Auteur: Lazarev N.N. and Starodubtseva A.M.
Jaar van uitgifte: 2015
Productive longevity of different alfalfa varieties depends on soil fertility, weather conditions, intensity of use and disease incidence. The pasture-type alfalfa (Medicago varia Martyn.) variety Pastbischnaya 88 was tested for long-term persistence on well cultivated soils. In the 5th and 6th years of use 36-72 plants were left per 1 m2 and dry matter yields reached 5-7 Mg ha‑1. Thinning of the swards was recorded both after unfavourable winter conditions and due to the diseases in the summer period. By the 15-17th year of use the productivity of alfalfa-based swards declined to 2.8-3.12 Mg ha‑1. Being well provided with P and K on the sod-podzolic soil, alfalfa persisted in the mixtures with smooth brome even in its 18th year of use. Presence of 1-7 alfalfa plants per 1 m2 provided significantly higher yields than pure grass stands. Smooth brome is a good companion grass in alfalfa-grass mixtures for long-term twice-a-season use. This species considerably resisted dandelion invasions and did not suppress alfalfa. The key condition of smooth brome persistence in mixtures with other gramineous grasses is annual application of N90. Without mineral nitrogen fertilization the swards were invaded by wild grasses and dandelion, and the share of smooth brome decreased to 10-18%. On moderately rich soils serious thinning of alfalfa-timothy swards was already recorded in the 4th year after sowing. Their productivity declined to a level of 1.58-2.92 Mg ha‑1. Productivity of alfalfa-grass mixtures exceeded that of the single-species timothy crop by 1.8-2.0 times.