Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy and water security

Abstract

Legacy phosphorus (P) that has accumulated in soils from past inputs of fertilizers and manures is a large secondary global source of P that could substitute manufactured fertilizers, help preserve critical reserves of finite phosphate rock to ensure future food and bioenergy supply, and gradually improve water quality. We explore the issues and management options to better utilize legacy soil P and conclude that it represents a valuable and largely accessible P resource. The future value and period over which legacy soil P can be accessed depends on the amount present and its distribution, its availability to crops and rates of drawdown determined by the cropping system. Full exploitation of legacy P requires a transition to a more holistic system approach to nutrient management based on technological advances in precision farming, plant breeding and microbial engineering together with a greater reliance on recovered and recycled P. We propose the term 'agro-engineering' to encompass this integrated approach. Smaller targeted applications of fertilizer P may still be needed to optimize crop yields where legacy soil P cannot fully meet crop demands. Farm profitability margins, the need to recycle animal manures and the extent of local eutrophication problems will dictate when, where and how quickly legacy P is best exploited. Based on our analysis, we outline the stages and drivers in a transition to the full utilization of legacy soil P as part of more sustainable regional and global nutrient management.

Legacy Nutrient Dynamics at the Watershed Scale: Principles, Modeling, and Implications

“…Legacy nutrients are of increasing concerned due to their considerable magnitude and more dispersive spatial distributions compared to current anthropogenic nutrient additions, and they have significant environmental and agronomic implications (Chen et al, 2015a;Meals et al, 2010;Powers et al, 2016;Rowe et al, 2016;Van Meter et al, 2016). Legacy N or P can be released and remobilized, acting as a continuing source to downstream waterbodies for years, decades, or even centuries (Chen et al, 2014b;Haygarth et al, 2014;Meals et al, 2010;Sanford and Pope, 2013;Sharpley et al, 2013;Van Meter et al, 2016).…”

Effect of phosphorus on arsenic uptake and metabolism in rice cultivars differing in phosphorus use efficiency and response

“…The widespread realization that improvements in P nutrition are crucial to the future need to raise global agricultural production has resulted in several recent reviews that have explored these different opportunities (Hinsinger 2001, McNeill and Penfold 2009, Richardson et al 2009, Ryan et al 2009, McLaughlin et al 2011, Simpson et al 2011, Rowe et al 2016.…”

“…Attempts to improve the P efficiency of cropping systems through plant breeding have predominantly focused on enhancing P acquisition from soils (Wissuwa et al 2009). However, at least conceptually, it is generally agreed that concurrent improvements in vegetative stage PUE should be an important complementary trait to enhanced P uptake in any breeding approach (Wang et al 2010, Rowe et al 2016.…”

A Century of Legacy Phosphorus Dynamics in a Large Drainage Basin

“…Once identified, soil-P reserves could be utilized by actively reducing the labile pool to agronomically critical levels. Rowe et al (2015) also argued that "full exploitation" of legacy P requires a more holistic approach to agriculture that involves technological advances, such as breeding more P-efficient crops and engineering microbes to better mobilize soil P. Buffer strips and sedimentation ponds are examples of common practices to intercept nutrient loss and reduce transport to surface water (Schoumans et al, 2014;Sharpley, 2016). To be effective, these measures must be adapted to local conditions and informed by research that links farming practices with nutrient loss pathways (Withers, Neal, et al, 2014).…”