[Recommended N/K Ratio For Wisconsin Golf Greens].pdf

A Wisconsin soils report addresses several questions from the floor.

1. High phosphorus levels in soil tests are not a cause for worry but rather a concern, as they can trigger micronutrient deficiencies, although this is rare. The concern is how the soil phosphate became excessive, which represents years of unnecessary phosphate applications. To address this, one should examine their fertilization program and avoid applying phosphate until soil test levels drop.

2. N-Sure, a product using a new fertilizer formula called triazine, has controlled release, low burn, and high stability. While it appears capable of satisfying turfgrass N needs for 12 to 14 weeks, field testing has not been extensive, and it's recommended to experiment with it on a limited basis.

3. Switching from a sand topdressing program to an amended sand material is possible if done correctly, without creating abrupt soil layers that differ substantially in moisture characteristics.

4. The "high K bandwagon" exists due to experimental evidence that high K levels in turfgrass are associated with greater stress tolerance. Recommended N/K ratios for Wisconsin golf green turf depend on whether it's a USGA greens mix or natural soil. For USGA greens mixes, a fertilizer N:K20 ratio of 1:1 to 1:2 is generally required, while for natural soil, an annual application of 0.8 lbs K20/M for every pound of N applied is recommended once soil test K is built to 300+ lbs/A.

5. Rising soil pH values due to irrigation with hard water are a concern, as they can lead to nutrient availability problems. Applying elemental sulfur can help, but the amount and timing depend on various factors, and it's recommended to consult with a soil expert for specific guidance.