A large number of farms in developing countries are smallholder farms. In China, this trend is expected to persist for the foreseeable future. However, smallholder farmers in China face several challenges, including excessive fertilizer use for higher yields, low levels of education, aging and limited credit information. Moreover, they are struggling with a digital divide, which hampers their agricultural productivity and limits their economic and social integration. Agricultural services based on information and communication technology (ICT) can bridge the digital gap, but are hindered by complexity and cost. Aiming at serving the numerous smallholders and building a sustainable digital ecosystem, this paper presents a distributed agriculture service system that provides decision support to farmers by considering both social and physical information. The system is lightweight, low cost and intelligent, managing personnel, plots, crops and equipment using technologies such as wireless sensor networks, cloud computing and distributed systems architecture. Services include crop planning, production guidance, equipment control, etc. User terminals include computers, mobile applications and Applets. A case study on fruit production in a typical solar greenhouse illustrates the system's functionality. The distributed agricultural services system can well support smallholder farmers and promote sustainable agriculture.