Animal Manure Improved Antioxidants in Two Brassicaceae Plants: Arugula and Mustard

The use of animal manure in agricultural production systems is an affordable way to reduce dependence on inorganic fertilizers and protects natural water resources. Arugula (Eruca sative) and mustard (Brassica juncea) were field-grown under four soil management practices: 1) control (no-mulch untreated soil); 2) sewage sludge (SS); 3) horse manure (HM); and 4) chicken manure (CM) amended soils. The objectives of this investigation were to assess the impact of mixing native agricultural soil with animal manure on i) arugula and mustard yield, ii) arugula and mustard vitamin C, total phenols, and soluble sugars content, and iii) to respond to Kentucky farmers concern, if animal manure could reduce dependence on inorganic fertilizers and provide an alternative source for improving soil and plant nutrient status. Regardless of crop type, SS, CM, and HM significantly (P< 0.05) increased vitamin C (ascorbic acid) content in arugula and mustard leaves by 82, 90, and 31%, respectively. Whereas, SS, CM, and HM significantly (P< 0.05) increased total phenols by 77, 70, and 36%, respectively compared to no mulch bare soil. The increased costs of commercial inorganic fertilizers and release of large amounts of SS, CM, and HM worldwide have made cropland application of this waste an attractive disposal option.