Correlations between soil abiotic factors and soil oxygen concentrations were non-significant in 2013, but will be repeated in 2014. However, numerous significant relationships were observed between environmental/weather parameters and soil oxygen content. In general, significant positive correlations were observed between maximum air temperature, solar radiation, average daily/maximum wind speed, and evapotranspiration and soil oxygen content. However, significant negative correlations were observed between relative humidity and soil oxygen content.

There were no correlations between soil oxygen content and SDS severity. However, pre-planting pH and sand content were significant and negatively correlated to SDS severity at two of the census dates. Silt and clay content were positively and significantly correlated to SDS severity at two of the census dates. This result suggests that planting on heavier soil types result in greater SDS severity. Irrigation treatments (interval and amount) did not have a significant effect upon SDS severity, however genotype (SDS tolerant vs. SDS susceptible) was significant (P < 0.0001).

Unexpectedly, there were negative and significant correlations between F. virguiliforme populations and SDS severity when measured at two census dates and overall (AUDPC). Correlations between soil abiotic and biotic properties were complex and will require additional years to bear out. Yield obtained from plots at the Rossville, Kansas SDS experiment site at the end of the 2013 growing season were significantly lower in the SDS susceptible variety regardless of irrigation treatment, i.e. 51-54% of the SDS resistant variety (P < 0.0001). As with charcoal rot, interval/timing of irrigation has a significant effect upon yield (P = 0.0074), with V4-V5 irrigations having the greatest impact upon yield. In general, when NDVI measurements were obtained from plots, the SDS-tolerant variety has significant higher (P < 0.0001) values than the SDS-susceptible variety.