Agricultural farms in modern production system are specialized; therefore, animal-origin organic fertilizers are not available for many of them. Researches on the use of organic products in agriculture to restrict the use of pesticides and mineral fertilizers have been performed for a long time. Nowadays different organic preparations that are acquired as a result of complex processes are produced, ensuring ready-to-use biologically active substances in them and also activating their properties. One of the purposes of the research was to evaluate the impact of extracts from organic products on the potato (Solanum tuberosum) yield and tuber quality in the conventional cultivation system. A field experiment using cultivars ‘Borodyansky Rozovij’ (early maturity) and ‘Lenora’ (mid-early maturity) was arranged in the State Stende Cereals Breeding Institute in 2011 and 2012. Peat elixir and vermicompost extract obtained at different temperatures: + 45 °C and + 95 °C, as well as a mixture of these extracts were used for treatment of tubers and plants. The research included 24 treatments in total, including control (without treatment) and a standard potato cultivation technology. Tubers were treated immediately before planting, but plants were treated three times during the vegetation period. Average two-year research results showed that the use of organic product extracts significantly (p is less than 0.05) affected the tuber yield in different treatments for both cultivars ‘Borodyansky Rozovij’ and ‘Lenora’. The content of nitrates in tubers, using extracts, did not exceed the allowable level (160 mg kgE-1) in any of treatments.

peer reviewed

peer reviewed | Perionyx excavatus, cultured in Vietnam in early 1990s, showed an important role in managing organic wastes and supplying a very nutritious feed for animals. To develop vermiculture in practice, four treatments of different substrates including 100% fresh cattle manure (CM); cattle manure + pig manure in 50:50 ratio (CPM); cattle manure + pig manure + rice straw in 50:40:10 ratio (CPMRS) and pig manure + rice straw in 90:10 ratio (PMRS) were prepared to examine worms’ growth and their decomposition efficiency. All substrates were composted 45 days before feeding to worms. The result showed that cattle manure (CM) was the best substrate for worm growth (biomass gained 713 g after 45 days or 242.6% of growth rate). The worm biomass achieved in CPMRS and PMRS treatments was significantly lower than that in CM treatment. As compared to primary substrates, vermicomposts exhibited an excellent result with a great increase in the amount of total P (0.3 – 0.6%), total K (0.09 – 0.23%), Ca (0.51 – 0.79%) and a decrease in N-NH3 and N-NH4+. A study was carried out to evaluate the influence of feed supplemented with worms on the growth and meat quality of broiler chickens (n=148). Starting at 4 weeks old the chickens were divided into a control group and three experimental groups corresponding to worm levels in the diet of 1, 1.5 and 2% on a dry matter basis according to a completely randomized design. Chicken fed the diet supplemented with 2% worms had the highest live weight at 10 weeks (1925 g/head vs 1823 g/head for the control). Percentage of breast and leg meat was also higher than in the control group. Chickens in the three worm groups had better FCR. The different levels of red worm supplementation did not affect meat quality (pH, color, and the rate of dehydration after storage and processing).

There is an increasing demand in the development of new and better types of organic plant fertilizers. The aim of the present study was to evaluate if the beneficial effect of vermicompost on plant growth and development could be further promoted by adding different amounts of bat guano using two model species under controlled conditions, as well as to assess the microbiological characteristics of bat guano and soil after its application. The study was performed at the Faculty of Biology, University of Latvia, during 2013 and 2014. The amount of bacteria was significantly lower in guano in comparison to vermicompost samples. No actinobacteria were present, but yeasts were found in the guano sample. Soil fungal populations after the application of organic fertilizer from vermicompost and bat guano were dominated by potentially plant growth promoting fungi Trichoderma and Mortierella. However, at increased guano concentration (300 g kg˗1) the proportion of potentially plant pathogenic fungi significantly increased. Addition of bat guano to vermicompost fertilizer significantly enhanced the positive effect of the fertilizer on growth and development of winter rye (Secale cereale L.) and potato (Solanum tuberosum L.) plants.