Energy and greenhouse gas analysis of northeast U.S. dairy cropping systems

Abstract

Dairy farms in the northeast typically produce their own forage, import grain crops, and rely heavily on other inputs. Feed production inputs include fertilizers, herbicides, pesticides, and fuel that require fossil energy and produce greenhouse gas (GHG) emissions during their manufacture and transport. This study uses the Farm Energy Analysis Tool (FEAT) to compare and contrast the fossil energy consumption, energy efficiency, and GHG emissions for three different Pennsylvania dairy cropping systems that vary in their reliance on imported grains and fuel, and thus, land area to produce the same quantity of milk. One novel cropping system, implemented at Penn State University, includes a diverse rotation designed to produce forage, grain, and fuel on-farm (NSVO). The ‘NSVO’ cropping system employs a number of best management practices, including manure injection, cover crops, and integrated pest management. The two modeled-systems require fewer hectares than ‘NSVO’ because they do not produce fuel on-farm but produce forage only (FOR), or forage and grain (FORGr), while producing the same amount of milk. Relative to the ‘FOR’ system, even while requiring larger land areas locally, we found that the ‘NSVO’ and ‘FORGr’ systems lowered total fossil energy inputs per Mg of milk produced by 18% and 15% respectively, largely by importing 77% and 71% less feed crops that would have been grown elsewhere. GHG emissions were similar among farms, on the order of 229kg CO2e Mg-milk−1. On-farm fuel production in the ‘NSVO’ system lowered fossil energy inputs but required more land area and may not provide economic savings with current diesel fuel prices. To reduce the fossil energy impact of their operations, dairy farmers in the Northeast should consider growing more livestock grain on-farm.