EFFECTS OF HETEROGENEOUS NUTRIENT SUPPLY ON ROOT-GROWTH AND NUTRIENT-UPTAKE IN RELATION TO NUTRIENT SUPPLY ON DUPLEX SOILS

Most duplex soils in Western Australia are characterised by multiple nutrient deficiencies. Applications of micronutrients, as well as the macronutrients phosphorus, potassium, nitrogen and sulfur, have been essential for crop and pasture production on these soils. Duplex soils are characterised by heterogeneity in the distribution of mineral nutrients with depth. Additionally, there is heterogeneity both vertically and horizontally in suitability of soil conditions for root growth. There are at least 2 consequences of this heterogeneity for the mineral nutrition of plants on duplex soils. First, there are important effects of localised nutrient supply on root growth and nutrient uptake. Second, identification of nutrient deficiencies by soil and plant analysis is complicated by variation in nutrient supply through time and with depth. These 2 consequences are examined.