Development of P-Hyperaccumulator Plant Strategies to Remediate Soils with Excess P Concentrations

Abstract

The U.S. livestock industry has evolved to confine a large number of animals on a few farms in concentrated areas in many states. The trend to fewer, larger operations coupled with highly intensive production methods has resulted in more concentration of manure nutrients within relatively small geographic areas. Researchers in these areas have reported that manure production is contributing more phosphorus (P) than available cropland can assimilate. Overapplication of manure nutrients combined with low P removal rates by many crops is frequently cited as a reason for the accumulation of excess soil P. We propose that higher amounts of soil P can be removed from soil using vegetative management. Soil P concentration can be reduced in fields with excess levels by using P-hyperaccumulator plants or growing plants that have been modified to increase their P-uptake characteristics through traditional breeding and transgenic techniques. In this context, we identify plant properties (root architecture, secretion of organic acids, etc.) that may be improved using these two techniques.

Double-cropping annual ryegrass and bermudagrass to reduce phosphorus levels in soil with history of poultry litter application

“…Analysis of M3-P within each sampling date found no significant effect of forage system (P [ 0.10) or its interaction with litter rate (P [ 0.20). While this result indicates that increased P uptake by ryegrass-bermudagrass did not translate to significant reductions in M3-P, this lack of integration has been encountered in other phytoremediation studies (Novak and Chan 2002;Read et al 2007). But we also observed that M3-P levels were elevated by about 23 mg kg -1 in ryegrassbermudagrass when 0 or 8.96 Mg ha -1 litter was used (Table 4).…”

“…Although P uptake by forages is a function of P concentration and aboveground biomass yield, the importance of the latter often overrides the first (Brink et al 2004). Consequently, the high yield potential of bermudagrass coupled with its pronounced yield response to N makes this species an ideal forage crop for phytoremediation of high P soil in the southeastern USA (Novak and Chan 2002;Read et al 2007). Because a strong correlation was obtained between P uptake and forage biomass at each harvest date (Table 2), improving N fertility and harvest management of annual ryegrass would probably enhance P removal, providing growth of ryegrass in late spring does not reduce bermudagrass yield to the extent that total P removal is decreased (Rowe et al 2006).…”

“…Nevertheless, STP will remain high in these soils unless the added P is either tied-up through soil amendments or assimilated by plants. Phytoremediation strategies to minimize the potential risks of high soil P on the environment include (1) substituting fertilizer N additions for litter N to enhance the growth and overall nutrient uptake by forage crops (Evers 2002;Read et al 2006), and (2) the cessation of litter application and continued harvest and biomass removal until STP returns to a target level (Novak and Chan 2002). Improved hybrid bermudagrass [Cynodon dactylon L.…”

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

“…Agricultural crops do not appear to be P hyperaccumulators and so phyto-extraction as a strategy to reduce legacy P more quickly for environmental gain appears limited without investment in transgenic biology (Novak and Chan 2002;Sharma et al 2009). However, Dodd et al (2014) found that strategic N additions could increase the drawdown of legacy P in pasture soils by increasing P uptake with highly significant reductions (up to 70 %) in dissolved P losses in surface runoff.…”

Dissolved Phosphorus Transport During Storm and Base Flow Conditions From an Agriculturally Intensive Southeastern Coastal Plain Watershed

“…n the southeastern Coastal Plain region, intensive manure applications to limited land areas have produced excess P concentrations in some soils (Sims et al, 1998;Kellogg et al, 2000;Novak and Chan, 2002). As a result, these soils have an increased potential for P movement to surface water systems (Sims et al, 1998;Kellogg et al, 2000).…”