Aminifard, M.H., Daghighi, S., 2021. Comparative effects of humic and fulvic acids as biostimulants on growth, antioxidant activity and nutrient content of yarrow (Achillea millefolium L.). Scientia Horticulturae 279: 109912.

Budanov, N., Aitbayev, Т., Buribayeva, L., Zhylkibayev, A., Yertayeva, Z., 2023. Impact of different organic fertilizers on soil available nutrient contents, potato yield, tuber nitrate contents . Eurasian Journal of Soil Science 12(3): 215-221.

Butler, T.J., Muir, J.P., 2006. Dairy manure compost improves soil and increases tall wheatgrass yield. Agronomy Journal 98(4): 1090–1096.

Chen, X.G., Kou, M., Tang, Z.H., Zhang, A.J., Li, H.M., Wei, M., 2017. Responses of root physiological characteristics and yield of sweet potato to humic acid urea fertilizer. PLoS ONE 12: e0189715.

Chen, Y., Clapp, C.E., Magen, H., 2004. Mechanism of plant growth stimulation by humic substances: The role of organo-iron complex. Soil Science and Plant Nutrition 50: 1089-1095.

de Moura, O.V.T., Berbara, R.L.L., de Oliveira Torchia, D.F., Da Silva, H.F.O., van Tol de Castro, T.A., Tavares, O.C.H., Rodrigues, N.F., Zonta, E., Santos, L.A., García, A.C., 2023. Humic foliar application as sustainable technology for improving the growth, yield, and abiotic stress protection of agricultural crops. A review. Journal of the Saudi Society of Agricultural Sciences 22(8): 493-513.

Jindo, K., Canellas, L.P., Albacete, A., Figueiredo dos Santos, L., Frinhani Rocha, R.L., Carvalho Baia, D., Oliveira Aguiar Canellas, N., Goron, T.L., Olivares, F.L., 2020. Interaction between humic substances and plant hormones for phosphorous acquisition. Agronomy 10 (5): 640.

Jones, Jr. J.B., 2001. Laboratory Guide for Conducting Soil Tests and Plant Analysis. CRC Press, 384p.

Kalra, Y.P., 1998. Handbook of Reference Methods for Plant Analysis. CRC Press, 320p.

Kanai, S., Moghaieb, R.E., El-Shemy, H.A., Panigrahi, R., Mohapatra, P.K., Ito, J., Nguyen, N.T., Saneoka, H., Fujita, K., 2011. Potassium deficiency affects water status and photosynthetic rate of the vegetative sink in green house tomato prior to its effects on source activity. Plant Science 180(2): 368-374.

Li, C., Yao, W., Wang, J., Wang, J., Ai, Y., Ma, H., Zhang, Y., 2019. A novel effect of glycine on the growth and starch biosynthesis of storage root in sweetpotato (Ipomoea batatas Lam.). Plant Physiology and Biochemistry 144: 395-403.

Li, X., Li, D., Lu, Q., Wang, D., Ren, X., Lv, L., Ahmed, T., Yan, J., Li, B., 2022. Effects of different organic fertilizers on sweet potato growth and rhizosphere soil properties in newly reclaimed land. Agronomy 12(7): 1649.

Li, Y., Fang, F., Wei, J., Wu, X., Cui, R., Li, G., Zheng, F., Tan, D., 2019. Humic acid fertilizer improved soil properties and soil microbial diversity of continuous cropping peanut: A three-year experiment. Scientific Reports 9: 12014.

Liu, Z.X., Chen, X.M., Jing, Y., Li, Q.X., Zhang, J.B., Huang, Q.R., 2014. Effects of biochar amendment on rapeseed and sweet potato yields and water stable aggregate in upland red soil. Catena 123: 45–51.

Loebenstein, G., Manadilova, A., 2003. Potatoes in the Central Asian Republics. In: Virus and virus-like diseases of major crops in developing countries. Loebenstein, G., Thottappilly, G. (Eds.). Springer. pp.195-222.

Lumactud, R.A., Gorim, L.Y., Thilakarathna, M.S., 2022. Impacts of humic-based products on the microbial community structure and functions toward sustainable agriculture. Frontiers in Sustainable Food Systems 6: 977121.

Mora, V., Bacaicoa, E., Zamarreno, A.M., Aguirre, E., Garnica, M., Fuentes, M., Garcia-Mina, J.M., 2010. Action of humic acid on promotion of cucumber shoot growth involves nitrate-related changes associated with the root-to-shoot distribution of cytokinins, polyamines and mineral nutrients. Journal of Plant Physiology 167: 633-642.

Mukhametov, A., Ansabayeva, A., Efimov, O., Kamerova, A., 2024. Influence of crop rotation, the treatment of crop residues, and the application of nitrogen fertilizers on soil properties and maize yield. Soil Science Society of America Journal 88(6): 2227–2237.

Muminova, S., Tastanbekova, G., Kashkarov, A., Azhimetova, G., Balgabaev, A., 2022. Effect of foliar mineral fertilizer and plant growth regulator application on seed yield and yield components of soybean (Glycine max) cultivars. Eurasian Journal of Soil Science 11(4): 322-328.

Nardi, S., Pizzeghelloa, D., Muscolob, A., Vianelloc, A., 2002. Physiological effects of humic substances on higher plants. Soil Biology and Biochemistry 34(11): 1527-2536.

Nikbakht, A., Kafi, M., Babalar, M., Xia, Y.P., Luo, A., Etemadi, N.A., 2008. Effect of humic acid on plant growth, nutrient uptake, and postharvest life of gerbera. Journal of Plant Nutrition 31(12): 2155–2167.

Rathor, P., Upadhyay, P., Ullah, A., Gorim, L.Y., Thilakarathna, M.S., 2024. Humic acid improves wheat growth by modulating auxin and cytokinin biosynthesis pathways, AoB PLANTS 16(2): plae018.

Santi, M.A., Somboon, S., Thip-Amat, S., Sukitprapanon, T.S., Lawongsa, P.,  2024. Effects of humic acid application on bacterial diversity under maize cultivation. Agrosystems, Geosciences & Environment 7(3): e20547.

Singh, Y.V., 2024. Standard Methods for Soil, Water and Plant Analysis. CRC Press, 324p.

Suh, H.Y., Yoo, K.S., Suh, S.G., 2014. Tuber growth and quality of potato (Solanum tuberosum L.) as affected by foliar or soil application of fulvic and humic acids. Horticulture, Environment, and Biotechnology 55 (3): 183–189.

Tang, C., Li, Y., Song, J., Antonietti, M., Yang, F., 2021. Artificial humic substances improve microbial activity for binding CO2. iScience 24(6): 102647.

Tastanbekova, G., Tokbergenova, Z., Sharipova, D., Jantassova, A., Surimbayeva, K., Azhimetova, G., Zhylkibayev, A., 2024. Enhanced tomato (Solanum lycopersicum L.) yield and soil biological properties through integrated use of soil, compost, and foliar fertilization under greenhouse conditions. Eurasian Journal of Soil Science 13(4): 366 - 375.

Tiessen, A., Hendriks, J.H.M., Stitt, M., Branscheid, A., Gibon, Y., Farré, E.M., Geigenberger, P., 2002. Starch synthesis in potato tubers ıs regulated by post-translational redox modification of ADP-Glucose Pyrophosphorylase : A novel regulatory mechanism linking starch synthesis to the sucrose supply. The Plant Cell 14(9): 2191–2213. 

Verlinden, G., Pycke, B., Mertens, J., Debersaques, F., Verheyen, K., Baert, G., Bries, J., Haesaert, G., 2009. Application of humic substances results in consistent increases in crop yield and nutrient uptake. Journal of Plant Nutrition 32(9): 1407–1426.

Xiong, Q., Wang, S., Lu, X., Xu, Y., Zhang, L., Chen, X., Xu, G., Tian, D., Zhang, L., Jing, J., Ye, X., 2023. The effective combination of humic acid phosphate fertilizer regulating the form transformation of phosphorus and the chemical and microbial mechanism of ıts phosphorus availability. Agronomy 13(6): 1581.

Zhao, W.R., Li, J.Y., Jiang, J., Lu, H.L., Hong, Z.N., Qian, W., Xu, R.K., Deng, K.Y., Guan, P., 2020. The mechanisms underlying the reduction in aluminum toxicity and improvements in the yield of sweet potato (Ipomoea batatas L.) After organic and inorganic amendment of an acidic ultisol. Agriculture, Ecosystems & Environment 288: 106716.

Zhou, L., Monreal, C.M., Xu, S.T., McLaughlin, N.B., Zhang, H.Y., Hao, G.C., Liu, J.H., 2019. Effect of bentonite-humic acid application on the improvement of soil structure and maize yield in a sandy soil of a semi-arid region. Geoderma 338: 269–280.