Nutrient management

Nutrient management is the science and practice directed to link soil, crop, weather, and hydrologic factors with cultural, irrigation, and soil and water conservation practices to achieve optimal nutrient use efficiency, crop yields, crop quality, and economic returns, while reducing off-site transport of nutrients (fertilizer) that may impact the environment. It involves matching a specific field soil, climate, and crop management conditions to rate, source, timing, and place (commonly known as the 4R nutrient stewardship) of nutrient application. Nutrient management is the science and practice directed to link soil, crop, weather, and hydrologic factors with cultural, irrigation, and soil and water conservation practices to achieve optimal nutrient use efficiency, crop yields, crop quality, and economic returns, while reducing off-site transport of nutrients (fertilizer) that may impact the environment. It involves matching a specific field soil, climate, and crop management conditions to rate, source, timing, and place (commonly known as the 4R nutrient stewardship) of nutrient application. Important factors that need to be considered when managing nutrients include (a) the application of nutrients considering the achievable optimum yields and, in some cases, crop quality; (b) the management, application, and timing of nutrients using a budget based on all sources and sinks active at the site; and (c) the management of soil, water, and crop to minimize the off-site transport of nutrients from nutrient leaching out of the root zone, surface runoff, and volatilization (or other gas exchanges). There can be potential interactions because of differences in nutrient pathways and dynamics. For instance, practices that reduce the off-site surface transport of a given nutrient may increase the leaching losses of other nutrients. These complex dynamics present nutrient managers the difficult task of achieve the best balance for maximizing profit while contributing to the conservation of our biosphere. A crop nutrient management plan is a tool that farmers can use to increase the efficiency of all the nutrient sources a crop uses while reducing production and environmental risk, ultimately increasing profit. It is generally agreed that there are ten fundamental components of a Crop Nutrient Management Plan. Each component is critical to helping analyze each field and improve nutrient efficiency for the crops grown. These components include: When such a plan is designed for animal feeding operations (AFO), it may be termed a 'manure management plan.' In the United States, some regulatory agencies recommend or require that farms implement these plans in order to prevent water pollution. The U.S. Natural Resources Conservation Service (NRCS) has published guidance documents on preparing a comprehensive nutrient management plan (CNMP) for AFOs. The International Plant Nutrition Institute has published a 4R plant nutrition manual for improving the management of plant nutrition. The manual outlines the scientific principles behind each of the four R’s or “rights” (right source of nutrient, right application rate, right time, right place) and discusses the adoption of 4R practices on the farm, approaches to nutrient management planning, and measurement of sustainability performance. Of the 16 essential plant nutrients, nitrogen is usually the most difficult to manage in field crop systems. This is because the quantity of plant-available nitrogen can change rapidly in response to changes in soil water status. Nitrogen can be lost from the plant-soil system by one or more of the following processes: leaching; surface runoff; soil erosion; ammonia volatilization; and denitrification. Nitrogen management aims to maximize the efficiency with which crops use applied N. Improvements in N use efficiency are associated with decreases in N loss from the soil. Although losses cannot be avoided completely, significant improvements can be realized by applying one or more of the following management practices in the cropping system. Nitrate is the form of nitrogen that is most susceptible to loss from the soil, through denitrification and leaching. The amount of N lost via these processes can be limited by restricting soil nitrate concentrations, especially at times of high risk. This can be done in many ways, although these are not always cost-effective.