How nutrients are managed for crop production will depend on many other components of the whole farm operation. The 4R concept of nutrient management is an approach that is essential to the development of sustainable agriculture and is focused on the “4 Rs”: the right nutrient sources at the right rate, right time and in the right place.
4R stewardship or nutrient management is a systems approach that considers the following components:
- Inventory of nutrients on the farm
This includes organic (manure), inorganic, the nutrients needed by the crop and those already in the soil.
- Characteristics of field and farm
Nutrients are managed according to land base availability, production goals, proximity to water resources, farmstead layout, equipment availability and safety concerns.
- Site conditions when nutrients are applied
Crop requirement and baseline fertility levels from regular soil testing are used to determine best application rates. At the time of application, field conditions are assessed to determine the best nutrient source and the best option for nutrient placement.
Where manure or other organic amendments are applied, special consideration is given to odour, potential nutrient loss and maintaining an adequate distance from sensitive areas.
- Residual nutrients from previous crops
Where legumes are used in rotation, or where manure or other organic amendments are applied regularly, credit is given to available nutrients and is subtracted from commercial fertilizer needs.
- Nutrient use efficiency
Nutrient use efficiency ensures that the nutrients are available when the crop requires them, resulting in reduced nutrient loss and sustained soil fertility.
- Production vs profit
Maximum yield will not always give the most profitable yield. It is important to know the cost of production and the break-even costs for each field/crop. Crop production practices should always strive for maximum economic yield.
- Other farm management considerations
Nutrient management is part of a comprehensive crop production system that includes soil and water management, crop rotation, variety selection, planting techniques, tillage systems and pest management. How nutrients are managed will depend on these other components of the whole farm operation, including some of the social aspects such as family needs and outside-farm interests.