Irrigation and nitrogen management effects on potato yield, tuber quality, and nitrogen uptake

Irrigation and N management are perhaps the most important aspects of successful potato (Solanum tuberosum L.) production in central Minnesota. With rising concern about current irrigation and N management practices and ground water quality, a two-year study was undertaken to evaluate the impact of alternative irrigation and N management practices on potato yield, tuber quality, and N uptake. The treatments were different irrigation schemes (sprinkler and drip), irrigation triggers (70 and 40% of available water [AW] remaining), drip tape placements (surface or buried at 25 cm), N sources (urea, turkey manure, sulfur-coated urea [SCU]), and timings of inorganic N fertilizer application. Rainfall in the area was less in 1994 (260 mm) than in 1995 (380 mm). As a result, irrigation applications in 1994 were greater than in 1995. Drip irrigation amounts were less than half of that applied by sprinkler irrigation treatments in both years. Except for the buried drip with fertigation (43.0 and 27.8 Mg ha^-1 in 1994 and 1995) and the control (36.5 and 13.3 Mg ha^-1 in 1994 and 1995), total tuber yields were similar regardless of irrigation and N source treatment. The turkey manure treatments in 1994 had significantly higher marketable tuber yields than the control, averaging 48.3 Mg ha^-1 for both years. Total N uptake in 1994 was nearly 100% of that applied, while in 1995 it accounted for only 60% of the application. Lower N uptake was observed for the control (85.3 and 30.2 kg N ha^-1 in 1994 and 1995, respectively), SCU (165.2 and 111.3 kg N ha^-1 in 1994 and 1995), and BDF (157.2 and 80.1 kg N ha^-1 in 1994 and 1995) treatments. The results showed that the use of unconventional N sources such as turkey manure and SCU are viable alternatives for potato production, provided they are managed properly.