Soil constraints to productivity improvement

Abstract

Evidence from investigations into fumigation, fungicide application, fallowing and growth of sugarcane on recently cultivated soils strongly suggests that yields in established cane growing areas are being restricted by soil-borne biological factors. The yield restriction may be in the order of 20-40%. The soil-borne pathogens Pachymetra, Pythium and also nematodes probably account for a proportion of this yield loss, but other unknown deleterious microorganisms may be involved. In most cases nutrient deficiencies do not appear to be limiting growth. Zinc deficiency which has recently been identified in northern districts may be affecting growth on some soil types. Excesses of some nutrients, such as phosphorus may be interacting with other nutrients and/or soil-borne pathogens. A multi-disciplinary study of soil-borne limits to yield in sugarcane is needed to identify the major factors involved and to develop satisfactory treatments to ameliorate the problem.