Phosphorus is essential for the development of all living organisms and is a component of almost all chemical reactions involving energy. It is essential to photosynthesis and plant metabolism. Phosphate affects the formation of abundant root system of the plants, thereby reducing their sensitivity to stress, and also allows extensive uptake minerals from the soil. The appropriate amount of phosphorus in plants is very important for obtaining high and good quality yields. Only 19% of Polish soil has a high content of available phosphorus, while almost 48% have a low abundance of this macroelement. However, even on soils rich in phosphorus plants may exhibit symptoms of deficiency, since phosphorus is very readily immobilized and becomes to form low available to the plant. The availability of phosphorus for plants depends on the content of the element in the soil, but also on the conditions of the habitat and agricultural technology used. An important element in agricultural technology is weed control, because weeds very often prevail crop plants in the competition for nutrients, including phosphorus and may reduce its availability for plants. An important role in increasing the availability of phosphorus for plants can also play an interspecific interaction and changes in the rhizosphere observed in intercropping (mixed cropping).