High density planting as an economic production strategy: (b) theory and trial results

The theory behind high density planting (HDP) is based on the fact that current crops intercept less than 60% of the light radiation available during the season. HOP can significantly increase light interception in the period prior to canopy closure and can also make better use of available water and nutrient resources during this period. Simulation modeling of crop growth suggests that close rows (0.5 m apart) have the potential to increase crop yield by about 60 tonnes of cane per hectare (TCH) under a range of geographic conditions. Results from replicated field trials conducted at several locations throughout the industry have confirmed that yield increases of this magnitude can be reliably obtained from close rows, usually with no need for additional irrigation or fertiliser application. The yield increase is obtained in plant and ratoon crops and in spring and autumn planted crops. Dual rows (pairs of rows 0.5 m apart with 1.8 m between the centres) can provide a yield increase of about 20 TCH and can be adopted by growers with only minor changes to equipment and production practices. However, close rows can not be adopted by using current equipment or farming practices. Commercial adoption of close rows will require the development of more precise farming systems and purpose built multi-row planting and harvesting equipment. Thus, HOP offers the sugar industry the opportunity to adopt a new, precise farming system that optimises the use of resources, and increases productivity.