Soil and Crop Effects of a Subsurface Fluid Lime Applicator

Authors: Casanova, Joaquin; LETOURNEAU, MELISSA - Former ARS Employee; Heineck, Garett; Hansen, Jeremy; CARLSON, JENNY - Washington State University; Huggins, David

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2024
Publication Date: 5/25/2024
Citation: Casanova, J.J., Letourneau, M.K., Heineck, G.C., Hansen, J.C., Carlson, J.L., Huggins, D.R. 2024. Soil and Crop Effects of a Subsurface Fluid Lime Applicator. Applied Engineering in Agriculture. 40(3):351-362. https://doi.org/10.13031/aea.15939.
DOI: https://doi.org/10.13031/aea.15939

Interpretive Summary: Pacific Northwest soils are becoming more and more acidic. This is driven by agricultural practices such as nitrogen fertilizers and removal of crop residues after harvest. To fix acidified soils, farmers can apply calcium carbonate (lime), but it is usually applied on the surface under no-tillage which does not correct acidity below the surface or incorporated using tillage which can increase the hazard for soil erosion. We present the design and test results of a subsurface applicator for fluid lime that maintains surface residues that protect soil from erosion while targeting soil acidity issues that develop under no-tillage. A technology like this is useful to farmers and groups interested in conservation and soil health as it effectively places fluid lime where soil acidity is most apparent, beneath the soil surface, and results in improved efficiency of lime use to address soil acidity in no-tillage.

Technical Abstract: Deep-banding ammonia and urea-based nitrogen fertilizers under continuous no-tillage can result in stratified acidification at the fertilizer-injection depth. Currently, producers address this acidification through primary tillage operations that mix the soil and dilute the acidification, but increase the hazard for soil erosion. Typically, lime is required to ameliorate soil acidity, however, surface applied lime does not immediately address subsurface acidity and often tillage is used to incorporate lime and correct acidified layers created through deep-banded fertilizer placement under no-tillage. Here, we designed, developed, and tested a subsurface applicator for fluid lime that can target specific soil depths and rates. The liming system was tested in Eastern Washington on a field that had been under continuous no-tillage for 25 years, had stratified soil acidity and was to be planted to winter pea, a crop known to be sensitive to acid soil conditions. Soil pH and carbon distribution, microbial changes, biomass, LAI, and UAV imagery were monitored. Results indicated that the lime targeted the seed zone and raised pH significantly, effects on biomass were marginally significant, and effects on LAI and vegetation cover were not significant. Topography had a significant effect on all variables, due to changes in applicator effectiveness with changes in soil mechanics, meaning as-applied rates varied from desired rates.