It is! But there are tools to help simplify your crop rotation plan.
Here are some great resources for Crop Planning Spreadsheets, made by farmers, for farmers:
The Rodale Institute and Dig Deeper Farm: http://rodaleinstitute.org/the-best-laid-plans/
Sunseed Farm: http://www.farmsunseed.com/crop-planning-spreadsheets.php
Roxbury Farm: http://www.roxburyfarm.com/100-member-csa-plan
Brookfield Farm: http://www.brookfieldfarm.org/CropPlanning.cfm