Over 10% of the UK population consumes insufficient calcium (Ca) or magnesium (Mg) for adequate health. Magnesium intakes are especially low for >40% of UK women aged 19-34. Dietary delivery of bioavailable Ca and Mg can be increased through genetic (breeding) and agronomic (fertiliser) biofortification of crops. Successful biofortification requires increasing the Ca and Mg concentration of edible crop portions whilst minimising the content of antinutrients such as oxalate and phytate. Antinutrients inhibit Ca and Mg uptake in the human gut. Vegetable Brassica crops are good targets as they have a high capacity for Ca and Mg, and low oxalate and phytate contents, along with other health benefits. Targeted genetic improvement of vegetable Brassica can have significant effects on Ca and Mg delivery to UK and global diets. Building on previous evolutionary studies, we showed recently for the first time that relatively few genetic loci control leaf Ca and Mg concentration (leaf-Ca and Mg; Broadley MR et al. 2008; Plant Physiol. 146, 1707-20). We also showed that sufficient natural genetic variation and heritability exists to attempt genetic biofortification in Brassica. Based on UK dietary surveys, consumption of a single portion of Brassica leaf or floret (e.g. broccoli, cabbage, kale, pak choi) - bred for realistically-achievable Ca and Mg contents - could increase UK intakes to levels greater than the LRNIs (Lower Reference Nutrient Intake) for three (Ca) and five (Mg) million adults. However, at present, genetic loci and individual genes controlling leaf-Ca and Mg are insufficiently resolved to be useful in breeding or to reveal the regulation of genes controlling leaf-Ca and Mg. We have assembled an expert consortium to address this timely opportunity. First, we will resolve candidate loci associated with leaf-Ca and Mg to the gene level. We will exploit our recently-published datasets and new Brassica technologies including gene expression arrays for association analysis (genetical genomics, or eQTL). This work is only now becoming possible because of the emerging crop Brassica genome sequence and new Brassica genetic/genomic resources. We will determine the function of candidate genes in planta using new populations of B. rapa mutants, alongside functional studies of Ca-transporter genes known to have complex effects on leaf-Ca and Mg in Arabidopsis. Public-good pre-breeding pipelines within the consortium will be used to disseminate information. Second, we will develop a modelling framework that defines regulatory gene networks controlling leaf-Ca and Mg in Brassica. We will integrate mineral input and output data, gene activity and allelic variation using state-of-the-art systems-based expertise and resources. We will define genes, alleles, and their regulatory network architecture in the context of increasing industry-use of calcium nitrate (Ca(NO3)2) fertiliser. Ca(NO3)2 is a desirable N fertiliser since it improves Brassica crop quality, reduces greenhouse gas emissions, and improves the security of fertiliser transport and storage, since it cannot be used in explosives.

Magnesium (Mg) plays an important role in many basic processes in living cells, and is therefore essential for animal health. Low Mg status (hypomagnesaemia) gives rise to conditions called tetany, or staggers, in ruminants like cattle and sheep. These conditions are remarkably widespread among ruminants in Europe, often with high fatality rates. Avoiding hypomagnesaemia is therefore important for animal welfare and farm business profitability. Typically the condition is managed by use of feed mixes or dietary supplements or by directly administering Mg to animals as a medicine. However, these approaches are costly and can be inefficient and ineffective. Another approach is to ensure that the grass grazed by animals in the field or eaten as hay or silage provides a good source of Mg. This approach is under-developed in UK agriculture, as is forage fertilizer management. To develop these approaches requires three advances. First, we must understand the natural variation in the capacity of the soil to supply Mg, caused by differences across the country in the properties of the soil and the composition of the rocks from which they are derived. Second, we must understand how farmers currently use Mg in a range of enterprises as supplements, additives, fertilizers and veterinary interventions. Third, we must understand the mechanisms by which Mg is transferred from soil to plant to animal and how these can be exploited. For example, forage grass varieties that accumulate more Mg were selected by plant breeders in the 1970/80s. For example, a variety of Italian ryegrass (Lolium multiflorum 'Magnet/RVP2067') which accumulates more Mg was selected in UK breeding programmes. This variety performed consistently across sites and was shown to improve ruminant Mg status in feeding studies. However, this trait has not since been pursued in modern hybrid or perennial ryegrass varieties now favoured by the sector. We aim to develop novel and resilient nutrient management strategies for Mg in the UK ruminant sectors. The primary nutritional focus of this project is Mg due to its strategic importance to the UK ruminant sector. However, new data, knowledge and management and communication tools arising from this project will apply to other nutrients/elements which are important for animal health. The project will therefore have wider potential to make animal production more efficient and resilient and will improve our wider understanding of landscape-scale processes. This project will draw on a range of scientific disciplines including soil chemistry, geology, statistics economics and plant sciences. The four primary objectives are: (1) to use varied soil data to map the regions of England, N. Ireland and Wales where the soil supply of Mg is likely to be insufficient (2) to develop new understanding of Mg transfers on the farm and how these are managed, (3) to develop genetic markers and crop management strategies to increase leaf Mg concentration in modern forage grasses, and (4) to integrate these streams of knowledge and information into a decision tool that allows the farmer to improve forage nutrient management at farm scale and also help advisors or policy makers to examine management options at regional scale. The tool will take into account the economic impact of nutrient management scenarios based upon delivery via mineral supplements or improved grazing management via enhanced nutritional forage profiles given local and regional soil conditions. Decision support will be delivered via a user-friendly web/smart-phone interface. User-defined inputs will include spatial data (soil characteristics, climate, etc.), choice of grass variety, fertiliser-management, supplement use, and economic costs. Outputs will enable the economic benefits of the various Mg nutrition options to be compared and communicated, at farm-to-regional scales.

Nitrogen (N) is vital for crop productivity, however, typically half of the N we add to agricultural land is usually lost to the environment. This wastes the resource and produces threats to air, water, soil, human health and biodiversity, and generates harmful greenhouse gas (GHG) emissions. These environmental problems largely result from our inability to accurately match fertiliser inputs to crop demand in both space and time in the field. If these problems are to be overcome, we need a radical step change in current N management techniques in both arable and grassland production systems. One potential solution to this is the use of technologies that can 'sense' the amount of plant-available N present in the soil combined with sensors that can report on the N status of the crop canopy. On their own, these sensors can provide useful information on soil/crop N status to the farmer. However, they need refining if they are then to be used to inform fertiliser management decisions. This is because climate variables (e.g., temperature, rainfall, sunlight hours) and soil factors (e.g., texture, organic matter content) can have a major influence on soil processes and plant growth, independent of soil N status. These sensors therefore need to be combined with other data and improved soil-crop growth models to provide a more accurate report of how soil N relates to crop N demand at any given point in time. In this project, we are demonstrating how adoption of precision agriculture techniques (in the form of soil nitrate sensors) can be used to improve N use efficiency in both arable (wheat, oilseed rape) and grassland systems. While we are focusing on soil nitrate, as it arguably represents the key form of soil N associated with productivity and the environment, the approaches we are taking are also readily applicable to other nutrients for which sensors are currently being developed (e.g., ammonium, phosphate, potassium). We have designed our research programme in accordance with the strategic objectives of the BBSRC-SARIC programme and those recently produced by HM Government to facilitate delivery of sustainable intensification strategies. To maximise the potential for technology development, commercialisation and adoption we are working closely with a range of industry partners throughout the programme. Overall, we aim to (i) demonstrate the use of novel N sensors for the real-time measurement of soil N status; (ii) use geo-statistical methods to optimise the deployment of these in situ sensors; (iii) produce new mechanistic mathematical models which allow accurate prediction of crop N demand; (iv) validate the benefits of these sensors and models in representative grassland and arable systems from a N use and economic standpoint; and (v) explore how these new technologies can improve current fertiliser management and guidelines through enhanced industry-focused decision support tools. Ultimately, this technology shift could result in substantial savings to the farmer by both reducing costs, maximising yields and minimising damage to the environment. For example, if our technology improves N use efficiency by 10% in agricultural land where fertiliser is applied in the UK (8.2 million hectares of grassland and tilled crops), we estimate it would save 100 thousand tons of N fertiliser (equivalent to a saving of £69 million per annum to farmers). When the direct and indirect costs of nitrate pollution are considered (e.g., removing nitrate from drinking water is estimated to cost UK water companies >£20 million annually), and the reduction in direct and indirect greenhouse gas emissions from manufacture and use of 100 thousand tons of N fertiliser are accounted for, the benefits of adopting a validated precision agriculture approach are clear.