Residue management practice effects on soil surface properties in a young wheat-soybean double-crop system

Approximately 25% of the soybean [Glycine max (L.) Merr.] grown in the mid-South is produced in a wheat (Triticum aestivum L.)-soybean double-crop system. Pre-soybean field preparations often consist of removing wheat residue by burning followed by conventional tillage (CT). However, crop residue burning has serious negative environmental consequences and will likely be outlawed in the future. Therefore, the objective of this study was to evaluate the short-term effects of alternative wheat-residue management practices, tillage [no-tillage (NT) and CT], burning (burn and no burn), and wheat-residue level (low and high), on soil surface properties after two full cropping cycles in a wheat-soybean double-crop production system on two silt-loam Alfisols in east-central Arkansas. Soil bulk density increased over time, but the increase was unaffected by imposed treatments. Changes in soil pH and electrical conductivity (EC) were generally unaffected by tillage or burning, whereas soil EC increased by 7% under the high and decreased by 8% under the low wheat-residue level treatment at one location, but not the other. Mehlich-3-extractable Mg and Zn increased more and Na decreased less under NT than CT at one location or the other. Soil organic matter and total N and C also increased more under NT than CT at one location, but not the other. The results of this study indicate that, in a wheat-soybean double-crop production system in a relatively warm and wet environment, numerous soil properties can be improved more under NT than CT and more when crop residues are left unburned than when they are removed by burning. Extended use of alternative wheat-residue management practices that improve soil tilth will result in more sustainable agriculture and likely increase production.