Chicken manure increased concentration of organic sulfur compounds in field-grown onions

Abstract

A field study was conducted at Kentucky State University (KSU) Research Farm. The soil in five plots was mixed with sewage sludge, five plots were mixed with yard waste compost, five plots were mixed with laying hen manure each at 15 t acre⁻¹, and five unamended plots that never received soil amendments were used for comparison purposes. Plots were planted with onion, Allium cepa L. var. Super Star-F1. The objectives of this investigation were to: 1) determine the concentrations of two organosulfur compounds (dipropyl disulfide and dipropyl trisulfide) in onion bulbs and 2) investigate the effect of mixing soil with three amendments (sewage sludge, yard waste, and chicken manure) on the concentration of dipropyl disulfide and dipropyl trisulfide in onion bulbs. Gas chromatographic/mass spectrometric (GC/MS) analyses of onion oil in chloroform extracts revealed the presence of two major fragment ions that correspond to dipropyl disulfide and – trisulfide. Concentration of these two organic sulfur compounds was greatest (1.5 and 0.8 mg 100 g⁻¹ fresh weight, respectively) in onion bulbs of plants grown in chicken manure and lowest (0.4 and 0.07 mg 100 g⁻¹ fresh weight, respectively) in onion bulbs of plants grown in yard waste compost treatments. We concluded that chicken manure could be exploited in growing onions with health-promoting properties.

Keywords:

• Allium cepa
• dipropyl disulfide
• dipropyl trisulfide
• soil amendments
• sewage sludge

Acknowledgments

We thank Jami Rogers and Eric Turley for their assistance in preparing onion extracts. This investigation was supported by a grant from (United States Department of Agriculture) USDA/CSREES to Kentucky State University under agreement No KYX-10-08-43P.