Effect of humus and soil substrates on production parameters and quality of organic strawberries

ABSTRACT This study aims to verify the most suitable substrate formulation based on proportions of earthworm humus and soil to improve the quality of organic strawberries. Vermicomposting generated humus and strawberry seedlings were planted in different humus:soil ratios: (0:100; 20:80; 40:60; 60:40; 80:20 and 100:0, respectively). The proportional conditions were characterized after planting and after 60-day cultivation, plants were harvested, and chemical characterizations of the soil and plants were made. We verified that with an increase of humus content in the substrate, an increase in values of N, P, K, pH and organic matter in soil and dry and fresh mass in shoot area of the plants were noticed. In relation to fruits, pH, humidity and sodium concentration, the authors noticed no change under any conditions and ash content was lower when an increase of humus in soil was observed. Higher values of potassium and protein occurred from 40:60 and 60:40, respectively. Higher values for average strawberry production were verified from 60:40 condition. Reducing sugars and titratable acidity increased and stabilized at 20:80 and 60:40, respectively. Thus, in order to avoid excess of nutrients in the substrate, which can hinder plant growth, humus condition in the ratio 60:40 humus:soil is recommended for higher values of production, nutrients and protein in strawberry cultivation.