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Orchard soil health

Orchard compostThose of you who read chapter three of The Holistic Orchard with me this week will probably feel like you were drinking from a fire hose.  The section took me days to digest and I suspect I'll be trying out Phillips' techniques for the next several years.  Feel free to comment about other parts of the chapter (of which there were many), but I want to focus my post on soil health this week.

It's very handy to read this chapter with soil test results in hand.  I didn't actually test my orchard soil last winter, but I have test results from the back garden, which started with the same type of soil, even if it has been treated slightly differently over the years.  Here are the relevant portions of the test results:

pH 7.3
% OM 15
P (ppm) 556
K (ppm) 615
Ca (ppm) 6801
Mg (ppm) 926
CEC 56
% Sat. K 3.7
% Sat. Mg 17.6
% Sat. Ca 78.8


Phillips follows an Albrecht-like ratio approach to soil health, focusing on the relative (rather than absolute) amounts of nutrients.  When I got my results back for the garden, all of the cations were listed as "very high", so I figured I was fine.  But Phillips notes that if there's too much magnesium (Mg) in relation to the calcium (Ca) in the soil (for example), plants will accidentally take up magnesium while looking for calcium and may end up deficient in the latter.  In addition, he points out that calcium tends to spread soil apart, which can be handy for drainage and aeration in clay soil, while magnesium pulls soil particles together (useful in sand, but not elsewhere).

Effects of calcium on clay soilThe optimal Ca:Mg ratio (compared using the percent of base saturation figures, not the absolute ppm figures) is 5:1 for sandy soil and 7:1 for clay.  As you can see, my ratio is 4.5:1, meaning that some of my drainage issues might be improved by boosting calcium.  However, since my pH is already too high, I don't want to just add lime, so I'll need to look into gypsum, which increases calcium content in soil without sweetening the ground.

Similarly, you want to consider the ratio of phosphorus (P) to potassium (K).  Phillips recommends P:K values of 2:1 to produce the most nutrient-dense fruits, although 1:1 is okay in young orchards.  My P:K value of 0.9:1 is typical and signifies a need to boost phosphorus levels without increasing the soil's supply of poassium.  I'm going to have to do some research into phosphate amendments to see which ones won't raise our pH, but Phillips lists black rock phosphate, colloidal phosphate, Tennessee brown phosphate, bonemeal, and bone char as possibilities.

If your head's awhirl with numbers, here are some non-numeric soil factors to consider.  As I've mentioned previously, the goal in orchard soils is to boost fungi at the expense of bacteria, which Phillips explains results in more nitrogen being available in the form of ammonia.  Bacterially-dominated soils tend to have nitrogen in the form of nitrates, which Fungi in wood chipsresults in happy-looking trees and big fruits, but low nutrient density and flavor, along with more susceptability to disease.  Phillips recommends keeping your soil fungally-dominated by making special compost for the orchard out of deciduous wood chips slow-composted with animal manures.

When should you apply that compost?  I've always thought that early spring was the best time, but Phillips gets more scientific.  He explains that the white feeder roots that suck up nutrients are even more ephemeral than leaves --- they generally only live 14 to 60 days before dying back.  Trees produce multiple flushes of feeder roots throughout the year, generally during periods when growth on top of the tree has slowed, and if you time your compost applications to match root growth periods, you'll get more nutrients to the tree.  Trees focus on blooms in early spring, roots in mid spring, leaves in early summer, and roots in late summer and fall.  Cutting herbaceous plants under the tree canopy (like grass or comfrey) during peak root growth can help feed your tree at just the right time, and so can spreading compost in autumn when half of the leaves have fallen.  Meanwhile, a heavy mulch in the fall can keep the roots growing later into the winter, and can also muffle spring warmth so trees bloom up to ten days later and miss fruit-killing freezes.

If you can handle another eye-opening chapter, we'll read chapter 4 "Orchard dynamics" for next Wednesday.  Those new to the club might want to check out previous chapters on beginning a holistic orchard and techniques for designing a holistic orchard.  And, as always, I'm looking forward to hearing your thoughts on this fascinating subject.

The Weekend Homesteader is full of projects that make a difference, but don't break the bank.


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Do most vegetables prefer fungal or bacterial soils?

You talk about making fungus-friendly compost. Assuming your soil fertility is good, could you get the same effect through chop-and-drop?

Comment by BeninMA Wed Oct 17 13:39:09 2012
very interesting, I will have to make sure my tree's are well mulched then. Wonder if it works for Lilacs also?
Comment by Irma Wed Oct 17 13:59:45 2012
An unmulched tree sort of looks naked to us these days. Not sure about the Lilacs, I guess it would depend on how much dynamic accumulation occurred.
Comment by anna Wed Oct 17 14:10:10 2012

BeninMA --- Each vegetable is a little different in terms of the fungi to bacteria ratio they prefer. You'd have to do a bit of legwork to find out anything beyond what I mentioned in the linked post --- unfortunately, that's all I know.

Chop and drop will definitely help you veer toward fungally dominated soil. You'll still need to feed most fruits and vegetables something to bring up nitrogen levels, but it's a great start.

Irma --- Mark accidentally logged in as me when he commented above. I'd definitely recommend mulch around lilacs --- all woody perennials except nitrogen-fixers are going to enjoy that.

Comment by anna Wed Oct 17 14:54:13 2012

Anna,

Go all out on the gypsum. Do it to everything you got. It's some of the best stuff I ever used. It doesn't just break up hard soils and boots calcium, but does much much more. It's beneficial to vegetables, flowers, and fruits. Be very liberal also. It doesn't burn at all. Also you can used it often.

Comment by Marco Wed Oct 17 18:26:35 2012
I loved the root growth vs top growth part. I never paid much attention until after reading this chapter a little earlier in the year.
Comment by Brian Wed Oct 17 20:08:09 2012
I was about to give up on mulching all my fruit and nut trees and mowing/weedeating instead... but this week I've started kill mulching around the trees again after reading so far. As for all the chemistry - I'm going to have to read that again after I get a soil test done. I'm wondering if the standard state of VA extension soil test is what you used? Seems like the author uses special labs?
Comment by De Wed Oct 17 20:19:00 2012

I have to admit that all of those numbers all at once did rather get my brain in a whirl; I'll have to let them soak in a few days and re-read this post a time or two to really get my head wrapped around the point of the numbers.

On the other hand, the stuff about the feeder roots and when it's best to apply compost really got me excited! :) I just can't wait until I actually have this book in hand to read myself! :)

Comment by Ikwig Wed Oct 17 21:08:00 2012

I read this and my eyes started glazing over... And my first thought was " huh.?" So I just went back to look at the puppy. :-)

Comment by Deb Wed Oct 17 22:02:44 2012

Marco --- Well, I suspect that like any soil amendment, you don't want to go all out without knowing from a soil test that gypsum is what your soil wants. From my understanding of the way it works, it causes magnesium to get washed away, which is good for my soil, but could be terrible for someone who has low magnesium levels! I'm definitely going to give it a try, though, and am thrilled to hear that your soils were perked up by the addition.

Brian -- Me too! I'm still trying to decide if I can buck conventional wisdom and spread compost in the fall or if that's just too scary for me. :-)

De --- It's definitely much easier to read the chemistry part once you have a soil test in hand. I actually used UMass Amherst because I wanted to test for heavy metals once in the farm's life, just in case. You might enjoy reading my post about soil testing labs and comparing the cheaper options to our extension service. There are special labs that focus more on biology of the soil, but they tend to be very expensive and I'm not sure whether I believe all of their claims, so I've steered clear so far.

Ikwig --- Yeah, this part definitely needed digestion!

Comment by anna Thu Oct 18 08:40:57 2012
I wouldn't over do it but I have started adding it to anything I transplant now. Another awesome use is on lawns that end at roads with heavy winter salt use tend to get burned from the salt. If you use gypsum on the lawn heavily for the first 15' nearest the road it will remedy the problem.
Comment by Marco Thu Oct 18 22:15:38 2012

Marco --- (Your subject line made me smile, again. :-) )

I read up a bit on gypsum after responding to your comment, and I could see how it would be hard to overdo it. The application rates are extremely high, 1,000 to 2,000 pounds per acre! And it sounds like you're totally right about the salts too. I sent Mark to the feed store after some, but they're having to order it for us. Once it comes in, we're definitely going to try some soon.

Comment by anna Fri Oct 19 07:29:48 2012

I know I'm almost 3 months behind, but I only recently had this book given to me and am getting through it now.

Although we have access to some of the materials Phillips uses to keep his soil fungally-dominated, we will need to scrounge to get it in the volume he uses.

One thing we do have access to is coffee grounds, given to us by a local coffee establishment. I'm not sure whether that would be better for the fungus in the soil (for orchards) or the bacteria (for gardens). Is there any way for me to determine this for coffee grounds - or any other compost inputs we run across? I want to make sure I apply my amendments in the places that they're most beneficial if possible.

Comment by Jono Tue Jan 8 08:36:17 2013
Jono --- I was just flipping back through this chapter last night, actually. Although it can be a little more complex, I recommend looking at the C:N of a mulch to see whether it fits in the vegetable garden or around the woody perennials. I explain this in more depth in Weekend Homesteader: May, but the short version is that a low C:N, like you find in coffee grounds, is best around vegetables or in a compost pile. A higher C:N promotes fungi and makes a good mulch around fruit trees.
Comment by anna Tue Jan 8 09:29:04 2013