In a world where the notion of ‘sharing of knowledge’ has been gained much prominence in the recent past, the importance of information and communications technologies (ICTs) to promote sustainable agriculture, especially when combined with mobile and open source software technologies is discussed critically. On this rationale, this study was carried out to explore the applicability of the concept of converging ‘Free and Open Source Software (FOSS)’ to promote sustainable knowledge sharing amongst the agricultural communities in Sri Lanka. A multi-stage community consultative process with a set of designated officials (“Sponsors”) and a series of semi-structured questionnaire survey with a cross section of smallholder agriculture farmers (n=246), were carried out in the Batticaloa, Kurunegala and Puttalam districts to gather the baseline data. This was followed by a number of field experiments (“Campaigns”) with the farmers (n=340) from same geographical areas. The two FOSS, namely: (1) “FrontlineSMS” for ‘Text Messaging’ and (2) “FreedomFone” for ‘Interactive Voice Responses’, were applied to evaluate the effectiveness of knowledge sharing within the farming communities. It was found that FOSS intervention increases the ‘Text messaging’ and ‘Voice Call’ usage in day-to-day agricultural communication by 26 and 8 percent, respectively. The demographic factors like age and income level of the farmers has positively influence on the knowledge sharing process. And also the ‘Mobile Telephony’ was the most extensive mode of communication within the communities. The outcome of analysis, as a whole, implies that, with a fitting mechanism in place, this approach can be promoted as a “drive for positive changes” in agriculture-based rural communities in developing countries like Sri Lanka, and those in South and East Asia with similar socio-economic and cultural perspectives.