EPIC and APEX Models
The Environmental Policy Integrated Climate (EPIC) Model is a cropping system model developed to by Texas A&M that simulates roughly 80 different crops. The model predicts how management decisions will affect soil loss, water quality, and crop yields for areas with homogeneous soils.
The Agricultural Policy Environmental eXtender (APEX) model, also developed by Texas A&M, is a watershed simulation model that predicts the impacts of nutrient management practices, tillage, cropping systems, conservation practices, and other management decisions on surface runoff, and sediment or nutrient loss.
Both models can be downloaded through the website provided below.
Website: EPIC/APEX | EPIC & APEX Models (tamu.edu)
Developer: Texas A&M
Cost: Free
Time Investment: High