No abstract

The purpose of the research was to examine whether selected organic materials could increase the net energy concentration, net energy of lactation, and energy yield of two grass species. The main factors in the experiment were soil conditioners with the content based on compost, vermicompost and humus extract, applied separately and supplemented with NPK fertilizers. The second factor is grass species, Dactylis glomerata and Lolium perenne. Mineral fertilizer and compost extract resulted in a reduction in net energy concentration by about 5%. The largest value of net energy of lactation (NEL) was obtained after the application of humus extract with NPK. The average value of the energy yield was the biggest on units where biological extracts were applied together with NPK. That increase was from 63% for NPK applied together with humus extract to 76.5% for the NPK applied with compost extract. Of the applied humic substances, those applied together with mineral fertilizer had the greatest impact on net energy value and NEL. The use of compost extract contributed to a substantial increase in the yield of feed energy. Other biological substances applied together with mineral fertilizer also had a positive impact. Weather conditions in various years of the research differentiated feed energy values. Due to the complexity of the environment (soil, climate, plant), it is impossible to provide a universal combination of fertilizers that increases the energy value of forage. Therefore, it is important to carry out practical field experiments that will indicate the optimal fertilizer combinations suitable for the selected region.