Research report to the Oregon Processed Vegetable Commission
Ed Peachey and Aaron Heinrich
OSU Dept. of Horticulture
Dan Sullivan
OSU Dept. of Crop and Soil Science
In Western Oregon almost no research has been done on the phosphorus (P) utilization of snap beans over the past 30 yrs, and no research has been done on the relationship between bean root rot and P uptake. As a result, P recommendations in OSU’s western Oregon bush bean fertilizer guide (#FG 28) have not been updated in decades. The overall objective of this research project was to provide updated information on P utilization by snap beans. Total P2O5 uptake from 6 grower fields was 35 lb/A (range 11-22); of which approximately 1/3rd was removed in the harvested product (pods) while 2/3rd remained in the field to be cycled back into the soil. Five of 6 sites had very high soil test P (STP) levels (>120 ppm Bray 1P); a high enough concentration that little or no P fertilizer is needed, especially in latter plantings when soil temperatures are higher. Due to a continuing trend of increasing STP levels in the Willamette Valley, we recommend shifting away from low N, high P analysis fertilizers (such as 10-34-0 or 11-52-0) to higher N, lower P fertilizers and blends. N and K2O uptake was 153 lb/A (range 110-124) and 126 lb/A (range 62-198), respectively, and like P, approximately 1/3rd was removed in the harvested product (pods) while 2/3rd remained in the field to be cycled back into the soil. To elucidate the relationship between bean root rot and P uptake, we conducted a fumigation trial in a grower’s field. Although we had some challenges in the first year of the experiment, fumigation significantly reduced root rot severity, increased pod yield, and appeared to increase P uptake compared to unfumigated plots. These preliminary results suggest that a higher P fertilization rate may be necessary when severe root rot is expected (such as when there is a short rotation)
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