Evaluating performance of short-rotation woody crops for bioremediation purposes

Abstract

Decommissioned animal waste lagoons contain large quantities of nutrients including nitrogen (N) and phosphorus (P) and can cause pollution of nearby water resources. Using short-rotation woody crops (SRWCs) for nutrient uptake and biomass production might be an inexpensive and eco-friendly method for the stabilization of decommissioned lagoons. We evaluated the annual growth performance and nutrient uptake by sycamore (Platanus occidentalis) for five growing seasons and 25 different clones of eastern cottonwood (Populus deltoides) for four growing seasons in a soil backfilled, de-watered swine lagoon in north-central Oklahoma. Growth performance and nutrient uptake of cottonwood was higher than the sycamore in our study. At the end of the study, 5-year old sycamore reached an average height of 5.84 m [standard error (SE) = 0.39] and had an average diameter at breast height (dbh) of 5.91 cm (SE = 0.20), compared to 4-year old cottonwood height of 7.58 m (SE = 0.15) and dbh of 8.22 cm (SE = 0.34), respectively. Sycamore produced almost 30 Mg ha−1of total biomass, whereas cottonwood produced 53 Mg ha−1 by the end of the study. Total N and P uptake by sycamore was 327 (SE = 24) and 51 (SE = 4) kg ha−1 respectively, whereas cottonwood N and P uptake was 699 (SE = 41) and 99 (SE = 6) kg ha−1, respectively, by the end of the study. We conclude that SRWCs can use substantial amounts of nutrients from the decommissioned lagoons while producing wood and fiber products.