Chemical composition of stubble crop biomass depending on a crop plant species and tillage system

The aim of this study was to compare the macro- and micronutrient content in the biomass of stubble crops grown in a three-year spring wheat monoculture under conventional plough tillage and no-tillage (reduced tillage) systems. This research tested the suitability of the following plants grown as stubble crops: white mustard, lacy phacelia, and a mixture of legumes (faba bean + spring vetch). The study was conducted over the period of 2013-2015, at the Czeslawice Experimental Farm belonging to the University of Life Sciences in Lublin. The chemical composition of cover crop biomass was analyzed (the content of the following nutrients: N, P, K, Mg, Ca, Cu. Zn, Mn, and Fe). For this purpose, at the end of stubble crop growth, plant samples were taken from an area of 0.25 m(2) of each plot (plants cut right above the soil surface). It was proven that the chemical composition of stubble crop biomass was primarily determined by the cover crop plant species. The individual stubble crops showed different degrees of accumulation of macro- and micronutrients. The highest content of N, Mn, and Fe was found in the biomass of the mixed legume crop, Fe - in white mustard biomass, while Zn - in lacy phacelia biomass. In comparison with plough tillage, conservation tillage (no-till) practices contributed to a decrease in the content of the studied nutrients in cover crop biomass (this decrease was significant in the case of N, K, Mg, and Mn). as linked to monoculture duration. To sum up, the content of macro- and micronutrients in the biomass of stubble crop is more closely related to species characteristic of the plant than to agrotechnical factors. It was proven that the stubble crops beneficially affected spring wheat productivity, whereas white mustard biomass ploughed into soil in autumn had the greatest beneficial effect. Under the soil and climate conditions of the Lublin region, white mustard was characterized by the best and most reliable yields.