# BHutch 2021 Soil Test



## bhutchinson87 (Jun 25, 2018)

Not sure why I waited so long to get my first soil test (Waypoint SW3 with texture analysis) but here it is. I'm using this to bounce my plan off of anyone who would like to critique it. I believe I've developed a good strategy this year from reading through RRs and other soil threads on here.

Based on a total of 6 active growing months (April-September, give or take) and a consumption rate of 3-1-2 for NPK, I will need to apply a total of 3# of P and 7# of K to end with target levels of 30ppm and 250ppm, respectively. My understanding is that 1#/M of nutrient is roughly equal to 20ppm in the soil profile. I have a few 50# bags of 8-10-10 and one 50# bag of 0-0-50, so I would prefer to use that before going out and purchasing more fertilizer.

pH: Apply 1#/M of citric acid once a month after green up, and my main nitrogen source will be ammonium sulfate. Alternative solution is to apply 5#/M of elemental sulfur in the spring, but I've already purchased the CA.

Nitrogen: Dissolve and spray 1#/M of 21-0-0 ammonium sulfate weekly. Every other application will also include iron/manganese and TNex as needed.

Phosphorous: Target ppm: 30; Three applications of 8-10-10 fertilizer at 10#/M starting at spring green up 4 weeks apart. This should give me adequate levels of P as well as a buffer until the end of the season before overseeding.

Potassium: Target ppm: 250; At this point I will have already applied 3# of K from the start of the season and should be rolling into summer now. I'm not sure if applying 1#/M of 0-0-50 every other week during a Texas summer is a good idea so I'm open to suggestions on this. Maybe 0-0-22 K-Mag is a good idea here to also raise the magnesium levels.


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## bhutchinson87 (Jun 25, 2018)

Please correct me if I am wrong, but it seems boron toxicity is a threat here. The 8-10-10 fertilizer I use has 0.02% boron in the form of sodium borate, so if I apply 30#/M in the spring I will be adding approximately 0.12ppm and approaching 3.0ppm. I did notice that Ware's soil test in 2018 came back with 17ppm so maybe there's no reason to be concerned.


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## g-man (Jun 15, 2017)

Typical texas soil. Your plan seems good except:

- I dont think you need phosphorous. I think with the elemental sulfur, it should help your pH and make that phosphorous more available. It wont hurt to add some of it either.

- Do the elemental sulfur now if the budget allows it and still do the CA too.

- I avoid SOP in the summer too. I dont think you need to raise your magnesium levels.

- if possible, avoid adding more boron.


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## Ridgerunner (May 16, 2017)

Just an observation: Your BI (Olsen), considered the best predictor of available P levels in high pH soils, is 16 ppm. This is on the lower end of suggested "sufficiency" levels - 12-28 ppm. Lower down in the test printout are Mehlich 3 (M3) P levels. (FYI; Suggested M3 "sufficiency" levels are 26 - 54 ppm, but M3, like strong Bray (B2) is not considered a good indicator of sufficient availability of P because, as a strong acid, it tends to include a large portion of non labile/unavailable P.) M3 and B2 levels can be used to give a relative indication of how much soil P content is locked up (unavailable). An Olsen level of 16 ppm and a M3 level of 114 ppm suggests that the vast % of applied P (maybe as much as 80%ish) will likely rapidly become unavailable. It's the reason that spoon-feeding P is often recommended in high pH soils. Alternatively, some portion of the locked up P ca become available by maintaining more acidic soil solution by following @g-man"s advice of applying elemental sulfur (and maybe citric acid too).


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## bhutchinson87 (Jun 25, 2018)

Thank you @g-man and @Ridgerunnerfor the feedback. I did notice the difference in the M3 and Olsen levels of P, but didn't think much of it. It's pretty interesting to be able to see how much is locked up in the soil. I will incorporate your suggestions of applying the elemental sulfur this spring, and supplementing with little CA throughout the season.

Side question, is there anything noteworthy between the soil pH and the buffer pH?


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## Ridgerunner (May 16, 2017)

bhutchinson87 said:


> Side question, is there anything noteworthy between the soil pH and the buffer pH?


pH is the measurement of H+
Soil pH is the measurement of H+ in the soil solution (water).
In acidic soils, only a small proportion of total soil H+ is in solution. A large amount is loosely attached to the soil cation sites. As H+ is removed from the soil solution, which would cause pH to rise (by leaching, chemical interaction, or a lime application), the H+ removed will be replaced by H+ held in buffer on the cation sites and pH will again lower. 
Buffer pH is method of measuring the amount of H+ both in solution *and* the amount held on cation sites (in reserve, i.e. in buffer) for purposes of more accurately determining the amount of lime needed to reach a desire final soil pH.


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