Potash for heavy soils

Introduction

There is a general belief that heavy soils are rich in potash. Certainly this element is abundant in specific clay minerals which occur in some soils. Other clay minerals are less rich in K.

Heavy soils differ in the amount and type of clay which they contain and this is reflected in the quantity of their potash reserves. Fertiliser use must be adjusted according to the characteristics of individual soils and this note outlines the principles and possible strategies for different situations.

Potash cycle for Heavy Soils

As can be seen the quantity of immediately available K in soil solution is very small and this is replenished rapidly from exchangeable forms in response to plant demand. By comparison the non exchangeable K reserves in heavy soils are very large indeed but tend to be more slowly available.

The cover picture was kindly provided by Dowdeswell Engineering