Biological efficiency of biofertilizers emosan and seasol on pepper (Capsicum annuum L.) cultivated under organic farming conditions

Abstract Biofertilizers based on processed organic manure are proven alternative to mineral fertilizers. The experiments were carried out in 2009 to 2011 on an organic farm of the Agroecological Centre at the Agricultural University- Plovdiv (Bulgaria). The study included pepper variety „Sofiiska Kapiya”. The biofertilizers Seasol (Earthcare) and Emosan (Hemozym Bio N5) were applied as vegetative feeding on top of two basic fertilizations with the solid biofertilizers Boneprot and Lumbrical. The objectives were to investigate impact of biofertilizers on agroecological conditions for pepper growth and on biological and productive parameters of pepper under organic farming. The investigated parameters were standard yield and economic productivity of plants (i.e. average number of fruits per plant, mass of fruits and pericarp thicknesses). The present study found that treatments with biofertilizers Emosan and Seasol on the basic fertilizations ensured more nutrients in the soil comparison with the single applications of the basic fertilization. It was shown by the agrochemical status of soil, i.e. at the end of vegetation, a higher total absorbable N after application of the biofertilizer Emosan on basic fertilization with Boneprot was found. Nevertheless, the treatment with biofertilizer Boneprot lead to a higher humus and major nutrient content compared to control (non-fertilized) plants. All treatments showed ‘a good level of supply' of the soil with К2O. This determines the positive impact of the biofertilization for enrichment of soil with potassium thus assuring a valuable reserve for the next crops. The optimal agroecological conditions provided by the addition of biofertilizers reflected in higher standard yield of pepper compared to the control plants. The results showed the positive effect of application of biofertilizer Emosan, regardless of the type of basic fertilization. The highest standard yields in all three experimental years were shown by the pepper plants fed with the biofertilizer Emosan on the basic fertilization Lumbrical, i.e. the average increase was 47.2 % compared to the control plants. The biofertilizers applied as single treatments or as combined treatments increased the number of fruits per plant (i.e. 1.5- 4.0 pcs) and the average pericarp thickness of fruits by 0.58 - 1.16 mm. The research findings provide grounds for suggesting the studied bioferilizers as an effective solution for maintaining soil fertility in organic production of pepper.