This research paper demonstrates Web services based business process management system, developed to aid marketing of agricultural produce. For achieving relevance to real-life practice, we carefully follow the business process suggested in model act that is planned for implementation in all the Agricultural Produce Marketing Committees (APMC) throughout India. Our proposal exposes various business functionalities explained in the act, in the form of Web services that can also utilize the existing IT infrastructure of the APMCs. With the help of above mentioned and any other external Web services, a trader can execute a complete trading business process. We follow Web service orchestration specifications to achieve our objectives. We also demonstrate a complete business process that is initiated by a farmer with a mobile PDA involving trade of an agricultural produce in the market place.