Effects of vermicompost placement on nutrient use efficiency and yield of tomato (Lycopersicum esculentum)

ABSTRACT This study investigated different methods of applying vermicompost (VC), with the aims of improving yield in organic tomato production and decrease the amount of fertiliser required. Three methods of placement (application) of the VC were used in the field trial: a) VC placed in a row on the soil surface with incorporation behind the planting lines (R), b) broadcast in the field (B), and c) in the transplant hole under the root plug of the transplant (U). As a second factor, VC was applied at three different rates of application (3, 6 and 9 t ha−1 for R and B, and 2, 4 and 6 t ha−1 for U). In both years, the different rates and placement methods had no significant effect on the fresh yield of tomatoes. However, in 2015, the treatment with the higher rate and the U placement of the VC increased the dry matter (DM) yield of the plants by up to 48% (8.4 t ha−1). Evidently, treatments with the U method had 23 % higher nitrogen (N) uptake (156 kg ha−1) compared with the treatments where VC was broadcast in the field (121 kg ha−1). In 2015, the N use efficiency was significantly higher for the U method (102%) compared with the R and B methods (38 and 34%, respectively) and the phosphorous and potassium use efficiency followed a similar pattern. The study demonstrated that the U placement method for VC increased DM yields, nutrient uptake and nutrient use efficiency in organic tomato production.