Subsistence farmers in Africa depend largely on the soil organic matter to sustain crop productivity. Long\uffe2\uff80\uff90term changes in soil organic carbon and nitrogen were measured after woodland clearance for smallholder subsistence farming or for commercial farming. The contents of organic carbon and nitrogen in soil under reference woodlands were largest (53.3\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921, 4.88\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921) in a red clay soil (\uffe2\uff88\uffbc\uffe2\uff80\uff8350% clay + silt), followed by a granitic sand (\uffe2\uff88\uffbc\uffe2\uff80\uff8312% clay + silt; 22.8\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921, 1.47\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921) and least (19.5\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921, 0.88\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921) in a Kalahari sand (\uffe2\uff88\uffbc\uffe2\uff80\uff835% clay + silt). Organic carbon declined rapidly under cultivation to attain new equilibria within 10\uffe2\uff80\uff83years on all smallholdings. Greatest losses occurred in soils that initially contained most carbon and nitrogen in the order: red clay (22.4\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921 and 1.0\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921) > granitic sand (13.2\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921 and 0.8\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921) > Kalahari sand (10.6\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921 and 0.5\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921). On the clay soil, commercial farming with intensive use of mineral fertilizers and incorporation of maize stover led to more gradual decline: at equilibrium, contents of carbon and nitrogen were 15\uffe2\uff80\uff83t C ha\uffe2\uff88\uff921 and 1.7\uffe2\uff80\uff83t N ha\uffe2\uff88\uff921 greater than on smallholdings with similar soil and climate.
In the Kalahari sand the \uffce\uffb413C of organic C remained constant after woodland clearance, and maize contributed less than 10% of the total C even after 55\uffe2\uff80\uff83years. The \uffce\uffb413C signature increased slightly with increasing duration of cultivation by smallholders in the granitic sands and red clay soil where maize contributed 29% and 35% of the C at equilibrium. Under more productive commercial farming, the carbon derived from maize accounted for 50% of the total after 10\uffe2\uff80\uff83years of cultivation and 67% at equilibrium. The persistence of woodland carbon in the sandy soil is attributed to chemical stabilization resulting from large concentrations of lignin and polyphenols in the tree litter, or as charcoal.
", "keywords": ["2. Zero hunger", "agroecosystems", "c-13 natural-abundance", "carbon dynamics", "spodosols", "04 agricultural and veterinary sciences", "15. Life on land", "maize", "stabilization", "residues", "vegetation", "0401 agriculture", " forestry", " and fisheries", "sandy soils", "isotope"], "contacts": [{"organization": "Shamie Zingore, Ken E. Giller, Ken E. Giller, P. Nyamugafata, C. Manyame,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1111/j.1365-2389.2005.00707.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/European%20Journal%20of%20Soil%20Science", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.1365-2389.2005.00707.x", "name": "item", "description": "10.1111/j.1365-2389.2005.00707.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.1365-2389.2005.00707.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-04-11T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=spodosols&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=spodosols&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=spodosols&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=spodosols&offset=1", "hreflang": "en-US"}], "numberMatched": 1, "numberReturned": 1, "distributedFeatures": [], "timeStamp": "2026-05-30T11:59:06.520847Z"}