Conditioning harvested almonds on the orchard floor to reduce drying time of wetted almonds
Almond production in California, USA, relies upon gradual, in-field drying of the harvested crop to deliver a cost effective, quality product. Almonds may dry on the orchard floor for one to two weeks after shaking before pickup and delivery to the huller. Significant early rainfall (September/October) during the drying stage of harvest in 2010 and 2011 led to quality losses including concealed damage (CD) in the Sacramento Valley growing region. To identify active management practices to accelerate in-field almond drying time following rain, an applied research project was conducted in 2012 and 2013. Field-dried 'Monterey' cultivar almonds ready for pickup were sprayed with irrigation water to simulate rain and left on the orchard floor to dry for 13 days (2012) or 30 days (2013) in October. Kernel and hull moisture levels were measured at regular intervals. Good drying conditions - low humidity and no rainfall NDASH characterized both study years. Treatments in both years included conditioning windrows (tumbling almonds and removing dirt/leaves) before and/or after wetting. A raking treatment, prior to windrowing, was added in 2013, and significantly reduced median hull and kernel moisture compared to unraked almonds prior to a second wetting. In 2012 and 2013, conditioning windrows after wetting significantly reduced kernel and hull moisture levels at study end compared to the unconditioned treatment. Conditioning before wetting, only, significantly reduced kernel and hull moisture compared to the unconditioned treatment at the study end in 2012 but not 2013. Based on these study results, waiting to condition almonds after rain is recommended as a cost-effective alternative to conditioning both before and after rain.
Niederholzer, F.J.A., Lampinen, B., Johnson, B. and Cutter, S. (2018). Conditioning harvested almonds on the orchard floor to reduce drying time of wetted almonds. Acta Hortic. 1219, 243-250
Prunus dulcis, field drying, conditioning, kernel moisture, hull moisture