High Carbon Amendments Increase Nitrogen Retention in Soil After Slurry Application—an Incubation Study with Silty Loam Soil

Abstract Excess nitrogen (N) after animal slurry application is a persistent problem of intensive agriculture, with consequences such as environmental pollution by ammonia (NH 3 ) and nitrous oxide (N 2 O) emissions nitrate (NO − leaching. High-carbon organic soil amendments (HCAs) large C:N ratio have shown the potential mitigating unintended N losses from soil. To reduce gaseous leaching slurry, laboratory incubation study was conducted silt loam We tested three different types HCA—wheat straw, sawdust, leonardite (application rate 50 g C L −1 for each HCAs)—to mitigate loss amendment pig cattle using two common modes (slurry HCA mixed overnight subsequent addition to vs. sequential addition) at an equivalent 80 kg ha . Compared control only reduced NH both slurries 32–64%. Leonardite also total O 33–58%. Wheat straw 40–46%, but had no effect on emission. 15 labeling showed that associated highest retention in (24% average recovery), followed wheat (20% recovery). The mitigation observed although less consistent compared straw. Mixing tended losses, not across all treatments. In conclusion, improved more effectively than sawdust.