Optimal spacing and cultivation intensity for an industrialized crop production system

The overall design of an industrial crop production system should optimize the system's global parameters, such as total area required, intensity of cultivation and general production schedule. The key element is the optimal intensity of cultivation for the prevailing climatic and economic environments. A single-state-variable vegetative crop model (e.g. lettuce) was used to optimize a crop production system for two economic environments: quota- and area-limited production. A strictly uniform weather (every hour of the season) was assumed initially. Continuous spacing was a central control element. The main conclusions of the analysis with our model are: (1) plants of all ages can grow together in a single climatic compartment; (2) spacing should be scheduled to maintain a constant canopy density; (3) optimal canopy density is an increasing function of available light and a decreasing function of temperature; (4) where produce-price is high relative to the prices of rent and energy, the optimal cultivation intensity for an area-limited operation is higher than for a quota-limited operation; the opposite is true where rent is expensive; and (5) the marginal price to be paid for supplementary light is smaller where available natural light is more plentiful.