Agroecological and biological crop-protection practices for climate adaptation and food security in Nigeria: context dependence, trade-offs and evidence gaps

Nigeria requires crop-production strategies that address climatic stress, soil degradation, pest pressure and food insecurity. This review evaluated agroecological and biological crop-protection practices as pathways to climate resilience and food security in Nigeria. A PRISMA-guided systematic evidence review and narrative synthesis were conducted using Scopus, Web of Science Core Collection, CAB Abstracts, Google Scholar and African Journals Online. Ninety substantive evidence sources were included, comprising Nigerian primary studies and contextual regional and international evidence. Nigerian primary evidence included field experiments, observational studies, household surveys and economic evaluations, while reviews, meta-analyses and mechanistic studies were used for contextual interpretation. Intercropping and crop-density management affected component-crop yields, soil moisture and resource capture; higher cassava density increased storage-root yield by 16%, whereas higher maize density increased maize yield by 11% but reduced second-cycle cassava yield by 7%. Maize–legume systems improved soil carbon, nitrogen and aggregation. Combined phosphorus and rhizobial inoculation increased soybean yield by 777 kg ha −1 , although the highest-yielding combinations were not always the most profitable. Atoxigenic Aspergillus flavus reduced aflatoxin by 82%–95% at harvest and 80%–100% after storage. Botanical pesticides reduced pest survival and crop damage, but yield responses were inconsistent. Observational evidence associated conservation and climate-smart practices with higher productivity, efficiency and income, whereas household food-security outcomes were less consistent. Most evidence concerned adaptive-capacity indicators rather than performance or recovery under defined climatic shocks. Scaling requires locally tested practices, reliable biological products, extension, finance, regulatory oversight and longer-term evaluation of climatic, ecological, economic and nutritional outcomes.