Assessment of physical properties for cover crop and manure applied soils in Idaho’s Magic Valley

Authors: KRUGER, KEVIN - University Of Idaho; Krecker-Yost, Jenifer; Leytem, April; Dungan, Robert - Rob; MOORE, AMBER - Oregon State University; SCHOTT, LINDA - University Of Idaho

Submitted to: Waste to Worth Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/27/2022
Publication Date: 3/7/2022
Citation: Kruger, K., Yost, J.L., Leytem, A.B., Dungan, R.S., Moore, A.D., Schott, L.R. 2022. Assessment of physical properties for cover crop and manure applied soils in Idaho’s Magic Valley. In: Waste to Worth Conference, April 18-22, 2022, Oregon, OH. 138171.

Interpretive Summary: Idaho ranks in the top 10 in the US for dairy, potato, barley, hay, sugarbeet, corn silage, and dry bean production, and the highest producing region is South Central Idaho. The soils in this region are prone to crusting, have low organic matter, and are high in calcium carbonates making these soils unique to much of the United States. Thus, the overall goal of this project was to identify management practices that enhance soil health physical properties in the Magic Valley. The Long-Term Manure and Cover Crop study sites were located on the USDA-ARS Northwest Irrigation & Soils Laboratory farm in Kimberly, Idaho. At the Long-Term Manure study, three different amounts of dairy manure were applied annually or biennially, and the cropping rotation was common for the region. At the Cover Crop study, continuous corn was used, and triticale was used as a winter forage cover crop in half of the plots. Soil physical properties (soil aggregate stability, runoff rate, bulk density) were measured at both study sites. No differences were found at Long-Term Manure, and this is possibly due to intensive tillage and harvest practices which destroys the soil structure. At Cover Crop, all three treatments had a higher aggregate stability when compared to the control when using the Cornell Sprinkle Infiltrometer. There were also differences between the treatments in bulk density from 0-5 cm. These results give insight into which physical properties are sensitive to management changes in the Magic Valley and should be assessed in the future.

Technical Abstract: Idaho ranks in the top 10 in the US for dairy, potato, barley, hay, sugarbeet, corn silage, and dry bean production, and the highest producing region is South Central Idaho. The soils in this region are prone to crusting, have low organic matter, and are high in calcium carbonates making these soils unique to much of the United States. Thus, the overall goal of this project was to identify management practices that enhance soil health physical properties in the Magic Valley. To address this goal, soil aggregate stability, runoff rate, bulk density, and compaction were measured at two field sites located on the USDA-ARS Northwest Irrigation & Soils Research Laboratory farm in Kimberly, Idaho. Long-Term Manure study was established in 2013 and had eight treatments: annual application of solid dairy manure at a rate of (i) 18, (ii) 36, and (iii) 52 Mg ha-1 (dry weight), biennial application of solid dairy manure at a rate of (iv) 18, (v) 36, and (vi) 52 Mg ha-1 (dry weight), (vii) application of inorganic fertilizer, and (viii) no amendments (control). The Cover Crop study was established in 2016 and tillage was the main experimental factor (strip till vs disk/chisel plow) and treatment was the sub-factor (cover crop, cover crop with manure, manure, and control). Two methods (wet sieving and Cornell Sprinkle Infiltrometer) were compared for accessing soil aggragate stability among the two studies. No differences in aggregate stability were found when the wet sieving method was used among treatments for both studies. However, the Cornell Sprinkle Infiltrometer method was found to be statistically different at an operational height of 30 cm among treatments at mean values of 3.73 ± 0.36 mm (cover crop with manure), 3.67 ± 0.38 mm (cover crop only), and 3.70 ± 0.30 mm (manure only) as compared to the control (3.13 ± 0.46 mm) for the Cover Crop study. Significant differences in rainfall before runoff were found between treatments in the Cover Crop study, and cover crop with manure (14.6 ± 1.4 cm) was higher than the control. Differences in bulk density were also found from 0-5 cm in the Cover Crop study. No differences were found in the Long-Term Manure study. These results give insight into which physical properties are sensitive to management changes in the Magic Valley and should be assessed in the future.