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Discussion in 'Fertilizer Application' started by americanlawn, Jan 16, 2014.
I certainly have learned a thing or two from your posts.
Just a little plug:
On Wed, Feb. 26 Mike Reed of Holganix & I will be discussing an IPM Approach with Bio Stimulants to Reduce Pesticide & Nitrogen Needs 9AM at the NJ Landscape Contractors Association Trade Show. http://www.njlca.org/pages/TradeShow/2014/2014TSBrochureWeb.pdf
I don't think many soil scientists would agree with you that Olsen is necessarily better than Mehlich III for high pH soils. In fact, Mehlich III and Olsen are better correlated at pH>7.4 than they are at ph<7.4 (nearly 1:1).
Let's also remember what a soil test is and what it's not. A soil test is an index value, it's not a measure of nutrient availability. There are way more factors affecting nutrient availability than what could be gleaned from any single test. A soil test by itself is only part of the equation that gives you a fertilizer recommendation. The other part is the correlation/calibration studies.
Theres nothing special about the number that is generated by a soil test report if we dont know what value is associated with a properly performing crop and what impact different fertilizer application rates have on soil test values. These are usually done by universities, but the academic controversy is that this information isnt always determined for different turfgrass species.
Most soil test reports include recommendation. I would like to see the recommendations that accompanied Larrys report. I have a feeling that theres not much recommendation other than nitrogen apps and pH adjustment.
MVTL Labs has a Nutrient Analysis Guide and is available online and see for yourself this is what they say in regards to pH. and extraction method choice.
I had the question about Sodium to larry as I am curious about dispersed soil issues specific with clays.
Larry did mention in earlier posts that OM was recommended and I am not sure he realizes another way to get some Carbon down at the soil surface was adding some Humic Substances to his liquid feed mixes.
I do not use soil testing as the only decision maker but some key markers are there in the result Larry put up that points me to more soil Carbon for better results.
I'm sure MVTL has their reasons for extractant choice. However, my education, years of research in academia (prof of soils and plant physiology), years of practical application in this industry, and a review of current university recommendations from across the midwest lead to me previous response.
Perhaps I missed the recommendations he listed from this test. I wonder if he would repost them.
Sure, increasing OM is going to provide some help, but OM usually increases during healthy plant growth. We grow very healthy turf stands in 100% sand all the time, so we know that it can be done quite easily in low OM and low CEC soils. It looks like the OM is the least of the worries here. It sounds like pH is the largest issue.
In my opinion it would be more beneficial if a soil sample could give populations of microbial activity. With out microbial activity, nutrients will have little effect, no mater what the soil sample shows. Even with the most perfect soil pH matched to the most nutrients available. If you have little microbial activity. How would turf and plants eat successfully? Liquids (NPK) in nitrate form. Liquid minors?
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Good to see your input coming from years of study in Theory and in Practice.
Sure there is more than one way to get results and a green plot of turf and without question this is Subjective.
Some good Dialogue could come from this discussion and want to go a bit off track to make a point you can understand, and hopefully folks thinking "Outside The Box" can be Objective when they ponder what the read and understand......
We are in New Jersey and have a "Fertilizer Law" that limits the amount of N and P we can apply and at certain times and seemingly for good reason, yet when I talk to the local corn farmer that tells me State Agronomists are telling him to apply lime and 160 units of N in soils with a CEC of less than 10. Last year crappy yields with the rain (duh) and no cover crops.
They do not talk of the benefits of Humic Substances that could be applied through the feed knife and the advantages of both better CEC as well as AEC, AND better soil biology/more water holding capacity in the A Horizon.
I have done it the old way with Turf and had awesome results. The new fertilizer law made we want to try new ways to get more with less N. So far I see good quality color with the addition of humic substances and more importantly when I do soil digs to look at the soil, I see it getting darker and more life in it.
I think Larry will be surprised to see results by adding some liquid Carbon and can eventually cut back on the N as soils become more bio active.
Carbon too can cause his pH to drop.
I don’t see much value in quantifying microbial populations. Their activity is highly variable and dependent on many different factors, so any attempt to quantify it would be just a snapshot in time valid for only those specific conditions. Also, research has shown that microbial populations are almost inherent to a site and its conditions.
Work was done at Tx A&M that compared microbial populations in perennial ryegrass stands established in an outdoor field and perennial ryegrass established in a greenhouse in autoclaved sand (heated to the point that all microbial life was destroyed). In this experiment, even the perennial ryegrass seeds were autoclaved, so they had no microorganisms living on them when they were planted. Both the indoor and outdoor ryegrass stands were irrigated with double-deionized water (treated to kill all microorganism living in it).
Microbial populations were measured and it was found that at two days after seedling emergence, there was no difference in microbial populations between the grass grown in field soil and the grass grown in autoclaved sand. The conclusion was that doing the things that create healthy turf also create healthy microbial populations.
So microbial activity and there populations, are determined by proper cultural practices, only under ideal environmental conditions along with ideal topical geographical habitat with no ability for manipulation? If these conditions are not met is there no point in soil samples or will lime stimulation of microbial activity even have any effect.
I don't have the education that most of you have received in schools beyond 12th grade. Also, in my 26 years of being in the greens industry have never had to use so much science to problem solve horticultural issues. Though I'm not knocking on the higher education. I understand the geographical territory in my area of the plant and have never been unsecusfull in maintaining healthy landscapes under any environmental conditions. I'm glad I'm in Florida and deal with sand/soil.
I am learning allot about northern hardships and appreciate all intelligent posts. I have learned to understand signs in the environment as well as in the landscape in order to understand what my landscapes are saying. Just like someone who understands sign when speaking to a deaf person. I cannot speak sigh to a person but I sure understand what the landscape is telling me even though we use different ways to communicate. No science needed.
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Microbial populations are determined by the conditions that exist at a particular site. There are a lot of things that impact this, like temperature, pH, nutrient sources, soil chemical composition, C:N ratios in soil organic matter, etc. When a set of conditions exist on a site, populations of microbes that thrive in those conditions increase. Populations of microbes that do not thrive under those conditions decrease.
The microbial populations that beneficially interact with plants are found in the highest numbers in places where plant life is healthy and abundant. Research from Tx A&M showed that the microbes didnt have to be there for this to begin. Microbes will colonize in areas that have the resources they need. When we do the things that stimulate healthy plant populations, the microbial populations naturally follow.
I think understanding the science behind what we do is important. I think its important to know not only what to do, but also why to do it. Knowledge is power. It helps you to separate good product info from bad info. It helps you to understand the different things youll come across in this business and not be stumped just because a particular situation is different from your routine. It also helps to establish professionalism for our industry.