Dairy forage cropping best management practices: A comparison of yield, forage quality, soil carbon sequestration, and greenhouse gas emissions

Increases in greenhouse gas (GHG) emissions have been found to contribute toward global warming. Better management practices in agriculture have been proposed as a partial solution to this problem. This study evaluated forage cropping systems and additions of manure or compost for their ability to sequester carbon (C) and reduce GHG emissions from the soil. Cropping systems and C additions were compared at a southern Michigan (KBS) and northern Michigan (UP) location. Compost was applied at KBS and manure slurry was applied at UP at rates to supply 3000 kg C ha-1. Results indicated forage quality differences (P<0.0001) between forage species within each location. There were also significant (P<0.0001) yield differences between crops. The addition of compost at the KBS location had a significant (P<0.0459) impact on yield. The addition of manure at the UP location resulted in significant interactions on yield between crop x year (P<0.0001) and crop x manure (P<0.0442). GHG fluxes at the KBS location were not significantly different due to crop or compost additions, however N2O fluxes were significantly greater (P<0.040) with manure additions at the UP location. Total soil C measured at KBS was greater with compost additions than without (0.943 kg C cm-2 and 0.798 kg C cm-2 respectively). POM differences at KBS were also significant (P<0.0037) (0.211 kg POM C cm -2 with compost additions and 0.202 kg POM C cm-2 without compost). The UP location TSC and POM did not respond in a measurable way to manure additions or cropping treatments.