Soil Carbon in the Sandy Soils of Wisconsin.

Forests (native, planted), agriculture, and grasslands are important land-use types found on sandy soils. We created a global database for sandy soils using the data from 80 research papers that had information on land-use and soil properties (pH, texture, SOC). On average, SOC content was the lowest in the soils under agriculture (5 g C/kg) and highest in the soils of the planted forest (21 g C/kg). The SOC stock was highest in the soils of the native forests (12 Mg C/ha) and lowest in the soils under agriculture (8 Mg C/ha). This database was then compared to two different farms in the central sands. The Central Sands of Wisconsin are predominantly used for irrigated agriculture and most soils are classified as Psamments and are composed of a minimum of 85% sand content. There was a small range in SOC values (6 to 11 g C/kg) and the SOC stocks were over 60 Mg/ha after 30 years of intensive cultivation. The carbon stocks in the central sands were greater than what has been found in the global database. In general, SOC stocks in sandy soils were high.