Surfactant Impact on Nitrogen Utilization and Leaching in Potatoes

Abstract

Some producers face a unique problem with potato (Solanum tuberosum) production on sandy soils where a dry zone can develop in the potato hill. Surfactants may reduce this dry zone by decreasing water surface tension, thus enhancing water and nutrient uptake. A study was established to determine if band applying nonionic surfactant at 9.35 L ha −1 in the seed furrow at planting would reduce nitrate-nitrogen (NO3-N) leaching and in- crease potato yield and quality. Nitrogen (N) fertilizer was applied at 34, 168, 236, and 303 kg N ha −1 . Porous cup samplers were installed beneath the row at 1-m depth in three treatments, with soil solution samples collected weekly. Nitrate-N concentration and irrigation+rainfall data were used to estimate nitrate leaching. Surfactant applica- tion resulted in changes of total NO3-N load between+6.0 and −46.7% for this 3- year study; however, because of high within-treatment variation for the soil water NO3-N samples, these differences were not statistically significant at the < 0.10 p-value, although a two sample t-test of +/− surfactant treatments across N rates and years resulted in a < 0.01 p-value. Nitrate-N leaching increased with increas- ing N fertilization rate. Soil NO3-N concentration 20 days after the last N fertilization was significantly less (30.1%) with surfactant application across all years and N rates. Soil NH4-N at this time also tended to be decreased with surfactant application (19.7% reduction, p=0.12). Total potato yield was not affected by surfactant use, but increased with increasing N rate. Tuber N content increased with surfactant use, resulting in increased crop N uptake. Resumen Algunos productores se enfrentan a un problema unico con la produccion de papa (Solanum tuberosum )e n suelos arenosos, donde se puede desarrollar una zona seca en la zona radicular de siembra de papa. Tensioactivos pueden reducir esta zona seca mediante la disminucion de la tension superficial del agua, mejorando asi la absorcion de agua y nutrientes. Se establecio un estudio para determinar si la aplicacion en banda a la siembra de surfactante no ionico 9.35 L ha −1 en el surco de siembra reduciria la lixiviacion del nitrato-nitrogeno (NO3-N) y aumentaria el rendimiento y la calidad de la papa. Se aplico fertilizante nitrogeno (N) a 34, 168, 236, y 303 kg N ha −1 . Se instalaron muestreadores de