Potato yield response and nitrate leaching as influenced by nitrogen management

Nitrogen management for irrigated potato (Solanum tuberosum L.) is important from both a production and environmental standpoint. Nitrogen deficiency can limit yield, while excessive N can leach to groundwater. The objective of this study was to investigate the effects of early-season N management on irrigated 'Russet Burbank' potato yield, N recovery, and NO3-N leaching. A 2-yr experiment was conducted on a Hubbard loamy sand (Udorthentic Haploborolls), using four N treatments and a 0 N control. Total N applied was 270 kg N ha(-1); the portion applied at planting was 0, 45, 90, and 135 kg N ha(-1), with the remainder applied in equal quantities at emergence and hilling. In 1991, increasing the amount of N applied st planting did not affect total yield, but significantly increased the yield of nonmarketable tubers. In 1992, total yield again was not affected, but the yield of smaller tubers significantly increased and the yield of larger tubers decreased as the proportion of N applied at planting increased. During 1991, when heavy leaching occurred, an average of only 33% of applied N was recovered by the crop. In contrast, during 1992, when fewer leaching events occurred, recovery of N averaged 56%. In both growing seasons, the amount of NO3-N leached increased linearly as the proportion of N applied at planting increased. The strategy of reducing N application at planting for irrigated Russet Burbank potato can reduce the potential for NO3-N leaching, increase N uptake, and improve marketable yield.