Key facts and figures

• Nutrients are elements found in nature that provide nourishment to plants, animals and other living organisms.
• Eighteen elements have been shown to be essential for higher plants, but not all elements are required by all plants. Each plant nutrient fulfills a specific role in plant growth and food production. Nutrients cannot be substituted for one another.
• The nutrients in plants ensure that enough quality food can be grown, but those nutrients often fulfill important functions for human health as well, some of which are very distinct from the way plants use the same nutrients.
• Most fertilizer nutrients are mined, but nitrogen is primarily captured from the atmosphere.
• Nutrients are not consumed in the sense that fuels are. They continue to exist in natural cycles, but the cost and technical feasibility of recovering them varies once high-concentration mineral deposits are no longer available.
• Resources of all the major nutrients are considered adequate for the foreseeable future. As the most economic resources are exhausted, the incentive for technical breakthroughs to improve the feasibility of recycling nutrients will increase. In the meantime, it is critical to use nutrient resources as judiciously as possible.
• The majority of nutrient inputs to agriculture come from commercial mineral fertilizers. Organic manures play a significant but lesser role in providing nutrients.
• Organic forms of nutrients must be mineralized before they can be used by crops and other plants. Fertilizers generally provide nutrients in their inorganic, or mineral, forms.
• Although inorganic sources of nutrients are often called “manufactured” or “chemical” fertilizer, all of these nutrient forms exist in nature.
• The chemical breakthroughs that led to the modern process for ammonia synthesis were considered so important for humanity that they earned two distinct Nobel Prizes for Chemistry.
• The ongoing removal of soil nutrients from successive crops with little or no replenishment is a major cause of low crop yields in parts of the developing world. This negatively affects food supplies and farmers’ profitability. Nutrients lost from African soils every year are equivalent to USD 4 billion worth of fertilizers.
• The farming systems currently used in Africa are unsustainable. Intensification is needed to feed growing populations, but it must be done in a way that uses soil nutrient and water resources efficiently and that relieves pressure on forests and other fragile lands.
• Nutrients may be absorbed by crops, immobilized by the soil or lost from the soil system. Depending on the nutrient and various conditions, these can be lost to the atmosphere by volatilization or denitrification, through soil erosion, or by leaching.
• Some nutrients, like nitrogen, are extremely mobile in the environment.
• The efficiency of agricultural nitrogen use is generally very low – around 40-50% globally. Frameworks to improve nitrogen management often cross boundaries and require cooperation at different geographic levels.
• In addition to known environmental impacts, there are concerns that excessive reactive nitrogen in the environment may have unwanted impacts on human health.
• Most P transported from soil to water is in eroded soil particles to which P is adsorbed. The impacts of P on the environment and effective responses are often different from those that concern nitrogen. P is often the limiting nutrient in aquatic ecosystems.
• Good nutrient management occurs when farmers manage organic and inorganic sources of nutrients in an integrated fashion. Good management increases the amount of nutrient absorbed by the crop or stored in the soil, making less available to be lost to the environment.
• Recycling nutrients from within the agricultural value chain should be the starting point for crop nutrition.
• A number of issues need to be addressed before urban and industrial wastes will be commonly recycled as nutrient sources. These include concerns about food safety and hygiene as well as poor economic viability of transporting the wastes and related environmental impacts.