Eurasian Journal of Soil Science

Abstract

Phosphorus (P) adsorption and desorption regulate P availability, soil fertility, and the risk of P loss from terrestrial ecosystems; however, these processes remain poorly characterized in Nepalese soils. Despite their significance, there is limited understanding of these processes in Nepalese soils. This study aimed to explore how P adsorption and desorption vary across agro-ecological zones in central Nepal. A total of 225 soil samples, equally distributed among the high-hills, mid-hills, and Terai regions (75 from each), were collected across diverse locations. Isothermal P adsorption and desorption experiments were conducted to evaluate these behaviors, employing Langmuir, Freundlich, and Temkin models to assess P adsorption-desorption characteristics. Adsorbed P was highest in the high-hills (28.67–525.91 µg g⁻¹), followed by the Terai (28.57–494.68 µg g⁻¹) and mid-hills (25.63–422.14 µg g⁻¹). Similarly, P desorption was also highest in high-hills (3.39 to 69.38 µg g-1), followed by the Terai (5.15 to 56.00 µg g-1) and mid-hills (3.14 to 47.91 µg g-1). The P adsorption and desorption parameters, namely P adsorption capacity, bonding energy, maximum P buffering capacity (MPBC), P sorption index (PSI), P desorption capacity, maximum P desorption capacity, standard P requirement (SPR), external P requirement (EPR) were highest in the high-hills, while lowest in the mid-hills. However, maximum P adsorption capacity and P desorption capacity were highest and lowest, respectively, in the Terai. Moreover, the P desorption intensity, readily desorbable P (RDP), degree of P saturation (DPS), and P eutrophication risk index (PERI) were highest in the mid-hills, while lowest in the Terai. In contrast, the P buffering capacity (PBC) did not significantly differ among zones. These contrasting patterns demonstrate the need for zone-specific P management: the high-hills and Terai have comparatively greater fertilizer-P requirements, whereas the mid-hills exhibit higher laboratory-derived indicators of potential P loss. This study offers valuable insights for developing improved soil P management strategies for sustainable agriculture in diverse agro-ecological zones.

Keywords

High-hills, Isotherm models, Mid-hills, Phosphorus adsorption, Phosphorus desorption, Terai.

References

<p>Ahmed, M.F., Kennedy, I.R., Choudhury, A.T.M.A., Kecsk&eacute;s, M.L., Deaker, R., 2008. Phosphorus adsorption in some Australian soils and influence of bacteria on the desorption of phosphorus. <em>Communications in Soil Science and Plant Analysis</em> <em>39</em>: 1269-1294.</p>

<p>Allen, B.L., Mallarino, A.P., 2006. Relationships between extractable soil phosphorus and phosphorus saturation after long-term fertilizer or manure application. <em>Soil Science Society of America Journal 70</em>(2):454&ndash;463.</p>

<p>Ayenew, B., Tadesse, A.M., Kibret, K., Melese, A., 2018. Phosphorous status and adsorption characteristics of acid soils from Cheha and Dinsho districts, southern highlands of Ethiopia. <em>Environmental Systems Research </em>7 :17.</p>

<p>Bache, B.W., Williams, E.G., 1971. A phosphate sorption index for soils. <em>European Journal of Soil Science</em> 22:289-301.</p>

<p>Ben&iacute;cio, L.P.F., Constantino, V.R.L., Pinto, F.G., Verg&uuml;tz, L., Tronto, J., Costa, L.M., 2017. Layered double hydroxides: new technology in phosphate fertilizers based on nanostructured materials. <em>ACS Sustainable Chemistry &amp; Engineering </em>5(1):399-409.</p>

<p>Bhandari, P.S., Neupane, H.S., 2016. Fertilizing Nepalese agriculture: The effects of the distribution system on chemical fertilizer use. <em><em>Nepalese Journal of Agricultural Sciences</em> </em><em>14</em>: 261-272.</p>

<p>Bouyoucos, G. J., 1927. The hydrometer as a new method for the mechanical analysis of soils. <em>Soil Science</em> <em>23</em>(5):343&ndash;353.</p>

<p>Chen, B.L., Sheng, J.D., Jiang, P.A., Liu, Y.G., 2010. Study on characteristics of phosphorus adsorption and desorption of cotton field with different soil textures. <em><em>Chinese Journal of Soil Science</em> </em><em>41</em>(2): 303-307.</p>

<p>Debicka, M., Kocowicz, A., Weber, J., Jamroz, E., 2016. Organic matter effects on phosphorus sorption in sandy soils.&nbsp;<em>Archives of Agronomy and Soil Science</em>&nbsp;62(6):840-855.</p>

<p>Desta, M.B., 2013. Batch sorption experiments: Langmuir and Freundlich isotherm studies for the adsorption of textile metal ions onto teff straw (Eragrostis tef) agricultural waste.&nbsp;<em>Journal of Thermodynamics</em>&nbsp;Article ID: 375830.</p>

<p>Dieter, D., Elsenbeer, H., Turner, B.L., 2010. Phosphorus fractionation in lowland tropical rainforest soils in central Panama. <em>Catena </em>82(2): 118-125.</p>

<p>Estefan, E., Sommer, R., Ryan, J., 2013. <em>Methods of soil, plant, and water analysis: A manual for the West Asia and North Africa region</em>. International Center for Agricultural Research in the Dry Areas (ICARDA).</p>

<p>Fang, H., Cui, Z., He, G., Huang, L., Chen, M., 2017. Phosphorus adsorption onto clay minerals and iron oxide with consideration of heterogeneous particle morphology. <em>Science of the Total Environment</em> 605:357-367.</p>

<p>Fanjana, F., Haile, W., Mitike, G., 2017. Phosphorus fractionation and P sorption capacities of Fincha Sugar Estate soils, Western Ethiopia. <em>African Journal of Agricultural Research</em> 12(25): 2131&ndash;2139.</p>

<p>Fisher, R.A., 1925. <em>Statistical methods for research workers</em>. Oliver and Boyd, London. 299p.</p>

<p>Fox, R. L., Kamprath, E. J., 1970. Phosphate sorption isotherms for evaluating the phosphate requirements of soils. <em>Soil Science Society of America Journal</em> 34: 902-907.</p>

<p>Freundlich, H., 1926. <em>Colloid and capillary chemistry</em>. Methuen and Co. Ltd., London. 95p.</p>

<p>Gerard-Marchant, P., Hively, W.D., Steenhuis, T.S., 2006. Distributed hydrological modelling of total dissolved phosphorus transport in an agricultural landscape, Part I: Distributed runoff generation. <em>Hydrology and Earth System Sciences</em> 10: 245&ndash;261.</p>

<p>Ghodszad, L., Reyhanitabar, A., Maghsoodi, M.R., Lajayer, B.A., Chang, S.X., 2021. Biochar affects the fate of phosphorus in soil and water: A critical review. <em>Chemosphere</em> 283: 131176.</p>

<p>Gupta, P.K., 2009. <em>Soil, plant, water and fertilizer analysis,</em> 2nd ed. Agribios. India. 331p.</p>

<p>Hadgu, F., Gebrekidan, H., Kibret, K., Yitaferu, B., 2014. Study of phosphorus adsorption and its relationship with soil properties, analyzed with Langmuir and Freundlich models. <em>Agriculture, Forestry and Fisheries</em> 3(1): 40-51.</p>

<p>Heidari, S., Reyhanitabar, A., Oustan, S., 2017. Kinetics of phosphorus desorption from calcareous soils using DGT technique. <em>Geoderma</em> 305: 275&ndash;280.</p>

<p>Hiradate, S., Uchida, N., 2004. Effects of soil organic matter on pH-dependent phosphate sorption by soils. <em>Soil Science and Plant Nutrition</em> 50(5): 665-675.</p>

<p>Hooda, P.S., Rendell, A.R., Edwards, A.C., Withers, P.J.A., Aitken, M.N., Truesdale, V.W., 2000. Relating soil phosphorus indices to potential phosphorus release to water. <em>Journal of Environmental Quality</em> 29(4):1166&ndash;1171.</p>

<p>Huang, P.M., Wang, M.K., 1997. Formation chemistry and selected surface properties of iron oxides. In: <em>Soil and Environment &ndash; Soil Processes from Mineral to Landscape Scale</em><em><em>, </em></em>Auerswald, K., Stanjek, H., Bigham, J.M. (Eds.). <em>Advances in Geoecology</em>, Reiskirchen, Germany, pp. 241-270<em>.</em></p>

<p>Huang, Q., Wang, Z., Wang, D., Wang, C., Ma, M., 2004. Phosphorus sorption capacity of the surface sediment in the Lake Taihu and risk assessment of phosphorus release. <em>Journal of Lake Sciences</em> 16(2):97-104.</p>

<p>Indiati, R., Sequi, P., 2004. Phosphorus intensity-quantity relationships in soils highly contrasting in phosphorus adsorption properties. <em>Communications in Soil Science and Plant Analysis</em> 35(1-2):131-143.</p>

<p>Jackson, M. L., 1973. <em>Soil chemical analysis</em>. Prentice Hall of India Pvt. Ltd., New Delhi.</p>

<p>Jalali, M., Jalali, M., 2016. Relation between various soil phosphorus extraction methods and sorption parameters in calcareous soils with different texture. <em>Science of the Total Environment</em> 566-567: 1080&ndash;1093.</p>

<p>Juo, A.R.S., Fox, R.L., 1977. Phosphate sorption characteristics of some benchmark soils of West Africa. <em>Soil Science</em> <em>124</em>: 370-376.</p>

<p>Karki, R., Talchabhadel, R., Aalto, J., Baidya, S. K., 2016. New climatic classification of Nepal. <em>Theoretical and Applied Climatology</em> 125: 799&ndash;808..</p>

<p>Kharel, M., Dahal, B. M., Raut, N., 2022. Good agriculture practices for safe food and sustainable agriculture in Nepal: A review. <em>Journal of Agriculture and Food Research </em>10: 100447.</p>

<p>Khiari, L., Parent, L. E., Pellerin, A., Alimi, A.R.A., Tremblay, C., Simard, R.R., Fortin, J., 2000. An agri-environmental phosphorus saturation index for acid coarse-textured soils. <em>Journal of Environmental Quality</em> 29(5): 1561&ndash;1567.</p>

<p>Kuo, S., 1996. Phosphorus. In: Methods of Soil Analysis: Part 3 Chemical Methods. Sparks, D.L., Page, A.L., Helmke, P.A., Loeppert, R.H., Soltanpour, P.N., Tabatabai, M.A., Johnston, C.T., Sumner, M.E. (Eds.). SSSA Book Series No. 5, SSSA and ASA, Madison, USA. pp. 869&ndash;919.</p>

<p>Kuo, S., Jellum, E.J., Pan, W.L., 1988. Influence of phosphate sorption parameters of soils on the desorption of phosphate by various extractants. <em>Soil Science Society of America Journal</em> 52(4): 974-979.</p>

<p>Lair, G.J., Zehetner, F., Khan, Z.H., Gerzabek, M.H., 2009. Phosphorus sorption-desorption in alluvial soils of a young weathering sequence at the Danube River. <em>Geoderma</em> 149: 39&ndash;44.</p>

<p>Lamichhane, S., Kumar, L., Adhikari, K., 2021. Updating the national soil map of Nepal through digital soil mapping. <em>Geoderma</em> 394: 115041.</p>

<p>Langmuir, I., 1918. The adsorption of gases on plane surfaces of glass, mica and platinum. <em>Journal of the American Chemical Society</em> 40: 1361-1403.</p>

<p>Levene, H., 1960. Robust tests for equality of variances. In:<em> Contributions to probability and statistics: Essays in honor of Harold Hotelling</em><em>,</em> Olkin, I. (Ed.). Stanford University Press, pp. 278-292.</p>

<p>Li, M., Hou, Y. L., Zhu, B., 2007. Phosphorus sorption-desorption by purple soils of China in relation to their properties. <em>Australian Journal of Soil Research</em> 45(3): 182&ndash;189.</p>

<p>Li, Z., Zhang, R., Liu, C., Zhang, R., Liu, Y., 2019. Phosphorus spatial distribution and pollution risk assessment in agricultural soil around the Danjiangkou Reservoir, China. <em>Science of the Total Environment</em> 699: 134417.</p>

<p>Lindsay, W.L., 1979. <em>Chemical equilibria in soils</em>. John Wiley &amp; Sons, Inc. 449p.</p>

<p>Lindsay, W.L., Norvell, W.A., 1978. Development of a DTPA soil test for zinc, iron, manganese, and copper. <em>Soil Science Society of America Journal</em> 42(3): 421&ndash;428.</p>

<p>Liu, W., Liu, G., Li, S., Zhang, Q., 2010. Phosphorus sorption and desorption characteristics of wetland soils from a subtropical reservoir. <em>Marine and Freshwater Research</em> 61(5): 507-512.</p>

<p>Masud, M.M., Moniruzzaman, M., Islam, M.R., Saleque, M.A., 2006. Phosphorus sorption characteristics in some calcareous, non-calcareous and acid piedmont soils of Bangladesh. <em>Bulletin of the Institute of Tropical Agriculture, Kyushu University</em> 29(1): 55-68.</p>

<p>McDonald, G.J., Norton, S.A., Fernandez, I.J., Hoppe, K.M., Dennis, J., Amirbahman, A., 2019. Chemical controls on dissolved phosphorus mobilization in a calcareous agricultural stream during base flow. <em>Science of the Total Environment </em>660: 876&ndash;885.</p>

<p>McDowell, R., Sharpley, A., Withers, P., 2002. Indicator to predict the movement of phosphorus from soil to subsurface flow. <em>Environmental Science &amp; Technology </em>36(7): 1505-1509.</p>

<p>McLean, E.O., 1965.&nbsp; Aluminium&nbsp; In:&nbsp; Method of soil analysis Part 2 Chemical and microbiological properties. Black, C.A., Evans, D.E., White, J.L., Ensminger, L.E. and Clark, F.E. (Eds.). Agronomy No. 9, American Society of Agronomy, Madison Wisconsin, USA. p. 927-932.</p>

<p>Ministry of Agriculture and Livestock Development (MoALD), 2023. Statistical information on Nepalese agriculture. Singhdurbar, Kathmandu, Nepal.</p>

<p>Ministry of Agriculture and Livestock Development (MoALD), 2024. Statistical Information on Nepalese Agriculture. Singhdurbar, Kathmandu, Nepal.</p>

<p>Ministry of Finance (MoF), 2023. Budget speech of fiscal year 2023/24. Government of Nepal.</p>

<p>Muindi, E.M., Mrema, J.P., Semu, E., Mtakwa, P.W., Gachene, C.K., Njogu, M.K., 2015. Phosphorus adsorption and its relation with soil properties in acid soils of Western Kenya. <em>International Journal of Plant &amp; Soil Science</em> 4(3): 203-211.</p>

<p>Munhoz, R.O., Berton, R.S., Camargo, O.A., 2011. Phosphorus sorption and redistribution on soil solid phase in a Brazilian Haplorthox amended with biosolids. <em>Applied and Environmental Soil Science</em> Article ID 283061.</p>

<p>Olsen, S.R., Cole, C.V., Watanabe, F.S., 1954. Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate. USDA Circular No. 939, US Government Printing Office.</p>

<p>Pal, S.K., 2011. Phosphorus sorption-desorption characteristics of soils under different land use patterns of eastern India. <em>Archives of Agronomy and Soil Science</em> 57(4): 365-376.</p>

<p>Panta, H.K., 2018. Supply chain of subsidized chemical fertilizers in Nepal. <em>Journal of Institute of Agriculture and Animal Science</em> 35(1): 9-20.</p>

<p>Pautler, M.C., Sims, J.T., 2000. Relationships between soil test phosphorus, soluble phosphorus, and phosphorus saturation in Delaware soils. <em>Soil Science Society of America Journal</em> 64(2): 765-773.</p>

<p>Pizzeghello, D., Berti, A., Nardi, S., Morari, F., 2016. Relationship between soil test phosphorus and phosphorus release to solution in three soils after long-term mineral and manure application. <em>Agriculture, Ecosystems &amp; Environment </em>233: 214&ndash;223.</p>

<p>Prasad, J., Mathur, B.S., 1997. Influence of long-term use of fertilizers, manure and lime on phosphate adsorption parameters in acid Alfisols of Ranchi. <em><em>Journal of the Indian Society of Soil Science</em> </em><em>45</em>: 24-27.</p>

<p>Rashmi, I., Parama, V.R.R., Biswas, A., 2016. Phosphate sorption parameters in relation to soil properties in some major agricultural soils of India. <em>SAARC Journal of Agriculture</em> 14(1): 1-9.</p>

<p>Reddy, D.D., Subba Rao, A., Takkar, P.N., 1999. Phosphate sorption behavior of a typic haplustert in relation to long-term use of fertilizer P and manure under soybean-wheat rotation. <em><em>Journal of the Indian Society of Soil Science</em> </em><em>47</em>:425-430.</p>

<p>Roberts, T.L., Johnston, A.E., 2015. Phosphorus use efficiency and management in agriculture. <em>Resources, Conservation and Recycling</em> 105: 275-281.</p>

<p>Rowe, H., Withers, P.A., Baas, P., Chan, N.I., Weintraub, M., 2015. Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy, and water security. <em>Nutrient Cycling in Agroecosystems </em>104: 393-412.</p>

<p>Roy, A., Pal, S.K., 2018. Effect of aggregation on phosphate sorption-desorption behaviour of soils under various land use patterns of Eastern India.&nbsp;<em>Journal of the Indian Society of Soil Science</em>&nbsp;66(2): 136-143.</p>

<p>Samadi, A., 2006. Phosphorus sorption characteristics in relation to soil properties in some calcareous soils of western Azarbaijan province. <em>Journal of Agricultural Science and Technology</em> 8: 251-264.</p>

<p>Sanchez, P.A., Uehara, G., 1980. Management considerations for acid soils with high phosphorus fixation capacity. In. The role of phosphorus in agriculture. Khasawneh, F.E., Sample, E.C., Kamprath, E.J. (Eds.). ASA, CSSA, SSSA, Madison, Wisconsin, USA. pp. 471-514.</p>

<p>Sertsu, S., Ali, A., 1983. Phosphorous sorption characteristics of some Ethiopia soils. <em>Ethiopia Journal of agricultural Science</em> 5: 1-12.</p>

<p>Sims, J.T., 2009. Phosphorus sorption index. In: <em>Methods of phosphorus analysis for soils, sediments, residuals, and waters.</em> Kovar J.L., Pierzynski, G.M. (Eds.). 2nd ed., Southern Cooperative Series Bulletin No. 408, Virginia Tech University.</p>

<p>Singh, B., Gilkes, R.J., 1991. Phosphorus sorption in relation to soil properties for the major soil types of south-west Australia. <em>Australian Journal of Soil Research</em> 29: 602-618.</p>

<p>Singh, V., Dhillon, N. S., Brar, B. S., 2006. Influence of long-term use of fertilizers and farmyard manure on the adsorption-desorption behaviour and bioavailability of phosphorus in soils. <em>Nutrient Cycling in Agroecosystems</em> 75: 67-78.</p>

<p>Sparks, D.L., 2003. <em>Environmental soil chemistry</em> (2nd ed.). Academic Press.</p>

<p>Sui, Y., Thompson, M.L., 2000. Phosphorus sorption, desorption and buffering capacity in a biosolids amended mollisol. <em>Soil Science Society of America Journal</em> 64: 164-169.</p>

<p>Temkin, M.I., Pyzhev, V., 1940. Kinetic of ammonia synthesis on promoted iron catalysts. <em><em>Acta Physiochimica</em> </em><em>12</em>: 327-356.</p>

<p>Vaidya, S. N., Sah, K., 2015. Preparation of a database and soil map of Nepal using WRB 2010 classification system. In: Proceedings of the Second National Soil Fertility Research Workshop. Karki, K. B., Tripathi, B. P., Manandhar, R., Adhikary, B. P (Eds.). Nepal Agricultural Research Council, Nepal. pp. 393-402.</p>

<p>Walkley, A., Black, I. A., 1934. An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. <em>Soil Science</em> 37(1): 29-38.</p>

<p>Wang, B., Sun, J.S., Liu, H., Ma, Y.B., 2017. The characteristics of phosphorus adsorption and desorption in gray desert soil of Xinjiang, China. IOP Conference Series: Earth and Environmental Science 77: 012020.</p>

<p>Wang, L., Liang, T., 2014. Effects of exogenous rare earth elements on phosphorus adsorption and desorption in different types of soils. <em>Chemosphere</em> 103: 148-155.</p>

<p>Welch, B.L., 1951. On the comparison of several mean values: An alternative approach. <em>Biometrika</em> 38(3-4): 330-336.</p>

<p>Wogi, L., Msaky, J., Rwehumbiza, F., Kibret, K., 2015. Phosphorus adsorption isotherm: A key aspect for soil phosphorus fertility management. <em>American Journal of Experimental Agriculture</em> 6(2): 74-82.</p>

<p>Xiong, J.B., Mahmood, Q., 2010. Adsorptive removal of phosphate from aqueous media by peat. <em>Desalination</em> 259(1): 59&ndash;64.</p>

<p>Yan, X., Wang, D., Zhang, H., Zhang, G., Wei, Z., 2013. Organic amendments affect phosphorus sorption characteristics in a paddy soil. <em>Agriculture, Ecosystems &amp; Environment</em> 175: 47-53.</p>

<p>Yang, X., Chen, X., Yang, X., 2019. Effect of organic matter on phosphorus adsorption and desorption in a black soil from Northeast China. <em>Soil and Tillage Research</em> 187: 85&ndash;91.</p>

<p>Yousuf, T., Hossain, M.E., Afsar, M.Z., Osman, K.T., 2019. Phosphate sorption indices as affected by the calcareousness of soils. <em>Dhaka University Journal of Biological Science</em> 28(1): 93-110.</p>

<p>Zhang, H., Schroder, J.L., Fuhrman, J.K., Basta, N.T., Storm, D.E., Payton, M.E., 2005. Path and multiple regression analyses of phosphorus sorption capacity. <em>Soil Science Society of America Journal</em> 69: 96-106.</p>

<p>Zhang, Y., Huang, S., Guo, D., Zhang, S., Song, X., Yue, K., Zhang, K., Bao, D., 2019. Phosphorus adsorption and desorption characteristics of different textural fluvo-aquic soils under long-term fertilization. <em>Journal of Soils and Sediments </em>19: 1306-1318.</p>

<p>Zhang, Y., Li, Y., Wang, S., Umbreen, D., Zhou, C., 2021. Soil phosphorus fractionation and its association with soil phosphate-solubilizing bacteria in a chronosequence of vegetation restoration. <em>Ecological Engineering</em> 164: 106208.</p>

<p>Zhu, J., Li, M., Whelan, M., 2018. Phosphorus activators contribute to legacy phosphorus availability in agricultural soils: A review. <em>Science of the Total Environment</em> 612: 522&ndash;537.</p>

Abstract

Phosphorus (P) adsorption and desorption regulate P availability, soil fertility, and the risk of P loss from terrestrial ecosystems; however, these processes remain poorly characterized in Nepalese soils. Despite their significance, there is limited understanding of these processes in Nepalese soils. This study aimed to explore how P adsorption and desorption vary across agro-ecological zones in central Nepal. A total of 225 soil samples, equally distributed among the high-hills, mid-hills, and Terai regions (75 from each), were collected across diverse locations. Isothermal P adsorption and desorption experiments were conducted to evaluate these behaviors, employing Langmuir, Freundlich, and Temkin models to assess P adsorption-desorption characteristics. Adsorbed P was highest in the high-hills (28.67–525.91 µg g⁻¹), followed by the Terai (28.57–494.68 µg g⁻¹) and mid-hills (25.63–422.14 µg g⁻¹). Similarly, P desorption was also highest in high-hills (3.39 to 69.38 µg g-1), followed by the Terai (5.15 to 56.00 µg g-1) and mid-hills (3.14 to 47.91 µg g-1). The P adsorption and desorption parameters, namely P adsorption capacity, bonding energy, maximum P buffering capacity (MPBC), P sorption index (PSI), P desorption capacity, maximum P desorption capacity, standard P requirement (SPR), external P requirement (EPR) were highest in the high-hills, while lowest in the mid-hills. However, maximum P adsorption capacity and P desorption capacity were highest and lowest, respectively, in the Terai. Moreover, the P desorption intensity, readily desorbable P (RDP), degree of P saturation (DPS), and P eutrophication risk index (PERI) were highest in the mid-hills, while lowest in the Terai. In contrast, the P buffering capacity (PBC) did not significantly differ among zones. These contrasting patterns demonstrate the need for zone-specific P management: the high-hills and Terai have comparatively greater fertilizer-P requirements, whereas the mid-hills exhibit higher laboratory-derived indicators of potential P loss. This study offers valuable insights for developing improved soil P management strategies for sustainable agriculture in diverse agro-ecological zones.

Keywords: High-hills, Isotherm models, Mid-hills, Phosphorus adsorption, Phosphorus desorption, Terai.

References

Ahmed, M.F., Kennedy, I.R., Choudhury, A.T.M.A., Kecskés, M.L., Deaker, R., 2008. Phosphorus adsorption in some Australian soils and influence of bacteria on the desorption of phosphorus. Communications in Soil Science and Plant Analysis 39: 1269-1294.

Allen, B.L., Mallarino, A.P., 2006. Relationships between extractable soil phosphorus and phosphorus saturation after long-term fertilizer or manure application. Soil Science Society of America Journal 70(2):454–463.

Ayenew, B., Tadesse, A.M., Kibret, K., Melese, A., 2018. Phosphorous status and adsorption characteristics of acid soils from Cheha and Dinsho districts, southern highlands of Ethiopia. Environmental Systems Research 7 :17.

Bache, B.W., Williams, E.G., 1971. A phosphate sorption index for soils. European Journal of Soil Science 22:289-301.

Benício, L.P.F., Constantino, V.R.L., Pinto, F.G., Vergütz, L., Tronto, J., Costa, L.M., 2017. Layered double hydroxides: new technology in phosphate fertilizers based on nanostructured materials. ACS Sustainable Chemistry & Engineering 5(1):399-409.

Bhandari, P.S., Neupane, H.S., 2016. Fertilizing Nepalese agriculture: The effects of the distribution system on chemical fertilizer use. Nepalese Journal of Agricultural Sciences 14: 261-272.

Bouyoucos, G. J., 1927. The hydrometer as a new method for the mechanical analysis of soils. Soil Science 23(5):343–353.

Chen, B.L., Sheng, J.D., Jiang, P.A., Liu, Y.G., 2010. Study on characteristics of phosphorus adsorption and desorption of cotton field with different soil textures. Chinese Journal of Soil Science 41(2): 303-307.

Debicka, M., Kocowicz, A., Weber, J., Jamroz, E., 2016. Organic matter effects on phosphorus sorption in sandy soils. Archives of Agronomy and Soil Science 62(6):840-855.

Desta, M.B., 2013. Batch sorption experiments: Langmuir and Freundlich isotherm studies for the adsorption of textile metal ions onto teff straw (Eragrostis tef) agricultural waste. Journal of Thermodynamics Article ID: 375830.

Dieter, D., Elsenbeer, H., Turner, B.L., 2010. Phosphorus fractionation in lowland tropical rainforest soils in central Panama. Catena 82(2): 118-125.

Estefan, E., Sommer, R., Ryan, J., 2013. Methods of soil, plant, and water analysis: A manual for the West Asia and North Africa region. International Center for Agricultural Research in the Dry Areas (ICARDA).

Fang, H., Cui, Z., He, G., Huang, L., Chen, M., 2017. Phosphorus adsorption onto clay minerals and iron oxide with consideration of heterogeneous particle morphology. Science of the Total Environment 605:357-367.

Fanjana, F., Haile, W., Mitike, G., 2017. Phosphorus fractionation and P sorption capacities of Fincha Sugar Estate soils, Western Ethiopia. African Journal of Agricultural Research 12(25): 2131–2139.

Fisher, R.A., 1925. Statistical methods for research workers. Oliver and Boyd, London. 299p.

Fox, R. L., Kamprath, E. J., 1970. Phosphate sorption isotherms for evaluating the phosphate requirements of soils. Soil Science Society of America Journal 34: 902-907.

Freundlich, H., 1926. Colloid and capillary chemistry. Methuen and Co. Ltd., London. 95p.

Gerard-Marchant, P., Hively, W.D., Steenhuis, T.S., 2006. Distributed hydrological modelling of total dissolved phosphorus transport in an agricultural landscape, Part I: Distributed runoff generation. Hydrology and Earth System Sciences 10: 245–261.

Ghodszad, L., Reyhanitabar, A., Maghsoodi, M.R., Lajayer, B.A., Chang, S.X., 2021. Biochar affects the fate of phosphorus in soil and water: A critical review. Chemosphere 283: 131176.

Gupta, P.K., 2009. Soil, plant, water and fertilizer analysis, 2nd ed. Agribios. India. 331p.

Hadgu, F., Gebrekidan, H., Kibret, K., Yitaferu, B., 2014. Study of phosphorus adsorption and its relationship with soil properties, analyzed with Langmuir and Freundlich models. Agriculture, Forestry and Fisheries 3(1): 40-51.

Heidari, S., Reyhanitabar, A., Oustan, S., 2017. Kinetics of phosphorus desorption from calcareous soils using DGT technique. Geoderma 305: 275–280.

Hiradate, S., Uchida, N., 2004. Effects of soil organic matter on pH-dependent phosphate sorption by soils. Soil Science and Plant Nutrition 50(5): 665-675.

Hooda, P.S., Rendell, A.R., Edwards, A.C., Withers, P.J.A., Aitken, M.N., Truesdale, V.W., 2000. Relating soil phosphorus indices to potential phosphorus release to water. Journal of Environmental Quality 29(4):1166–1171.

Huang, P.M., Wang, M.K., 1997. Formation chemistry and selected surface properties of iron oxides. In: Soil and Environment – Soil Processes from Mineral to Landscape Scale, Auerswald, K., Stanjek, H., Bigham, J.M. (Eds.). Advances in Geoecology, Reiskirchen, Germany, pp. 241-270.

Huang, Q., Wang, Z., Wang, D., Wang, C., Ma, M., 2004. Phosphorus sorption capacity of the surface sediment in the Lake Taihu and risk assessment of phosphorus release. Journal of Lake Sciences 16(2):97-104.

Indiati, R., Sequi, P., 2004. Phosphorus intensity-quantity relationships in soils highly contrasting in phosphorus adsorption properties. Communications in Soil Science and Plant Analysis 35(1-2):131-143.

Jackson, M. L., 1973. Soil chemical analysis. Prentice Hall of India Pvt. Ltd., New Delhi.

Jalali, M., Jalali, M., 2016. Relation between various soil phosphorus extraction methods and sorption parameters in calcareous soils with different texture. Science of the Total Environment 566-567: 1080–1093.

Juo, A.R.S., Fox, R.L., 1977. Phosphate sorption characteristics of some benchmark soils of West Africa. Soil Science 124: 370-376.

Karki, R., Talchabhadel, R., Aalto, J., Baidya, S. K., 2016. New climatic classification of Nepal. Theoretical and Applied Climatology 125: 799–808..

Kharel, M., Dahal, B. M., Raut, N., 2022. Good agriculture practices for safe food and sustainable agriculture in Nepal: A review. Journal of Agriculture and Food Research 10: 100447.

Khiari, L., Parent, L. E., Pellerin, A., Alimi, A.R.A., Tremblay, C., Simard, R.R., Fortin, J., 2000. An agri-environmental phosphorus saturation index for acid coarse-textured soils. Journal of Environmental Quality 29(5): 1561–1567.

Kuo, S., 1996. Phosphorus. In: Methods of Soil Analysis: Part 3 Chemical Methods. Sparks, D.L., Page, A.L., Helmke, P.A., Loeppert, R.H., Soltanpour, P.N., Tabatabai, M.A., Johnston, C.T., Sumner, M.E. (Eds.). SSSA Book Series No. 5, SSSA and ASA, Madison, USA. pp. 869–919.

Kuo, S., Jellum, E.J., Pan, W.L., 1988. Influence of phosphate sorption parameters of soils on the desorption of phosphate by various extractants. Soil Science Society of America Journal 52(4): 974-979.

Lair, G.J., Zehetner, F., Khan, Z.H., Gerzabek, M.H., 2009. Phosphorus sorption-desorption in alluvial soils of a young weathering sequence at the Danube River. Geoderma 149: 39–44.

Lamichhane, S., Kumar, L., Adhikari, K., 2021. Updating the national soil map of Nepal through digital soil mapping. Geoderma 394: 115041.

Langmuir, I., 1918. The adsorption of gases on plane surfaces of glass, mica and platinum. Journal of the American Chemical Society 40: 1361-1403.

Levene, H., 1960. Robust tests for equality of variances. In: Contributions to probability and statistics: Essays in honor of Harold Hotelling, Olkin, I. (Ed.). Stanford University Press, pp. 278-292.

Li, M., Hou, Y. L., Zhu, B., 2007. Phosphorus sorption-desorption by purple soils of China in relation to their properties. Australian Journal of Soil Research 45(3): 182–189.

Li, Z., Zhang, R., Liu, C., Zhang, R., Liu, Y., 2019. Phosphorus spatial distribution and pollution risk assessment in agricultural soil around the Danjiangkou Reservoir, China. Science of the Total Environment 699: 134417.

Lindsay, W.L., 1979. Chemical equilibria in soils. John Wiley & Sons, Inc. 449p.

Lindsay, W.L., Norvell, W.A., 1978. Development of a DTPA soil test for zinc, iron, manganese, and copper. Soil Science Society of America Journal 42(3): 421–428.

Liu, W., Liu, G., Li, S., Zhang, Q., 2010. Phosphorus sorption and desorption characteristics of wetland soils from a subtropical reservoir. Marine and Freshwater Research 61(5): 507-512.

Masud, M.M., Moniruzzaman, M., Islam, M.R., Saleque, M.A., 2006. Phosphorus sorption characteristics in some calcareous, non-calcareous and acid piedmont soils of Bangladesh. Bulletin of the Institute of Tropical Agriculture, Kyushu University 29(1): 55-68.

McDonald, G.J., Norton, S.A., Fernandez, I.J., Hoppe, K.M., Dennis, J., Amirbahman, A., 2019. Chemical controls on dissolved phosphorus mobilization in a calcareous agricultural stream during base flow. Science of the Total Environment 660: 876–885.

McDowell, R., Sharpley, A., Withers, P., 2002. Indicator to predict the movement of phosphorus from soil to subsurface flow. Environmental Science & Technology 36(7): 1505-1509.

McLean, E.O., 1965.  Aluminium  In:  Method of soil analysis Part 2 Chemical and microbiological properties. Black, C.A., Evans, D.E., White, J.L., Ensminger, L.E. and Clark, F.E. (Eds.). Agronomy No. 9, American Society of Agronomy, Madison Wisconsin, USA. p. 927-932.

Ministry of Agriculture and Livestock Development (MoALD), 2023. Statistical information on Nepalese agriculture. Singhdurbar, Kathmandu, Nepal.

Ministry of Agriculture and Livestock Development (MoALD), 2024. Statistical Information on Nepalese Agriculture. Singhdurbar, Kathmandu, Nepal.

Ministry of Finance (MoF), 2023. Budget speech of fiscal year 2023/24. Government of Nepal.

Muindi, E.M., Mrema, J.P., Semu, E., Mtakwa, P.W., Gachene, C.K., Njogu, M.K., 2015. Phosphorus adsorption and its relation with soil properties in acid soils of Western Kenya. International Journal of Plant & Soil Science 4(3): 203-211.

Munhoz, R.O., Berton, R.S., Camargo, O.A., 2011. Phosphorus sorption and redistribution on soil solid phase in a Brazilian Haplorthox amended with biosolids. Applied and Environmental Soil Science Article ID 283061.

Olsen, S.R., Cole, C.V., Watanabe, F.S., 1954. Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate. USDA Circular No. 939, US Government Printing Office.

Pal, S.K., 2011. Phosphorus sorption-desorption characteristics of soils under different land use patterns of eastern India. Archives of Agronomy and Soil Science 57(4): 365-376.

Panta, H.K., 2018. Supply chain of subsidized chemical fertilizers in Nepal. Journal of Institute of Agriculture and Animal Science 35(1): 9-20.

Pautler, M.C., Sims, J.T., 2000. Relationships between soil test phosphorus, soluble phosphorus, and phosphorus saturation in Delaware soils. Soil Science Society of America Journal 64(2): 765-773.

Pizzeghello, D., Berti, A., Nardi, S., Morari, F., 2016. Relationship between soil test phosphorus and phosphorus release to solution in three soils after long-term mineral and manure application. Agriculture, Ecosystems & Environment 233: 214–223.

Prasad, J., Mathur, B.S., 1997. Influence of long-term use of fertilizers, manure and lime on phosphate adsorption parameters in acid Alfisols of Ranchi. Journal of the Indian Society of Soil Science 45: 24-27.

Rashmi, I., Parama, V.R.R., Biswas, A., 2016. Phosphate sorption parameters in relation to soil properties in some major agricultural soils of India. SAARC Journal of Agriculture 14(1): 1-9.

Reddy, D.D., Subba Rao, A., Takkar, P.N., 1999. Phosphate sorption behavior of a typic haplustert in relation to long-term use of fertilizer P and manure under soybean-wheat rotation. Journal of the Indian Society of Soil Science 47:425-430.

Roberts, T.L., Johnston, A.E., 2015. Phosphorus use efficiency and management in agriculture. Resources, Conservation and Recycling 105: 275-281.

Rowe, H., Withers, P.A., Baas, P., Chan, N.I., Weintraub, M., 2015. Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy, and water security. Nutrient Cycling in Agroecosystems 104: 393-412.

Roy, A., Pal, S.K., 2018. Effect of aggregation on phosphate sorption-desorption behaviour of soils under various land use patterns of Eastern India. Journal of the Indian Society of Soil Science 66(2): 136-143.

Samadi, A., 2006. Phosphorus sorption characteristics in relation to soil properties in some calcareous soils of western Azarbaijan province. Journal of Agricultural Science and Technology 8: 251-264.

Sanchez, P.A., Uehara, G., 1980. Management considerations for acid soils with high phosphorus fixation capacity. In. The role of phosphorus in agriculture. Khasawneh, F.E., Sample, E.C., Kamprath, E.J. (Eds.). ASA, CSSA, SSSA, Madison, Wisconsin, USA. pp. 471-514.

Sertsu, S., Ali, A., 1983. Phosphorous sorption characteristics of some Ethiopia soils. Ethiopia Journal of agricultural Science 5: 1-12.

Sims, J.T., 2009. Phosphorus sorption index. In: Methods of phosphorus analysis for soils, sediments, residuals, and waters. Kovar J.L., Pierzynski, G.M. (Eds.). 2nd ed., Southern Cooperative Series Bulletin No. 408, Virginia Tech University.

Singh, B., Gilkes, R.J., 1991. Phosphorus sorption in relation to soil properties for the major soil types of south-west Australia. Australian Journal of Soil Research 29: 602-618.

Singh, V., Dhillon, N. S., Brar, B. S., 2006. Influence of long-term use of fertilizers and farmyard manure on the adsorption-desorption behaviour and bioavailability of phosphorus in soils. Nutrient Cycling in Agroecosystems 75: 67-78.

Sparks, D.L., 2003. Environmental soil chemistry (2nd ed.). Academic Press.

Sui, Y., Thompson, M.L., 2000. Phosphorus sorption, desorption and buffering capacity in a biosolids amended mollisol. Soil Science Society of America Journal 64: 164-169.

Temkin, M.I., Pyzhev, V., 1940. Kinetic of ammonia synthesis on promoted iron catalysts. Acta Physiochimica 12: 327-356.

Vaidya, S. N., Sah, K., 2015. Preparation of a database and soil map of Nepal using WRB 2010 classification system. In: Proceedings of the Second National Soil Fertility Research Workshop. Karki, K. B., Tripathi, B. P., Manandhar, R., Adhikary, B. P (Eds.). Nepal Agricultural Research Council, Nepal. pp. 393-402.

Walkley, A., Black, I. A., 1934. An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Science 37(1): 29-38.

Wang, B., Sun, J.S., Liu, H., Ma, Y.B., 2017. The characteristics of phosphorus adsorption and desorption in gray desert soil of Xinjiang, China. IOP Conference Series: Earth and Environmental Science 77: 012020.

Wang, L., Liang, T., 2014. Effects of exogenous rare earth elements on phosphorus adsorption and desorption in different types of soils. Chemosphere 103: 148-155.

Welch, B.L., 1951. On the comparison of several mean values: An alternative approach. Biometrika 38(3-4): 330-336.

Wogi, L., Msaky, J., Rwehumbiza, F., Kibret, K., 2015. Phosphorus adsorption isotherm: A key aspect for soil phosphorus fertility management. American Journal of Experimental Agriculture 6(2): 74-82.

Xiong, J.B., Mahmood, Q., 2010. Adsorptive removal of phosphate from aqueous media by peat. Desalination 259(1): 59–64.

Yan, X., Wang, D., Zhang, H., Zhang, G., Wei, Z., 2013. Organic amendments affect phosphorus sorption characteristics in a paddy soil. Agriculture, Ecosystems & Environment 175: 47-53.

Yang, X., Chen, X., Yang, X., 2019. Effect of organic matter on phosphorus adsorption and desorption in a black soil from Northeast China. Soil and Tillage Research 187: 85–91.

Yousuf, T., Hossain, M.E., Afsar, M.Z., Osman, K.T., 2019. Phosphate sorption indices as affected by the calcareousness of soils. Dhaka University Journal of Biological Science 28(1): 93-110.

Zhang, H., Schroder, J.L., Fuhrman, J.K., Basta, N.T., Storm, D.E., Payton, M.E., 2005. Path and multiple regression analyses of phosphorus sorption capacity. Soil Science Society of America Journal 69: 96-106.

Zhang, Y., Huang, S., Guo, D., Zhang, S., Song, X., Yue, K., Zhang, K., Bao, D., 2019. Phosphorus adsorption and desorption characteristics of different textural fluvo-aquic soils under long-term fertilization. Journal of Soils and Sediments 19: 1306-1318.

Zhang, Y., Li, Y., Wang, S., Umbreen, D., Zhou, C., 2021. Soil phosphorus fractionation and its association with soil phosphate-solubilizing bacteria in a chronosequence of vegetation restoration. Ecological Engineering 164: 106208.

Zhu, J., Li, M., Whelan, M., 2018. Phosphorus activators contribute to legacy phosphorus availability in agricultural soils: A review. Science of the Total Environment 612: 522–537.