Beef manure and urea applied to corn show variable effects on nitrous oxide, methane, carbon dioxide, and ammonia

Land application of beef cattle (Bos taurus) manure can improve soil health and increase corn (Zea mays L.) yield compared with commercial fertilizers. However, ammonia (NH₃), nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) emissions may lead to nutrient losses and environmental concerns. The objective of this research was to quantify NH₃, N₂O, CO₂, and CH₄ emissions from commercial and manure fertilizers applied to corn. In addition, residual soil N, corn yield, plant tissue N, and grain N were determined. The 2-yr field study was conducted in Fargo-Ryan silty clay soil. Treatments consisted of urea only (UO), solid beef manure (SM), solid beef manure with straw bedding (BM), and no fertilizer (NF). All treatments were applied to meet the corn N demand and yield goal of 10,760 kg ha^–1 (160 bu ac^–1). Greenhouse gases were quantified using static flux chambers, and NH₃ was quantified using acid traps, for a total of 13 measurement dates in each growing season. Manure applied to soil reduced cumulative N₂O by 23% in SM and 31% in BM compared with the UO soil. Cumulative CO₂ emission (cCO₂) was 42% lower in UO than in SM or BM. Cumulative CH₄ emission (cCH₄) ranged from –0.04 (NF) to 0.21 (BM) kg CH₄–C ha^–1, with the highest emission from BM. Cumulative NH₃ emission (cNH₃) was 11% lower in manure than UO. Cumulative residual soil N was 11% greater in Year 2. Fertilizer source did not affect the yield and grain N uptake (P > 0.05). The results highlight the challenges that come with variability in manure, soil, and weather as well as the potential for meeting crop N demand while reducing greenhouse gas emissions when using manure as an N source.