Alfalfa - a crop with high feed value and climate tolerance
As a forage crop, alfalfa has high crude protein and crude fiber contents. Due to its deep root system, it can also be grown in warm and dry regions. Alfalfa also has a phytosanitary effect, as it can help to suppress weeds due to its competitiveness as a crop rotation element.
- Potassium is the basis for achieving high and safe yields
- Sulfur ensures efficient nitrogen utilization
- Magnesium has an effect on high protein content and quality
- Micronutrients boron, molybdenum, and zinc are also essential
Alfalfa - an ideal crop rotation element
Due to its high yields and excellent feed value, alfalfa is mainly grown as forage. It can be fed both ensiled and freshly cut. Alfalfa belongs to the legume family and therefore fixes nitrogen symbiotically with nodule bacteria, which has a positive effect on the humus and nitrogen balance of the soil. Alfalfa can survive long periods of drought due to its deep root system. It prefers deep, warm soils with an adequate supply of nutrients and water, as well as an almost neutral pH. Alfalfa is suitable for cultivation on ecological priority areas and can be credited as a greening measure.
The most important nutrients for alfalfa
Potassium - affects the formation of yields
- Alfalfa requires about 240 kg K/ha with average yields of 100 dt DM/ha. Potassium fertilization should ideally be applied 3 weeks before sowing, as alfalfa is sensitive to potassium salts.
- Potassium is of great importance for N fixation by nodule bacteria and consequently for seed and protein yield.
- The effect is due to both increased nodule formation and increased bacterial activity.
- A good potassium supply promotes the formation of proteins from amino acids, as potassium activates important enzymes for this.
Sulfur - for efficient nitrogen utilization
- Alfalfa has a high S requirement of 30 kg/ha.
- Sulfur is essential for the synthesis of the essential amino acids methionine and cysteine, influences the overall protein synthesis and therefore has a positive effect on yield.
- An optimal sulfur supply leads to efficient nitrogen utilization. If there is a lack of sulfur, the nitrogen taken up cannot be converted into proteins and a signal is sent to the roots to take up less nitrogen, as there are already too many free nitrogen compounds in the cell sap.
- Sulfur is a component of the metabolic product glutathione, which, as an antioxidant, renders oxygen radicals formed during drought stress harmless and thus prevents necrosis of the leaves.
- Sulfur is important for the production of the plant's own defense substances (phytoalexins, glutathione).
Magnesium - for yield and quality
- The magnesium requirement for an average yield of alfalfa is 45 kg/ha.
- A good magnesium supply to the crop guarantees long-lasting assimilation of the leaves and therefore ensures optimum storage of the carbohydrates in the grains. This has a positive effect on yield.
- Magnesium activates a large number of enzymes in protein metabolism and therefore influences protein content and quality.
Don't forget micronutrients and calcium
Alfalfa also has high requirements for boron, calcium, copper, and molybdenum.
- Molybdenum and boron are required by alfalfa for the development of nodule bacteria, among other things.
- Boron stabilizes the cell walls.
- Copper also contributes to the healthy development of nodule bacteria.
- Calcium increases the alfalfa's tolerance to diseases and pests.
Fertilization recommendations for alfalfa
The aim of fertilization is to maintain soil fertility so that the natural yield potential can be exploited in the long term. For this purpose, an optimum nutrient content must be maintained in the soil (in Germany, soil content class "C"), i.e., nutrients removed with the harvested crop must be replaced by fertilization. Additional to the nutrient removal, there are supplements for site-specific losses (for example, through leaching) and to compensate for earlier deficiencies.
The following fertilizer recommendations are calculated based on the nutrient removal of the main crop product on the basis of optimum soil nutrient contents (in Germany, soil content class "C"). Supplements for site-specific losses due to leaching, fixation or erosion are not taken into account.
Recommendation for soil fertilization
For an alfalfa yield of 285 dt/ha, the following fertilizer application is recommended for nutrient withdrawals at optimum nutrient soil content class "C" measured by total withdrawals and withdrawals by main crop products:
Total removal (including crop residues): 324 kg K2O, 45 kg MgO, 30 kg S per ha.
- 6-8 dt/ha magnesia kainite
- 3 dt/ha grain potash each at the first and second cut