The use of compost from agricultural waste and coffee produces larger lettuce and spinach with fewer pathogens, according to the thesis of Alicia Hernández, researcher at CEBAS-CSIC and PhD from the Polytechnic University of Cartagena (UPCT).
It is a circular and sustainable economy technique for the biological control of crop diseases that provides agronomic and edaphological improvements by optimising crop yields and microbial and fungal activity in the soil, according to UPCT sources in a statement.
“The agricultural waste and the additives incorporated during the composting process improve the compost as a growing medium and as an organic amendment in solarisation processes for soil disinfection,” explained Hernández.
The trials were carried out by combining tomato, leek, olive pomace and pruning waste and incorporating different additives such as coffee, thyme, lavender and rockrose waste during the composting process.
“The lettuce plants grown in compost showed significantly higher fresh weight values than those grown in peat, with the compost with coffee showing the highest yields,” says the thesis of the new doctor of the Polytechnic of Cartagena, who has been directed by Margarita Ros and José Antonio Pascual, under the supervision of Professor Catalina Egea.
The research also highlights that the tomato and leek residues added with lavender offered the greatest capacity to eliminate plant pathogens such as ‘Pythium irregulare’, known as water mould, which rots plants.
“This compost can be used as a partial substitute for peat in greenhouse lettuce cultivation,” recommended the researcher, for whom the aim “is to improve soil fertility, maintaining a safe environment by reducing the application of pesticides and chemical fertilisers,” she added.
The combination of compost and solarisation process for soil disinfection practice increased total organic carbon, total nitrogen and microbial activity. The compost produced significant changes in soil bacterial and fungal communities, which were maintained after harvesting, Hernandez’s thesis concludes.