Skip to main content
Bull. Spec. CORESTA Symposium, Taormina, 1986, p. 52, A12, ISSN.0525-6240

A possible exception to the rule : irrigated flue-cured tobacco on black clay soils

STREUTKER A.
Tobacco and Cotton Research Institute, Rustenburg, South Africa
The black clay soils in South Africa are in several aspects similar to the Australian"black earths", the Indian"regur", pellic vertisols (FAO) and vertisols-pelloxerets (USDA). Fluctuation in rainfall (200-500 mm per growing season and 150 mm/3-5 days) and the low infiltration rate of these soils require surface drainage as well as supplementary irrigation for good tobacco production. Between 1967 and 1981 fourteen tobacco irrigation experiments were carried out. The treatments were furrow and ridge planting, furrow and sprinkler irrigation, three N-levels and three tobacco cultivars. During rather dry seasons there were significant differences in yield and quality of the tobacco crops. Yield increased with 15% from furrow planting to ridge planting and another 12% from furrow irrigation to sprinkler irrigation for ridge planting; a total increase from 2100 kg/ha to 2700 kg/ha. The total alkaloid value increased by 0,3% from furrow to sprinkler irrigation and fluctuated over the years between 1,3% and 2,0%. The red. sugar/total alkaloid ratio decreased to 10 under sprinkler irrigation and ridge planting compared to 20 for furrow irrigation. Although the management of sprinkler irrigation and N-application are now well known, irrigation scheduling by means of drip systems and fertigation, if at all practical on these black clay soils, has yet to be investigated.