Soil structural stability assessment with the fluidized bed, aggregate stability, and rainfall simulation on long-term tillage and crop rotation systems

Authors: NOUWAKPO, SAYJRO - University Of Nevada; SONG, JUANLI - Northwest Agriculture And Forestry University; Gonzalez, Javier

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2017
Publication Date: 12/29/2017
Citation: Nouwakpo, S.K., Song, J., Gonzalez, J.M. 2017. Soil structural stability assessment with the fluidized bed, aggregate stability, and rainfall simulation on long-term tillage and crop rotation systems. Soil and Tillage Research. 178:65-71. https://doi.org/10.1016/j.still.2017.12.009.
DOI: https://doi.org/10.1016/j.still.2017.12.009

Interpretive Summary: Soil structure is an important indicator of soil susceptibility to erosion and a factor defining soil health. On cropland, tillage practices and crop rotations have shown to affect soil properties which affect soil erosion. Thus, the implementation of conservation practices is encouraged to reduce erosion and to improve soil health and water quality. We evaluated the effect of tillage and crop rotation on soil strength, aggregate stability and erosion from fields managed under chisel tillage (CT) and no-till practice (NT) with four rotations (continuous corn, continuous soybean, corn-soybean, and soybean-corn). No-till increased soil strength by 81% in the top 15 cm soil layer, compared to chisel tillage. Furthermore, NT increased the water-stable macroaggregates, an indicator of good soil structure, by 78%, compared to the chisel tillage. The effect of crop rotation was limited to that of residues present at the time of soil sampling with little influence of the preceding crop. Corn residues improved aggregate stability compared to soybean residues, by increasing both the 0-15 cm and 15-30 cm soil layers by 18% and 13%, respectively. Losses of sediments, an indicator of soil erosion, were consistent with the soil strength and aggregate stability experiments in that CT fields yielded 20 times more soil loss than NT fields. The effect of corn residue on aggregate stability showed a much greater soil loss in CT fields compared to NT fields, 380 versus 6.7 kg·ha-1 soil loss, respectively. Policymakers and farmers can use the information in this study in planning conservation practices to improve soil health and reducing soil erosion.

Technical Abstract: The formation of stable soil aggregates is an important indicator of soil susceptibility to erosion and a factor defining soil health. On cropland, tillage practices and crop rotations have shown to control soil biophysical properties with potential consequences on erosion susceptibility. Thus, the implementation of conservation practices to reduce soil erosion and to improve soil health and water quality is desired. In this paper, a suite of techniques was used to evaluate the effect of tillage and crop rotation on soil cohesion, aggregate stability, and sediment loss. Fluidized bed experiments to estimate soil cohesion and aggregate stability tests were performed on samples collected from plots managed under chisel tillage (CT) and no-till practice (NT) and four rotations (continuous corn [Zea mays], CC; continuous soybean [Glycine max], BB; corn-soybean, CB; and soybean-corn, BC). At the same site, rainfall simulation experiments were conducted and sediment loss was correlated to fluidized bed and aggregate stability experiments. No-till practice had a positive effect on soil cohesion in the 0-15 cm soil layer; average pressure drop at fluidization (Delta Pf ) values were 30.82 Pa for NT and 17.04 Pa for CT and a higher proportion of stable macroaggregates was present under NT practice (51.4% vs. 28.9%). The effects of crop rotation on the parameters measured in this study were essentially limited to that of residue present at the time of sampling. Corn residues were associated with improved soil aggregation in both the 0-15 and 15-30 cm soil layers with 18% and 13% more aggregates than soybean residues, respectively. Sediment losses from the rainfall simulation were consistent with fluidized bed and aggregate stability experiments in that CT fields yielded 20 times more sediment loss than NT fields. The effect of corn residue on aggregate stability was significantly higher in chiseled fields: 380 kg ha-1 whereas NT practice only yielded 6.7 kg·ha-1 sediment loss. The information in this study can be used by policymakers and farmers when planning conservation practices to reduce soil erosion and to improve soil health.