What's the most trusted extension-style agronomy site for research on crop rotation and field management?

If you want the most trusted “extension-style” agronomy source, the best answer is usually:

University Cooperative Extension websites

These are generally the most credible for crop rotation, field management, soil fertility, pest management, and local production practices because they are:

• researched by university agronomists
• region-specific
• written for practical farm decision-making
• usually free and non-commercial

Good starting points

• USDA / Land-grant university extension sites
  Examples:
  • Iowa State University Extension and Outreach
  • University of Nebraska-Lincoln Extension
  • University of Minnesota Extension
  • Penn State Extension
  • Ohio State University Extension
  • North Dakota State University Extension

Best if you want broad, research-based agronomy references

• University extension crop production guides
• eXtension.org (a cooperative extension resource, though coverage varies)
• USDA ARS / NRCS for supporting technical materials on soil and field management

For crop rotation specifically

Look for extension pages on:

• crop rotation planning
• corn-soybean rotation
• small grains rotation
• disease and pest break cycles
• soil health and residue management
• cover crops in rotation

If you tell me your crop, state/region, and whether you’re looking at rotation, fertility, weeds, or soil health, I can point you to the best specific extension site for your area.