Factorial field trial finds minor chemical soil improvements under farmer-managed conservation agriculture across semi-arid croplands, highlighting site-specific nutrient responses.
Key Points
To assess the medium-term impacts of farmer-managed conservation agriculture systems compared to conventional tillage and undisturbed soils on selected soil chemical properties in northeastern Namibia.
Applied a factorial experimental design evaluating three tillage systems (conservation agriculture [CA], conventional tillage [Con], and natural undisturbed system [Nat]) in Kavango East and Zambezi, Namibia.
Sampled five depth intervals from 0–10 cm to 50–100 cm (at 10 cm increments) to analyze pH, electrical conductivity (EC), soil organic carbon (SOC), Olsen phosphorus, ammonium (NH₄⁺), potassium, sodium, and soil quality index (SQI).
Soil organic carbon was significantly higher under Con than CA in Kavango East (average 0.62% vs. 0.39%) and slightly higher in Zambezi (0.33% vs. 0.31%, p < 0.05).
CA recorded slightly higher pH (7.60–7.67 vs. 7.24–7.17) and significantly lower EC (114.73–120.44 vs. 208.70–379.25 µS/cm, p < 0.05) in Kavango East, whereas pH and EC did not differ significantly in Zambezi.
Overall soil quality indices varied by site: Con achieved a higher SQI in Kavango East (0.502 vs. 0.396), while CA achieved the highest SQI in Zambezi (0.548 vs. 0.391 for Con).