Land Application of Oily Food Waste and Corn Production on Amended Soils

Abstract

Oily food waste containing high concentrations of fat, oil, and grease (FOG) is produced by the food service and food production/processing industries. Fat, oil, and grease have a high C/N ratio (90:1) and, if applied to agricultural soils, may affect the availability of N to crops, due to soil N immobilization during its decomposition. Several field experiments were conducted on silt loam and loam soils (fine‐loamy mixed, mesic Glossoboric Hapludalfs) from 1995–1997 to determine: (i) effect of FOG on corn (Zea mays L.) crop yields, (ii) N requirements of corn grown on FOG‐amended soils, (iii) contribution to soil C, and (iv) its accumulation in soil after continuous application. Corn grain yields were maintained with FOG applied at 5, 10, and 15 Mg ha−1, providing that sufficient N was available to fulfill the needs of soil microorganisms during FOG decomposition and crop growth. The N rates ranged from 170 to 510 kg N ha−1 for these FOG application rates. Soil organic C was significantly increased by 9 and 19% with the continuous FOG application for 3 yr at 10 and 15 Mg FOG ha−1 yr−1. The residual FOG contents after 3 yr at these application rates were <2% of the total FOG applied with no expected FOG buildup in soil. Corn grain yields were not affected by FOG application in fall and were equal to control plots during 1996 and 1997. However, corn grain yields were decreased by FOG applied in spring, and supplemental N (62 and 59 kg N ha−1 in 1996 and 1997, respectively) was required to maintain yields similar to control plots.