Living Mulch - Drawbacks

Drawbacks

Unfortunately, living mulches compete for nutrients and water with the main crop, and this can reduce yields. For example, Elkins et al. (1983) examined the use of tall fescue (Festuca arundinacea), smooth bromegrass (Bromus inermis), and orchargrass (Dactylis glomerata) as living mulches. They found that herbicides killed 50% to 70% of the mulches but corn yield was reduced 5% to 10% at the end of the harvest.

Although leguminous cover crops have large biomass production and turnover, they are not likely to increase soil organic matter. This is because legumes used as living mulches have greater N contents and a low C to N ratio. So when legume residue decomposes, soil microbes have sufficient N available to enhance their breakdown of organic materials in the soil.