Impacts of Biochar on Trifolium incarnatum and Lolium multiflorum: Soil Nutrient Retention and Loss in Sandy Loam Amended with Dairy Manure

Biochar has many potential benefits in agroecosystems such as increasing productivity of crops and modifying soil nutrient content. Biochar is sourced from many waste materials which could easily and sustainably remedy current challenges in concentrated agricultural operations that use manure-based fertilizers. However, relatively little is known about its effects on forage species in conjunction with manure or biochar enriched with manure effluent. Our objective was to look at the effect of biochar and dairy effluent soil amendments on a forage legume and a grass. In this study, sandy loam soil was amended with a variety of biochar (BC) in a greenhouse setting. Factors included (1) BC type; (2) BC loading percentage; (3) effluent saturation of BC; and (4) forage inclusion. The study was repeated twice: once with Trifolium incarnatum and once with Lolium multiflorum. Plant material was assayed for biomass (BM) and C and N content. Soil was assayed for nutrient content and micronutrients. Data were not normally distributed and were consequently analyzed for variance using non-parametric methods in R. Overall, T. incarnatum showed a very strong negative (p ≤ 0.05) impact associated with increasing loading percentages of blend and manure BC on herbage BM, while effluent saturation showed no effect (p > 0.05). In contrast, L. multiflorum showed a strong (p ≤ 0.05) positive impact of increasing loading percentages of saturated wood, blend, and manure BC on herbage BM. BC impact on soil nutrients and forage varied greatly depending on type of BC, loading percentage, and forage species included. Results indicated the importance of BC properties and rates, as well as forage species for nutrient tolerances when choosing a BC amendment and loading rate.