Timing of Soil Tests

[Stocker Steve]

I realize soil test results with vary during different times of the year. Do you have any suggestions other than being consistent year to year?

 

[jonbquick.com]

I test every cutting. I test both the soil and the hay.

 

[Stocker Steve]

How much soil test variation do you see between cuttings?

 

[jonbquick.com]

How much soil test variation do you see between cuttings?

I see enough. On a large area it makes a difference.

Frequent testing allows me to tune my fertilizer to what the grass needs. I have little waste, not too much and not too little, but just right.

 

[Herefordcross]

testing after every cut?? Joking Right.???

 

[cowwrangler]

if you can use gps to sample in the same place every year and see if it changes

 

[Dave]

Actually only the nitrate-nitrogen and sulfur will show much of a seasonal difference. The P and K are relatively stable in the soil. If you are only sampling once a year, spring works as good as any other time.
I know of one custom grazer who tests both the soil and the forage after every rotation. And using a gps is the way to go. There can be some fairly big differences in a short distance within a field. Using the gps allows you to sample the same spot every time.
I just got back from a ag/info conference. It is amazing the lengths some crop farmers are going to in sampling. But if done properly it is good information. Good information helps you to make good business decisions.

 

[LonghornRanch]

Test are cheap, fertilizer cost $$$.

 

[hayray]

Actually only the nitrate-nitrogen and sulfur will show much of a seasonal difference. The P and K are relatively stable in the soil. If you are only sampling once a year, spring works as good as any other time.
I know of one custom grazer who tests both the soil and the forage after every rotation. And using a gps is the way to go. There can be some fairly big differences in a short distance within a field. Using the gps allows you to sample the same spot every time.
I just got back from a ag/info conference. It is amazing the lengths some crop farmers are going to in sampling. But if done properly it is good information. Good information helps you to make good business decisions.

Acutually K increases through the winter.

 

[hayray]

I realize soil test results with vary during different times of the year. Do you have any suggestions other than being consistent year to year?

I just asked this question at a soil fertility seminar that Extension was giving and they agreed that fall was the best time to test and that spring was the best time to fertilize, they are moving away from fall applications of K, at least up as far north as you and I are.

 

[Dave]

Hayray,
Who told you that K increases over the winter? And how is this supposed to happen? Matter can niether be created or destroyed so if increases it has to come from somewhere. I would be interested in seeing the sceintific studies showing how this happens Of the three major elements required for plant growth K is the most stable and least likely to move.
Dave

 

[hayray]

Hayray,
Who told you that K increases over the winter? And how is this supposed to happen? Matter can niether be created or destroyed so if increases it has to come from somewhere. I would be interested in seeing the sceintific studies showing how this happens Of the three major elements required for plant growth K is the most stable and least likely to move.
Dave

Thanks for that thermodynamics lesson - ha, ha. Anyways, it is the amount of K that is not bound up in the soil and then detected in the soil test I think. There is a lot of research that shows that as you take soil test starting in the fall and through the winter into spring that the K levels in the soil test increase. So that is why they are recommending using the soil test results from the fall rather than winter or spring.

 

[Dave]

There is a lot of P that is tied up in th soil which is not plant available and doesn't show up on tests. However, I have never hear this about K. Neither one of these would become more plant available because of a change in season. A change in soil pH can make a significantly difference in available P and to a lesser degree K. Elements bound in the soil don't release easily. There has to be a change that causes their release.

 

[Stocker Steve]

they agreed that fall was the best time to test and that spring was the best time to fertilize, they are moving away from fall applications of K, at least up as far north as you and I are.

What is the drawback for fall K fertilization?

 

[Dave]

I have never heard of a draw back to fall K. Lots of fertilizer blends put P and K together. There are some real advantages to fall P. Most of the P is used in the plant roots. Root growth begins in the fall (generally about sept 1 at this latitude). Lots of P gets tied up in the soil. Especially if it is a clay soil. So supplying P in the fall allows the plants to take in the P at a time when they need it for root growth and before it can become attached to the clay particals in the soil.

Dave

 

[hayray]

they agreed that fall was the best time to test and that spring was the best time to fertilize, they are moving away from fall applications of K, at least up as far north as you and I are.

What is the drawback for fall K fertilization?

Ok, here is the bulletin that I got some of my information from :

North Central Multistate Report 348, Minnesota Agricultural Experiment Station, University of Minnesota.

Page 4, Variation in soil test values over time: Mentions that soil moisture is one of the factors that affects soil K test.