Using water efficiently

Seasonal dry periods are a key risk for agriculture. Dry and hot periods in spring and early summer have increased in Germany and other European countries. In the future, climate change will continue and weather extremes will occur more frequently.

This will have dramatic consequences for the cultivation of agricultural crops. Weather extremes expose the plants to high stress, increase the risk of yield losses and therefore directly affect the economic success of any agricultural business.

Yet there are good ways of minimizing the risks.In addition to the selection of crops and varieties appropriate to the location and suitable cultivation methods, plant nutrition has a significant influence on plant's stress resistance.

In an extensive research project conducted in cooperation with the universities of Giessen, Halle, Kiel and Istanbul, K+S has demonstrated that the use of potassium and magnesium as fertilizers increases water use efficiency. The exact relationships have been explored in detail at the Institute of Applied Plant Nutrition, or IAPN in short. The IAPN is a joint research institute operated by the Georg-August-University of Göttingen and K+S.

The result of the research project: crops withstand drought stress better with potassium and magnesium - water use efficiency increases. There are several reasons for this:

• Potassium plays an important role in the water balance of the entire plant and regulates the function of the stomata on the underside of the leaves. The available water is efficiently used by the plant for biomass production via well-regulated transpiration.
• Potassium and magnesium are important for photosynthesis and promote the transportation of assimilates deriving from photosynthesis to the roots and yield organs. Therefore, both nutrients ensure good root growth and, at the same time, successful yield formation.
• A strong root system, which can absorb water from deeper soil layers, protects plants even during prolonged drought stress.
• Potassium increases the water storage capacity of the soil so that less water seeps away unused and is therefore available to the plants for growth and yield formation.

Due to potassium and magnesium, resistance increases to drought stress and good yields can be achieved even in the event of a reduction of the supply of water.

Sulfur is a component of the metabolic product glutathione. This acts as an antioxidant and renders the oxygen radicals that are produced during drought stress harmless in order to prevent consequences for cells, such as the formation of necrosis. A demand-oriented supply of sulfur therefore enables the plant to optimally maintain its physiological processes even under drought stress and to avoid or at least minimize yield losses.

Balanced fertilization with potassium, magnesium, and sulfur in a water-soluble form that is immediately available to plants provides crops exactly what they need for high water use efficiency.

Take sugar beet, for example: Field tests by K+S and research partners show that fertilizing with 300 kg of grain potash (40 % K2O, 6 % MgO and 12.5 % SO3) per ha reduces water consumption per kilogram of white sugar by 14 percent. For this purpose, the water uptake of the beet roots was measured in fertilized and unfertilized variants and set in relation to the sugar yield.

Potassium, magnesium, and sulfur are essential for growth and yield formation - not only during periods of drought. Fertilization pays off even under optimal growth conditions. It is particularly effective in years with pronounced dry periods: the plant is under stress and therefore benefits all the more from the positive effects of the nutrients.

Field tests prove that the yield increase for combined fertilization with potassium, magnesium, and sulfur is particularly high compared with lack of fertilizer use in dry years:

Conversely, regular fertilization reduces the risk that unfavorable weather conditions will cause avoidable yield losses.