Environmental considerations

Key points

Accounting for the weather

Several tools are available for estimating N status:

• Soil N test - can be used in the fall after harvest. Spring soil N tests can be used in western Minnesota.
• Tissue tests
  • In-season tissue tests - can be useful, but are not predictive and not correlated with fertilizer recommendations.
  • Basal stalk nitrate-N test - is used at the end of the season to estimate whether or not N was adequate (or excessive) for the crop during the growing season. This is a post-mortem test and not predictive.
• Supplemental N worksheet - takes into account application timing, spring conditions and crop appearance to suggest whether or not supplemental N would be recommended.
• Crop modeling

Conservation: What can be achieved?

MPCA has set a goal of reducing Minnesota's nitrate load to the Gulf of Mexico by 20% by 2025. Strategies fall into three major categories:

• Fertilizer and manure management - Optimum nitrogen rate and application timing practices are least expensive to implement and have the greatest probability for savings.
• Water management - These practices include engineering projects, such as controlled drainage, bioreactors and wetlands.
• Cropping system changes - include installing riparian buffers, incorporating cover crops and planting more perennials on marginal cropland.