Moisture and heat supply influence on the botanical composition and yield of the long-term agrophytocoenosis during the fertilizers after-effect under the Privilyuy agrolandscape of the Yakutia middle taiga subzone conditions

The purpose and objective of research is to study the long-term impact of the aftereffect of a longevous regimen of mineral nutrition on the botanical composition and productivity of grass-forb-cereals phytocenosis when hayed for the production of voluminous fodder. Studies of the influence of weather conditions on the botanical composition and productivity of long-term meadow phytocenoses in the period after the application of mineral fertilizers were carried out from 2011 to 2019. The history of monitoring studies begins with the foundation of the “Great Experience” in 1974, where single-species crops of awnless brome variety Kamalinsky 14, fibrous couch grass of the local population, Siberian wheatgrass variety Kamalinsky7 and mixed crops with the introduction of various doses of mineral fertilizers were studied. In the period from 1974 to 2010, different levels of mineral nutrition were researched: the minimum (control) was N62P60K11 kg/ha of a.i., the average was N202P175K43, and the maximum was N318P362K189. After 6-8 years, the sown grass stands were reformed into cereals - forb phytocenoses. Under the conditions of the Privilyuy agrolandscape of the middle taiga subzone, it was found that the botanical composition and yield during the aftereffect of the mineral diet mainly depended on the conditions of heat and moisture supply during the growing seasons. During the period of long-term aftereffect of fertilizers in the herbage of forb - cereals phytocenosis, creeping wheatgrass up to 42 %, short-leaved barley up to 24.3 % with forbs content up to 38 % DM were preserved. The yield of a long-term phytocenosis during the aftereffect period decreased by 58-81 %, depending on weather conditions and the aftereffect of various levels of the mineral diet. At the same time, hay forage of previously improved phytocenoses contained up to 8.9-9.1 MJ of metabolizable energy, up to 0.62-0.65 feed units, and up to 80-90 g of digestible protein, which corresponds to the zootechnical norm.