From soilto life

Potassium and efficient water use

Farmers can prepare the soil and the plant for a limited supply of water and thus prevent drought stress. As well as selecting a suitable strain, or variety, and soil preparation, plant nutrition in particular has a substantial impact on efficient water use.

Controlled transpiration:

Potassium combined with magnesium ensures that the plant can use water sparingly because less water evaporates unproductively. Potassium is essential thanks to its osmotic effect/function when opening and closing the stomata and therefore plays an important role in the plant’s water management. Because the stomata do not function in the optimum way when there is a deficiency of potassium, withering is a typical symptom of potassium deficiency.

Efficient photosynthesis:

Photosynthesis and subsequently the transport of created carbohydrates constitute a sequence of complex processes. Disturbances of these processes therefore quickly result in reduced growth and often also lower yields. Magnesium acts in different ways on the photosynthesis and transport of assimilates. The most commonly known function of magnesium is that of central chlorophyll atom (leaf green). Consequently, magnesium is essential for optimum light absorption by the plant, a prerequisite for high production of biomass. This is also the reason why a serious magnesium deficiency results in the withering of leaves, also referred to as chlorosis.

A well-developed root system:
What effects does inhibited distribution of carbohydrates have on the plant? Withering of the leaves, for example, is only a very late symptom of magnesium deficiency. If this happens, a lower yield shall most definitely occur. The growth of the roots is limited at a much earlier stage, even before the growth of the shoots is inhibited (Fig. 5). A healthy root growth is therefore important for access to water and nutrients, especially in adverse growth conditions.

Improve water-retention capacity:
The water-retention capacity of the soil is largely determined by the pores in the soil. For growth of plants the pore size distribution of the soil is extremely important. Soil pores which are too small bind the surface water to such an extent that plants can no longer absorb it. If the pores are too large the water will seep into deeper soil layers where the plant’s root system is unable to reach. The research results demonstrate that a good supply of potassium from the soil increases the available field capacity. The available field capacity (also referred to as soil water/moisture supply) indicates the quantity of available water for plants which the soil can store.