Garden soil test numbers and my new tester.

[Chasdev]

I'm down the rabbit hole of soil testing for N-P-K values.
Got some advice to stop fussing around with fertilizer N-P-K ratios until I know if my soil is out of balance for the veg I am tring to grow.
I looked for home soil test kits and even ordered two only to return after looking in the boxes.
Finally found a digital tester that was way cheap compared to "real testers" and am playing with it now.
The test results show my blended organic garden soil (mixed 50/50 with organic compost) is close to correct for most of my veg.
So now I know I just need to fertilize with fertilizers that match the needs of the individual veg's.
The test results I get from the average of 24 pots are an average of N=8.5/N=9.5/P=22.
These numbers are pretty close to what my research found for leeks, tomatoes, corn (but too low on N), pinto beans, mini watermellons, mini canteloupes, peppers and yukon gold taters.
I'm going with 10-10-10 or 10-20-20 for the leeks, 5-10-10 or 10-10-10 for the Habenero's, 20-20-20 for the corn,
5-10-10 or 10-20-20 for the pinto's, 5-10-10 or 10-10-10 for the jalapeno's, 5-10-10 or 4-6-8 for the melons.
During vegetatativbe stages they seem to need more nitrogen though.
Here's a chart supplied by the tester manufacturer.
At first I thought it was pretty cheesey but I've found this type of representation in pro soil test lab sources too..
Here's the chart..The tester is sold by (and perhaps made by?) Yieryi.

 

[JIMSMOKES]

I'm no help with your numbers. I've always been a 10-10-10 with 46-0-0 to side dress my corn.

 

[Fueling Around]

Your numbers are really low. Adding fertilizer takes time for the transformation to plant available.

Yes, high levels of nitrogen are used in agriculture (as outside of side dressing corn) it is a one-time application. As plants get closer to maturity, the nitrogen levels need to deplete (denitrification) to slow the green growth and set the berries, kernels or root crop.

For many garden crops the nitrogen can stay higher as we are looking for continuous plant growth and harvest.

 

[Chasdev]

I'm doing a test by adding increasing doses of of N to the same depleted soil (in a large container) and testing after each addition.
After adding three gallons of water with perhaps 5 times the called for single teaspoon of pure N, I finally got it up in a more "normal" ppm range but for some reason the other values went up too.
At least I finally am getting more reasonable test results even if I can't use the dirt until it drys out.
I called the manufacturer of the N and asked about large doses, they said mix with water and stir into the dirt then deal with the excess water later, so that's what I did.
I let the slurry sit overnight with the tub tilted to assist drainage and then extracted the excess water. It still too wet to use but it's drying out under a fan now.

 

[Fueling Around]

I'm not exactly sure why your other numbers have changed.
I suspect your tester needs a minimum moisture level to get accurate readings and you weren't there in previous samples.
Nitrogen fertilizer is very water soluble and easily leached out. That is why we read about nitrate contamination of ground and well waters. Phosphorus and Potassium do not leach out.
You need to turn any standing water back into the soil as it dries down to get accurate test results.

Urea nitrogen is the fastest to convert to plant available and widely used to side dress crops. Anhydrous ammonia is also use but it takes longer for the decay.

 

[Chasdev]

I found, but failed to bookmark, an article which says that N can cause bound up P and K to be "released", but not having paid attention in high school, I didn't undermastand the sciencey parts...
My latest experiment is a virgin batch of blended soil and compost that has the low readings and treating it with 1t of N and 1 T of 20-20-20 powder to a gallon of water and see what readings I get from watering potted leek starters with that mix.