CropSyst
CropSyst is a is a user-friendly, conceptually simple but sound multi-year multi-crop simulation model with daily time step. The model simulates the soil water budget, soil-plant nitrogen budget, crop canopy and root growth, dry matter production, yield, residue production and decomposition, and erosion. Management options include: cultivar selection, crop rotation (including fallow years), irrigation, nitrogen fertilization, tillage operations (over 80 options), and residue management.
The model is intended for crop growth simulation over a unit field area (m2). Growth is described at the level of whole plant and organs. Crop development is simulated based on thermal time required to reach specific growth stages. The accumulation of thermal time may be accelerated by water stress. Thermal time may also be modulated by photoperiod and vernalization requirements whenever pertinent. Daily crop growth is expressed as biomass increase per unit ground area. The model accounts for four limiting factors to crop growth: water, nitrogen, light, and temperature. The water budget in the model includes precipitation, irrigation, runoff, interception, water infiltration, water redistribution in the soil profile, crop transpiration, and evaporation. The nitrogen budget in CropSyst includes N transformations, ammonium sorption, symbiotic N fixation, crop N demand and crop N uptake.
A complete description of the model is given in the User’s manual.
CropSyst has been applied to several crops (corn, wheat, barley, soybean, sorghum, and lupins) and regions (Western US, Southern France, Northern and Southern Italy, Northern Syria, Northern Spain, and Western Australia), generally with good results and also a few problems, particularly for applications to conditions not simulated by the model (for example, water balance of cracking vertisols). Validation work performed using data from US locations and from northern Syria have indicated a satisfactory performance of CropSyst.
CropSyst is bundled with ClimGen, a climatic data generator. ClimGen generates synthetic daily weather data in locations where daily climatic data, required by CropSyst, are not available, unreliable or too erratic to be representative. Reliable generated daily weather data must have similar statistical characteristics as actual weather data for a given area. ClimGen generates daily maximum and minimum temperature, and precipitation from either daily weather data, if available, or from monthly summaries.