The Occurrence of Legacy P Soils and Potential Mitigation Practices Using Activated Biochar

Abstract

The long-term application of manures in watersheds with dense animal production has increased soil phosphorus (P) concentration, exceeding plant and soil assimilative capacities. The P accumulated in soils that are heavily manured and contain excess extractable soil P concentrations is known as legacy P. Runoff and leaching can transport legacy P to ground water and surface water bodies, contributing to water quality impairment and environmental pollution, such as eutrophication. This review article analyzes and discusses current and innovative management practices for soil legacy P. Specifically, we address the use of biochar as an emerging novel technology that reduces P movement and bioavailability in legacy P soils. We illustrate that properties of biochar can be affected by pyrolysis temperature and by various activating chemical compounds and by-products. Our approach consists of engineering biochars, using an activation process on poultry litter feedstock before pyrolysis to enhance the binding or precipitation of legacy P. Finally, this review article describes previous examples of biochar activation and offers new approaches to the production of biochars with enhanced P sorption capabilities.

Leaching Potential of Phosphite Fertilizer in Sandy Soils of the Southern Coastal Plain, USA

“…This transformation of Phi into Pi could change the equilibrium between the labile and soluble P pools and alter the risk of Phi and Pi leaching in a relatively short time. Future studies on the risk of Phi leaching losses should include the transformation of Phi into Pi in time, the effect of soil pH on sorption and desorption of Phi and Pi, and potential contributions of Phi to legacy P [2].…”

“…High application of P fertilizers above crop requirements usually occurs in P-fixing soils to provide sufficient plant-available P [1]. Although soils have a high capacity to retain P, continued application of P fertilizers could eventually exceed the plant and soil assimilative capacities, resulting in the loss of P from soil to water bodies through runoff or leaching [2,3]. In turn, global demand for P fertilizers in intensive agriculture due to a growing population leads to the depletion of finite reserves of rock phosphate to produce inorganic P fertilizers [4].…”

Effect of soil pH and mineralogy on the sorption and desorption of phosphite and phosphate in Ultisols of the Southeastern Coastal Plain

“…The inherent soil acidity and an abundance of Al‐ and Fe‐oxides, which have a high affinity for anionic Pi at low pH, limit the plant availability of P in Ultisols (Giesler et al., 2005; Pérez et al., 2014; Trakoonyingcharoen et al., 2005). Therefore, to overcome low P availability, Pi‐based fertilizers often applied over plant requirements can result in P‐saturated soils that pose an environmental risk to aquatic ecosystems receiving agricultural runoff (Cerven et al., 2021; Dari et al., 2018). Instead, using transgenic crops adapted to Phi‐based fertilizers in agricultural systems of the Coastal Plain is a promising strategy for improving plant P‐use efficiency while aspiring to minimize the environmental risk of excess soil P (López‐Arredondo & Herrera‐Estrella, 2012).…”

‘Soil and Plant Nutrition’—A Section of Agronomy: Advances and Perspectives

“…Biochar is the most intensively investigated amendment and is widely described in the literature, including in the 'Soil and Plant Nutrition' section [6,[21][22][23][33][34][35][36][37][38][39]. Many review papers (1327 reviews indexed in the Web of Science Core Collection in categories related to agronomy) and meta-analyses have already been written on this subject [40][41][42][43][44][45][46][47][48]. Biochar has been recognized as a soil amendment that provides opportunities for soil improvement and mitigates climate change by promoting carbon sequestration.…”