Crop responses to topsoil replacement within eroded landscapes

Authors: Schneider, Sharon; CAVERS, CURTIS - Agriculture And Agri-Food Canada; Duke, Sara; SCHUMACHER, JOSEPH - Retired Non ARS Employee; SCHUMACHER, THOMAS - Retired Non ARS Employee; LOBB, DAVID - University Of Manitoba

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2021
Publication Date: 5/6/2021
Citation: Schneider, S.K., Cavers, C., Duke, S.E., Schumacher, J.A., Schumacher, T.E., Lobb, D.A. 2021. Crop responses to topsoil replacement within eroded landscapes. Agronomy Journal. 113:2938-2949. https://doi.org/10.1002/agj2.20635.
DOI: https://doi.org/10.1002/agj2.20635

Interpretive Summary: Conservation measures are critically needed to slow and even reverse soil erosion in order to protect the soil resource and improve global food security. In these studies, we evaluated targeted replacement of topsoil to rehabilitate eroded land. Approximately 15 cm of topsoil were moved from lower landscape positions, where soil accumulates during erosion to the upper slope, where soil is removed by erosion. Plant response was measured in the years that followed soil movement. Two sites were monitored: (1) a severely eroded landscape, where plant response was monitored for three years of soybean and three years of corn production, and (2) a moderately eroded landscape, where plant response was monitored for two years of soybean and two years of wheat production. Soil-landscape rehabilitation improved grain yields in a severely eroded landscape, but not a moderately eroded one. In the severely eroded landscape, addition of 15 cm of soil increased crop biomass by 25 to 95% on a kg ha-1 basis and increased grain yields by 20-49% (corn) and 12-59% (soybean), with the largest yield increases recorded in the most eroded landscape positions. Soil addition increased corn grain protein and test weight. No significant differences were observed in crop emergence rate or stand establishment, and evidence indicated that lower yields were due to a lower number of seeds produced in eroded positions. In the moderately eroded landscape, soil addition significantly increased crop biomass, but not grain yield. These experiments were conducted in relatively droughty years, and the lower slope was uncharacteristically the highest-yielding portion of the field. During this study, areas of soil removal produced lower yields than areas from which no soil was removed. Results from areas of soil removal may be partially an artifact of the plot design, and more research is needed to evaluate approaches to prevent a decline in productivity in areas of soil removal. The results of these studies indicate that soil-landscape rehabilitation may provide immediate and long-term benefits to soil productivity. Growers, land managers, and conservation planners can use these results to include soil-landscape rehabilitation as a valuable part of an overall conservation plan to preserve and restore productivity to severely eroded soils.

Technical Abstract: Approaches to restore productivity to eroded soils are urgently needed to sustain food security. We evaluated plant response to soil-landscape rehabilitation, in which approximately 15 cm of topsoil was moved from depositional landscape positions to the eroded upper slope. Crop response was monitored for six years of a corn-soybean rotation at a severely eroded site and for four years of a wheat-soybean rotation at a moderately eroded site; experiments were conducted in relatively droughty years. In the severely eroded landscape, addition of 15 cm of soil increased crop biomass by 25 to 95% on a kg ha-1 basis and increased grain yields by 20-49% (corn) and 12-59% (soybean), with the largest yield increases recorded in the most eroded landscape positions. Soil addition increased corn grain protein and test weight. No significant differences were observed in crop emergence rate or stand establishment, and evidence indicated that lower yields were due to a lower number of seeds produced in eroded positions. In the moderately eroded landscape, soil addition significantly increased crop biomass, but not grain yield. In both landscapes, yields were lower in areas of soil removal than in adjacent areas from which no soil was removed, which is likely at least partially an artifact of the plot design. While more research is needed to evaluate long-term impacts, the results of these studies show that soil-landscape rehabilitation may help alleviate the effects of past erosion and provide immediate benefits to the productivity of severely eroded soils.