Field‐Scale Application of Oily Food Waste and Nitrogen Fertilizer Requirements of Corn at Different Landscape Positions

Oily food waste (FOG; fat + oil + greases) containing high concentrations of fat, oil and grease is produced by the food service, production, and processing industries. It has a high C to N ratio (90:1) and can recycle soil available N through immobilization and remineralization during its decomposition. Experiments were conducted at a farm (Hillsburg fine sandy loam; Typic Hapludalf) having rolling topography (5 and 9% slope) during 1995 and 1996. Objectives of this study were to (i) examine the variability of available N and corn ( Zea mays L.) grain yield at different landscape positions of FOG‐amended fields and (ii) determine whether N fertilizer management could be improved by considering the spatial variability of soil NO 3 –N at different landscape positions in FOG‐amended fields. A spatial and temporal variability in soil NO 3 –N was observed during both years. Corn grain yields at all N fertilizer application rates were affected by slope position and followed the pattern: lower > upper ≥ middle. Nitrogen fertilizer requirements for corn production in conjunction with FOG management were also affected by slope position. Essentially no additional fertilizer N was required for corn production at the lower landscape position. It was estimated that site‐specific fertilizer N management on FOG‐amended fields could result in an average savings of 51 and 63 kg N ha −1 (with a potential economical savings of US$42 and US$52 ha −1 ) during 1995 and 1996, respectively.