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All plants require nutrients to grow and a significant portion of these nutrients are removed and exported when a crop is harvested. Sustainable crop production requires the nutrients that are removed to be replaced with synthetic fertilizers, manures or municipal wastes.
If nutrients are supplied to crops at rates below crop requirements, yields will be reduced and the long term productivity of the land will decline. However, if nutrients are applied in excess of crop requirements and removal, they increase the risk of agronomic problems such as crop lodging (in the case of N), nutrient imbalances or toxicities and environmental problems such as nitrate leaching to groundwater, P runoff to surface water and release of greenhouse gases to the atmosphere.
The main challenge for managing nutrients in crop production systems is to provide sufficient nutrients for optimum plant growth without causing unacceptable risk to the environment. MAFRI encourages producers to follow the 4R Nutrient Stewardship system. This approach relies on the adoption of BMPs by producers to deliver nutrients from the Right Source @ Right Rate, Right Time, Right Place®. Soil testing and crop nutrient requirements are the cornerstones of nutrient management.