ASSESSMENT OF COVER CROP SELECTION ON NITROGEN CYCLING IN A THREE-YEAR POTATO ROTATION
Alternative potato rotations are increasingly being examined that can supply N to potato crops and mitigate nitrate (NO3-) leaching from the root zone. This study examined a legume (RC), grass (T) or legume/ grass mixture (M) on soil N supply, and soil solution N in a subsequent potato crop. The below-ground N contribution of cover crops was also examined using 15N labeled fertilized. Total N uptake in unfertilized potatoes was greater under RC and M than T but did not significantly affect total tuber yield. Overall, NO3- susceptible to leaching was lowest under T. From steel lysimeters, at 80 cm below-ground, the M and T treatments resulted in a 66 and 86% reduction in NO3- respectively from 83 mg NO3-N L-1 from unfertilized potato crops grown subsequent to RC. Labeled root N accounted for 24% of total 15N recovered from residues into a subsequent unfertilized potato under RC and M.