Developed by Colorado State University, it provides recommendations for producers on irrigation timing and nutrient scheduling. Crop development and irrigation needs are driven by local climatic inputs. Nutrient balances are determined and a seasonal accounting is made as to plant uptake depending on the health and vigor of the plant from appropriate timing and amounts of irrigation. Depending on plant health and vigor, a mid year correction is presented to allow for modification of nutrient applications. Nutrient needs are based on yields and input soil sampling information.
Nutrients considered are manure, organic, and commercial.
This includes prior year on crop residue and manure application. Accounting is made for the method of tillage, manure source and application, and method of commercial application. The model is in BETA test stage. The components include infiltration, percolation, upflux, surface ponding, climate, and evapotranspiration. SPAW includes a pond module to evaluate surface inflows from adjacent watersheds and outflows for irrigation, livestock water, and other uses.