Identifying Soil Health Indicators for Management of a Sodic Soil.

Soil health awareness has received national and international recognition through numerous programs conducted by the United States Department of Agriculture, Food and Agriculture Organization of the United Nations, and other international programs. As agriculture expands onto marginal lands, ensuring soils remain productive is imperative. This research employs indicators of soil health to monitor the impact of change in land use and remediation of sodicity in an Exline soil (fine, smectitic, frigid Leptic Natrudolls) with and without subsurface water management and amendments (gypsum, sugarbeet lime). Our study utilizes a novel application of successional vectors in ordination space to compare the direction and magnitude of shifts in soil health parameters. Baseline soil samples were taken in a hay field in fall of 2012. The field was converted to corn production in 2013 during which samples were collected in spring, at silking and harvest from 45, 24 x 24 m plots. A suite of 23 biological (percent total soil carbon and soil enzyme assays), chemical (electrical conductivity (EC), pH, sodium adsorption ratio (SAR)), and physical (texture) properties were reduced to a minimum data. Nonmetric Multidimensional Scaling and perMANOVA were used to identify differences amongst treatment combinations. Shifts in ordination space between treatments were a function of time, conversion from perennial to annual cropland, and amendments. Successional vectors of the gypsum amendments converged in a cluster separate from lime and control treatments. Ordination axis 1 explained 51% of the variation and was related to the enzymes, nitrate reductase, B-glucosidase, arylsulfatase, and alkaline phosphatase. Axis 2 explained 39% of the variation and was related to pH, EC, SAR, Mg and Ca concentrations. These 9 soil properties can be measured and used to monitor land management decisions and assess their impacts on soil health on the Exline soil series.