Comparing Constant and Variable Rate Applications of Solid Cattle Manure on Greenhouse Gas Emissions From Dark Brown Chernozems
Although field application of solid cattle manure (SCM) is an alternative, low-cost nitrogen (N) source to conventional synthetic fertilizers, gaseous losses of manure-N, occurring via volatilization and denitrification, are well documented. However, the effect of variable rate application of SCM on gaseous N emissions at a landscape-scale has received less attention. The objective of this study was to compare the nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) fluxes from watershed basins within the same field, with and without the addition of fresh feedlot SCM applied at either constant blanket or variable landscape-adjusted rates. Gas samples were collected in 2019 and 2020 with gas sampling locations further classified according to their catchment area size. The non-manured watershed basins had low cumulative N2O and CO2 emissions, and were strong CH4 sinks compared to manured basins. Additionally, basins receiving the Variable Rate manure application had lower N2O emissions than those receiving the Constant Rate manure application. The low elevation, larger catchment area landscape positions contributed proportionally more to cumulative N2O and CO2 emissions, along with reduced CH4 consumption, compared to the smaller catchment areas higher in the landscape, due to greater soil moisture and organic matter content within those depressional soils.
Fertilizer, Manure, Gaseous Emissions
Soils and Crops Workshop