we have been using Western Ag Labs for our soils test for several years now. We like their computer program, and also like the fact that they are not trying to sell us any fertilizer, so we know they won't needlessly tell us to put on more fertilizer than we need. However, their prices have got out of control. I can have a local fertilizer dealer soil test for a fraction of the price. But maybe they try to mis-lead us in our fertilizer purchases too. Its fact, most retailers will encourage you to keep your fert rates high, they will never soil test a tell you that you dont need much N because it was summer fallow. So my, question is, do any of you have your retailer soil test, then make your own fertility plans? If yes, do you use an app or website to help determine how much fertilizer you need based on expected yield??? What website or app do you use?
Soil tests
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I used to think that a lot of the amounts needed from the fertilizer tests were high. Gone to a few canola production workshops lately and I discovered that the recommendations from the fertilizer tests were fairly consistent with the canola production workshop numbers.
When I looked at my old soil tests and then added what I applied and estimated the mineralization from my organic matter level it was almost exactly the bushels of canola that I actually got in the fall. For example the canola workshop said it takes something like 3.2 lbs of N to grow a bushel of canola. If my soil test said I had 20 lbs of N and I applied 100 lbs of N and then added 20 lbs of N from mineralization (4% organic matter x 5 lbs N per %) I got a total N of 140 for that crop. That should give me 44 bushels of canola (140N/3.2 lbsN per bushel). Some years you will get more mineralization and some less.
I found when I went back and looked at the soil tests, looked in my notes at what I applied for N and my crop insurance records for yield, I was surprized at how close the actual yield was to the N I provided for that crop. In my case I found that I was drastically under fertilizing my canola.
Not sure how accurate the soil tests are for P, K and S though. I try to replace my P and S levels according to the yield estimate that I am using and I have high K levels in my soil. I do not think that any fertilizer seller is doing soil tests with the idea of upselling you more fertilizer.
With most fertilizing equipment today it is very easy to up the rate by 50% on a pass or 2 in a few fields and see if there is a difference. Allows you to test fertilizer rates that you don't think will work in a very easy and affordable way. Also gives you some safety just in case your seeding system cant handle the higher rates and you get seed injury or hoses plugging, it is only confined to a pass or 2.
When I looked at my old soil tests and then added what I applied and estimated the mineralization from my organic matter level it was almost exactly the bushels of canola that I actually got in the fall. For example the canola workshop said it takes something like 3.2 lbs of N to grow a bushel of canola. If my soil test said I had 20 lbs of N and I applied 100 lbs of N and then added 20 lbs of N from mineralization (4% organic matter x 5 lbs N per %) I got a total N of 140 for that crop. That should give me 44 bushels of canola (140N/3.2 lbsN per bushel). Some years you will get more mineralization and some less.
I found when I went back and looked at the soil tests, looked in my notes at what I applied for N and my crop insurance records for yield, I was surprized at how close the actual yield was to the N I provided for that crop. In my case I found that I was drastically under fertilizing my canola.
Not sure how accurate the soil tests are for P, K and S though. I try to replace my P and S levels according to the yield estimate that I am using and I have high K levels in my soil. I do not think that any fertilizer seller is doing soil tests with the idea of upselling you more fertilizer.
With most fertilizing equipment today it is very easy to up the rate by 50% on a pass or 2 in a few fields and see if there is a difference. Allows you to test fertilizer rates that you don't think will work in a very easy and affordable way. Also gives you some safety just in case your seeding system cant handle the higher rates and you get seed injury or hoses plugging, it is only confined to a pass or 2.
From my experience you may find you will use less fertilizer if you switch away from western ag labs especially when it comes to potash and sulfur. I love the principles behind their extraction methods and analysis but they have some flaws as well. N and S recommendations are very difficult to make accurately when only testing to the 4" depth I've seen them do as both N and S are mobile in the soil so must be tested for at a greater depth because your crop roots much deeper than that and brings N and S up from those depths.
Where I like their extraction methods is with the immobile nutrients like P and K but their flaw is they don't consider what is available throughout the season as compared to the what is extracted during the duration of the test. Using Western Ag labs you will notice this most with K. To sum it up simply as a plant uses K from the pool of available K in the soil more will be released from the pool of unavailable K to maintain a certain equilibrium based on the total concentration and some other factors. The Western Ag labs test shows what is available today and not what is available throughout the season as the crop grows so therefore they often recommend much more K be applied than is actually needed.
Where I like their extraction methods is with the immobile nutrients like P and K but their flaw is they don't consider what is available throughout the season as compared to the what is extracted during the duration of the test. Using Western Ag labs you will notice this most with K. To sum it up simply as a plant uses K from the pool of available K in the soil more will be released from the pool of unavailable K to maintain a certain equilibrium based on the total concentration and some other factors. The Western Ag labs test shows what is available today and not what is available throughout the season as the crop grows so therefore they often recommend much more K be applied than is actually needed.
I was wondering the same things tested every field every year since 2010 with them but I think its $4 or more an acre now or more I cant remember I know it took a huge jump in 2013 they felt there service was undervalued at $2.50 an acre
CR960 I have heard neighbours echo your thoughts on Potash and hence some have gone from suing soil tests to just following nutrient removal charts and fertilizing for what crop they want. I have also heard guys tell me they grow 54bpa canola on 60lbs of actual nitrogen so going by nutrient removal charts I know there either lying or have good nutirients in there soil I am thinking its the first option thiugh
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I've used Western Ag for years and have never had a recommendation for K.
I'm not arguing that the K recommendations are not high in your case, but to say K recommendations are high from WAL in general is incorrect.
It is actually a standard soil test (from ALS) that K is high for me. This is because it always recommends 5-15 lb/ac almost independent of extraction results (same field WAL shows I don't need it).
I'm not arguing that the K recommendations are not high in your case, but to say K recommendations are high from WAL in general is incorrect.
It is actually a standard soil test (from ALS) that K is high for me. This is because it always recommends 5-15 lb/ac almost independent of extraction results (same field WAL shows I don't need it).
This is interesting I use PRS and Western Ag on my farm as well as consult for about 45 client customers Yes the price has gone to $4/ acre with early season discounts for pre booking We don't provide the same results as a traditional "soil test" Our lab doesn't use chemical extraction We only use distilled water- similar to rain fall Our results show the "flux" or release of nutrients over a given time We don't measure total nutrient content of the soil That is a useless number as the plant only uses what becomes plant available in the growing season Similar to the fill hose on a fuel tank Diesel comes out a lot faster from a 1.25 inch than a .25 inch hose The modeling software that the results are uploaded into allow the grower to change environmental conditions and play the " what if" game Can you do that with a conventional soil test? Mineralization is different with 5 inches versus 10 inches rainfall I take exception to the comment that Western Ag recommendations are higher than other "soil sampling" services We strive to work in the growers comfort zone He has full input into the fertility plan Some growers wince at 80lbs N and other growers feel 100lbs is a min target
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