Leaf mold compost reduces waste, improves soil and microbial properties, and increases tomato productivity

Abstract

Soils in urban settings are often degraded, which can prevent growers from optimizing the health and productivity of their crops. In this study, we investigated whether amending soil with a locally made leaf-mold compost could (a) improve soil chemical and biological properties, (b) increase survival of a microbial inoculant with plant growth promoting and disease suppressive capabilities, and (c) enhance the yield and quality of a tomato crop. Results were promising, with dramatically greater concentrations of active soil organic matter (SOM) and marketable fruit in plots receiving the amendment in both years of the study. Foliar disease severity was also lower in compost-amended plots in the second year of the trial. Inoculating tomato (Solanum lycopersicum L.) transplants with Trichoderma harzianum T-22 reduced deaths that are due to transplant stress in one of the cultivars evaluated, and the compost supported greater populations of this microbe in soil demonstrating that it is possible to enhance the efficacy of beneficial microbial inoculants in field settings using targeted practices. These results indicate that urban farmers can improve the productivity of their farms by amending soils with leaf mold compost, which will help ensure the long-term sustainability of urban farming initiatives. However, all composts should be tested to ensure they do not contain toxic levels of heavy metals or pathogens, and farmers should avoid overapplication since this can reduce crop health and lead to environmental challenges.