Use of zone sampling to measure soil health: Differentiating between spatial variability and the effects of soil conservation practices

Authors: Fortuna, Ann Marie; STEINER, JEAN - Kansas State University; Moriasi, Daniel; Starks, Patrick

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Abstract Only
Publication Acceptance Date: 7/12/2020
Publication Date: 10/8/2020
Citation: Fortuna, A., Steiner, J.L., Moriasi, D.N., Starks, P.J. 2020. Use of zone sampling to measure soil health: Differentiating between spatial variability and the effects of soil conservation practices[abstract]. In: ASA-CSSA-SSSA International Annual Meeting. Translating Visionary Science to Practice, Novemeber 2020. https://scisoc.confex.com/scisoc/2020am/meetingapp.cgi/Paper/127747.

Interpretive Summary: Abstract only

Technical Abstract: Most of the research relevant to land managers is conducted at field to watershed scales with areas of one or more hectares. However, many biogeochemical processes vary significantly within a few meters. Creating replicate sampling zones that define landform complexes representing uniform zones of management without the confounding effects associated with inherent spatial variability can aid researchers in addressing the issue of scale. Our experiment established in 1976 contains eight 1.6 ha watershed treatments in paddocks that are representative of southern tall grass prairie or winter wheat (Triticum aestivum) in tilled or reduced tillage systems with and without forage cover crop mixes. A class I soil survey was conducted in 2018 and watersheds were grid sampled across a catena creating four replicate sampling zones per landscape position enabling a randomized complete block design to be applied across the watersheds. This design allowed for testing of interactions among management and landscape effects as well as to obtain means and standard errors for soil health measurements. Additionally, samples were analyzed using principle components analysis. A suite of soil health measurements was taken randomly within 4 replicate blocks, 4.6 m x 3.8 m at top, side and toe slopes with a hydraulic probe. Baseline measurements included: Mehlich 3 P, Ca+2, Mg+2, K+, micronutrients, soil texture, bulk density, pH, soil organic C and N, particulate organic matter and the resistant fraction of soil organic C. The majority of variables associated with soil classification varied with landscape position and depth. These included clay content, base saturation (Ca, Mg, K) and pH as well as S and P. Carbon and N fractions varied with land use and or depth. Our initial efforts to parameterize the inherent spatial variability of these watersheds in order to determine the effects of land management on soil health were successful.