The effects of legume-cereal mixtures are usually expressed in the yield of seeds and total protein, sometimes in the yield of straw and post-harvest residues. Species composition and proportion of components in the mixture are a factor that strongly varies it. The aim of the research was determining productivity (the yield of seeds and straw as well as of the biomass of post-harvest residues) of a mixture of field pea with spring barley on the plot after potato, spring barley and after itself. The studies were carried out based on a statistical field experiment set up on rusty-brown soil, developed from silty loamy sand, deposited on slightly loamy sand and sand. The legume-cereal mixture was cultivated in six 4-plot crop rotations with its 25and 50% proportion. In the growing season, no chemical protection was applied against diseases and weeds, however, zoocides were used against pests. It was indicated that yield of the seed mixture was similar compared to plots with crop rotation. Selection of the forecrop also did not have an effect on the straw yield, while it significantly varied the biomass of post-harvest mixture of barley with pea. The smallest quantity of residues was found after potato, while the largest in the crop rotation with field pea. In the structure of residual biomass, roots constituted lower proportion than the aboveground parts. The total production of the biomass of legume-cereal mixture, expressed in the total aboveground and underground biomass of mixture canopy was significantly higher in the crop rotation with field pea than after potato, where there occurred a significant reduction in biomass of the aboveground vegetative part of the plant.

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