Zvomuya Francis, Rosen Carl J, Russelle Michael P, Gupta Satish C
Dep. of Soil. Water, and Climate, Univ. of Minnesota, St. Paul, MN 55108-6028, USA.
J Environ Qual. 2003 Mar-Apr;32(2):480-9. doi: 10.2134/jeq2003.4800.
High N fertilizer and irrigation amounts applied to potato (Solanum tuberosum L.) on coarse-textured soils often result in nitrate (NO3) leaching and low recovery of applied fertilizer N. This 3-yr study compared the effects of two rates (140 and 280 kg N ha(-1)) of a single polyolefin-coated urea (PCU) application versus split applications of urea on 'Russet Burbank' potato yield and on NO3 leaching and N recovery efficiency (RE) on a loamy sand. Standard irrigation was applied in all years and excessive irrigation was used in another experiment in the third year. At the recommended rate of 280 kg N ha(-1), NO3 leaching during the growing season was 34 to 49% lower with PCU than three applications of urea. Under standard irrigation in the third year, leaching from five applications of urea (280 kg N ha(-1)) was 38% higher than PCU. Under leaching conditions in the first year (> or = 25 mm drainage water in at least one 24-h period) and excessive irrigation in the third year, PCU at 280 kg N ha(-1) improved total and marketable tuber yields by 12 to 19% compared with three applications of urea. Fertilizer N RE estimated by the difference and 15N isotope methods at the 280 kg N ha(-1) rate was, on average, higher with PCU (mean 50%) than urea (mean 43%). Fertilizer N RE values estimated by the isotope method (mean 51%) were greater than those estimated by the difference method (mean 47%). Results from this study indicate that PCU can reduce leaching and improve N recovery and tuber yield during seasons with high leaching.
在质地粗糙的土壤上，对马铃薯（Solanum tuberosum L.）施用大量氮肥和进行大量灌溉，往往会导致硝酸盐（NO3）淋失，且施用的氮肥回收率较低。这项为期3年的研究比较了单次施用两种用量（140和280千克氮/公顷）的聚烯烃包膜尿素（PCU）与分次施用尿素对“褐皮伯班克”马铃薯产量、NO3淋失和氮回收效率（RE）的影响，试验土壤为壤质砂土。所有年份均采用标准灌溉，第三年的另一项试验采用了过量灌溉。在推荐用量280千克氮/公顷的情况下，生长季期间PCU处理的NO3淋失比三次施用尿素的情况低34%至49%。在第三年的标准灌溉条件下，五次施用尿素（280千克氮/公顷）的淋失量比PCU高38%。在第一年的淋溶条件下（至少一个24小时时段内排水量≥25毫米）和第三年的过量灌溉条件下，280千克氮/公顷的PCU处理与三次施用尿素相比，使块茎总产量和可上市块茎产量提高了12%至19%。在280千克氮/公顷用量下，通过差值法和15N同位素法估算的肥料氮回收率，PCU平均（均值50%）高于尿素（均值43%）。通过同位素法估算（均值51%）的肥料氮回收率高于差值法估算（均值47%）的值。本研究结果表明，在淋溶量大的季节，PCU可以减少淋失，提高氮回收率和块茎产量。
