Zinc, copper, iron, manganese and boron uptake by cotton on cracking clay soils of high pH

Abstract

To determine the extent and timing of uptake of some micronutrients in cotton, 35 cotton crops were surveyed in 1 season and detailed sampling of whole plants and node segments at 1 site was done in 2 seasons. The soils were cracking clays of high pH. Meaned over all sites, iron was taken up in greatest amounts (600 g/ha), followed by manganese (450 g/ha), boron (200 g/ha), zinc (60 g/ha) and copper (20 g/ha). Based on critical values established elsewhere, none of the sites was judged to be primarily deficient or excessive in any of these micronutrients, but Zn status was the lowest in plant tissue and Mn the highest. At the levels found, there were poor relationships between soil tests and subsequent uptake of each micronutrient. Copper, boron and zinc were taken up throughout the season but Fe uptake was almost complete by flowering. It was calculated that continued uptake of Zn throughout the season was necessary, as redistribution from leaves was insufficient to sustain boll requirements. An analysis of fuzzy seed and lint indicated that 3 g of copper, 12 g manganese, 13g zinc, 21g boron and 66 g of iron are removed at harvest for each bale (225 kg) of lint.