Short‐term effects of bioenergy cropping on soil carbon and nitrogen dynamics in a Florida Ultisol

Abstract

Although perennial bioenergy crops provide a potential for soil C sequestration, high fertilizer inputs are required to sustain yields. Land application of bioenergy byproducts can be an effective strategy to reduce the use of inorganic fertilizer. This study examined the impacts of elephantgrass [Pennisetum purpureum (L.) Schum.] bioenergy cropping and conventional pasture on soil C and N responses. Treatments included (a) bahiagrass + 50 kg N ha−1 yr−1 (BHG), (b) elephantgrass + 50 kg N ha−1 yr−1 (E50), (c) elephantgrass + 50 kg N ha−1 yr−1 + fermentation residual (E50FR), (d) elephantgrass + 50 kg N ha−1 yr−1 + biochar (E50BC), and (e) elephantgrass + 250 kg N ha−1 yr−1 (E250). Soil C and N responses occurred mainly at the 0‐ to 10‐cm depth. Biochar resulted in the largest increase in soil C stocks at the 0‐ to 10‐cm depth (5.8 Mg C ha−1 in 2012 vs. 40 Mg C ha−1 in 2016), but no differences were observed among the other treatments. Conversely, greater soil N stocks at the 0‐ to 10‐cm depth were associated with the BHG (0.8 and 0.34 Mg N ha−1 for other treatments). Biochar favored N and C accumulation in the mineral‐associated (<53 μm) fraction, possibly from the accumulation of fine biochar fragments. In contrast, fermentation residual promoted C accumulation in unprotected light fraction. These results are supported by the δ13C signature and C/N ratios of the fractions. Results underscore the value of recycling biochar in bioenergy cropping systems as a means of improving C in coarse‐textured soils.

Can surface‐applied biochar improve soil health and plant performance in a perennial cool‐season grass forage system?

“…Similarly, in a study on temperate pastures in Australia, CO 2 ‐C losses from biochar ranged between 2% and 7% after 12 months (Singh et al., 2015). Biochar‐derived C may migrate downward in the soil profile (Jaffé et al., 2013; Silveira et al., 2020; Singh et al., 2015). Therefore, it is possible that some of the C from the higher rates accumulated below our sampling depth of 0–15 cm.…”

A Qualidade Do Solo a Partir Do Manejo Agroecológico: Análises Químicas E Físicas

“…De acordo com dados do Instituto Brasileiro de Geografia e Estatística (IBGE) em 2020 no Brasil havia em média 218.150.298 cabeças de bovinos. Devido ao aumento pela procura da carne bovina, os sistemas de pastagens estão se tornando cada vez mais extensivos (SILVEIRA, et al, 2020).…”