Impact of Age, Management, and Soil Properties on C and N Accumulation in Turfgrass Soils of Wisconsin.

Turfgrass can accumulate up to twice the soil organic C and comparable quantities of N of the agricultural crops that they replace. Understanding how soil organic matter accumulates and mineralizes is important for making adjustments to fertilizer guidelines as well as for the standpoint of soil management. No study has used a multi-site, replicated chronosequence to describe C and N accumulation and mineralization from turfgrass soils across a broad area. The objective of this study was to characterize turfgrass soil organic C and N storage in Wisconsin, using golf course roughs and fairways as a model system. Thirty-seven golf courses (9 to 119 years of age) on Alfisols in Southern and Northern Wisconsin were selected for this study. Golf course fairways and roughs were sampled at each site to gauge the effect of fertilization. Fairways received an average of 109 kg N ha^-1 annually, while roughs received 41 kg N ha^-1 annually. Soil organic C ranged from 24 to 84 Mg ha^-1, with a mean of 46 Mg ha^-1. Soil organic N ranged from 2.4 to 7.8 Mg ha^-1 with a mean of 4.5 Mg ha^-1.  Surprisingly, soil properties did not influence soil organic C and N accumulation; however soil organic C and N increased with both age of site and cumulative N fertilizer applied. Land use history was an important factor in determining soil organic C and N content trends over time with decreased soil organic C and N in former forest and increased soil organic C and N in former cropland. The broad scale characterization of C and N of this study will allow for the evaluation and calibration of predictive models of C and N which may eventually be useful for making fertilizer recommendations.