ABSTRACT
The growth of plants depends on inputs from both the soil and the atmosphere. The elements in plant material are obtained by Carbon and oxygen is obtained from CO2 in the atmosphere, being assimilated by photosynthesis in the leaves. Hydrogen and oxygen are taken up as water through the roots. The forms and average amounts of potassium in 20 British soils. There are very large reserves of potassium in soil minerals, particularly in heavy-textured soils. The forms of potassium in soils. Vermiculite is the weathered part of the clay crystal. Potassium that can be slowly released is in the iolite adjacent to the expanded region. The amount of slowly exchangeable K+ taken up over any time period can be found from the potassium budget. In general, N is required in the largest amounts, followed by potassium, with the remaining nutrients all required in smaller amounts but with much variation between crops.
