temperatures above 0°C
tolerant from slightly acidic to alkaline, optimal: pH 6.2-7.2
at least 300-500l/m²
30-60 days at 3-10°C
usually between 330 and 380 grains/m²
Durum wheat (Triticum durum), also called durum or glass wheat, is from an economic point of view the most important type of wheat after soft wheat (Triticum aestivum). Durum's current production line is pasta, penne and spaetzle, as well as couscous and bulgur. Since many old winter durum varieties are at danger of outwintering damage, in Germany and Austria, up until a few years ago, it was predominantly the low-yielding summer durum that was cultivated. Newer winter varieties bring significant benefits in terms of yield and yield security.
Durum wheat is tetraploid unlike soft wheat (hexaploid) and probably bred from emmer. It prefers medium to heavy soils at a neutral pH.
It is crucial to apply the right amount of nutrients according to a defined strategy and to pay attention to the right time of application.
Depending on the yield, durum deprives the soil of an unequal amount of nutrients (see table). The amount of nutrients left in the field after harvesting is well below the extraction rate.
In order to maintain soil fertility, the withdrawn nutrient amounts must be returned. This can be done both by organic and by mineral fertilizer or by a balanced combination of both.
(Unit/t of production)
(Unit/t of production)
The table shows both the nutrient uptake by the plant and the extraction per tonne of crop. Wheat is extremely sensitive to N deficiency; however, phosphorus and sulphate also play an important role in durum fertilization.
Wheat, with a production target of 7t/ha (15% crude protein) absorbs 245kg N/ha. Assuming an average N replenishment from the soil (e.g. 50 N/ha) and additional N availability by means of a legume as a preceding crop (e.g. 30 N/ha), fertilisation of 165kg N/ha is required. With the harvest, 147kg N/ha leave the field.
First dose in spring at the beginning of the vegetation
The first application in spring achieves a quick and early growth start. This dose is crucial for the tillering and influences the formation of the ears/m².
Especially after the winter break, it is important to provide phosphorus, potash and sulphur, as the nutrients in the soil are not yet mobilised due to the cold.
Water-soluble NPK(S) fertilizer-formulae ensure the necessary supply of nutrients in the upper root areas for rapid absorption. Special attention should be paid to the nitrogen form. Only nitrate nitrogen is readily available under these conditions. The conversion of ammonium to nitrate, at 5°C soil temperature, takes up to several weeks. This, in turn, means that the fertilized nitrogen would come into effect too late.
Dose at the start of shooting
The second dose is given in the period from the start of shooting to the 2-node stage (EC 30-32). In this phase, the development of the spike takes place in the stalk and this stage is crucial for the formation of the grains per ear. A denser stock should be fertilized a little later (EC 32). Thus, the wheat has enough time to reduce the shoots due to lack of nitrogen. If the stock is too sparse, every single stalk must develop into a productive ear. Here it is necessary to perform the second dose earlier (EC 30) so as not to lose any shoots. The crop density can in turn be controlled best with nitrate nitrogen.
Dose at ear emergence
The last application is made when the flag leaf (EC 37) appears until the beginning of the ear emergence (EC 51). At this stage, nitrogen administration has a significant impact on grain weight and protein content.
The decisive factor for durum is achievement of the desired quality goals (glassiness, dark-stained grains, colour value, number of drops and crude protein content), otherwise it is difficult to sell the harvest. Crude protein content of at least 14.5% is important for glassiness. This makes the 3rd dose extremely important. With the 3rd application of N, the crude protein content increases, as does the thousand-grains weight.
At normal yield levels, a dose of 60kg N/ha is common at the beginning of ear emergence (BBCH 49 to 51). In cases of high yield, the third dose is partially split, the last dose is then given at the start of flowering in order to increase the protein content further.