The Collaborative International Dictionary of English v.0.48:

Geoponics \Ge`o*pon"ics\, n. [Gr. ?: cf. F. g['e]oponique.]
   The art or science of cultivating the earth; agriculture.
   --Evelin.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "geoponics":
   agrarianism, agricultural geology, agriculture, agrology,
   agronomics, agronomy, contour farming, cultivation, culture,
   dirt farming, dry farming, dryland farming, farm economy, farming,
   fruit farming, grain farming, husbandry, hydroponics,
   intensive farming, mixed farming, rural economy, sharecropping,
   strip farming, subsistence farming, tank farming, thremmatology,
   tillage, tilth, truck farming