1. College of Land and Environment, Shenyang Agricultural Univ.; Shenyang 110866 China
2. USDA-ARS, Dale Bumpers Small Farms Research Center; Booneville AR 72927
3. Crop, Soil and Environmental Sciences; Univ. of Arkansas; Fayetteville AR 72701
4. Crop Science Research Lab., USDA-ARS; 810 Hwy 12 East Mississippi State MS 39762
5. USDA-ARS, Poultry Production and Products Safety Research Unit; Fayetteville AR 72704
6. USDA-NRCS; Lincoln NE 68508