Competition for nitrogen, phosphorus, potassium and magnesium between spring wheat and Persian clover depending on the density of plants

A pot experiment completed in 2010-2012 analysed the relationship between spring wheat and the undersown Persian clover in the competition for nitrogen, phosphorus, potassium and magnesium depending on the plant density during the spring wheat growth stages of inflorescence emergence (BBCH 54-56) and ripening (BBCH 87-89). A mixture was composed according to the additive pattern. The analyses covered the aerial parts and roots of both species. The species were cultivated in a mixture and pure sowing at higher density (consistent with agricultural technology recommendations) and a density 20% lower than recommended. Based on the measurements of dry mass of the aerial organs and roots, as well as the content of N, P, K and Mg in the plant parts, the uptake of these elements by both species was calculated. The above data were the basis for computing the relative yield (uptake) – RY, relative yield total (uptake) – RYT, index of competitive balance (Cb) and relative efficiency index (REI). It has been shown that spring wheat and Persian clover competed for the whole pool of nitrogen and potassium and almost the entire content of phosphorus and magnesium. Wheat was a stronger competitor in obtaining the nutrients than clover. It showed the strongest competition against undersown clover for magnesium and the weakest one for nitrogen. Wheat competed more intensively with Persian clover for phosphorus and potassium in the treatment where the density was lower than recommended during the inflorescence emergence stage and for nitrogen and magnesium during the ripening stage.