PRODUCTIVITY OF SOWN MEADOWS OF THE LENA RIVER TERRACE ABOVE THE FLOOD-PLAIN

Productive capacity of soil in sown meadows of terrace above the flood-plain has changed during the period. Positive changes occurred in accumulation of organic matter in soil – increase in humus from 2.4 to 2.5 in depos- its and 3.5% in sown meadows. The content of nitrogen in humus has increased, it contributes to nitrogen accre- tion of humus substance in soil and protects colloids from washout of divalent cations, which have coagulating capacity. In soil of legumes and grasses, the mobile phosphorus content remains high, exchangeable potassium content – low. Aqueous suspension is alkaline 8% pH, total soluble salts – 0.08%. The herbage consists of 31% of alfalfa, up to 6–7% of brome, 14% of psathyrostachus, 50% of red fescue grass and introduced species of poa stepposa, the herbage productivity amounts to 1.8 t/ha. Metabolizable energy amounts to 12 GJ/ha, crude protein – 290 kg/ha. A lack of moisture in the summer leads to the intensive mineralization of organic remains, meadow grass roots. Organic matter in soil increases the content of humus in soil from 2.5 to 3.5%.