Abstract

The application of organic amendments is an increasingly widespread practice, which allows fertilizing and restoring soils in a sustainable and environmentally friendly way. Improving the quality of amendments through the application of microorganisms has been a challenge in recent years. The objective of the study was to determine the effects of microalgae+compost (1:1) mixture on the yield of cauliflower (Brassica oleracea L. var. botrytis L.) plants grown in a sandy loam soil with low nutrient availability. Yields were compared with the application of compost, cattle manure and two chemical fertilizers. The treatments applied were: T1 prepared with urea (NPK 46-0-0), triple superphosphate (NPK 0-46-0) and potassium saltpeter (NPK 15-0-14); T2 commercial fertilizer (NPK 12-11-18); T3 microalgae biomass (T3); T4 compost; T5 1:1 microalgae+compost mixture; T6 cattle manure; and T0 control (no fertilization). The experiments were conducted in 30 L pots using 40 g soil per plant and 4 g N as a reference to standardize fertilizer application. The results showed that the fresh weight (FW) and dry weight (%DW) of T5 and T6 were not significantly different from those of T1 (p > 0.05), on the contrary, FW of T5 and T6 was 43.8% and 40% higher than in T2, as well as the %DW was 0.59% and 0.6% w w-1, also higher than in T2. These results suggest that the microalgae+compost mixture is an alternative fertilizer, equivalent to chemical fertilizers and manure, presenting the advantages of being more stable, sustainable, and environmentally friendly. However, further studies are needed to determine the necessary dose per cultivated plant species.