Improving Phosphorus Management on Irrigated Potato
Assessed the effect of phosphorus management on potato yield and quality under Manitoba’s irrigated production systems.
IPNI-2003-CAN-MB19
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