Carbon and nitrogen stocks in Lithic soils: Environmental drivers and land-use implication in Brazilian dry ecosystems

Lithic soils (with lithic contact up to 50 cm deep) are common in global drylands. Historically, have been little studied over time and the natural and anthropogenic factors that affect the storage of carbon (C) and nitrogen (N) in this soil group are little known.

We used 118 lithic soil profiles to understand how climate (semi-arid and dry sub-humid), lithology, relief, and land-use (agriculture, pasture, secondary forest, and native forest) affect soil C and N stocks in drylands, northeastern Brazil.

Climate did not affect C and N stocks in lithic soils. However, soils with sedimentary lithology showed, on average, 17.4 and 27.1% less C and 20.5 and 38.2% less N than soils under metamorphic and igneous lithology, respectively. Soils under wavy relief presented the highest C (30.5 ± 16.9 Mg ha⁻¹) and N (2.7 ± 1.2 Mg ha⁻¹) stocks, while those under flat relief presented the lowest values (19.6 ± 16.3 Mg C ha⁻¹ and 2.1 ± 1.5 Mg N ha⁻¹), because of more significant anthropic use in profiles under flat relief. In general, soils under pasture and agriculture showed, on average, 73.6% and 65.8% less C than soils under native forest and the natural recovery of C and N stocks in soils (areas under natural regeneration) was limited, because of lithic contact close to the surface.

We concluded that lithology, relief, and land use were the main factors affecting the accumulation of C and N in lithic soils, northeastern Brazil. Our results may be useful for sustainable use of lithic soils in drylands according to their aptitude and support capacity.