Wood chipping almond brush to reduce air pollution and to study the effect of wood chips on harvest, soil nutrients, soil aggregation, and the microbial community

Authors: HOLTZ, B - UNIV OF CALIFORNIA; MCKENRY, M - UNIV OF CALIFORNIA; Caesar, Thecan; Caesar, Anthony

Submitted to: Almond Industry Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2005
Publication Date: 12/1/2005
Citation: Holtz, B., Mckenry, M., Caesar, T., Caesar, A.J. 2005. Wood chipping almond brush to reduce air pollution and to study the effect of wood chips on harvest, soil nutrients, soil aggregation, and the microbial community. 33rd Almond Industry Conference Proceedings. Almond Board of California, December 6-7, 2006 in Modesto, California. 33:225-234.

Interpretive Summary: The wood chipping of almond prunings could provide an alternative to burning that would not contribute to air pollution and add valuable organic matter to soils. The success of wood chipping depends on whether the wood chips interfere with harvest or delete the soil of critical nutrients necessary for tree growth. An average of 502 pounds per acre of wet weight prunings were pruned in our orchard trial in the fall of 2004. Harvest wind-rows in the wood chipped treatments had significantly more (0.136 kg wood/22 ft row) wood debris than the wind-rows of nuts in treatments without wood chips (0.073 kg of wood/22 ft row). Ten-pound bulk in-shell almond samples taken from harvest carts harvested from both the wood chipped and non-wood chipped treatments were analyzed by the USDA with respect to foreign material consisting of wood debris. The wood chipped treatments averaged 1.49 % wood debris and were significantly greater than non-wood chipped treatments that averaged only 0.79 % wood debris. Leaf analysis showed no effect of the wood chips on tree nutrient status in the orchard trial. There were more free-living bacterial (bacterivorous) and fungal feeding (fungivorous) nematodes in the wood chipped soils when compared to non-chipped soils. Rhizosphere inhabiting bacteria from wood chipped soils were found to be distinctive from bacteria from non wood chipped soils based on analysis of 95 tests for their utilization of carbohydrate, polymers, organic acids, and other compounds. Significantly more soil aggregating basidiomycetes fungi in water stable aggregates were found in wood chipped soils when compared to non-wood chipped soils.

Technical Abstract: The wood chipping of almond prunings could provide an alternative to burning that would not contribute to air pollution and add valuable organic matter to soils. The success of wood chipping depends on whether the wood chips interfere with harvest or delete the soil of critical nutrients necessary for tree growth. An average of 502 pounds per acre of wet weight prunings were pruned in our orchard trial in the fall of 2004. Harvest wind-rows in the wood chipped treatments had significantly more (0.136 kg wood/22 ft row) wood debris than the wind-rows of nuts in treatments without wood chips (0.073 kg of wood/22 ft row). Ten-pound bulk in-shell almond samples taken from harvest carts harvested from both the wood chipped and non-wood chipped treatments were analyzed by the USDA with respect to foreign material consisting of wood debris. The wood chipped treatments averaged 1.49 % wood debris and were significantly greater than non-wood chipped treatments that averaged only 0.79 % wood debris. Leaf analysis showed no effect of the wood chips on tree nutrient status in the orchard trial. There were more free-living bacterial (bacterivorous) and fungal feeding (fungivorous) nematodes in the wood chipped soils when compared to non-chipped soils. Rhizosphere inhabiting bacteria from wood chipped soils were found to be distinctive from bacteria from non wood chipped soils based on analysis of 95 tests for their utilization of carbohydrate, polymers, organic acids, and other compounds. Significantly more soil aggregating basidiomycetes fungi in water stable aggregates were found in wood chipped soils when compared to non-wood chipped soils.