Effects of compost application on nematode populations and the yield of a carrot crop
Composts may be used either in soilless cultivation or applied to soil, increasing its organic matter content and improving the physical, chemical and biological properties. This study evaluated the effects of compost application to the soil cropped with carrot on nematodes diversity, biocontrol of phytopathogenic nematodes and crop yield. A commercial compost (Organical®, TerraFértil, Portugal) was applied to a sandy soil, at the rate of 0, 12.5, 25, 50 and 100 t ha‑1 and incorporated to a 15 cm depth. A carrot crop (Daucus carota L.) was sown with a density of 62.5 plants m‑2. At the end of the growing period, when the longer roots had reached about 15 cm, plant growth and yield were quantified. Compost increased carrot yield. Following harvest, soil samples were collected near the roots (root zone) and randomly at three soil depths: 0 to 15 cm, at 30 cm and at 50 cm. Nematodes species were identified and quantified in these four zones, and the damages observed were ranked. Compost influenced nematode populations. Near the roots beneficial nematode populations increased with the compost rate application. Phytopathogenic nematodes were present mainly in the treatments with less compost. Furthermore, nematode genera were distributed according to soil depth. Bacteriophage/saprophyte nematodes were found mainly at 50 cm depth, at the surface and in the root zone. Plant parasitic nematodes were located near the surface (0-15 cm) and at 50 cm depth. Predator nematodes prevailed near the surface, in the root zone and at 50 cm depth. The lower populations of nematodes were found at 30 cm depth. This work showed that the dynamics of nematode populations in the soil is affected by soil depth and compost dose, suggesting that compost can reduce the population of phytopathogenic nematodes and increase bacteriophage/saprophyte and predator nematode populations.
Coelho, L., Reis, M., Bueno-Pallero, F., Guerrero, C. and Gonçalves, M.A. (2021). Effects of compost application on nematode populations and the yield of a carrot crop. Acta Hortic. 1305, 163-170
biological control, entomopathogenic, predators, soil