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Increase nutrient efficiency

Optimal use of nitrogen and phosphorus

KALI Academy
Using nutrients as efficiently as possible is an absolute priority for agriculture. Against the background of the new fertilizer regulations, we identify approaches to increasing nutrient efficiency and support farmers in securing their yields.

Using nutrients as efficiently as possible is the order of the day for agriculture around the world. In the case of nitrogen alone, only about 40 percent of the amount applied is, on average, actually absorbed by the plants. Nutrient losses of this magnitude not only pollute the environment but also reduce profitability. In addition, there are legal requirements, such as the new fertilizer ordinance, which further increase the pressure to use nutrients efficiently.

Measures to increase nitrogen efficiency

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In addition to N fertilization, it is also important to prevent another nutrient from becoming a limiting factor.

Optimal efficiency through balanced nutrient supply

Balanced fertilization makes an important contribution to optimization. Liebig's law of the minimum, according to which the scarcest resource determines the growth of the plant, also applies to nutrient efficiency. Applied to the supply of nutrients, this means that if a certain nutrient is not available in sufficient quantities, this impairs the uptake of other nutrients. This relationship is well documented scientifically, for example for optimal nitrogen uptake, which depends not least on an adequate supply of potassium.

Potassium is actively involved in nitrate uptake through the root and is therefore needed for the onward transportation of nitrate to the shoot. Moreover, potassium is an important factor in the formation of proteins from the absorbed nitrogen. If potassium is lacking for the physiological conversion of the nitrate, unfinished protein building blocks accumulate in the cells and slow down further nitrogen uptake. This means that potassium deficiency not only leads to reduced nitrogen uptake, but also to poorer utilization of the available nitrogen and consequently to lower nutrient efficiency.

Significant yield increases possible

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Typical sulfur deficiency symptoms are low growth, yellowing and rigidity of the plants. Attention: Sulfur deficiency is easily confused with nitrogen deficiency! (Photograph: K+S)

This effect can be seen above all in significant increases in yields and in quality in the event of undersupply, as field trials by the Kiel University of Applied Sciences with winter wheat have shown. Using 60er Kali (120 kg K2O/ha) as a fertilizer increased yields by over 10 dt/ha with the same amount of nitrogen. If, instead of pure potash, Korn-Kali was used, which also provides sulfur and magnesium, the additional yield even doubled to over 20 dt/ha. At the same time, the average protein content increased by up to 5.4 percent.

This result confirms the law of the minimum. After all, the positive effect of potassium also ultimately depends on sufficient availability of other essential nutrients - such as sulfur and magnesium. Sulfur is an important constituent of many enzymes that are elementary for the protein metabolism of the plant. If certain enzymes cannot be formed due to a lack of sulfur, this leads to a nitrate buildup in the plant, which in turn impairs further nitrogen uptake and therefore efficiency.

The importance of magnesium is underestimated

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Root growth is inhibited in the case of magnesium deficiency. This also means that less nitrogen and phosphorus can be absorbed from the soil.

Magnesium is also an important factor in the efficient absorption of nutrients such as nitrogen and phosphorus in particular. Nevertheless, the importance of sufficient use of magnesium as a fertilizer is often underestimated in practice, as the quantities required are much smaller than for potassium or nitrogen.

As an enzyme activator, magnesium plays a decisive role in the transportation of sugars and other carbohydrates, which are needed for root development and for filling harvest organs. The better this transportation works, the larger the root system of the plant is and the more nitrogen and phosphorus is absorbed. Phosphorus in particular can be better broken down and utilized by the excretion of the root hairs.

Trace nutrient calibration

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Boron deficiency is manifested in sugar beet by so-called heart rot and dry rot. If this type of damage occurs, the deficiency situation is particularly severe. (Photo: K+S)

The law of the minimum and the influence on nutrient efficiency continue down to the micronutrients. Manganese, zinc or boron are also important for the optimal use of nitrogen or phosphorus by a plant. For example, leaf fertilization can be applied to sugar beets or cerealsachieve significant effects in the case of an existing undersupply. Since deficiency symptoms often cannot be clearly assigned to a nutrient, regular soil analysis, which also includes trace nutrients, is recommended.

Conclusion

Increase nutrient efficiency through balanced fertilization

For optimal nitrogen and phosphorus efficiency, a balanced nutrient supply of potassium, magnesium, sulfur, and microelements is essential. In particular, potassium deficiency must be avoided, as otherwise the uptake and utilization of nitrogen will be restricted. Magnesium improves root growth and therefore nutrient uptake from the soil. 

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