Examining trophic-level nematode community structure and nitrogen mineralization to assess local effective microorganisms’ role in nitrogen availability of swine effluent to forage crops

Abstract

Culturing and using effective microorganisms from locally derived microorganisms has become a common practice employed by farmers throughout Central America as well as parts of South America and Southeast Asia to control foul odors and flies around compost piles and livestock facilities. These local, effective microorganisms (LEM) are applied in a concentrated solution fermented from carbohydrate-rich substrates inoculated with locally-sourced, actively decomposing leaf litter. Despite its growing prevalence among small-scale farmers in some parts of the world, there is little published research that explores the beneficial or detrimental effects of changing the biome of animal-based nutrients and the soils to which LEM are applied. The objectives of this study were to evaluate the effect of combining LEM with swine effluent to fertilize annual ryegrass (Lolium multiflorum) on plant-available nitrogen, nematode community structure, and forage productivity. Forage performance was good across all of the treatments – with relative feed quality (RFQ) values above 200 and 100 in the March and May harvests respectively. In the first, second and third sampling dates, soils from 0 to 5 cm depth showed more nitrogen mineralized in LEM-treated soils than in control soils (p = 0.178, p < 0.0001 and p = 0.027) respectively. After nutrient applications, soil-nematode community structure (0–10 cm) at the trophic group level changed over time. Most changes were similar between treatments, however, plant parasitic nematode populations were found to be significantly higher in LEM-treated plots in all but one of the sampling dates. LEM is gaining popularity as a natural amendment and although we have shown that it does increase N availability and changes trophic-level nematode community structure, more research is needed to optimize the potential of these benefits.