Declining soil fertility is a major constraint to potato farming, the second most important food crop in Kenya. The objective of the study was to determine the effect of different rates of biochar and inorganic fertilizer on some soil properties; soil pH, soil phosphomonoesterases, inorganic nitrogen and extractable phosphorus. The study was conducted for two seasons (short and long rains) at two locations (Egerton University agricultural field and farmer’s field in Mau Narok) using a split-plot design in a randomized complete block (RCBD) arrangement with variety as the main plot and soil amendments as the subplot. Biochar and Diammonium Phosphate (DAP) at 0, 5, and 10 t ⋅ ha −1 and 0, 250, and 500 kg ⋅ ha −1 respectively, were applied, resulting in nine treatment combinations. Two potato varieties ( Shangi and Destiny ) were used in the study. A combination of 5 t ⋅ ha −1 biochar and 500 kg ⋅ ha −1 DAP and sole application of biochar at 5 t ⋅ ha −1 resulted in an increase of 1.25, 2.54 units in soil pH in two seasons, respectively. Similarly, a combination of 5 t ⋅ ha −1 biochar and 250 kg ⋅ ha −1 DAP increased soil available phosphorus by 105 units from 30.7 mg ⋅ kg −1 to 136 mg ⋅ kg −1 . The application rate of 5 t ⋅ ha −1 biochar with 250 or 500 kg ⋅ ha −1 DAP significantly increased soil nitrate by 102.11 and 116.14 units, respectively. Soils amended with biochar at 5 t ⋅ ha −1 combined with 500 kg ⋅ ha −1 DAP, 10 t ⋅ ha −1 of biochar combined with either 250 kg or 500 kg of DAP gave the highest alkaline enzymes (mM pNP × kg −1 × h −1 ). However, the highest acid soil phosphomonoesterases were obtained under the sole application of DAP at 500 ha −1 . Thus, using biochar with chemical fertilizer seems a plausible option to ameliorate the declining nutrient base of farmland in Kenya, which could sustainably support potato growth.
Stewart, Z.P., Pierzynski, G.M., Middendorf, B.J. and Prasad, P.V.V. (2020) Approaches to Improve Soil Fertility in Sub-Saharan Africa. Journal of Experimental Botany, 71, 632-641. https://doi.org/10.1093/jxb/erz446
Wawire, A.W., Csorba, á., Tóth, J.A., Michéli, E., Szalai, M., Mutuma, E., et al. (2021) Soil Fertility Management among Smallholder Farmers in Mount Kenya East Region. Heliyon, 7, e06488. https://doi.org/10.1016/j.heliyon.2021.e06488
Tully, K., Sullivan, C., Weil, R. and Sanchez, P. (2015) The State of Soil Degradation in Sub-Saharan Africa: Baselines, Trajectories and Solutions. Sustainability, 7, 6523-6252. https://doi.org/10.3390/su7066523
Bado, V.B. and Bationo, A. (2018) Chapter One-Integrated Management of Soil Fertility and Land Resources in Sub-Saharan Africa: Involving Local Communities. In: Sparks, D.L., Eds., Advances in Agronomy, Academic Press, Cambridge, 1-33. https://doi.org/10.1016/bs.agron.2018.02.001 https://www.sciencedirect.com/science/article/pii/S006521131830018X
Nair, K.P. (2019) Soil Fertility and Nutrient Management. In: Nair, K.P., Ed., Intelligent Soil Management for Sustainable Agriculture: The Nutrient Buffer Power Concept, Springer International Publishing, Cham, 165-189. https://doi.org/10.1007/978-3-030-15530-8_17
Ma, H., Egamberdieva, D., Wirth, S., Li, Q., Omari, R.A., Hou, M., et al. (2019) Effect of Biochar and Irrigation on the Interrelationships among Soybean Growth, Root Nodulation, Plant P Uptake, and Soil Nutrients in a Sandy Field. Sustainability, 11, Article 6542. https://doi.org/10.3390/su11236542
Beesigamukama, D., Mochoge, B., Korir, N., Musyoka, M.W., Fiaboe, K.K.M., Nakimbugwe, D., et al. (2020) Nitrogen Fertilizer Equivalence of Black Soldier Fly Frass Fertilizer and Synchrony of Nitrogen Mineralization for Maize Production. Agronomy, 10, Article 1395. https://doi.org/10.3390/agronomy10091395
MacCarthy, D.S., Darko, E., Nartey, E.K., Adiku, S.G.K. and Tettey, A. (2020) Integrating Biochar and Inorganic Fertilizer Improves Productivity and Profitability of Irrigated Rice in Ghana, West Africa. Agronomy, 10, Article 904. https://doi.org/10.3390/agronomy10060904
Frene, J.P., Frazier, M., Gardner, T.G. and Senwo, Z.N. (2022) Validation of Soil Enzyme Activity Assay for a Biogeochemical Cycling Index in Biochar Amended Soils. Advances in Enzyme Research, 10, 61-73. https://doi.org/10.4236/aer.2022.103004
Liu, W.Y., Yan, X., Li, J., Jiao, N. and Hu, S. (2017) Biochar Amendments Increase the Yield Advantage of Legume-Based Intercropping Systems over Monoculture. Agriculture, Ecosystems & Environment, 237, 16-23. https://doi.org/10.1016/j.agee.2016.12.026
Shikorire, T.J., Asudi, G.O., Ng’ang’a, M.M., Kirubi, G. and Hassanali, A. (2019) Analysis of Emission Profiles from Charcoal Produced from Selected Tree Species by Different Pyrolysis Methods. International Journal of Environmental Science and Technology, 16, 5995-6004. https://doi.org/10.1007/s13762-019-02220-x
Zhang, S.Y, Wu, Z., Yan, X., Gunina, A., Kuzyakov, Y., et al. (2020) Effects of Six-Year Biochar Amendment on Soil Aggregation, Crop Growth and Nitrogen and Phosphorus Use Efficiencies in a Rice-Wheat Rotation. Journal of Cleaner Production, 242, Article ID: 118435. https://doi.org/10.1016/j.jclepro.2019.118435
Tian, X., Li, Z., Wang, Y., Li, B. and Wang, L. (2021) Evaluation on Soil Fertility Quality under Biochar Combined with Nitrogen Reduction. Scientific Reports, 11, Article No. 13792. https://doi.org/10.1038/s41598-021-93200-0
Aneseyee, A.B. and Wolde, T. (2021) Effect of Biochar and Inorganic Fertilizer on the Soil Properties and Growth and Yield of Onion (Allium cepa) in Tropical Ethiopia. The Scientific World Journal, 2021, e5582697.
Yu, L., Lu, X., He, Y., Brookes, P.C., Liao, H. and Xu, J. (2017) Combined Biochar and Nitrogen Fertilizer Reduces Soil Acidity and Promotes Nutrient Use Efficiency by Soybean Crop. Journal of Soils and Sediments, 17, 599-610. https://doi.org/10.1007/s11368-016-1447-9
Jia, Y., Hu, Z., Ba, Y. and Qi, W. (2021) Application of Biochar-Coated Urea Controlled Loss of Fertilizer Nitrogen and Increased Nitrogen Use Efficiency. Chemical and Biological Technologies in Agriculture, 8, Article No. 3. https://doi.org/10.1186/s40538-020-00205-4
Obia, A., Mulder, J., Hale, S.E., Nurida, N.L. and Cornelissen, G. (2018) The Potential of Biochar in Improving Drainage, Aeration and Maize Yields in Heavy Clay Soils. PLOS ONE, 13, e0196794. https://doi.org/10.1371/journal.pone.0196794 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5947891/
Qian, L., Chen, L., Joseph, S., Pan, G., Li, L., Zheng, J., et al. (2014) Biochar Compound Fertilizer as an Option to Reach High Productivity but Low Carbon Intensity in Rice Agriculture of China. Carbon Management, 5, 145-154. https://doi.org/10.1080/17583004.2014.912866
Sika, M.P. and Hardie, A.G. (2014) Effect of Pine Wood Biochar on Ammonium Nitrate Leaching and Availability in a South African Sandy Soil. European Journal of Soil Science, 65, 113-119. https://doi.org/10.1111/ejss.12082
Yang, F., Sui, L., Tang, C., Li, J., Cheng, K. and Xue, Q. (2021) Sustainable Advances on Phosphorus Utilization in Soil via Addition of Biochar and Humic Substances. Science of the Total Environment, 768, Article ID: 145106. https://doi.org/10.1016/j.scitotenv.2021.145106
Bai, S.H., Reverchon, F., Xu, C.Y., Xu, Z., Blumfield, T.J., Zhao, H., et al. (2015) Wood Biochar Increases Nitrogen Retention in Field Settings Mainly through Abiotic Processes. Soil Biology and Biochemistry, 90, 232-240. https://doi.org/10.1016/j.soilbio.2015.08.007
Xu, C.Y., Hosseini-Bai, S., Hao, Y., Rachaputi, R.C.N., Wang, H., Xu, Z., et al. (2015) Effect of Biochar Amendment on Yield and Photosynthesis of Peanut on Two Types of Soils. Environmental Science and Pollution Research, 22, 6112-6125. https://doi.org/10.1007/s11356-014-3820-9
Mensah, A.K. and Frimpong, K.A. (2018) Biochar and/or Compost Applications Improve Soil Properties, Growth and Yield of Maize Grown in Acidic Rainforest and Coastal Savannah Soils in Ghana. International Journal of Agronomy, 2018, Article ID: 6837404. https://doi.org/10.1155/2018/6837404
Jin, Y., Liang, X., He, M., Liu, Y., Tian, G. and Shi, J. (2016) Manure Biochar Influence upon Soil Properties, Phosphorus Distribution and Phosphatase Activities: A Microcosm Incubation Study. Chemosphere, 142, 128-135. https://doi.org/10.1016/j.chemosphere.2015.07.015
Faloye, O.T., Alatise, M.O., Ajayi, A.E. and Ewulo, B.S. (2017) Synergistic Effects of Biochar and Inorganic Fertiliser on Maize (Zea mays) Yield in an Alfisol under Drip Irrigation. Soil and Tillage Research, 174, 214-220. https://doi.org/10.1016/j.still.2017.07.013
Margalef, O., Sardans, J., Fernández-Martínez, M., Molowny-Horas, R., Janssens, I.A., Ciais, P., et al. (2017) Global Patterns of Phosphatase Activity in Natural Soils. Scientific Reports, 7, Article No. 1337. https://doi.org/10.1038/s41598-017-01418-8
Yadav, V., Karak, T., Singh, S., Singh, A.K. and Khare, P. (2019) Benefits of Biochar over other Organic Amendments: Responses for Plant Productivity (Pelargonium graveolens L.) and Nitrogen and Phosphorus Losses. Industrial Crops and Products, 131, 96-105. https://doi.org/10.1016/j.indcrop.2019.01.045
Coomes, O.T. and Miltner, B.C. (2017) Indigenous Charcoal and Biochar Production: Potential for Soil Improvement under Shifting Cultivation Systems. Land Degradation & Development, 28, 811-821. https://doi.org/10.1002/ldr.2500
Cornelissen, G., Pandit, N.R., Taylor, P., Pandit, B.H., Sparrevik, M. and Schmidt, H.P. (2016) Emissions and Char Quality of Flame-Curtain “Kon Tiki” Kilns for Farmer-Scale Charcoal/Biochar Production. PLOS ONE, 11, e0154617. https://doi.org/10.1371/journal.pone.0154617
Li, Y., Hu, S., Chen, J., Müller, K., Li, Y., Fu, W., et al. (2018) Effects of Biochar Application in Forest Ecosystems on Soil Properties and Greenhouse Gas Emissions: A Review. Journal of Soils and Sediments, 18, 546-563. https://doi.org/10.1007/s11368-017-1906-y
Jaetzold, R., Schmidt, H., Hornetz, B. and Shisanya, C. (2007) Farm Management Handbook of Kenya: Subpart B1a Southern Rift Valley Province. Ministry of Agriculture, Kenya, in Cooperation with the German Agency for Technical Cooperation (GTZ).
Okalebo, J.R., Gathua, K.W. and Woomer, P.L. (2002) Laboratory Methods of Soil and Plant Analysis: A Working Manual. Vol. 2, Second Edition, Sacred Africa, Nairobi, 131.
Hellmuth, H. (2019) Effects of Potato-Legume Intercropping and Variety on Potato Performance in Different. Master’s Thesis, University of California, Davis.
Mumia, B, Muthomi J.W., Narla, R.D., Nyongesa, M.W. and Olubayo, F.M. (2018) Seed Potato Production Practices and Quality of Farm Saved Seed Potato in Kiambu and Nyandarua Counties in Kenya. WJAR, 6, 20-30. https://doi.org/10.12691/wjar-6-1-5
Major, J. (2009) A Guide to Conducting Biochar Trials. International Biochar Initiative, NY, 32.
Bottomley, P.J., Angle, J.S. and Weaver, R.W. (2020) Methods of Soil Analysis, Part 2: Microbiological and Biochemical Properties. John Wiley & Sons, Hoboken, 1152.
Paz-Ferreiro, J., Trasar-Cepeda, C., Leirós, M.C., Seoane, S. and Gil-Sotres, F. (2009) Biochemical Properties in Managed Grassland Soils in a Temperate Humid Zone: Modifications of Soil Quality as a Consequence of Intensive Grassland Use. Biology and Fertility of Soils, 45, 711-722. https://doi.org/10.1007/s00374-009-0382-y
Tabatabai, M.A. and Bremner, J.M. (1969) Use of p-Nitrophenyl Phosphate for Assay of Soil Phosphatase Activity. Soil Biology and Biochemistry, 1, 301-307. https://doi.org/10.1016/0038-0717(69)90012-1
Kizito, S., Luo, H., Lu, J., Bah, H., Dong, R. and Wu, S. (2019) Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand. Sustainability, 11, Article 3211. https://doi.org/10.3390/su11113211
Neina, D. (2019) The Role of Soil pH in Plant Nutrition and Soil Remediation. Applied and Environmental Soil Science, 2019, e5794869. https://doi.org/10.1155/2019/5794869
Muthoni, J. and Nyamongo, D.O. (2009) A Review of Constraints to Ware Irish Potatoes Production in Kenya. Journal of Horticulture and Forestry, 1, 098-102.
Bista, P., Ghimire, R., Machado, S. and Pritchett, L. (2019) Biochar Effects on Soil Properties and Wheat Biomass vary with Fertility Management. Agronomy, 9, Article 623. https://doi.org/10.3390/agronomy9100623
Nigussie, A., Kissi, E., Misganaw, M. and Ambaw, G. (2012) Effect of Biochar Application on Soil Properties and Nutrient Uptake of Lettuces (Lactuca sativa) Grown in Chromium Polluted Soils. American-Eurasian Journal of Agricultural & Environmental Sciences, 12, 369-376.
Rees, F., Simonnot, M.O. and Morel, J.L. (2014) Short-Term Effects of Biochar on Soil Heavy Metal Mobility Are Controlled by Intra-Particle Diffusion and Soil pH Increase. European Journal of Soil Science, 65, 149-161. https://doi.org/10.1111/ejss.12107
Madiba, O.F., Solaiman, Z.M., Carson, J.K. and Murphy, D.V. (2016) Biochar Increases Availability and Uptake of Phosphorus to Wheat under Leaching Conditions. Biology and Fertility of Soils, 52, 439-446. https://doi.org/10.1007/s00374-016-1099-3
Meng, C., Tian, D., Zeng, H., Li, Z., Yi, C. and Niu, S. (2019) Global Soil Acidification Impacts on Belowground Processes. Environmental Research Letters, 14, Article ID: 074003. https://doi.org/10.1088/1748-9326/ab239c
Wang, X., Tang, C., Mahony, S., Baldock, J.A. and Butterly, C.R. (2015) Factors Affecting the Measurement of Soil pH Buffer Capacity: Approaches to Optimize the Methods. European Journal of Soil Science, 66, 53-64. https://doi.org/10.1111/ejss.12195
Ezike, O.B. (2016) Impact of Biochar, Cattle Manure and Mineral Fertilizer on Soil Properties and Grain Yield of Maize (Zea mays L.) in the Guinea Savannah Zone of Ghana. Master’s Thesis, Kwame Nkrumah University of Science and Technology, Kumasi Ghana.
Prommer, J., Wanek, W., Hofhansl, F., Trojan, D., Offre, P., Urich, T., et al. (2014) Biochar Decelerates Soil Organic Nitrogen Cycling but Stimulates Soil Nitrification in a Temperate Arable Field Trial. PLOS ONE, 9, e86388. https://doi.org/10.1371/journal.pone.0086388
Sarfraz, R., Shakoor, A., Abdullah, M., Arooj, A., Hussain, A. and Xing, S. (2017) Impact of Integrated Application of Biochar and Nitrogen Fertilizers on Maize Growth and Nitrogen Recovery in Alkaline Calcareous Soil. Soil Science and Plant Nutrition, 63, 488-498. https://doi.org/10.1080/00380768.2017.1376225
Zhang, M., Riaz, M., Zhang, L., El-desouki, Z. and Jiang, C. (2019) Biochar Induces Changes to Basic Soil Properties and Bacterial Communities of Different Soils to Varying Degrees at 25 mm Rainfall: More Effective on Acidic Soils. Frontiers in Microbiology, 10, Article 1321. https://doi.org/10.3389/fmicb.2019.01321 https://www.frontiersin.org/article/10.3389/fmicb.2019.01321
Cheng, C.H., Lehmann, J., Thies, J.E., Burton, S.D. and Engelhard, M.H. (2006) Oxidation of Black Carbon by Biotic and Abiotic Processes. Organic Geochemistry, 37, 1482-1488. https://doi.org/10.1016/j.orggeochem.2006.06.022
Yang, Y., Ma, S., Zhao, Y., Jing, M., Xu, Y. and Chen, J. (2015) A Field Experiment on Enhancement of Crop Yield by Rice Straw and Corn Stalk-Derived Biochar in Northern China. Sustainability, 7, 13713-13725. https://doi.org/10.3390/su71013713
Kaboneka, S., Ong’or, B., Chantal, K., Nsavyimana, G., Donatien, B. and Népomuscène, N. (2019) Effects of Urea and Di-Ammonium Phosphate Application on Acidification of Three Burundi Representative Soils. International Journal of Advances in Scientific Research and Engineering, 5, 183-191. https://doi.org/10.31695/IJASRE.2019.33474
Chan, K.Y., Van Zwieten, L., Meszaros, I., Downie, A. and Joseph, S. (2007) Agronomic Values of Greenwaste Biochar as a Soil Amendment. Soil Research, 45, 629-634.
Tang, X., Bernard, L., Brauman, A., Daufresne, T., Deleporte, P., Desclaux, D., et al. (2014) Increase in Microbial Biomass and Phosphorus Availability in the Rhizosphere of Intercropped Cereal and Legumes under Field Conditions. Soil Biology and Biochemistry, 75, 86-93. https://doi.org/10.1016/j.soilbio.2014.04.001
Adetunji, A.T., Lewu, F.B., Mulidzi, R. and Ncube, B. (2017) The Biological Activities of β-Glucosidase, Phosphatase and Urease as Soil Quality Indicators: A Review. Journal of Soil Science and Plant Nutrition, 17, 794-807. https://doi.org/10.4067/S0718-95162017000300018
Rejsek, K., Vranova, V., Pavelka, M. and Formanek, P. (2012) Acid Phosphomonoesterase (E.C. 3.1.3.2) Location in Soil. Journal of Plant Nutrition and Soil Science, 175, 196-211. https://doi.org/10.1002/jpln.201000139
Antonious, G.F., Turley, E.T. and Dawood, M.H. (2020) Monitoring Soil Enzymes Activity before and after Animal Manure Application. Agriculture, 10, Article 166. https://doi.org/10.3390/agriculture10050166
Maria Mihaela, M., Badulescu, L. and Israel-Roming, F. (2018) Effect of Pesticides on Enzymatic Activity in Soil. Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Animal Science and Biotechnologies, 75, 80-84. https://doi.org/10.15835/buasvmcn-asb:2017.0040
Riah, W., Laval, K., Laroche-Ajzenberg, E., Mougin, C., Latour, X. and Trinsoutrot-Gattin, I. (2014) Effects of Pesticides on Soil Enzymes: A Review. Environmental Chemistry Letters, 12, 257-273. https://doi.org/10.1007/s10311-014-0458-2
Bronson, K., Schepers, J.S. and Raun, W. (2008) Forms of Inorganic Nitrogen in Soil. In: Schepers, J.S. and Raun, W.R., Eds., Nitrogen in Agricultural Systems, John Wiley & Sons, Hoboken, pp. 33-38.
Carlisle, E., Myers, S.S., Raboy, V. and Bloom, A.J. (2012) The Effects of Inorganic Nitrogen form and CO2 Concentration on Wheat Yield and Nutrient Accumulation and Distribution. Frontiers in Plant Science, 3, Article 195. https://doi.org/10.3389/fpls.2012.00195 https://www.frontiersin.org/articles/10.3389/fpls.2012.00195/full
Zhang, P., Dumroese, R.K. and Pinto, J.R. (2019) Organic or Inorganic Nitrogen and Rhizobia Inoculation Provide Synergistic Growth Response of a Leguminous Forb and Tree. Frontiers in Plant Science, 10, Artticle 1308. https://doi.org/10.3389/fpls.2019.01308 https://www.frontiersin.org/article/10.3389/fpls.2019.01308
Nguyen, T.T.N., Xu, C.Y., Tahmasbian, I., Che, R., Xu, Z., Zhou, X., et al. (2017) Effects of Biochar on Soil Available Inorganic Nitrogen: A Review and Meta-Analysis. Geoderma, 288, 79-96. https://doi.org/10.1016/j.geoderma.2016.11.004
Huang, L.Q., Fu, C., Li, T.Z., Yan, B., Wu, Y., Zhang, L., et al. (2020) Advances in Research on Effects of Biochar on Soil Nitrogen and Phosphorus. IOP Conference Series: Earth and Environmental Science, 424, Article ID: 012015. https://doi.org/10.1088/1755-1315/424/1/012015
Zhang, L., Jing, Y., Chen, C., Xiang, Y., Rezaei Rashti, M., Li, Y., et al. (2021) Effects of Biochar Application on Soil Nitrogen Transformation, Microbial Functional Genes, Enzyme Activity and Plant Nitrogen Uptake: A Meta-Analysis of Field Studies. GCB Bioenergy, 13, 1859-1873. https://doi.org/10.1111/gcbb.12898
Huang, M., Zhang, Z., Zhai, Y., Lu, P. and Zhu, C. (2019) Effect of Straw Biochar on Soil Properties and Wheat Production under Saline Water Irrigation. Agronomy, 9, Article 457. https://doi.org/10.3390/agronomy9080457
Adekiya, A.O., Agbede, T.M., Olayanju, A., Ejue, W.S., Adekanye, T.A., Adenusi, T.T., et al. (2020) Effect of Biochar on Soil Properties, Soil Loss, and Cocoyam Yield on a Tropical Sandy Loam Alfisol. The Scientific World Journal, 2020, Article ID: 9391630. https://doi.org/10.1155/2020/9391630
Lehmann, J. and Rondon, M. (2006) Bio-Char Soil Management on Highly Weathered Soils in the Humid Tropics. In: Biological Approaches to Sustainable Soil Systems, CRC Press, New York.
Kristin, M. (2011) Biochar Amendments to Forest Soils: Effects on Soil Properties and Tree Growth. Master’s Thesis, University of Idaho, Moscow.
Johan, P.D., Ahmed, O., Omar, L. and Hasbullah, A. (2021) Phosphorus Transformation in Soils Following Co-Application of Charcoal and Wood Ash. Agronomy, 11, Article 2010. https://doi.org/10.3390/agronomy11102010
Bayu, D., Dejene, A., Alemayehu, R. and Gezahegn, B. (2017) Improving Available Phosphorus in Acidic Soil Using Biochar. Journal of Soil Science and Environmental Management, 8, 87-94. https://doi.org/10.5897/JSSEM2015.0540
Farooque, A.A., Zaman, Q., Abbas, F., Hammad, H.M., Acharya, B. and Easu, T. (2020) How Can Potatoes Be Smartly Cultivated with Biochar as a Soil Nutrient Amendment Technique in Atlantic Canada? Arabian Journal of Geosciences, 13, Article No. 336. https://doi.org/10.1007/s12517-020-05337-3
Puehringer, H. (2016) Effects of Different Biochar Application Rates on Soil Fertility and Soil Water Retention in On-Farm Experiments on Smallholder Farms in Kenya. SLU, Dept. of Soil and Environment, Uppsala. https://stud.epsilon.slu.se/8955/
Rawat, J., Saxena, J. and Sanwal, P. (2019) Biochar: A Sustainable Approach for Improving Plant Growth and Soil Properties. Biochar—An Imperative Amendment for Soil and the Environment, 1-17. https://doi.org/10.5772/intechopen.82151 https://www.intechopen.com/chapters/65070