Fertilization of rapeseed

Rapeseed is a popular crop with a wide range of uses, including in the food industry for the production of rapeseed oil and honey. In addition, it is used for animal feed, biofuel and varnish. It comes in two forms as: winter rapeseed and spring rapeseed. It is a plant with high nutritional requirements, and therefore requires appropriate, systematic fertilization.
Winter rapeseed and spring rapeseed are among the plants with high nutritional requirements. They take from the soil twice as much nitrogen, phosphorus and potassium and five times as much calcium as wheat; in addition, significant amounts of sulfur, magnesium and boron, molybdenum and manganese. Depending on the method of fertilization (organic + mineral or only mineral), the forecrop and the natural abundance of soil in the cultivation of this crop, mineral fertilizers should be used, the composition of which is selected to meet its specific needs.
Particularly important nutrients responsible for the proper growth and development of rapeseed are contained in Fosfan fertilizers: phosphorus, potassium, calcium, magnesium, sulfur, boron, molybdenum and nitrogen.

Winter rapeseed well supplied with phosphorus and potassium forms strong leaf rosettes before winter and roots strongly, which promotes good wintering. In the spring, phosphorus and potassium facilitate the rapid formation of new leaves and stems, while in the summer they accelerate the maturation of seeds in the siliques, increase seed yield and the amount of fat. Insufficient potassium supply in rapeseed is evidenced by dull green, withered leaves, dried and cracked at the edges. Yellow and brown spots of dead tissue form between the innervation of the oldest leaves.

Calcium is essential for the proper growth and development of rapeseed and the release of high seed yields. Deficiency of calcium in the soil causes the collapse of the tops of the stems, weakens flowering, accelerates the dropping of flowers, so that the siliques are few, they are distorted, and few and small seeds are formed in them.

Magnesium has a stimulating effect on the formation of seeds in siliques and increases the fat content of the seeds. Its deficiency is evidenced by yellowish and rust-colored spots on the oldest leaves (known as marbling or tiger-like leaves) and the dying of tissue between the nerves. In contrast to the symptoms of potassium deficiency, the edges of these leaves do not dry out and crack, and the main nerves remain green for a long time.

Sugar beets, fodder beets and other root crops have a high demand for boron, while most soils in Poland currently show a significant deficit of this element. Therefore, mineral fertilizers containing this element in their composition should be used to fertilize beets. Deficiency of the micronutrient causes curling of beet leaves. During the period of full development, the youngest, middle leaves turn yellow, while later they turn brown and die (the so-called heart leaf gangrene). Symptoms of boron deficiency are then seen in the roots in the form of dying and suberization of the parenchyma (known as dry root rot).

Sulfur, especially under conditions of high nitrogen fertilization of rapeseed rape, has a positive effect on the average yield of seeds per silique and fat content, and improves the nutritive value of meal. Increasingly, symptoms of sulfur deficiency are being observed in double-improved rapeseed plantations. At an early stage of plant development, a light green coloration of the leaf margins is visible, covering an increasing area of the blade, while the nerves remain green. The leaves in the rosette are upright and stiff. In spring, the so-called marbling of the youngest leaves and a slight curling of the leaf margins can be observed. The flowers are small, very pale, and the number of siliques is strongly reduced. They are also small, with a negligible number of seeds.

Lack of molybdenum in the soil negatively affects the growth and yield of rapeseed. Plants are weak and pale, leaf blades undulate, distorted and curled into a teaspoon shape. The youngest leaves have a severely reduced leaf blade.

In addition to the elements listed above, rapeseed, like all crops, requires nitrogen fertilization. High doses of nitrogen fertilizer have a positive effect on overall seed yield, as they promote better branching. As a result, despite some reduction in seed fat content, the total seed and fat yield obtained from a unit of cultivated area is higher than when fertilizing with low doses of this element. Nitrogen fertilization of rapeseed should always be balanced with an adequate amount of the other macro- and micro-nutrients necessary for rapeseed.