Tillage systems for root and tuber crops in the tropics

Although limited information is available on tillage practices for root crops, published results show that tillage methods vary widely depending upon the specific root crop, the soil type, the previous vegetation, as well as the socio-economic conditions of farmers. These aspects are discussed in this review.

In general terms, it has been found that root and tuber crops are sensitive to soil compaction, inadequate aeration or poor drainage and therefore respond favorably to intensive tillage, followed by ridging or mounding. However, large differences exist between crops, with potato, sweet potato and yam requiring more intensive cultivation than cassava and taro. On light-textured soils, cassava can be grown without or with minimum tillage as long as weeds are controlled; in heavy or compacted soil cassava responds favorably to tillage and yields tend to increase when grown on ridges. In order to reduce erosion as well as production costs, cassava should be grown with as little tillage as possible as long as high yield can be maintained. Contour ridging and mulching are other practices that not only tend to increase yields but also reduce erosion losses.

Organized data for use in a classification of the tillage requirements of different soils for the various root crops is lacking. We suggest that research efforts should be directed towards the characterization of the physico-chemical and biological factors which determine the tillage requirements of a given soil for a given root crop.