IPI Research Topics No. 22 Potassium and chloride in crops and soils: The role of potassium chloride fertilizer in crop nutrition.

by U. Kafkafi, G. Xu, P. Imas, H. Magen and J. Tarchitzky.

Potassium chloride, KCl (mostly known in agriculture as muriate of potash, MOP) is the major potash fertilizer used in agriculture. Those who use MOP are well aware of the beneficial effects that potassium, in concert with other essential nutrients, has on yield, quality and stress resistance of crops.

However, there is still widespread imbalance in potash use with negative potassium balances in many cropping systems in most regions of the world. The main reasons for its inadequate use are less spectacular visual crop responses to potassium compared to nitrogen, disregard of quality in crop procurement, or simply, lack of knowledge.

Inadequate potassium use not only restricts the full exploitation of a crop's genetic potential but also the efficiency with which other inputs, especially nitrogen, are used. In addition, negative potassium balances mean that soil potassium reserves are being mined endangering long-term soil fertility.

The accompanying element in MOP, the chloride ion, is an essential plant nutrient required in small amounts, but concern is sometimes raised about its role in soil salinity.

IPI-Research-Topics No. 22 describes in detail the functions of potassium and chloride in the plant and hence their importance in crop production. The booklet also discusses the behaviour of potassium and chloride in soils, how best to manage the use of MOP in both dry land and irrigated cropping systems, and how to minimize salinity effects due to chloride.

The Research-Topics No. 22 (220 pages, 36 tables, 28 figures and 12 colored plates) can serve as a reference for soil and plant scientists, advisors and fertilizer planners.