Phytoremediation of Phosphorus-Enriched Soils

After numerous years of application of phosphorus (P) fertilizer and/or manures, many soils accumulate high levels of P, increasing the risk of P transfer via surface runoff. While current and future regulations may limit P application to soil, little effort is given to the reduction of soils already enriched with P. To evaluate the potential of phytoremediation for decreasing available P in soil, the P uptake of several crops and vegetables grown on a high P soil was studied. Plant shoot and root P contents, plant-available soil P, and potential P removal under optimum conditions were examined. None of the plants were "true" P hyperaccumulators, although all removed some P from the soil. Whole corn plants (for silage) and Indian mustard removed the highest amount of P; 114 and 108 kg ha(-1), respectively. If only the grain from corn and Indian mustard were harvested, significantly lower amounts of P were removed from the field. These results show that there is extensive variation in the uptake of P by various crop species. For soils highly enriched with P, it may be desirable to grow a plant species capable of removing above average concentrations of P and to harvest the whole plant because a large fraction of the plant P is contained within the leaves and stems.