Efficiency of organic fertilizers in variegated alfalfa growing

The research goal was to evaluate the immediate and residual effects of increasing rates of organic fertilizers on the yield and forage quality of variegated alfalfa (Medicago varia), as well as on the fertility of meadow-brown bleached soil under the conditions of the collection plot at the Primorsky State Agrarian-Technological University. The total dry-matter gains of first-to third-year variegated alfalfa stands under increasing fertilizer rates amounted to 2.1-8.6 t ha, or 11.3-46.9% relative to the control, with the most pronounced yield gain (+14.8%) observed when the rate increased from 5 to 10 t ha, and the highest return - 481 kg of dry matter per ton of fertilizer - obtained with poultry manure at 10 t ha. Crude protein content increased from 17.9% in the control to 18.5-20.1%; digestible protein per kilogram of dry matter increased by 3.1-12.2%; its yield per hectare - by 24.6-52.4%, and metabolizable energy yield per hectare - by 12.3-48.1%, the maxima being recorded with poultry manure at 15 t ha and the Gigantin fertilizer in a rate of 20 t ha. Organic fertilizers also improved the fertility of the meadow-brown bleached soil; organic-matter content increased by 0.28-0.58% with higher poultry manure rates while available phosphorus increased by 5.0-36.4 mg per 100 g of soil (each ton of poultry manure raised P₂O₅ content by an average of 1.62 mg kg and each ton of Gigantin - by 1.82 mg kg). No exceedance of the maximum permissible nitrate concentration in the soil was detected.