Production of the forage halophyte Atriplex amnicola in metal-contaminated soils

Clean-up of contaminated soils is a costly and slow process that requires long periods of time to be effective. Therefore, direct use of contaminated sites with appropriate management is often likely to be a more efficient use of such land. Consequently, the production of safe animal forages from contaminated soils was the aim of this research. Field studies were conducted to evaluate the growth and elemental composition of river saltbush (Atriplex amnicola) grown on a metal-contaminated soil. The soil was amended with compost at rates of 0, 15 and 30 t/ha to assess its role on plant growth and metal uptake. Compost application significantly (P < 0.05) increased biomass yield, crude protein (CP) and ash content of river saltbush; in contrast, it decreased the Zn and Pb concentrations in shoot tissues. When 30 t/ha of compost was added, the Pb concentrations in the stems and leaves decreased by 32 and 38%, respectively. Despite the large total and extractable content of metals in the studied soil, shoot concentrations of these metals in A. amnicola were always maintained below potentially toxic levels. The biomass material of A. amnicola had a high nutritive value compared to conventional forage crops and could safely be used as animal forage. This work demonstrates that an Atriplex spp, A. amnicola, has significant potential for use as a safe forage crop in the sustainable on-site management of contaminated soils.