Influence of long-term feedlot manure amendments on soil hydraulic conductivity, water-stable aggregates, and soil thermal properties during the growing season
Miller, J.J., Beasley, B.W., Drury, C.F., Larney, F.J., Hao, X., Chanasyk, D.S. (2018). Influence of long-term feedlot manure amendments on soil hydraulic conductivity, water-stable aggregates, and soil thermal properties during the growing season. Canadian Journal of Soil Science, [online] 98(3), 421-435. http://dx.doi.org/10.1139/cjss-2017-0061
Plain language summary
Long-term application of feedlot amendments to a clay loam soil does not necessarily provide the positive benefits expected from increased organic matter as perhaps expected. The most likely explanation for this is that this Dark Brown Chernozemic and clay loam soil already has a well-developed A horizon with considerable organic matter, good physical structure, and fine-texture. Therefore, there may be little potential for improving the physical properties of these soils with feedlot amendments. Although beef producers will continue to apply manure amendments to already productive soils, our findings suggest that improvements in the physical properties of these soils may be limited to reduced bulk density. In addition, lower thermal conductivity of surface soil for amended than unamended soils may act as an insulator and reduce radiant heat flow deeper into the soil, which might have a negative effect on crop growth.
Long-term application of feedlot manure to cropland may change the physical properties of soils. We measured selected soil (surface) physical properties of a Dark Brown Chernozemic clay loam where different amendments were annually applied for 15 (2013), 16 (2014), and 17 (2015) yr. The treatments were stockpiled (SM) or composted (CM) manure with either straw (ST) or wood-chip (WD) bedding applied at three rates (13, 39, and 77 Mg ha−1) and an unamended control. The effect of selected or all treatments on selected properties was determined in 2013-2015. These properties included field-saturated (Kfs) and near-saturated hydraulic conductivity or K(ψ), bulk density (BD), volumetric water content, soil temperature, soil thermal properties, and wet aggregate stability. The hypotheses that selected soil physical properties would improve more for treatments with greater total carbon in the amendments (SM > CM, WD> ST) was rejected. The exceptions were significantly (P ≤ 0.05) lower soil BD for SM than CM and WD than ST for certain dates, and lower soil thermal conductivity for WD than ST. Most soil physical properties generally had no response to 15-17 yr of annual applications of these feedlot amendments, but a few showed a positive response.