Nitrogen Removal by Orchardgrass and Smooth Bromegrass and Residual Soil Nitrate
- J. W. Singer *a and
- K. J. Mooreb
Nitrogen removal by cool-season grasses may aid in capturing excess N from animal confinement operations or phytoremediation. Limited information exists on the N dynamics of these grasses near the asymptote of the N response curve. The objectives of this study were to evaluate N removal, residual soil NO3–N, and apparent N recovery in orchardgrass (Dactylis glomerata L.) and smooth bromegrass (Bromus inermis Leyss.) at annual N rates of 224, 448, and 672 kg ha−1 Species × harvest interactions were observed in both years, but no species × N rate interactions occurred. Orchardgrass removed 352 and 505 kg N ha−1 yr−1 at the 448 N rate compared with 207 and 371 in smooth bromegrass in 1999 and 2000, respectively. In a dry year, orchardgrass (r 2 = 0.41) and smooth bromegrass (r 2 = 0.31) exhibited linear N uptake. In a year with adequate rainfall, a quadratic relationship was observed for orchardgrass (R 2 = 0.92), while smooth bromegrass had linear uptake (r 2 = 0.66). Greater N removal was observed in orchardgrass partly because of superior fall growth, when 99 and 82 kg N ha−1 were removed in 1999 and 2000 at the 448 N rate compared with 23 and 15 kg N ha−1 in smooth bromegrass. These removal rates accounted for 28 and 16% of the seasonal total in 1999 and 2000 in orchardgrass and 11 and 4% in smooth bromegrass. Orchardgrass N removal exceeded smooth bromegrass in a three-cut system, and this difference was enhanced by utilizing the fall growth period to capture residual soil N.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2003.