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Assessing the synergistic impacts of poultry manure and biochar on nutrient-depleted sand and sandy loam soil properties and sweet potato growth and yield

Published online by Cambridge University Press:  28 November 2022

Taiwo Michael Agbede*
Affiliation:
Department of Agronomy, Adekunle Ajasin University, P.M.B. 001, Akungba-Akoko, Ondo State, Nigeria
Adefemi Oyewumi
Affiliation:
Department of Agricultural Technology, Rufus Giwa Polytechnic, P.M.B. 1019, Owo, Ondo State, Nigeria
Aruna Olasekan Adekiya
Affiliation:
Agriculture Program, College of Agriculture, Engineering and Science, Bowen University, Iwo, Osun State, Nigeria
Ojo Timothy Vincent Adebiyi
Affiliation:
Crop and Soil Sciences Programme, College of Agricultural Sciences, Landmark University, P.M.B. 1001, Omu-Aran, Kwara State, Nigeria
Thomas Adebayo Abisuwa
Affiliation:
Department of Agricultural and Bio-Environmental Engineering Technology, Rufus Giwa Polytechnic, P.M.B. 1019, Owo, Ondo State, Nigeria
Justin Orimisan Ijigbade
Affiliation:
Department of Agricultural Technology, Rufus Giwa Polytechnic, P.M.B. 1019, Owo, Ondo State, Nigeria
Catherine Temitope Ogundipe
Affiliation:
Department of Languages, Rufus Giwa Polytechnic, P.M.B. 1019, Owo, Ondo State, Nigeria
Segun O. Oladele
Affiliation:
Department of Agronomy, Adekunle Ajasin University, P.M.B. 001, Akungba-Akoko, Ondo State, Nigeria
Opeyemi Olaogun
Affiliation:
Department of Agronomy, Adekunle Ajasin University, P.M.B. 001, Akungba-Akoko, Ondo State, Nigeria
Ehiokhilen Kevin Eifediyi
Affiliation:
Department of Agronomy, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Ondo State, Nigeria
*
*Corresponding author. Email: agbedetaiwomichael@yahoo.com

Summary

Poultry manure (PM) has been shown to boost crop productivity. However, little is known about its favorable interactions with wood biochar (B) on sweet potato (Ipomoea batatas L.) growth and yield, and soil qualities. Hence, a 2-year field trial was conducted in the southwest Nigeria at two locations (Owo – site A and Obasooto – site B) to co-apply PM and wood B as soil amendments to boost sweet potato productivity and soil quality. The experiment consisted of a 3 × 4 factorial layout with three replications. PM and B significantly reduced soil bulk density and improved porosity and moisture content with their rate of application when compared to the control. As PM and B applications increased from 0 to 10.0 t ha−1 and 0 to 30.0 t ha−1, respectively, soil chemical properties and sweet potato growth and tuber yield increased. Co-application of 10.0 t ha−1 PM and 30.0 t ha−1 B increased tuber yield by 220% compared to treatments without PM or B. Significant synergistic interactions between PM and B were observed for all parameters. In comparison with other treatments, co-applying PM and B to sweet potato soils is a viable sustainable option for increasing sweet potato productivity and soil sustainability.

Type
Research Article
Copyright
© The Author(s), 2022. Published by Cambridge University Press

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References

Adekiya, A.O. and Agbede, T.M. (2017). Effect of methods and time of poultry manure application on soil and leaf nutrient concentrations, growth and fruit yield of tomato (Lycopersicon esculentum Mill). Journal of the Saudi Society of Agricultural Sciences 16, 383388.CrossRefGoogle Scholar
Adekiya, A.O., Agbede, T.M., Aboyeji, C.M., Dunsin, O. and Simeon, V.T. (2019). Effects of biochar and poultry manure on soil characteristics and the yield of radish. Scientia Horticulturae 243, 457463.CrossRefGoogle Scholar
Adeyemo, A.J., Akingbola, O.O. and Ojeniyi, S.O. (2019). Effects of poultry manure on soil infiltration, organic matter contents and maize performance on two contrasting degraded alfisols in southwestern Nigeria. International Journal of Recycling of Organic Waste in Agriculture 8, 7380.CrossRefGoogle Scholar
Agbede, T.M. (2010). Tillage and fertilizer effects on some soil properties, leaf nutrient concentrations, growth and sweet potato yield on an Alfisol in southwestern Nigeria. Soil and Tillage Research 110, 2532.CrossRefGoogle Scholar
Agbede, TM (2019) Influence of five years of tillage and poultry manure application on soil properties and ginger (Ziginber officinale Roscoe) productivity. Journal of Crop Science and Biotechnology 22, 9199.CrossRefGoogle Scholar
Agbede, T.M., Adekiya, A.O. and Eifediyi, E.K. (2017). Impact of poultry manure and NPK fertilizer on soil physical properties and growth and yield of carrot. Journal of Horticultural Research 25, 8188.CrossRefGoogle Scholar
Agbede, T.M. and Ojeniyi, S.O. (2009). Tillage and poultry manure effects on soil fertility and sorghum yield in southwestern Nigeria. Soil and Tillage Research 104, 7481.CrossRefGoogle Scholar
Agegnehu, G., Nelson, P.N. and Bird, M.I. (2016) The effects of biochar, compost and their mixture and nitrogen fertilizer on yield and nitrogen use efficiency of barley grown on a Nitisol in the highlands of Ethiopia. Science of the Total Environment 569–570, 869879.CrossRefGoogle ScholarPubMed
Agegnehu, G., Srivastava, A.K. and Bird, M.I. (2017). The role of biochar and biochar-compost in improving soil quality and crop performance: A review. Applied Soil Ecology 119, 156170.Google Scholar
Ahmad, A.A., Radovich, T.J.K., Nguyen, H.V., Uyeda, J., Arakaki, A., Cadby, J., Paull, R., Sugano, J. and Teves, G. (2016). Use of organic fertilizers to enhance soil fertility, plant growth, and yield in a tropical environment. In Larramendy, M.L. and Soloneski, S. (eds), Organic Fertilizers-From Basic Concepts to Applied Outcomes. Rijeka, Croatia: Intech, pp. 85108.Google Scholar
Alburquerque, J.A., Calero, J.M., Barrón, V., Torrent, J., del Campillo, M.C., Gallardo, A. and Villar, R. (2014). Effects of biochars produced from different feedstocks on soil properties and sunflower growth. Journal of Plant Nutrition and Soil Science 177, 1625.Google Scholar
Antonious, G.F. (2016). Soil amendments for agricultural production. In Larramendy, M.L. and Soloneski, S. (eds), Organic Fertilizers-From Basic Concepts to Applied Outcomes. Rijeka, Croatia: Intech.Google Scholar
ASTM D1762-84. (2021). Standard test method for chemical analysis of wood charcoal. Conshohocken, PA: American Society for Testing and Materials.Google Scholar
Basso, A.S., Miguez, F.E., Laird, D.A., Horton, R. and Westgate, M. (2013). Assessing potential of biochar for increasing water-holding capacity of sandy soils. Global Change and Biological Bioenergy 5, 132143.CrossRefGoogle Scholar
Berek, A.K., Hue, N.V., Radovich, T.J.K. and Ahmad, A.A. (2018) Biochars improve nutrient phyto- availability of Hawai’i’s highly weathered soils. Agronomy 8, 203.CrossRefGoogle Scholar
Blanco-Canqui, H (2017) Biochar and soil physical properties. Soil Science Society of America Journal 81, 687711.CrossRefGoogle Scholar
Bremner, J.M. (1996). Nitrogen-total. In Sparks, D.L. (ed), Methods of Soil Analysis, Part 3. Chemical Methods, second ed., SSA Book Series No. 5, ASA and SSSA, Madison, WI, USA, pp. 10851121.Google Scholar
Cantrell, K.B., Hunt, P.G., Uchimiya, M., Novak, J.M. and Ro, S.K. (2012) Impact of pyrolysis temperature and manure source on physicochemical characteristics of biochar. Bioresource Technology 107, 419428.CrossRefGoogle ScholarPubMed
Carter, M.R. and Gregorich, E.G. (2007). Soil Sampling and Methods of Analysis. 2 nd Edition. Boca Raton, Florida: Canadian Society of Soil Science, CRC Press, Taylor & Francis Group, 1264 pp.CrossRefGoogle Scholar
Chaganti, V.N. and Crohn, D.M. (2015). Evaluating the relative contribution of physiochemical and biological factors in ameliorating a saline-sodic soil amended with composts and biochar and leached with reclaimed water. Geoderma 259–260, 4555.CrossRefGoogle Scholar
Dikinya, O. and Mufwanzala, N. (2010). Chicken manure-enhanced soil fertility and productivity: effects of application rates. Journal of Soil Science and Environmental Management 1, 4654.Google Scholar
Duku, H.M., Gu, S. and Hagan, E.B. (2011). Biochar production potentials in Ghana – a review. Renewable and Sustainable Energy Review 15, 35393551.Google Scholar
El-Naggar, A., Lee, S.S., Rinklebe, J., Farooq, M., Song, H., Sarmah, A.K., Zimmerman, A.R., Ahmad, M., Shaheen, S.M. and Ok, Y.S. (2019). Biochar application to low fertility soils: A review of current status, and future prospects. Geoderma 337, 536554.CrossRefGoogle Scholar
Frank, K., Beegle, D. and Denning, I. (1998). Phosphorus. In Brown, J.R. (ed), Recommended Chemical Soil Test Procedures for the North Central Region. Columbia, MO, USA: North Central Regional Research Publication No. 221 (revised) Missouri Agric. Exp. Stn, pp. 2126.Google Scholar
Gamage, D.N., Mapa, R.B., Dharmakeerthi, R.S. and Biswas, A. (2016) Effect of ricehusk biochar on selected soil properties in tropical Alfisols. Soil Research 54, 302310.CrossRefGoogle Scholar
Gaunt, J. and Lehmann, J. (2008) Energy balance and emissions associated with biochar sequestration and pyrolysis bioenergy production. Environmental Science and Technology 42, 41524158.CrossRefGoogle ScholarPubMed
Gee, G.W. and Or, D. (2002) Particle-size analysis. In Dane, J.H. and Topp, G.C. (eds), Methods of Soil Analysis. Part 4. Physical Methods. Soil Science Society of America Book Series No. 5, Madison, Wisconsin, USA, pp. 255293.Google Scholar
Githinji, L. (2014) Effect of biochar application rate on soil physical and hydraulic properties of a sandy loam. Archives of Agronomy and Soil Science 60, 457470.CrossRefGoogle Scholar
Gul, S., Whalen, J.K., Thomas, B.W., Sachdeva, V. and Deng, H. (2015). Physico-chemical properties and microbial responses in biochar-amended soils: mechanisms and future directions. Agriculture, Ecosystems & Environment 206, 4659.CrossRefGoogle Scholar
Hass, A., Gonzalez, J.M., Lima, I.M., Godwin, H.W., Halvorson, J.J. and Boyer, D.G. (2012). Chicken manure biochar as liming and nutrient source for acid Appalachian soil. Journal of Environmental Quality 41, 10961106.CrossRefGoogle ScholarPubMed
Hendershot, W.H., Lalande, H. and Duquette, M. (2007). Ion exchange and exchangeable cations. Soil sampling and methods of analysis. In Carter, M.R. and Gregorich, E.G. (eds), Canadian Society of Soil Science, 2 nd ed. Boca Raton, Florida: CRC Press, pp. 197206.Google Scholar
Herath, H.M.S.K., Arbestain, M.C. and Hedley, M. (2013) Effect of biochar on soil physical properties in two contrasting soils: an Alfisol and an Andisol. Geoderma 209–210, 188197.CrossRefGoogle Scholar
Holatko, J., Hammerschmiedt, T., Mustafa, A., Kintl, A., Radziemska, M., Baltazar, T., Jaskulska, I., Malicek, O., Latal, O. and Brtnicky, M (2022) Carbon-enriched organic amendments differently affect the soil chemical, biological properties and plant biomass in a cultivation time-dependent manner. Chemical and Biological Technologies in Agriculture 9, 52.CrossRefGoogle Scholar
Hoover, N.L., Law, J.Y., Long, L.A.M., Kanwar, R.S. and Soupir, M.L. (2019). Long-term impact of poultry manure on crop yield, soil and water quality, and crop revenue. Journal of Environmental Management 252, 109582.CrossRefGoogle ScholarPubMed
Horwitz, W. Editor. (1997). Official Methods of Analysis of the Association of Official Analytical Chemists. 16 th ed. Gaithersburg, Maryland: AOAC International. 1298 pp.Google Scholar
IUSS Working Group WRB. (2015). World Reference Base for Soil Resources 2014, Update 2015. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports No. 106. FAO, Rome.Google Scholar
Jeffery, S., Abalos, D., Prodana, M., Catarina Bastos, A., van Groenigen, J.W., Hungate, B.A. and Verheijen, F. (2017). Biochar boosts tropical but not temperate crop yields. Environmental Research Letters 12, 053001.Google Scholar
Jeffery, S., Verheijen, F.G.A., van der Velde, M. and Bastos, A.C. (2011). A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agriculture, Ecosystems & Environment 144, 175187.CrossRefGoogle Scholar
Jones, D.L., Cross, P., Withers, P.J., DeLuca, T.H., Robinson, D.A., Quilliam, R.S., Harris, I.M., Chadwick, D.R. and Edwards-Jones, G. (2013). Nutrient stripping: the global disparity between food security and soil nutrient stocks. Journal of Applied Ecology 50, 851862.CrossRefGoogle Scholar
Kameyama, K., Miyamoto, T., Iwata, Y. and Shiono, T. (2016). Effects of biochar produced from sugarcane bagasse at different pyrolysis temperatures on water retention of a calcaric dark red soil. Soil Science 181, 2028.CrossRefGoogle Scholar
Khademalrasoul, A., Naveed, M., Heckrath, G., Kumari, K.G.I.D., de Jonge, L.W., Elsgaard, L., Vogel, H.-J. and Iversen, B.V. (2014). Biochar effects on soil aggregate properties under no-till maize. Soil Science 179, 273283.CrossRefGoogle Scholar
Kim, H.-S., Kim, K.-R., Yang, J.E., Ok, Y.S., Owens, G., Nehls, T., Wessolek, G. and Kim, K.-H. (2016). Effect of biochar on reclaimed tidal land soil properties and maize (Zea mays L.) response. Chemosphere 142, 153159.CrossRefGoogle ScholarPubMed
Laghari, M., Mirjat, M.S., Hu, Z., Fazal, S., Xiao, B., Hu, M., Chen, Z. and Guo, D. (2015). Effects of biochar application rate on sandy desert soil properties and sorghum growth. Catena 135, 313320.CrossRefGoogle Scholar
Lal, R. (2009). Soils and world food security. Soil and Tillage Research 102, 14.CrossRefGoogle Scholar
Lal, R. (2013). Food security in a changing climate. Ecohydrology & Hydrobiology 13, 821.CrossRefGoogle Scholar
Lampurlanes, J. and Cantero-Martinez, C. (2003). Soil bulk density and penetration resistance under different tillage and crop management systems and their relationship with barley root growth. Agronomy Journal 95, 526536.CrossRefGoogle Scholar
Lehmann, J., Gaunt, J. and Rondon, M. (2006). Bio-char sequestration in terrestrial ecosystems – a review. Mitigation and Adaptation Strategies for Global Change 11, 403427.CrossRefGoogle Scholar
Lehmann, J. and Joseph, S. (2015). Biochar for Environmental Management: Science, Technology and Implementation. London, UK: Earthscan.CrossRefGoogle Scholar
Lehmann, J., Kaempf, N., Woods, W.I., Sombroek, W., Kern, D.C. and Cunha, T.J.F. (2007). Classification of Amazonian dark earths and other ancient anthropic soils. In Lehmann, J., Kern, D.C., Glaser, B. and Woods, W.I. (eds), Amazonian dark earths: origin, properties, management. New York: Springer, pp. 77102.Google Scholar
Lentz, R.D., Ippolito, J.A. and Spokas, K.A. (2014). Biochar and manure effects on net N mineralization and greenhouse gas emissions from calcareous soil under corn. Soil Science Society of America Journal 78, 16411655.CrossRefGoogle Scholar
Lim, T.J., Spokas, K.A., Feyereisen, G. and Novak, J.M. (2016). Predicting the impact of biochar additions on soil hydraulic properties. Chemosphere 142, 136144.CrossRefGoogle ScholarPubMed
Lin, Y., Watts, D.B., van Santen, E. and Cao, G. (2018). Influence of poultry litter on crop productivity under different field conditions: a meta-analysis. Agronomy Journal 110, 807818.CrossRefGoogle Scholar
Lipiec, J., Usowicz, B., Klopotec, J., Turski, M. and Frac, M. (2021). Effects of application of recycled chicken manure and spent mushroom substrate on organic matter, acidity and hydraulic properties of sandy soils. Materials 14, 4036.CrossRefGoogle ScholarPubMed
Liu, X.H., Han, F.P. and Zhang, X.C. (2012). Effect of biochar on soil aggregates in the loess plateau: results from incubation experiments. International Journal of Agriculture and Biology 14, 975979.Google Scholar
Major, J., Rondon, M., Molina, D., Riha, S. J. and Lehmann, J. (2010). Maize yield and nutrition during 4 years after biochar application to a Colombian savanna Oxisol. Plant Soil 333, 117128.CrossRefGoogle Scholar
Major, J., Rondon, M., Molina, D., Riha, S.J. and Lehmann, J. (2012). Nutrient leaching in a Colombian savanna Oxisol amended with biochar. Journal of Environmental Quality 41, 10761086.CrossRefGoogle Scholar
Martinsen, V., Alling, V., Nurida, N.L., Mulder, J., Hale, S.E., Ritz, C., Rutherford, D.W., Heikens, A., Breedveld, G.D. and Cornelissen, G. (2015). pH effects of the addition of three biochars to acidic Indonesian mineral soils. Soil Science and Plant Nutrition 61, 821834.CrossRefGoogle Scholar
Mekuria, W., Noble, A., Sengtaheuanghoung, O., Hoanh, C.T., Bossio, D., Sipaseuth, N., McCartney, M. and Langan, S. (2014). Organic and clay-based soil amendments increase maize yield, total nutrient uptake, and soil properties in Lao PDR. Agroecology and Sustainable Food Systems 38, 936961.CrossRefGoogle Scholar
Mensah, A.K. and Frimpong, K.W. (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, 8.CrossRefGoogle Scholar
Minhas, W.A., Hussain, M., Mehboob, N., Nawaz, A., Ul-Allah, S., Rizwan, M.S. and Hassan, Z. (2020). Synergetic use of biochar and synthetic nitrogen and phosphorus fertilizers to improves maize productivity and nutrient retention in loamy soil. Journal of Plant Nutrition 43, 13561368.CrossRefGoogle Scholar
Mpanga, I.K., Adjei, E., Dapaah, H.K. and Santo, K.G. (2021). Poultry manure induced garden eggs yield and soil fertility in tropical and semi-arid sandy-loam soils. Nitrogen 2, 321331.CrossRefGoogle Scholar
Mpanga, I.K., Dapaah, H.K., Geistlinger, J., Ludewig, U. and Neumann, G. (2018). Soil type-dependent interactions of P-solubilizing microorganisms with organic and inorganic fertilizers mediate plant growth promotion in tomato. Agronomy 8, 213.CrossRefGoogle Scholar
Nelson, D.W. and Sommers, L.E. (1996). Total carbon, organic carbon and organic matter. In Sparks, D.L. (Ed.), Methods of Soil Analysis. Part 3. Second ed. ASA and SSSA Book Series No. 5, SSSA, Madison, WI, USA, pp. 9611010.Google Scholar
Njoku, J.C., Okpara, D.A. and Asiegbu, J.E. (2001). Growth and yield response of sweet potato to inorganic nitrogen and potassium in a tropical Ultisol. Nigerian Agricultural Journal 32, 3041.Google Scholar
Nur, M., Islami, T., Handayanto, E., Nugroho, W. and Utomo, W. (2014). The use of biochar fortified compost on calcareous soil of east Nusa Tenggara, Indonesia: 2. Effect on the yield of maize (Zea mays L) and phosphate absorption. Am-Eurasian Journal of Sustainable Agriculture 8, 105111.Google Scholar
O’Sullivan, J.N., Asher, C.J. and Blamey, F.P.C. (1997). Nutrient disorders of sweet potato. Australian Centre for International Agricultural Research (ACIAR) Monograph No. 48, ACIAR, Canberra, Australia, 136 pp.Google Scholar
Oni, B.A., Oziegbe, O. and Olawole, O.O. (2019). Significant of biochar application to the environment and economy. Annals of Agricultural Sciences 64, 222236.CrossRefGoogle Scholar
Ouyang, L., Wang, F., Tang, J., Yu, L. and Zhang, R. (2013). Effects of biochar amendment on soil aggregates and hydraulic properties. Journal of Soil Science and Plant Nutrition 13, 9911002.Google Scholar
Pandian, K., Subramaniayan, P., Gnasekaran, P. and Chitraputhirapillai, S. (2016). Effect of biochar amendment on soil physical, chemical and biological properties and groundnut yield in rainfed Alfisol of semi-arid tropics. Archives of Agronomy and Soil Science 62, 12931310.CrossRefGoogle Scholar
SAS Institute Inc., (2013). SAS 9.4 Statements: Reference. Cary, NC: SAS Institute Inc.Google Scholar
Senthilkumar, R., Muragod, P.P. and Muruli, N.V. (2020). Nutrient analysis of sweet potato and its health benefits, Indian Journal of Pure & Applied Biosciences 8, 614618.CrossRefGoogle Scholar
Shetty, R. and Prakash, N.B. (2020). Effect of different biochars on acid soil and growth parameters of rice plants under aluminium toxicity. Scientific Reports 10, 12249.CrossRefGoogle ScholarPubMed
Smyth, A.J. and Montgomery, R.F. (1962). Soils and Land Use in Central Western Nigeria. Ibadan, Nigeria: Government Printer, 265 pp.Google Scholar
Soil Survey Staff. (2014). Keys to soil taxonomy. 12 th ed. Washington, DC: United States Department of Agriculture, Natural Resources Conservation Service.Google Scholar
Soinne, H., Hovi, J., Tammeorg, P. and Turtola, E. (2014). Effect of biochar on phosphorus sorption and clay soil aggregate stability. Geoderma 219–220, 162167.CrossRefGoogle Scholar
Solomon, D., Lehmann, J., Thies, J., Schafer, T., Liang, B., Kinyangi, J., Neves, E., Petersen, J., Luizao, F. and Skjemstad, J. (2007). Molecular signature and sources of biochemical recalcitrance of organic C in Amazonian Dark Earths. Geochimica et Cosmochimica Acta 71, 22852298.CrossRefGoogle Scholar
Srivastava, S., Genitha, T.R. and Yadav, V. (2012). Preparation and quality evaluation of flour and biscuit from sweet potato. Journal of Food Processing & Technology 3, 1000192.CrossRefGoogle Scholar
Stephenson, A.H., McCaskey, T.A. and Ruffin, B.G. (1990). A survey of broiler litter composition and potential value as a nutrient resource. Biological Wastes 34, 19.CrossRefGoogle Scholar
Sun, F. and Lu, S. (2014). Biochars improve aggregate stability, water retention, and pore-space properties of clayey soil. Journal of Plant Nutrition and Soil Science 177, 2633.CrossRefGoogle Scholar
Tel, D.A. and Hagarty, M. (1984). Soil and Plant Analysis. Study guide for agricultural laboratory directors and technologists working in tropical regions. Ontario, Canada: International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria in conjunction with University of Guelph, 277 pp.Google Scholar
Verheijen, F.G.A., Zhuravel, A., Silva, F.C., Amaro, A., Ben-Hur, M. and Keizer, J.J. (2019). The influence of biochar particle size and concentration on bulk density and maximum water holding capacity of sandy vs sandy loam soil in a column experiment. Geoderma 347, 194202.CrossRefGoogle Scholar
Xia, L., Lam, S., Yan, X. and Chen, D. (2017). How does recycling of livestock manure in agroecosystems affect crop productivity, reactive nitrogen losses, and soil carbon balance? Environmental Science & Technology 51, 74507457.CrossRefGoogle ScholarPubMed