Humus balance in a short crop rotation of Right Bank Forest Steppe of Ukraine depending on fertilization systems of typical chornozemic soil

Abstract

Four year research (2015–2018) at Bila Tserkva National Agrarian University proved that plant residues and non-market products of the field five course grain row rotation are important sources for soil humus formation. On the unfertilized areas, fertilized withn8 t/ha of animal manure + N76P64K57, 12 t/ha of animal manure + N95P82K72 and 16 t/ha of animal manure + N112P100K86 humus percentage formed due to humification of plants matter was correspondently 51.4; 40.3; 37.7 and 36.1 %, with animal manure – 0; 15.3; 17.2 and 18.7 %, with by-products of farming – 44.0; 40.8; 41.7 and 42.1 %, with herbage of white mustard – 4.6; 3.6; 3.4 and 3.1 %. With the increase of fertilizers level this index regarding plants matter and green manure decreases, while animal manure provides for the index slight increase. On the unfertilized areas humus balance under cultivated crops as sunfl ower and corn is negative, but under other crops in rotation it is positive. On the fertilized areas under all crops this index is positive. When applying the biggest amount of fertilizers, annual gain in soil humus is 1.1 t/ha. Humus balance is negative on all the variants of research under the condition of disposal of non-market products from the fi elds of crop rotation. Along with plants matter, plant by-products and herbage of white mustard the amount of humus provided to the soil was equal to the application of correspondently 14–33, 12–36 and 1.3–2.6 t of animal manure per hectare of tilled fi eld. Under zero, the fi rst, the second and the third levels of soil fertilization, soil received correspondently 4.08; 5.98; 7.46 and 8.73 t of plants matter 68–71 % of which are root and the others are above surface. The percentage of by-products of crops in the rotation increases with fertilizers amount increase. Soy, winter wheat, sunfl ower and spring barley have a bigger gain in above surface rather than root mass due to increase of fertilizers amount. The highest productivity from one hectare of tilled fi eld in a crop rotation (5.63 t of dry matter, 7.84 t of fodder units, 0.671 t of digestible protein) is gained due to application of 16 t/ha of animal manure + N112P100K86, though the most economically viable amount is 12 t/ha animal manure + N95P82K72. Key words: humus balance, soil, fertilizers, crop, by-products, plants matter, crop rotation, grain crops, index of ecologization, productivity.