Soil and human health: Understanding agricultural and socio-environmental risk and resilience in the age of climate change

Prolonged monocropping of commodity crops, such as peanuts (Arachis hypogea L.) in West Africa, typically strips nutrients from soils and may exacerbate vulnerability to insects and diseases. In this paper, we focus on aflatoxins, toxic chemicals produced by certain molds growing on moist crops, as one risk of growing importance for its negative impacts on human health, crop yields, and agricultural livelihoods and ecosystems. We link the increased prevalence of this deadly fungus to the long history of peanut monoculture, exacerbated by market liberalization and China's increased investment and export demand for peanuts, climate change, food insecurity, as well as disregard for and displacement of traditional agricultural knowledge. We use a political ecology approach to place the public health threat from aflatoxin in the context of both historical pressures for cash-crop production of peanuts and contemporary soil degradation, food insecurity, climate change precarity and changes within social and economic systems of agriculture in Senegal.

Synergism and antagonisms between nutrients induced by copper toxicity in grapevine rootstocks: Monocropping vs. intercropping

The long-term use of Cu-containing fungicides contaminates vineyards soils, which can induce Cu toxicity and nutrient imbalances in several plant species. The aim of this work was to evaluate the effect of Cu toxicity on two grapevine rootstocks, Fercal and 196.17, and to elucidate if intercropping with oat can alleviate grapevine Cu toxicity. Plants were hydroponically-cultivated and treated with different Cu concentrations. At harvest the biomass accumulation, the SPAD index and the symplastic and apoplastic root and leaves ionome were measured to evaluate possible synergistic and/or antagonistic effects on other micro- and macronutrients. The root exudation analysis was correlated with genes expression (VvPEZ-like), whereas PCA analysis performed on the grapevine and oat ionome revealed that both mono- and intercropped 196.17 rootstock display a positive effect on Zn and Mn in the root tissues at high Cu concentrations. An increase of Zn and Mn in roots was also reported for the intercropped Fercal rootstock at high Cu concentrations while an antagonistic relation was reported for root Zn concentration in the monocropped Fercal rootstock. Our results showed that grapevine and oat compete for nutrient uptake and that this phenomenon can possibly alleviate grapevine Cu toxicity. However, Fercal rootstock is able to take advantage from oat, while 196.17 is disadvantaged by the intercropping system. Even though intercropping system seems to be a valuable tool to counteract grapevine Cu toxicity, the application of this agricultural practice has shown to be species dependent and should be evaluated for each rootstock.