It's the Interamerican Institute for Cooperation in Agriculture, and it's basically an extension office. It's US funded and as such, they are more than willing to help Americans with their newly purchased fincas. I'm not sure if there's a size limit, or should I say minimum, but they offer consultations and on-site help (free of charge, of course) with everything from testing your land, to suggesting best money-making uses, free trees (Citrus I know of, maybe other kinds as well. I told James I wanted some pine and willow and he said maybe.), veterinarian services, lending of small equipment (like pumps for cleaning out your well) and much more.
They are located at Km 10 Carretera Masaya, walk-ins are fine, and they have English speakers on staff.
Their website is www.iicanet.org