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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION SYSTEMS RESEARCH FOR IMPROVING ENVIRONMENTAL QUALITY AND PRODUCER PROFITABILITY Title: Surfactant Impact on Nitrogen Utilization and Leaching in Potatoes

Authors
item Arriaga, Francisco
item Lowery, Birl - UNIV. OF WISCONSIN
item Kelling, Keith - UNIV. OF WISCONSIN

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 18, 2009
Publication Date: October 1, 2009
Citation: Arriaga, F.J., Lowery, B., Kelling, K. 2009. Surfactant Impact on Nitrogen Utilization and Leaching in Potatoes. American Journal of Potato Research. 86:383-390.

Interpretive Summary: Some producers face a unique problem with potato production on sandy soils where a dry zone can develop in the potato hill. Surfactants, also known as wetting agents, have the potential to reduce this dry zone, thus enhancing water and nutrient uptake. A study was established to determine if applying a surfactant at planting would reduce nitrate leaching, and increase potato yield and quality. Nitrogen fertilizer was applied at four levels (none, low, medium and high rate). Soil water samplers were installed and soil solution samples were collected weekly. Nitrate leaching rates with drainage water were estimated from these data. Surfactant application reduced nitrate losses between 3.8 and 46.7% for the 3 years the study was conducted, however, these differences were not statistically significant due to natural high variability. Nitrate leaching increased with increasing fertilization rate. Soil samples collected 20 days after fertilization had significantly less (30.1%) nitrate with surfactant application. Soil ammonium at this time also tended to be decreased with surfactant application (19.7% reduction). Total potato yield was not affected by surfactant use, but increased with increasing nitrogen rate. However, crop nitrogen uptake was increased. Enhanced nitrogen management can help producers become profitable while protecting the environment.

Technical 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 have the potential to reduce this dry zone, thus enhancing water and nutrient uptake. A study was established to determine if applying a nonionic surfactant at 9.35 L ha-1 in a band in the seed furrow at planting would reduce nitrate-nitrogen (NO3-N) leaching and thereby increase potato yield and quality. Nitrogen (N) fertilizer was applied at four rates (0, 134, 202, and 269 kg N ha-1). Porous cup samplers were installed beneath the row at a 1-m depth in three of the treatments, and soil solution samples were collected weekly. Nitrate-N concentration and irrigation + rainfall data were used to estimate nitrate leaching rates. Surfactant application showed lower total NO3-N load between 3.8 and 46.7% for the 3 years the study was conducted; however, because of high within-treatment variation for the soil water NO3-N samples, these differences were not statistically significant at the 10% level. Nitrate-N leaching increased with increasing N fertilization rate. Soil NO3-N concentration 20 days after the last N fertilization was significantly less (30.1%) across all years and N rates with surfactant application. 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 up-take.

Last Modified: 10/25/2014