Improving Phosphorus Management on Irrigated Potato

Assessed the effect of phosphorus management on potato yield and quality under Manitoba’s irrigated production systems.


12 Jan 2007

2006 Annual Interpretive Summary

Improving Phosphorus Management in Irrigated Potato Production Systems, 2006

Rapid expansion of the processing potato industry in Manitoba has generated a need for information regarding fertilizer management strategies for irrigated potato. The final year of a 4-year study was conducted in 2006 to determine the impact of P fertilizer rate on potato tuber yield and quality, and the effectiveness of petiole P concentration in assessing P status of potato (cv. Russet Burbank).

A field experiment was conducted at one location near Douglas, MB, in 2006 to assess the effect of four P rates (0, 30, 60, and 90 lb P2O5/A as broadcast/incorporated monoammonium phosphate) on tuber yield and quality, petiole P status, and post-harvest soil P status. The experimental site selected had a spring soil test P level of 9.7 ppm Olsen-extractable P in the top 6 in., which would have resulted in a recommendation for P fertilizer. In 2006, total tuber yield averaged 422 cwt/A. Preliminary analysis indicated that increasing P fertilizer rate resulted in a quadratic increase in marketable tuber yield and a similar trend (p=0.11) in total yield. In both cases, yield increased with moderate rates of P then declined. In 2006, the application of P appeared to contribute to a comparatively higher yield of larger tubers, although the number of tubers produced per acre was not significantly affected by P application. Neither specific gravity nor defects were affected by P rate. However, a trend toward a quadratic relationship between P fertilizer rate and both sugar ends (p=0.08) and dark ends (p=0.11) was evident. In both cases, the occurrence of sugar/dark ends tended to increase with moderate rates of P, then declined as P rate was further increased. MB-19F