Biochar amendment did not influence the growth of two tree plantations on nutrient‐depleted Ultisols in the south Ecuadorian Amazon region

The literature suggests that biochar increases the fertility of degraded, nutrient-poor tropical soils. We hypothesized addition (a) tree growth in two plantations on Ultisols south Ecuadorian Amazon region, (b) reduces litterfall during dry season because soil remains moister, and (c) improves benefit–cost ratio plantation. grew species—the native leguminous Schizolobium parahyba var. amazonicum (Ducke) Barneby exotic Gmelina arborea Roxb—and used a full factorial split-split-plot design all treatments for both species at each sites. included amendment mineral fertilizer plus lime, 3 6 t ha–1 biochar, control. plots were replicated three or four times. Tree height (TH), basal diameter (BD), breast (DBH) measured several times 51 mo after planting September 2009 12 (March 2012–February 2013). site lime treatment had significant effects TH, BD, DBH. increased DBH by 47, 43, 58%, respectively, relative to G. was average 84% higher than S. parahyba. did not significantly influence DBH, litterfall. wood production >1 controls but <1 decreased with increasing biochar. Our results demonstrate assumption can be improve degraded soils cannot generalized.