Feeding recommendations with clippings removed or clippings returned | Asian Turfgrass Center

This question came in recently:

How do you estimate soil nutrient depletion and provide a recommendation if clippings are returned? Example: lawns or brush piles.

That’s a good one. See “How to Get a Quick Estimate of Grass Nutrient Use” for some background on this, especially the a + b – c formulation to find the amount of a nutrient to apply.

I responded with this:

Good question. Basically I look at the changes in soil test values ​​over time in relation to the nutrients applied. A site-specific calculation of the depletion rate can be made from these two values.

For a snapshot of a soil test it’s a little trickier, and I generally make a recommendation based on MLSN and then adjust it when the soil is tested a second time and I can calculate the change.

I haven’t thought about this much lately. I thought about it a while ago. And I think it made sense to me at the time to make a rough estimate that 50% of the nutrients coming back through the clippings could be considered fertilizer, and that 50% might be considered to be lost somehow. That wasn’t based on any calculation, but basically said, okay, if you send the clippings back, we’ve essentially cut the fertilizer amount in half and I feel pretty comfortable that that’s safe.

As for the test interval, on sand I want to test every year, regardless of whether clippings have been removed or not. On grounds, I would generally suggest testing once every three years. But if you are somehow close to the MLSN values ​​for P or K, you may want to test more often.