Alternatives to Bench Terraces on the Hillsides of Jamaica: II. Cropping Systems and Yields

Abstract

Various cropping systems for yam production were tested in the runoff plots at the Olive River Watershed where soil losses were measured. Yellow yam yields ranged between 42 and 63 t/ha, but differences were not significant for either of the two experimental years. Marketable yields were 47% to 57% of the gross yields. When yam was intercropped with Irish potato, gross yields of potato ranged from 12 to 14 t/ha. Marketable yields were 80 to 85% of the gross yields. The lower yam yields in treatments with more than one intercrop were offset by the extra cash flow produced by the intercrops. When the 2-year data were pooled, significant yield differences between treatments were obtained, indicating that intercrops affect yam yields adversely. The Napier grass buffer strip produced 42 to 48 t/ha/yr (green weight). Alternative soil conservation measures, other than bench terracing, such as hillside ditches and grass buffer strips, and intercropping with yam, increased production and crop diversification in hillsides; are relatively cheaper, simpler, easier to construct, and very effective in terms of soil conservation in the hillsides.