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Effect of liquid organic humate fertilizer Humustim on chemical composition of aboveground biomass, root biomass and grain of spring forage pea was studied at the Institute of Forage Crops, Pleven, Bulgaria (2002Bulgaria ( -2004. Presowing treatment of seeds and treatments during vegetation were applied. The treatment with Humustim increased content of crude protein, macro elements and water-soluble carbohydrates in the aboveground biomass of plants. The highest content of crude protein (13.69%) and water-soluble carbohydrates (8.40%) was found for presowing treatment with Humustim at the dose of 1.2 L/t seeds + one treatment during vegetation. Applying of Humustim decreased crude protein content in roots from 5.0% to 17.8%. Treatment with Humustim had no effect on crude protein content in grain and increased water-soluble content (from 3.3% to 10.0%) and Са (from 11.1% to 77.8%). Better growth and development of spring forage pea were observed after treatment with Humustim-plant height and root length increased.

Abstract:A field trial at the Institute of Forage Crops, Pleven, Bulgaria (2000-2003 was conducted to study the effect of mineral and organic fertilization on seed yield of alfalfa, root biomass accumulation and soil humus content. Alfalfa variety 'Victoria' was grown on a leached chernozem soil without irrigation. Rates of 70, 140 and 210 kg ha -1 mineral nitrogen (active ingredient) were tested as ammonium nitrate and well-matured cattle manure. It was found that mineral and manure fertilization at 140 and 210 kg ha -1 increased seed yield by 9.9% and 20.9% for mineral, and by 30.3% and 40.6% for manure. Seed yield was more stable under manure fertilization compared with mineral fertilization. Alfalfa accumulated between 2669 and 3098 kg ha -1 dry root mass after mineral fertilization and between 3310 and 3570 kg ha -1 after manure application. Additional root mass of 482 to 698 kg ha -1 was found to be accumulated for manure treatments compared to mineral fertilization. High ratios of nitrogen yields (192 -216 kg ha -1 ) and plant available nitrogen (77 -86 kg ha -1 ) have been obtained from the treatments with manure. The highest amount of humus remained in the soil after fertilization of alfalfa with manure at the rate of 210 kg ha -1 .

Abstract. Effect of the treatment with organic fertilizer Humustim on root biomass accumulation in vetch (Vicia sativa L.) (cv. Obrazets 666) was studied in a field trial carried out at the Institute of Forage Crops, Pleven, Bulgaria. Several doses of fertilizer were applied to the seed as a pre-sowing treatment, and during the vegetation growth phase (growing up and flowering stage), and as a combination between them. It was found that Humustim applications at all stages and rates resulted in increased root biomass. Plants accumulated from 661 to 717 kg/ha fresh, and from 254 to 280 kg/ha dry root biomass, which was 17.3 and 19.7%, respectively more than the untreated control. Humustim represent an excellent fertilizer in the modern trends such as sustainable agriculture and organic farming.

Abstract:The effect of increasing doses of mineral nitrogen fertilization (40, 80, 120 and 160 mg N kg -1 soil) on chemical composition of lucerne (Medicago sativa L.) was studied in pot trial at the Institute of Forage Crops, Pleven, Bulgaria. The plants were grown under optimum water supply (75-80% FC) and 10-days water deficiency stress (37-40% FC) at the stage of budding of lucerne. It was found that with increasing doses of mineral nitrogen fertilization, crude protein content in dry aboveground mass increased from 13 to 19% under the conditions of optimum moisture, and decreased from 6 to 14% under water deficiency stress. Crude fiber content in root mass under water deficiency stress increased most in unprovided and provided plants with low dose of mineral nitrogen. Ca:P ratio in dry aboveground mass remained almost unchanged in the conditions of optimal moisture, and increased significantly in the conditions of water-deficiency stress.