Soil Carbon Fractions in Rubber Trees, Pasture, and Secondary Forest Areas

Abstract This study quantify the total organic carbon content, light fraction organic matter (LFOM), and soil organic matter fractions (from chemical and physical fractionations) in four different cultivation areas: 1 and 2) rubber tree clonal plantations (FX 3864 and IAN 873); 3) a pasture; and 4) a secondary forest. The research was carried out using soil samples from clonal plantations of eight-year-old rubber trees, located in the coastal plain (Tabuleiros Costeiros) of the state of Rio de Janeiro. The difference in the management of the rubber tree clone area promoted improvements in the soil quality, as it increased the carbon contents of the granulometric fractions, LFOM, and humic substances from the IAN 873 clone area. Both rubber tree areas evaluated presented higher mineral-associated organic carbon levels and humic substances than did the pasture area, reinforcing the reforestation potential of areas with degraded pastures through hevea culture.

摘要 本研究量化了4类不同种植区域内的总有机碳含量、轻组分有机质（light fraction organic matter, LFOM）以及经化学和物理分级得到的土壤有机质组分。这4类区域分别为：1、2）橡胶树无性系种植园（品种FX 3864与IAN 873）；3）牧草地；4）次生林。本研究采集了位于巴西里约热内卢州沿海平原（Tabuleiros Costeiros）的8年生橡胶树无性系种植园的土壤样品开展实验。橡胶树无性系种植区域的管理差异可改善土壤质量，具体表现为IAN 873品种种植区的粒度分级组分有机碳、轻组分有机质及腐殖物质的碳含量均有所提升。相较于牧草地，本研究评估的两处橡胶树种植区均呈现出更高的矿质结合态有机碳水平与腐殖物质含量，这进一步佐证了通过橡胶树栽培修复退化牧草地的潜力。