Thanks olpea,that is interesting that Potassium went up that much.
Didn't they provide a value for Nitrogen? Brady

You can maintain the magnesium and sulfur if you wish easily enough by adding epsum salts (magnesium sulfate).
Some here recently have be praising it's use, maybe has some merit to it's use?

Wood chips basically are an organic fertilizer. So results look as we would expect.

I believe a 15% increase in OM is quite high considering you are already at the height of what is generally found in typical (well drained) soil- I wonder if the increase will continue at a similar rate as it has the first 7 years. It would probably take 2 or 3 years for it to create any measurable difference, I would think.

What I expect is the most crucial factor of long term heavy mulching is how the increasing organic matter along with the mulch itself affects water access for the trees. It has long been the belief of growers around here that the highest quality fruit is harvested after dry summers and too much water has been shown in research to reduce brix of the fruit of at least some species.

I would also consider available N and when it becomes available as an interesting factor, probably more important than the other elements you tested for. As I've stated in the past, N derived from organic matter in the soil increases with moisture and warmth, supplying fruit trees with higher levels at the least advantageous time for high quality fruit. You want the spur leaves to get it in early to mid spring, when the soil is still cool and usually wet. However, I was surprised when I searched, that high amounts of N, in general, don't seem to affect brix levels, at least in apples.

Why didn't you test for nitrogen? Oh yeah, testing for organically derived N is fairly expensive and can't be achieved by an acid wash soil test.

Did your test include the black humus directly under the mulch?

I should have mentioned that the extremely high level of K will likely restrict access to calcium. I need to check how that might affect peaches but already know the problems it can cause for apples.

Obviously, you already know that it hasn't been a problem with the quality of your fruit- but what about cold-hardiness? Back to google.

Bingo! there is an established relationship between reduced calcium in tissue of several species and ability to withstand cold.

Now you have another means of trying to help your peaches withstand test winters- calcium in the spray tank.

The lab I use (A&L Great Lakes Labs) doesn't test for N in their basic soil test packages (S1 & S3 package). I think the thought is that N is so mobile, it changes very rapidly, so a soil test for it is somewhat meaningless. For peach trees, their recommendations are to observe shoot growth for determining N applications. Still in their fertilizer recommendations, they did recommend 60 lbs. of N/acre.

I did not test the humus of the mulch. I scraped away the mulch and humus, and dug down about 4 to 6" in keeping w/ sample collection recommendations.

The high level of K is a concern, as any overabundance of a mineral is, but it's my understanding Ca deficiency in peaches is rare (unlike apples) and only evident in greenhouse, sand culture, or very acidic soils. Even though A&L labs rates K at 332ppm very high, WSU (Washington) only rates it as high for tree fruit (not becoming excessive until 800ppm).

I sent in for a leaf analysis years ago (after applying fertilizer, but before mulching) and the results showed low K in the leaf tissue (in spite of the fact that soil levels of K should have been adequate). I've read low K is a fairly common deficiency in peaches. Leaf analysis showed Ca in the normal range at that time.

I do think my peach blooms may be more susc. to frost than they should be, but I think that may relate to N, or possibly some "dehardening" effect of the mulch. Or perhaps it's the microclimate here at the house. I don't know.

At this point I don't think the mulch has a negative effect on dormant fruit bud hardiness of peaches. I examined other (unmulched) peach trees in my immediate area this year (two different sites) and they both showed the same winter bud kill as my trees.

I may not be able to continue this experiment long term because it is becoming exceedingly difficult to get wood chips anymore. Gardeners and people who mulch their flower beds have figured out you don't have to buy mulch in bags, but can have it delivered for free in truckloads. As a consequence, tree services have a long waiting list for mulch, and some are starting to charge for loads of mulch. Spreading plus the purchase costs make its use cost prohibitive for me.

You may find woodchips more available in fall when gardeners aren't asking for it- you can also use leaves for similar weed control potential- but they will probably really juice your trees.

I believe organic release of N. is exceedingly important in agriculture and that it is tested to evaluate how much synthetic N to use in most large commercial crop production systems. It is a more complicated test- I think some kind of incubation is required for a period of time to see what the OM releases- the cheap test is just an acid wash where what's analyzed is what comes out in the "wash". Nothing more than a snapshot of what your trees are getting. Of course, how much OM is in the soil is a snapshot of how much N is being released but I'm pretty sure not all OM in the soil is equal. The newest is breaking down and releasing much more nutrient than stuff that's been their for decades and highly resistant to break down.

Cold hardiness is not usually what is looked at in terms of calcium deficiency- so peaches could be just as prone to suffering from a deficiency in CA as apples, I figure, when it comes to this relatively obscure possible consequence. I just thought it was an interesting possibility, but as long as you have an unmulched control to compare your mulched trees to you've got the issue covered.

Hman,

Yes I think row croppers and other farmers do test for N, but N applied as a synthetic fertilizer is used or leached from the soil very rapidly, which is why it is generally recommended as a fall or spring application for fruit trees. By late summer enough N is used up to allow trees to harden off.

I looked at pics for Ca deficiency and the effects look fairly stark. I haven't seen any symptoms that I've noticed, but I appreciate you mentioning the possibility. As you know Ca has a +2 charge, while K has a +1, which would indicate Ca will more easily displace K in soil. If I run into a problem with Ca deficiency, I would think our soil contains a enough Ca that our heavy spring rains would leach K out of the root zone, in favor of Ca fairly quickly, if no additional K is added.

"Magnesium sulfate - Some here recently have be praising it's use, maybe has some merit to it's use?"

Drew,

I forgot to respond to your comment. I've read (or been on) various fruit forums for quite a few years. One thing you see over and over are people who claim they've found the "secret element" to raising some type of fruit or other. I've seen all kinds fertility recommendations on forums. Some of them, quite frankly, just plain cockamamie.

When it comes to micronutrients and trace elements, I wouldn't advise adding them unless a soil test or leaf analysis was completed. The only exception would be if someone is applying a complete fertilizer which has trace elements included. In that case, the fertilizer is adding trace elements in trace amounts.

It's way too easy to overdo a trace element when applying just the element, without the benefit of a soil test. Not only can too much of one element prohibit the uptake of another, but toxicity can easily result.

Sometimes it can take very small amounts. As an example, my soil test shows I need to apply 1 lb. of boron per acre at the house. Just one pound spread over a whole acre. That's w/ boron currently at 1.1ppm. On the other hand, boron toxicity occurs at 2ppm for most plants. Since a foot acre of soil weighs about 3 million pounds, that means 6 lbs. of boron per acre is toxic (1ppm would be 3 lbs. per acre. 2ppm would be 6 lbs. per acre). This is the dilemma of applying a trace mineral blindly.

What you want is a "balanced" soil. This is best achieved by soil testing/leaf analysis through a lab, which is supported by decades of soil/plant research, rather than some voice on the internet, who claims some micro-nutrient was a panacea for his/her plants.

That said, I have applied mulch without soil testing (for seven years). There is some risk of overdoing it there, but much smaller because the amounts of micro-nutrients and trace minerals applied is much smaller. Even then, the K is now a bit too high as a direct result of applying fertilizer (organic) without any soil testing.

I'm not saying lab recommendations are always in line w/ the individual goals (i.e. the lab may give recommendations to maximize yield, which may not be the individuals goals) but following lab recommendations will keep an individual from grossly over-applying a trace mineral or micro-nutrient.

My greenhouse soil tests ~600 ppm for K and 3500 for Calcium. In the former horse pens where I now have outside orchards, K is 2,000 ppm and Ca 6,000. No issues I've seen in either place. Only deficiency I've seen on fruit trees has been Zn.

My comment about Epsom salts was in regard to your soil tests, not to blindly use it. It made me think others may have the same situation, thus my comment about it may have merit as others may have similar situations. Then again you were not really deficient, but the trend shows you could become deficient, my comment was more about that. Curious as to why these elements were decreasing. As we all tend to do the same thing. Plus it's hard to OD plants on sulfur or magnesium, I would not worry about that. It can be done though. I grow lot's of plants in pots. I think I have about 60 plants in pots, getting a soil test for each pot is just not practical. Trace elements that leach easily are more of a concern in pots. And magnesium easily leaches out. I always use fertilizers with trace elements.
I have about 20 trees in the ground in 2 locations. I have soil tested the areas. I also grow in raised beds and the soil is what I put in so is more like a pot. For me it's impossible to solely rely on soil tests, I have to use my own experience at spotting problems to determine course of action. And in the 40 years of growing plants, I have had few times where deficiency was the problem. Using proper nutrition has always worked well for me. I never seen toxic levels of anything, although that could have happened? Sometimes plant death is for unknown reasons. Mg and sulfur really are not micronutrients IMHO. They are major nutrients. Silicon is a micro-nutrient. Boron too.

This post was edited by Drew51 on Sun, May 11, 14 at 7:07

I believe micro is about the quantity the plant needs not its importance.

The only exception would be if someone is applying a complete fertilizer which has trace elements included. In that case, the fertilizer is adding trace elements in trace amounts.

I have been wanting to ask a question regarding Steve Solomon's Complete Organic Fertilizer found in his awesome gardening book, Gardening When It Counts: Growing Food in Hard Times

It is for the reason you mentioned that I have never felt comfortable fertilizing my trees. However I would like to try this as it seems like you can't go wrong, I'd love others' perspectives.

Here is a link that might be useful: A Better Way to Fertilize Your Garden: Homemade Organic Fertilizer

Because nitrogen is the only nutrient a tree is likely to visibly respond to I would be interested to know how much the mulch adds to this availability and whether annually mulched trees keep supplying more and more as time goes by, as I suspect.

As I recall (treacherous waters, I know), I have read that with heavy feeding annual crops more than half the needed N for optimum production can be supplied from the organic matter in a decent soil.

It seems the math is supposedly something like this. Each percentage point of organic matter, on average, supplies about a half pound of N per 1,000 square feet annually, assuming all organic matter is equal, which seems highly doubtful to me.

However, that's probably a good enough ball park figure to consider some ramifications of notching up organic matter.

Here is a link that might be useful: nitrogen in soils

This has been a great thread. Thank you all for your input.

I'm still using the free, delivered, power company wood chips by the truckload so this info is wonderful.

"Because nitrogen is the only nutrient a tree is likely to visibly respond to I would be interested to know how much the mulch adds to this availability and whether annually mulched trees keep supplying more and more as time goes by, as I suspect.

Hman,

I've read before that remedial wood chips provide about 1% of their weight in N (as they break down). Of course there are variables which would vary the number, but I'm assuming that's a ballpark average.

I suppose the effect of mulch could be cumulative, but according the the article you linked, the cumulative effect of N would be fairly nominal. Only 20 lbs. of N/acre annually for every 1% increase in organic matter. I would have thought it would be more than that.

Fruitnut,

That's for posting your observation. 2000ppm K is definitely up there. I've heard of people applying wood ashes to their garden spot for years and years w/ no observable problems. I suspect that would also raise K quite high.

There seems to be a fair amount of interest in this thread. I don't know if it will further the discussion, but I'll add the soil test info from the farm, as compared to the backyard, along with the fertilizer recommendations provided.

Keep in mind the soils are similar (separated by 7 miles). The soil at the farm has not been mulched long enough to be changed by it significantly. Abbreviations: B=Backyard; F=Farm

Phosphorus
F: 10ppm Low
B: 29ppm Medium

Potassium
F: 116ppm Medium
B: 332ppm Very High

Magnesium
F: 280ppm Medium
B: 335ppm Medium

Calcium
F: 3500ppm Very High
B: 3000ppm Medium

Sulfur
F: 7ppm Low
B: 8ppm Medium

Zinc
F: 2.3ppm Low
B: 5.1ppm High

Manganese
F: 33ppm High
B: 36ppm High

Iron
F: 18ppm High
B: 45ppm High

Copper
F: 1.8ppm High
B: 1.8ppm High

Boron
F: 1.1ppm Medium
B: 1.0ppm Medium

Organic matter
F: 5.9%
B: 5.8%

pH
F: 6.9
B: 6.5

Fertilizer recommendations/acre:

Farm:
55 lbs. N
85 lbs P2O5
95 lbs. K2O
6 lbs. S
3 lbs. Zn
0.5 lbs. B

Backyard:
60 lbs. N
30 lbs. P2O5
4 lbs. S
1 lbs. Zn
1 lbs. B

I probably won't add any fertilizer to the backyard, as there aren't that many trees, and I feel comfortable the nutrient levels are close enough not to add fertilizer.

At the farm, I do plan to add P. Peach trees aren't heavy feeders of P, but P is important to flowering. I figure one application of P should be all the ground needs for as long as I grow peaches there, since the trees don't use much. My elevator sells DAP (diammonium phosphate) which is 18-46-0. Recommendations call for 85 lbs. of P2O5 (phosphate). DAP provides 46% phosphate and so would require 185 lbs. of DAP/acre to provide 85 lbs. of phosphate. This amount would also apply 33 lbs. of N per acre.

They recommend 95 lbs. of K2O/acre. The elevator sells KCl potash, which provides the equivalent of 60% K2O (0-0-60). This would require 158 lbs. of KCl/acre.

3 lbs. of Zn is recommended. Zinc sulfate is 35% Zn, which would require 8.5 lbs. of zinc sulfate.

0.5 lbs. of B is recommended. I'll probably just use Borax washing soda for this application. It's the same thing as agricultural borax. I've forgotten the % boron in Borax. I'll need to look that up.

For the S, I plan to use Ag sulfur, which is 90%.

Olpea, the affect of woodchips and other mulches is not nominal, in terms of the growth of the trees , it is quite dramatic, based on studies that I've posted here. I assume you attribute that to the greater availability of water, but so far, no one has teased that out by research. One would need to provide unmulched trees with equal water access to do this and that would only begin to answer the question.

I don't know of any study that explores the difference in vegetative growth created by slow release organic N compared to quick release in this context either. Access to water would play into this by making it possible to utilize this added N.

As a manager of fruit trees, I consider one of my major goals is to regulate the vigor of the trees I manage and to find the sweet spot- the Goldilocks point of moderate vigor. The richer the soil the more difficult it is for me to have any control of that vigor.

The more mulch you use, the richer the soil, and a 20% increase in organic matter is not insignificant to my mind at all nor is a half pound of added N per 1,000 square feet when the average maintenance suggestion by Cornell is 2 pounds of N that is only available when one wants it to be.

But then, where I manage orchards, we average 3-4" of rain every month of the year. In July through Sept, the sooner that water becomes unavailable to the trees, the higher the quality of the fruit is likely to be.

Hman,

I agree mulching accelerates the growth. As you know, it's been demonstrated in research, and my experience as well.

I don't know how much of the vigor is attributed to less weed competition, cooler summer soil temps, looser/more aerated soil, more water availability, or more N.

Just about any of those factors alone would reduce stress and probably increase vigor. I think extra vigor of mulching is probably a combination of all factors. The amount of vigor each factor contributes, I don't know.

I do think 1/2 lb of N per 1000 sqft. (or 20 lbs. N/acre) is nominal, if that is all the N applied. That is 1/4 of Cornell's rec. Even legumes will fix more N than that - much more.

I understand mulch applies N throughout the growing season, which isn't optimum, especially for inducing early fall dormancy. Because it's slow release, it's the timing that's the potential problem.

Milehigh,

No one has responded to your post yet, so I'll offer a few comments. I like the idea of natural fertilizers in many ways. I'll admit some of the appeal to me is psychological. If done correctly, I don't know if the plants care whether the fertilizer is natural or synthetic.

Nevertheless, I believe there are some real advantages to using natural fertilizers. Natural fertilizers add organic matter, which is really building soil. Even though there is considerable disagreement on this forum, I like soils w/ high organic matter. You can grow anything on a soil with high organic matter. On the other hand, sand is very limiting on what can be grown. It doesn't hold nutrients, it doesn't hold water. This means more nutrients leach out to pollute ground water, plus nutrients must be added more frequently to keep the soil balanced.

It's true peaches (and apricots ) are quite adapted to growing in sand, but I still think there are benefits to growing them in real dirt. It is true water-deficit will increase brix, but fructose is not the only aspect of nutrition or flavor (although I agree sweeter generally tastes better).

Many people claim our soils have been over-farmed to the point the soils are so tired, our food doesn't have the nutrition it once did. I don't know about that, but I do think for food to have lots of vitamins and minerals, the minerals must first be available to the plants via a rich well-balanced soil.

This isn't just my idea. I once read a fruit industry expert from MI say more or less the same thing. He claimed, here in the Midwest, we should be able to grow better quality fruit than in CA because we have better, more nutrient rich soil.

Soils w/ good OM, have lots of biological life which provide symbiotic relationships for nutrient uptake. You can't get that in sand or pure clay.

I'll probably get some vigorous disagreement about this, but that's my view.

All that said, I'm not sure how well the homemade fertilizer you linked is suited for your soil. I don't know much about the soil in Denver, but I would think you already have lots of limestone, so I'm not sure if your soil really needs more. When I think of organic fertilizer, I'm generally thinking of things like wood chips, stable waste, leaves, pine needles, etc., things which add some organic matter. My guess is soils in Denver don't have a lot of organic matter.

I'm not afraid to use synthetic fertilizer, especially to get the soil balanced initially, but I prefer natural fertilizer (if I can get it) after that.

Lastly, I don't want to ignore there can be some advantages to using synthetic fertilizers. Sometimes a quick release can be advantageous, as in the case of N application discussed above. Phosphorous is very immobile in soil. A natural product like rock phosphate won't move at all. It does virtually nothing for the plant, unless it's incorporated in the soil. A synthetic counterpart DAP is the most mobile form of P (even though still not very mobile, which is why incorporation, or banded applications are generally recommended) but has some potential to make it to the root zone when applied topically.

I grow fruit trees in a wide range of soils, from sand through clay and compare the results every season. Trees adjust to soil texture by growing proportionately more root in coarser soil so they are not negatively affected as much as annual crops might be.

Here in the northeast I have almost no doubt that the highest quality fruit I grow comes from the coarsest soils. In these soils I use plenty of wood mulch without much worry about the consequences, at least not for the first decade or so.

It is only on years with severe drought that I prefer a richer, finer base soil.

For annual vegetable crops, richer soil is best, but for fruit trees this kind of soil just doesn't create ideal conditions in the Northeast from my experience.

Hman,

I've found shading is the biggest disadvantage affecting fruit quality of vigorous trees, and read the same. If vigorous trees aren't summer pruned (sometimes multiple times) the fruit is more prone to taste like it comes from the interior of the tree.

I'm sure you've aware of this, just posting it on this thread for general information.

You've found this?. Summer pruning is said to increase fruit color but I've never seen research that indicates it increases brix (I so wish it did, as pruning is my main occupation). I have seen research that suggests it can decrease brix, but I always tell myself this is from excessive summer pruning.

I'm really not sure how all the summer pruning I do affects the quality, but I assume that at least it reduces summer fungus and may even increase the chances of annual production by keeping much more light on spur leaves. With peaches, it helps me maintain vigor throughout the tree, including the interior where you can end up with dead zones.

I "find" the taste of fruit is not much affected either way. You are a more studious and careful man than I (plus, you have a better lab to do this) so maybe you will put your idea to the test- leave a couple peach trees unpruned next to same varieties that are summer pruned and let us know the comparative brix levels. You will probably have to wait until next year when, hopefully, trees have normal crops.

"You've found this?"

Yes. Excessive shading reduces soluble solids. I'll admit, I've been all over the board on this issue in the past. It has taken me some time to learn to manage high vigor trees. And I'm not saying I have it all figured out now, but based on my anecdotal observations, shading can be a problem affecting fruit quality on vigorous trees (When I mention "fruit quality" I'm not referring to color, but "eating quality" - i.e. brix, etc., although many times fruit color and brix have a direct correlation.)

This makes sense to me logically as well. The most shaded parts of a peach tree have the poorest quality fruit, whereas the sweetest fruit is at the top of the canopy. Leaves + sunlight +CO2 = carbohydrates (which convert to sugar in the fruit). The harvest of sunlight is the critical component.

I know you are aware peaches are nourished locally (that is "fed" by the local shoot they are on). Excess vegetation above the "local" leaf source can only block sunlight.

I think even fruit thinning works to increase brix on somewhat similar principle. Too many fruit have to share what is really a fixed amount of "photosynthesis" on a given shoot. Reducing the fruit load in essence increases the photosynthesis ratio of the fruit. In my mind, increasing the amount of light the shoot receives is one way to increase photosynthesis. Although the research is inconsistent, reflective mulches have sometimes demonstrated this.

Another anecdotal observation I once witnessed occurred when I tried to use a "shade cloth" to prevent bird damage. It cost me a couple hundred dollars to get the shade cloth, and I've only used it one time. I put it on a peach tree, which the fruit had just started to color, and kept it on till harvest. The peaches harvested later than normal and weren't as sweet. I've never used the shade cloth since. In my mind, the same thing occurs when fruit is shaded by excessive leaf canopy.

I've read the same thing. Obviously I can't remember where I've read it, but I did a quick Google search and found the same thing (although this research relates to plums).

From the article:

"The plant growth was boosted by N application, resulting on increment of light interception from canopy (DOLINSKI et al., 2007). This might be the major reason for the continuous diminishing of SSC [Soluble Solids Concentration] as result of N increment (Figure 1). It is well known that there is a direct link between light exposition and SSC in stone fruits (PATTEN; PROEBSTING, 1986; SOUTHWICK et al., 1990; MARINI et al., 1991; MULEO et al., 1994). They attributed it to an improvement in the photosynthetic activity of adjacent leaves, which are not shaded, enhancing in this way the carbohydrates availability for the fruit development (SEELEY et al., 1980; BARRITT et al., 1987). This is a great treat to the fruit quality since the SSC represents the fruit sweetest and is one of the most important fruit property considered by consumers (PARKER at al., 1991; ROBERTSON et al., 1988; CRISOSTO et al., 1997; CRISOSTO et al., 2003)."

http://www.scielo.brscielo.php?pid=S0100-29452011000500041&script=sci_arttext

I think there are so many dynamic variables in a particular locale, it can be difficult to understand these things in a black and white sense, which would explain why there is discrepancy in this type of research.

You've mentioned you grow the best fruit on coarse soils. I don't doubt your observation, but about a week ago I stumbled across an old NYT article where Georgia peach growers claim their Georgia "red clay" is part of the secret to growing good peaches.

"Georgia peach farmers have been fighting back, focusing on what they argue is a superior flavor that can come only from the unique mix of heat and red clay soil in their state."

See link below.

My point is the variables are so intertwined, I think it can be difficult to isolate one variable for growing the best quality fruit.

Here is a link that might be useful: Peach Rivalry Becomes War Between the Tastes

THANKS for paying for the analytical, your write-up here,

and for what you are doing. Wood ash is loaded in potassium so it may be tempting to burn it to have a convenient quick easy to apply fertilizer...but what you are doing is right and just..and it is much more economically and ecologically friendly to let wood chips break down naturally to provide fertilizer slowly and to foster habitat for crucial microbiota.