The effect of dehydrated organic fertilizers on the lettuce mineral content

摘要

Intensive vegetables production is based on application of large amounts of mineral fertilizers and narrow crop rotation which results in reduction of soil organic matter. Dehydrated organic fertilizers can positively affect the amount of organic matter, structure, and microbiological activity of the soil. The research was conducted in autumn/winter growing season in 2013/2014 with the aim to determine the effect of dehydrated organic fertilizers on the lettuce mineral content. The two-factorial trial included two types of head lettuce (crisphead and butterhead) and five variations of fertilization (mineral, mineral with mature stable manure and mineral with three dehydrated organic fertilizers). Treatments were arranged according to split-plot design with three replications in an unheated greenhouse. Crisphead lettuce had higher values of calcium and magnesium, while butterhead lettuce achieved higher content of dry matter and phosphorus. Regarding the lettuce type x fertilization interaction, content of nitrate varied from 1581 to 2072 mg kg 1 NO3 of fresh weight and was within the allowed range. Dry matter content varied from 4.72 to 5.52% and application of all tested dehydrated organic fertilizers resulted in higher dry matter content in relation to mineral fertilization. The obtained results indicate that fertilization with Siforga+NPK+Urea could be recommended for autumn/winter growing season due to higher values of macroelements (4.68% K, 0.52% P, 1.60% Ca and 0.44% Mg) and the lowest accumulation of detrimental nitrates.