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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #328809
Title: Impact of irrigation scheduling on pore water nitrate and phosphate in coastal plains soils with corn production

Author
item Sigua, Gilbert
item Stone, Kenneth - Ken
item Bauer, Philip
item Szogi, Ariel
item Shumaker, Paul

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2017
Publication Date: 3/8/2017
Citation: Sigua, G.C., Stone, K.C., Bauer, P.J., Szogi, A.A., Shumaker, P.D. 2017. Impact of irrigation scheduling on pore water nitrate and phosphate in coastal plains soils with corn production. Agricultural Water Management. 186:75-85.

Interpretive Summary: Although there are considerable data available on nitrate (NO3) and phosphate (PO4) leaching; there is still limited information on the effects of irrigation scheduling and its interaction with nitrogen management (NM) on NO3 and PO4 leaching in humid region. Additionally, site-specific irrigation management system has the potential to reduce leaching of nitrogen (N) from the crop root zone, but this has not yet been fully demonstrated in the field. There is a need to find scheduling method to precision-apply water for maximum agronomic and environmental utility. A three-year (2012-2014) field study was conducted to evaluate and compare the effects of three irrigation scheduling methods (ISM): Irrigator Pro (IPRO); Normalized Difference Vegetative Index (NDVI) and Soil Water Potentials (SWP) and two levels of N applications: 157 and 224 kilogram N per hectare (kg N/ha) on pore water nitrate (NO3) and phosphate (PO4) in four soil types (ST) under corn production in Coastal Plains, USA. Soil pore water NO3 varied significantly with irrigation scheduling method (ISM) and NM, but not with ST. The IPRO method had the lowest soil water pore NO3 (11.1 milligram per liter, mg/L) followed by SWP (16.5 mg/L) and NDVI (17.9 mg/L). The low N application rate of 157 kg N/ha resulted in lower NO3 concentration (13.4 mg/L) than the high N rate of 224 kg N/ha (17.0 mg/L). Concentrations of soil water pore NO3 and PO4 varied significantly with soil depths. Soil water pore PO4 was not affected by ISM, NM and ST. The use of IPRO reduced the concentration of pore water NO3 by about 39% and 33% when compared with NDVI and SWP, respectively. Irrigator PRO may have some advantages in terms of minimizing the concentration of pore water NO3 and PO4 being leached during irrigation when compared with NDVI and SWP. Since the IPRO method resulted in lower soil pore water NO3 and PO4, the results indicate scheduling method may be a way to reduce fertilizer N losses to leaching on these soils.

Technical Abstract: Agriculture is one of the most important sources of nutrient contamination, mainly inorganic nitrogen (N) fertilization of intensive crops, such as corn (Zea mays L). Proper irrigation and nutrient management can reduce nutrient leaching while maintaining crop yield, which is critical in enhancing the sustainability of agricultural crops on soils with low water and nutrient holding capacities. A three-year (2012-2014) field study was conducted to evaluate and compare the effects of three irrigation scheduling methods (ISM): Irrigator Pro (IPRO); Normalized Difference Vegetative Index (NDVI) and Soil Water Potentials (SWP) and two levels of N applications (NA): 157 and 224 kilogram N per hectare (kg N/ha) on pore water nitrate (NO3) and phosphate (PO4) in four soil types (ST) with corn production in Coastal Plains, USA. Soil pore water NO3 varied significantly with ISM and NA, but not with ST. The IPRO method had the lowest soil water pore NO3 (11.1 milligram per liter, mg/L) followed by SWP (16.5 mg/L) and NDVI (17.9 mg/L). The low N application rate resulted in lower NO3 concentration (13.4 mg/L) than the high N rate (17.0 mg/ L). Concentrations of soil water pore NO3 and PO4 varied significantly (p=0.01) with soil depths. Soil water pore PO4 was not affected by ISM, NA and ST. The use of IPRO reduced the concentration of pore water nitrate by about 39% and 33% when compared with NDVI and SWP, respectively. Irrigator PRO may have some advantages in terms of minimizing the concentration of pore water NO3 and PO4 being leached during irrigation when compared with NDVI and SWP. Since the IPRO method resulted in lower soil water pore NO3 and PO4 concentrations, results indicate scheduling method may be a way to reduce nutrient losses to leaching on these soils.