Raw data "Declining cassava yields with increased land-use intensity mitigated by agronomic practices"

Résumé fourni par la source

Slash-and-burn agriculture remains widespread across sub-Saharan Africa, where repeated clearing and shortened fallows may reduce soil fertility and crop productivity. We assessed how land-use history, agronomic practices, and soil and plant nutrient status relate to cassava (Manihot esculenta) productivity across 120 smallholder fields in Tshopo Province, Democratic Republic of the Congo. We quantified cassava yields, agronomic practices, and soil and plant nutrient contents across gradients of fallow duration and previous clearing cycles.Marketable cassava yield averaged 9.0 ± 0.4 t ha-1 (mean ± SE) and increased with longer fallow periods, although the land-use history explained little yield variation. Yield was positively associated with soil carbon and nitrogen and use of two improved varieties rather than one, but negatively associated with cassava mosaic disease incidence. More previous clearing cycles were associated with higher non-marketable yield, planting density, and weeding frequency, indicating declining production efficiency with increasing land-use intensity. Repeated clearing was also associated with declines in total soil carbon and nitrogen and exchangeable phosphorus and potassium, alongside increases in total phosphorus, calcium, zinc, and soil pH.Overall, repeated clearing and shortened fallows were associated with reduced cassava production efficiency and progressive changes in soil nutrient availability, although effects on marketable yield were modest. Sustaining productivity under increasing land-use pressure will require integrated crop and soil management, including improved disease control and varietal choice, locally adapted nutrient management, and accessible organic or mineral nutrient inputs.

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