Cultivation legacies in soils after rehabilitation seeding in the Great Basin, USA

Authors: MORRIS, LESLEY - Oregon State University; Monaco, Thomas; Blank, Robert - Bob; Sheley, Roger

Submitted to: Arid Land Research and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2015
Publication Date: 4/27/2016
Citation: Morris, L.R., Monaco, T.A., Blank, R.R., Sheley, R.L. 2016. Cultivation legacies in soils after rehabilitation seeding in the Great Basin, USA. Arid Land Research and Management. 30:362-374.

Interpretive Summary: Integration of knowledge about impacts of historical cultivation on soils for restoration planning is limited even though these legacies can affect land productivity and future land uses for decades. Old fields are often actively transformed through restoration, afforestation or rehabilitation seedling. Rehabilitation seeding with the introduced perennial grass crested wheatgrass (Agropyron cristatum) was employed on about 2 million hectares in the western U.S., including old fields in the Great Basin desert region. Seeding continues to be the primary treatment in restoration today, yet little is known about how the underlying cultivation legacies affect these soils over the long term. We studied sites where rehabilitation seedings overlapped old fields and adjacent noncultivated land to compare soil properties including soil texture, pH, soil organic carbon (SOC), nitrogen (N), and C:N ratios. Because these sites were identical in all aspects except former cultivation, our approach allowed us to test the hypothesis that cultivation legacies can be detected in the soil today, and explore which soil properties most strongly reflect cultivation legacies using discriminant and principal components analyses. Discriminant analysis separated soils between the two land-use conditions with 95% confidence at all four sites. Of the six soil properties, SOC, N, and C:N ratios were most important for distinguishing the cultivation legacies at three sites, while soil pH was most important in one site. These results show that soils remain altered in these formerly cultivated sites even after being reseeded, suggesting that future productivity and management will also be affected.

Technical Abstract: Integration of knowledge about impacts of historical cultivation on soils for restoration planning is limited even though these legacies can affect land productivity and future land uses for decades. Old fields are often actively transformed through restoration, afforestation or rehabilitation seeding. Rehabilitation seeding with the introduced perennial grass crested wheatgrass (Agropyron cristatum) was employed on about 2 million hectares in the western U.S., including old fields in the Great Basin desert region. Seeding continues to be the primary treatment in restoration today, yet little is known about how the underlying cultivation legacies affect these soils over the long term. We studied sites where rehabilitation seedings overlapped old fields and adjacent noncultivated land to compare soil properties including soil texture, pH, soil organic carbon (SOC), nitrogen (N), and C:N ratios. Because these sites were identical in all aspects except former cultivation, our approach allowed us to test the hypothesis that cultivation legacies can be detected in the soil today, and explore which soil properties most strongly reflect cultivation legacies using discriminant and principal components analyses. Discriminant analysis separated soils between the two land-use conditions with 95% confidence at all four sites. Of the six soil properties, SOC, N, and C:N ratios were most important for distinguishing the cultivation legacies at three sites, while soil pH was most important in one site. These results show that soils remain altered in these formerly cultivated sites even after being reseeded, suggesting that future productivity and management will also be affected.