Using soil and plant properties and farm management practices to improve the micronutrient composition of food and feed

Improving the micronutrient composition of food and feed crops is an important aspect of food security and human health. A range of geochemical, environmental and management factors combine to influence micronutrient concentrations in different soil and plant species.The paper addresses four issues; (i) micronutrient concentrations of agricultural soils and implications for production, (ii) micronutrient composition of different crop species, (iii) impact of crop rotation, species mixtures and nutrient management on micronutrient status in soils and crops, and (iv) using farmgate balances to inform micronutrient management on farms. The paper is a literature review focusing on Northern Europe where soil micronutrient concentrations are often low resulting in food and feed crop concentrations failing to meet nutritional requirements. We illustrate the use of geochemical maps for identifying areas of different potential to supply micronutrients to crop production. We then evaluate the micronutrient concentration of a broad range of plant species, showing the value of diverse pasture species for livestock diets. Intercropping and crop rotations facilitate micronutrient management due in part to soil/plant/microbial interactions in the rhizosphere influencing micronutrient availability. Fertilisers and on-farm manures are also an important management mechanism but there are new opportunities to use other off-farm organic and inorganic by-products to optimise crop nutrition although care is needed to balance macro- and micronutrients and potentially toxic elements.Micronutrient farm balances complement soil and crop analysis and macronutrient balances for agricultural and environmental management and can be used to compare farming systems. Arable farms more often showed negative micronutrient balances (e.g. Cu) whereas on livestock farms, feed is a major source of micronutrient import. Farm management approaches such as those described here will complement other approaches e.g. plant breeding. We suggest a food-chain approach to micronutrient management to meet the demands not only of crops but also of livestock and humans; this requires inter-disciplinary collaboration between stakeholders in agriculture, environment and health.

► Crop micronutrient composition is affected by geochemistry and management factors
► Crop rotations and intercropping can alter plant micronutrient composition
► Risk of micronutrient depletion is greater in arable than livestock systems
► Farmgate balances, soil and crop analysis can aid micronutrient management
► A food chain approach is proposed optimising plant, livestock and human needs