Location: Soil and Water Management ResearchTitle: Regression-kriged soil organic carbon stock changes in manured corn silage-alfalfa production systems
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2017
Publication Date: 1/4/2018
Citation: Gamble, J.D., Feyereisen, G.W., Papiernik, S.K., Wente, C.D., Baker, J.M. 2018. Regression-kriged soil organic carbon stock changes in manured corn silage-alfalfa production systems. Soil Science Society of America Journal. 81:1557-1566. https://dio.org/10.2136/sssaj2017.04.0138.
Technical Abstract: Accurately measuring soil organic C (SOC) stock changes over time is essential for verifying agronomic management effects on C sequestration. This study quantified the spatial and temporal changes in SOC stocks on adjacent 65-ha corn silage-alfalfa production fields receiving liquid dairy manure in west central Minnesota. We employed regression kriging to interpolate SOC in four soil layers in 2006 and in 2015 and then calculated stock changes over time. Regression kriging with elevation, topographic wetness index, field (west/east), and irrigation (yes/no) accurately predicted SOC in the 0 – 15 cm (R2 = 0.89) and 15 – 30 cm layers (R2 = 0.51 to 0.95), where variogram analysis indicated moderate to strong spatial correlation. From 0 – 15 cm, SOC in the west field increased by 7% (+ 4.5 Mg C ha-1) over the study period due to gains in irrigated portions of the field, but no changes were found in the east field or at 15 – 30 cm in either field. Below 30 cm, a lack of spatial structure and lack of relationships between SOC and auxiliary variables was found, but simple means indicated SOC gains of 13% (+ 4.7 Mg C ha-1) in 30 – 60 cm layer and 24% (+ 3.9 Mg C ha-1) in the 60 – 90 cm layer across both fields. Current rates of C harvest in forage and manure C addition are maintaining or increasing SOC. Regression kriging with easily acquired auxiliary variables offers a highly accurate method to monitor SOC stock changes over time to 30 cm depth.