INFLUENCE OF COMPOST MIXTURE ON THE LETTUCE YIELD AND QUALITY FORMATION

Abstract

In Bulgaria there are many natural materials that present an interest for human activity in relation of their use and properties. Five natural products were tested. In base of their quantity and quality characteristics was offered different mixture in various combination of vermiculites, ash from straw biomass, wood biomass and pig manure. The aim of the study is based on the characterization and evaluation of the proposed natural products. Different ratio of mixtures was tested as a soil improver and their impact on yield and chemical characteristic of plant production. Pot experiment with lettuce is set out in the following versions: control, 2, 5, 7, and 11% by soil weight. The highest yield is obtained in variants with 11% of all compost mixture. In mixtures (2, 3 and 5) with large manure content has been observed highest increase of yield as a result of more imported nutrients by organic manure. Chemical characteristics of lettuce crop production, with the participation of all variants of compost mixtures show that the main nutrients - nitrogen, phosphorus and potassium are normal for plant species. The level of tested heavy metal is below toxic concentration. The results of total sugars content and photosynthetic activity correspond with data obtained in biomass harvesting in pot experiment. In all variants with 7-11% compost mixture was observed the highest level of photo-synthetically active chlorophyll "a".