On-farm energy use is expensive and internal combustion engines further contribute to air pollution. California walnut growers and processors implement and emphasize technologies that reduce energy requirements and thus costs:
- Minimum or non-tillage: Cultivation impacts soil quality over time and requires considerable internal combustion engine energy, increasing production costs. Walnut growers increasingly turn to selective, non-polluting herbicides to avoid cultivation (see Fig. 11).
Fig.11. Non-cultivated walnut orchard.
- Dehydration Efficiencies: Drying walnuts prior to processing requires considerable heat energy. California Walnut Board research funding supported development of 1) in-bin moisture sensing technology to avoid excessive drying and energy costs (see Fig. 12) importance of enclosing dehydrators in conserving energy resource. (see Fig. 13).
Fig. 12. Moisture sensors in walnut drying bin.
Fig. 13. Walnut dehydrator retrofitted with side curtains to conserve heat energy.
- Irrigation Efficiency: Low volume irrigation systems and use of tree water status technology for precision irrigation, developed through the California Walnut Board’s funded research program, save considerable energy for California walnut growers.
- Off Peak Irrigation: Due to energy costs, many walnut growers irrigate during off peak hours. In addition to grower benefits, this practice conserves energy for public use during high peak hours.
- Other cultural practices that reduce energy:
a) The IPM program component designed to reduce sprays coincidently reduces grower energy needs.
b) California Walnut Board funded research into the trees’ canopy management has developed practices such as every other year pruning directly reducing on-farm energy use.