Potato Response to Phosphorus Fertilizer on High Phosphorus Testing Soils
Date & Time
Monday, July 18, 2022, 4:00 PM

Potato yield often responds positively to phosphorus (P) fertilizer even in soils with high soil-test P, suggesting low P uptake or P use efficiency. This may be attributable to a limited root system or poor formation of mycorrhizal associations, possibly as a side effect of soil fumigation to control soilborne pathogens. The response might also be variety related, where some varieties are more responsive than others due differences in rooting characteristics. We conducted an experiment to assess the roles soil fumigation, fertilizer placement, inoculation with mycorrhizal fungi, and potato cultivar play in determining potato response to P fertilizer and P use efficiency. The experiment was conducted over two years on a loamy sand soil using two separate fields in a split-plot arrangement the first year and one field with a split-split plot arrangement the second year, with treatments replicated 4 times. Bray P and soil pH averaged 110 mg/kg and 6.7, respectively. Treatments included fumigation (no fumigant or fall-applied metam sodium), cultivar (Russet Burbank and Ivory Russet) and 9 fertilizer treatments. The fertilizer treatments included five in which P was broadcast-applied as triple super phosphate (0, 75, 150, 300, or 450 lbs/A P2O5), two in which a mycorrhizal product was applied in-furrow at planting and P was broadcast at 0 or 150 lbs/A P2O5, and two in which P was banded at 75 or 150 lbs/A P2O5. Yield increased linearly with P rate in Ivory Russet both years and Russet Burbank in the second year, with positive P responses in both fumigated and non-fumigated sites. Mycorrhizae inoculation did not reduce the need for P application. At equivalent P rates, banded application showed benefits to yield in one of the two years, suggesting that root spread may limit P use efficiency in potatoes.

Session Type
Parent Session
7/18 - Concurrent Sessions B