Since the retreat of the oceans, the land surface of planet Earth has for plant growth become widely deficient in nitrogen and phosphorus and to a smaller extent, potassium and sulphur. A century ago, agriculture was focused on adding these nutrients to solve production problems of otherwise good soils exhausted from many hundreds of years of cultivation and of new, more marginal lands being brought into production. The use of mineral fertilisers such as Chilean saltpetre, superphosphate and potash, together with the other then-known essential minerals, calcium and magnesium, brought production up to expectations, but to experienced eyes, anomalous results hinted at limitations to production as yet unknown. The micronutrients, as they became to be known, contributed greatly to the 20th century crop productivity. It is estimated that of the agricultural soils of the world, 49% were low in zinc, 31% low in boron, 15% low in molybdenum, 14% low in manganese, 10% low in copper and just 3% deficient in iron. The post war explosion in the human population put great stress on our food systems in the 1950s but the Green Revolution (1960–1980) more than doubled world food production and mass starvation was avoided. Instead, there was in the 1980s and 90s a massive rise in micronutrient deficiencies, especially in subsistence farming systems, which are still unresolved today. It appears that the Green Revolution emphasis on cereal production at the expense of pulses and other nutrient rich foods is the cause, and new food systems capable of addressing all human nutritional needs are being developed, a multifactorial challenge. Dealing with the complex nutritional requirements of new and effective food systems for the future is demanding new analytical capability to support plant breeders and agronomists in the field.
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