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This concerns the use of saturated paste (water) or dilute water extractants for assessing soil nutrient content, and specifically if data from those tests are a good way to decide if an element should be supplied as fertilizer.

I did an experiment in a greenhouse in which I grew creeping bentgrass in four different sands. I collected all the clippings and measured what was in them. And I tested the pH of the sands, and I did soil tests to measure the soil nutrient content.

1. Is water (or a saturated paste extractant, or mixing irrigation water with soil) a good way to look at soil nutrients? 2. What about two tests to look at “available” and “exchangeable” nutrients, is it good to look at both?

I’ve used equation 52 in Crop Evapotranspiration: Guidelines for computing crop water requirements (FAO Irrigation and Drainage Paper 56) to calculate the predicted ETo for San Digeo, California, and for Madison, Wisconsin.

At the Poipu Bay area of Kauai, most hotel lawns are seashore paspalum. This lawn at the Sheraton Kauai is a typical example. Under the trees, though, closer to the beach, a different species grows.

Jason Chennault and I had a conversation about interpreting soil tests. I had seen test results for a site and didn’t think there were any problems with the soil. Jason wrote back with more information.

I measured soil moisture and surface hardness on three fairways, approaches, and greens at a golf course in Thailand in September 2014. The fairways and approaches at this site are seashore paspalum on a sandcap.

In the Global Soil Survey (GSS), we looked at the soil nutrient levels in soil that was specially selected as being from areas where the grass is growing well. The first year of GSS data are available here.

I’ve been asked this question more times than I can remember. It usually goes something like this. We had the soil tested, and it turns out we are quite low in P (or K or Ca or Mg).

This is no secret among turfgrass scientists—there isn’t a lot of good justification to support what we call conventional guidelines for soil nutrients in turfgrass. And by that, I mean the conventional guidelines are broken.