Smallholder agroecosystems play a key role in the world's food security providing more than 50% of the food produced globally. These unique agroecosystems face a myriad of challenges and remain largely unsupported, yet they are thought to be a critical resource for feeding the projected increasing human population in the coming years. The new challenge to increase food production through agricultural intensification in shrinking per capita arable lands, dwindling world economies, and unpredictable climate change, has led to over-dependence on agrochemical inputs that are often costly and hazardous to both human and animal health and the environment. To ensure healthy crop production approaches, the search for alternative ecofriendly strategies that best fit to the smallholder systems have been proposed. The most common and widely accepted solution that has gained a lot of interest among researchers and smallholder farmers is the use of biological agents; mainly plant growth promoting microorganisms (PGPMs) that provide essential agroecosystem services within a holistic vision of enhancing farm productivity and environmental protection. PGPMs play critical roles in agroecological cycles fundamental for soil nutrient amelioration, crop nutrient improvement, plant tolerance to biotic and abiotic stresses, biocontrol of pests and diseases, and water uptake. This review explores different research strategies involving the use of beneficial microorganisms, within the unique context of smallholder agroecosystems, to promote sustainable maintenance of plant and soil health and enhance agroecosystem resilience against unpredictable climatic perturbations.

The steady decline in agrobiodiversity is not only a significant threat to the genetic stability of the rural agroecosystems but also places a huge impediment to the realization of global food security. Climate change and decline in arable land is forcing subsistence farmers to abandon the less productive but well-adapted local crops for the newer short term and drought-tolerant crops decimating agrobiodiversity further. This study sought to establish the on-farm species and genetic diversity status among the family farming systems of semiarid areas of Eastern Kenya and effect on food security, agrobiodiversity management strategies, their perception of climate change, and climate change coping strategies. Structured questionnaires were administered to 92 active farmers in Embu, Kitui, and Tharaka Nithi Counties of Eastern Kenya. On-farm diversity, socio-economic factors, and their impact on agrobiodiversity were determined. Possible correlations were established using Spearman’s Rank Correlation Coefficient. Remarkably, 26 crop species were recorded where legumes and cereals were dominant. According to the Shannon–Wiener Diversity index (H′), Tharaka Nithi County recorded the highest legumes and cereals diversity indices of 3.436 and 3.449, respectively. Food shortage was reported by over 50% of the respondents in the study area. The existence of weaker adaptive measures in response to climate change was evident. Family farming systems that had higher crop diversification and integrated livestock rearing in their farms were more food secure. Improved mitigation to climate change and diversification of farming systems among the smallholder farms is essential not only in boosting the food security but also in establishment of sustainable farming systems resilient to climate change.

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