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

中文翻译：

---

Biochar 修正物没有影响厄瓜多尔南部亚马逊地区营养耗尽的 Ultisol 上两个人工林的生长

文献表明，生物炭可以提高退化、营养贫乏的热带土壤的肥力。我们假设添加生物炭 (a) 增加了厄瓜多尔南部亚马逊地区 Ultisol 上两个种植园的树木生长，(b) 减少了旱季的凋落物，因为土壤保持湿润，以及 (c) 提高了效益成本比种植园的。我们种植了两种树种——本地豆科裂殖酵母变种。amazonicum (Ducke) Barneby 和异国情调的Gmelina arborea Roxb——并在两个地点的每一个地点对两种树种的所有处理使用全因子裂区设计。处理包括添加矿物肥料加石灰，3 和 6 t ha ^–1biochar 和对照。这些地块被重复三到四次。在 2009 年 9 月种植后的 51 个月内和 12 个月内（​​2012 年 3 月至 2013 年 2 月）的凋落物分别测量了树高 (TH)、基部直径 (BD) 和胸高直径 (DBH)。场地和矿物肥料加石灰处理对 TH、BD 和 DBH 有显着影响。相对于对照，矿物肥料加石灰的添加物使 TH、BD 和 DBH 分别增加了 47%、43% 和 58%。G. arborea的凋落物平均比S. parahyba高 84%. biochar 的添加对 TH、BD、DBH 或凋落物没有显着影响。在矿物肥料加石灰处理和对照中，木材生产的效益成本比 >1，但在生物炭处理中 <1，并且随着生物炭添加量的增加而降低。我们的结果表明，生物炭可用于提高退化亚马逊土壤肥力的假设不能一概而论。