ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
POTASSIUM FERTILIZER APPLICATION IN DRIP AND MICRO-JET IRRIGATED ALMONDS |
| Authors: | J.P. Edstrom, R.D. Meyer, Jiayou Deng |
| Keywords: | almond, yields, potassium, leaf potassium concentration |
| DOI: | 10.17660/ActaHortic.2008.792.29 |
| Abstract:
Potassium fertilizer recommendations for California almond [Prunus dulcis (Mill.) D.A. Webb] production were developed decades ago for flood and sprinkler irrigated full-coverage orchard conditions. High rates, up to 930 kg K ha-1, at considerable expense were often suggested on soils exhibiting high levels of K fixation. Today, almonds are widely produced under low volume irrigation, which greatly limits the wetted soil area and restricts almond root systems to a relatively small portion of total soil volume. A field trial was conducted comparing fall applied surface banded potassium sulfate (BKS) with in season injected potassium sources: sulfate (KS), thiosulfate (KTS) and mono-potassium phosphate (MKP) through three irrigation systems: single line drip (SLD), dual drip (DD) and micro-jet (MJ) on two almond cultivars, ’Nonpareil’ and ‘Butte’ at the Nickels Soil Laboratory. Yields for the SLD and DD were nearly the same in 1997 and 1998 but somewhat lower than the MJ. In 1999, the DD had the highest yield followed by the MJ and then the SLD. Three year average yields were 3111, 2990 and 2832 kg ha-1 for the MJ, DD and SLD systems, respectively. The Butte cultivar had significantly higher yields in 1997 and 1998 as well as the 3 year average yield of nearly 400 kg ha-1 higher than the NonPareil cultivar. The 1999 yields showed a strong trend for response to applied potassium with some significant differences over the control and between fertilizer sources and placement. The highest yield was recorded with 1.13 kg K tree-1 MKP, then by 2.26 kg K tree-1 from banded KS and injected KS, followed closely by the 1.13 kg K tree-1 of injected KS and KTS with the control yielding 800 kg ha-1 less than the highest yielding MKP. Leaf total K increased significantly with applied K over the three year study with MJ showing the greatest increase followed by DD and then SLD system. | |
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