The aim of the research was the estimation of wheat and rapeseed straw usefulness for fertilising plants in arable farming. The subject matter of the study was the analysis of the influence of soil fertilisation with wheat and rapeseed straw on the yield and changes in the content of phosphorus, potassium, calcium and magnesium in winter wheat grain cultivars: Finezja and Ludwig. The static field experiment was conducted at Agricultural Experiment Station, Grabów, Institute of Soil Science and Plant Cultivation – State Research Institute (51°21′ N, 21°40′ E) in the years 2008–2010 on Haplic Luvisol. The effect of fertilisation with wheat and rapeseed straw did not have a significant effect on grain yield of winter wheat cultivars ‘Finezja’ and ‘Ludwig’. The introduction of complementary nitrogen fertilisation caused an increase in grain yield of wheat cultivar Ludwig. Organic fertilisation with wheat and rapeseed straw as well as complementary nitrogen fertilisation did not significantly differentiate the content of phosphorus, potassium, calcium and magnesium in winter wheat grain cultivars ‘Finezja’ and ‘Ludwig’.