Organic Carbon and Aggregate Stability of Three Contrasting Soils as Affected by Arable Agriculture and Improved Pasture in Northern KwaZulu-Natal, South Africa

Abstract Changes in soil organic carbon (SOC) and aggregate stability as a result of agricultural practices have been extensively studied, but the extent these changes is site crop specific. In this study, SOC were evaluated under undisturbed grassland, cultivated pasture arable land uses northern KwaZulu-Natal, South Africa. The soils study sampled from 0–5, 5–10 10–20 cm depths Nitisol, Stagnosol Fluvisol, analysed for content stocks stability. all soils, was significantly lower cultivation (range 1.4 to 2.1%) compared grassland (3.4 4.2%) top 10 cm. followed similar trend uses. overall expressed mean weight diameter (MWD) also use (1.03 1.82 mm) (2.44 2.96 at except Stagnosol. MWD values equal soils. increased with up threshold 3.0–3.9% indicating importance aggregation. weak correlation suggests that other factors are important soil. loss decline over period 38 years continuous near surface layers two potentially problematic sustainability longer term.