IMPACT OF ORGANIC PRODUCT EXTRACTS ON POTATO 'BORODJANSKIJ ROZOVIJ' TUBER YIELD IN ORGANIC CROP PRODUCTION SYSTEM

Products of organic origin used in agriculture to reduce the application of artificial pesticides and fertilizers are investigated world-wide now. Composting organic fertilizers, plant residue and household waste results in new products of organic origin. In several countries (USA, Russia, Belorussia, and some others), the role of earthworms in organic waste processing and the possible further use of this processed product have been investigated. In Latvia, similar investigations are few but they are needed. A goal of our investigation was to investigate the impact of extracts made from the products of organic origin on potato (Solanum tuberosum) tuber yield in biological crop production system. A field experiment was established at the State Stende Cereals Breeding Institute in 2011, using an early-maturing potato variety 'Borodjanskij Rozovij' suitable for growing both in conventional and organic production systems. Tubers or plants were treated with peat elixir and earthworm biohumus extract obtained at different temperatures: +45 degrees C and +95 degrees C, and their mixtures. In total, 18 treatments and untreated control variant were included in the experiment. Tubers were treated just prior to planting, but potato plants were treated three times in season. In the first production year, the obtained potato tuber yield ranged 26.16-45.38 t ha(-1) in treated plots, and 35.27 t ha(-1) in untreated control plot. Data were subjected to analysis of variance. In 2011, tuber yield was significantly dependent on organic extracts applied, which increased the yield significantly (p<0.05) in four treatments, but in the rest of them significantly decreased if compared to control.