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Need advice on soil amendment for citrus tree

Posted by blazeaglory 9b-10 Westminster CA (My Page) on
Thu, Mar 29, 12 at 20:41

Hello. Im looking for advice on how to fix a Navel Orange tree I planted last year. Today I have removed a 2'x 2' area of grass from the tree. The problem is the tree is very skinny and some what pale green but the roots extend far out from the 2 foot square I have just cut. The tree is also full of many flowers and small fruit. My questions are...

#1 I have accidentally chopped some of the ends of those long shallow roots, will the tree be OK? I cannot believe how small the tree is with such a nice root system.

#2 I am planning on amending the soil with half cow manure and half normal soil for now. Maybe feeding in the coming weeks or month with a liquid citrus fertilizer as well?

#3 Do you think the grass will grow back from under the compost? I have dug down to about 3" - 4"

You guys are pros and any help would be great. I plan on doing the same thing with my peach tree tomorrow. Do you think it will interfere with the blooming of the peach as the buds are just about the go pink?


Follow-Up Postings:

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RE: Need advice on soil amendment for citrus tree

Don't amend soil, blaze. Instead, top dress your soil. You can add several inches of compost, a small amount of chicken manure (cow manure is WAY too hot), then top it with bark mulch to retain soil moisture. And, you must be very careful with grass removal, as citrus feeder roots are very superficial (as you're found out). Will it survive? You'll just have to watch and see. 3 to 4 inches is PLENTY to remove grass. If you top it with the above, any grass that manages to sneak through will be easy to pull out. Clear the grass out to just past the drip line (edge of canopy) to give you tree. Add your fertilizer to the drip line and water in very well. If you want to add some liquid gold, add some worm castings. Make sure all this is not up against the trunk, as that can cause rot. Keep a 3 to 4" ring clearance around the trunk.

Patty s.


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RE: Need advice on soil amendment for citrus tree

Thank you so much!

Yes what I meant instead of amend was to add everything to the top layer. See little things like that is what separates us from the pros ;)

It looks so much better already! If it wasnt for you and this site I dont think I would have been able to do this.

As for the roots. I only nicked off an inch or so of one or two of the roots so I hope its OK. I cant believe how shallow they were and how much they have grown! The sad thing is is that my roots are twice the length of my canopy :( The grass roots were right in with the orange roots.. The soil is a little moist already do you think it would be OK to wait until morning to water?

Do you think I should do the same thing with my peach tree? It seems a little more forgiving. As of now it only has a 1' ring or white rock around it. Its about 6' tall and getting bigger with a caliper bigger than 1". Im thinking I should just do the same to all my fruit trees??

Thanks again!! :)


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RE: Need advice on soil amendment for citrus tree

Patty, you probably know I love you, but your ideas about soil amendment are just wrong; I don't know if someone told you this, or if you just made it up.

I am at Weslaco, TX today, trying to learn what I can from the gurus of the Citrus Research Center; I also went out and talked with several growers in the Rio Grande Valley

All of the Research center gurus, and all of the growers agreed with my position... if you can afford to amend the soil, DO IT. The reason commercial growers don't amend their soil is the cost is prohibitive. I don't amend my field soils because I can't afford to do it; I amend every one of my garden trees; and every one of my garden trees exceeds my field trees...Ask the container growers if they believe in amending soil.

Next, Cow manure may be the most perfect fertilizer for citrus that God ever invented; and FYI... chicken manure is much "hotter" than cow manure.

When I can get it, I would prefer cow manure for my Meyers over the best citrus fertilizer I can buy.

Tomorrow I fly back to Los Angeles to meet with my exporter to "see" some Calif. citrus operations; but I doubt we will learn anything near to what I am learning here in S. Texas.

Keep a good thought

John


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RE: Need advice on soil amendment for citrus tree

Actually, John, this is the latest theory here, at least in my neck of the woods - do NOT amend soil. It is better to top dress than to amend. I just attended a seminar through the San Diego Horticultural Society. One of the most renowned urban foresters in the country, Robin Rivet, happens to live in San Diego county. She spoke about how to correctly plant a tree, and did confirm this is the latest recommendations. UC Riverside also recommends the exact same thing, based on my class I just attended there, "Citrus in the Garden" taught by Tom Shea and Dr. Tracy Kahn. So, my information is coming from pretty substantial sources. Our chicken manure in bags is well cooked. Actually, your best, best manure is chicken, then horse, then cow. At least, this was the information I received at my Master Gardener's classes through Purdue University. Here's the info from Center for Urban Forestry:

"Do not amend the soil. Adding soil amendments to the backfill is another discredited practice. Some bagged soil products advertise adding one bag (3 cu ft) per tree. The tree roots need to get into the native soil as soon as possible in order to encourage them to grow beyond the dug hole. Amended backfill soil, while encouraging of root growth for a short distance, stunts further growth."

You can access this document here: http://ucce.ucdavis.edu/files/datastore/391-272.pdf

So, this is the current thinking. It is new, John, and based on some recent research. So, sharing what I've learned recently from some very astute and well-experienced sources. So, perhaps the gurus in Texas might want to confer with the gurus in California! I think the logic prevails with planting in native soil. You can't possibly amend soil in a large enough hole to assure proper root growth. And, your amended soil will eventually revert to native soil, so that's a huge amount of effort that will not assure solid root growth. The thinking now is to try to replicate what nature does - provide good organic materials that support excellent microorganisms in the top soil by top dressing, that will percolate down to the feeder roots. It makes much more sense to me. I respect the folks in Texas, they're great and do a wonderful job with their citrus. But in this, I respectfully disagree with them :-)

Patty S.

And from UC Davis', "Questions and Answers to Citrus Management" by Tom Shea and Dr. Peggy Mauk:

2. When should I plant, how deep should I plant and how big a tree should I plant?
The best planting time is after frost danger (after February 15 in the Riverside area) and before the onset
of hot weather. Although fall planting can be successful it is generally better to wait until spring. Always
choose a location that has full sun throughout the day.
It is best to plant in well-drained soil (see Q. 3). Dig the planting hole as deep as the root ball and as wide
or wider than the root ball. Be certain that the tree is not buried below the graft union. The graft union
(slight dogleg shape in the trunk) should be located several inches above the soil level. Trees buried too
deep may not survive. It is always best to fill the planting hole with the same soil that was removed when
digging the hole. Do not add any mulch or potting soil into the tree hole. These materials retain more
water and may increase the chances of root rot."

I understand that the citrus gurus in Texas are great folks. But perhaps they might want to confer with the citrus gurus in California who are espousing an updated philosophy about amending versus top dressing. This is supported by some fairly significant research, John. If I can dig up the research, I'd be happy to send it to you. But I'm sticking to this. It just makes more sense to me, and the research backs this up.

Patty s.

Here is a link that might be useful: Center for Urban Forestry, San Diego County Trees: Proper Planting


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RE: Need advice on soil amendment for citrus tree

Excellent. Nice debate.

I have to say Southern California is known for our Oranges:)

I would think that topdressing the soil as compared to "amending" the soil would eventually over time become amended anyways. You know? Also, trying to amend with all the shallow citrus roots seems such a task. The trickle down method of top dressing seems, on the surface (no pun intended) the better method as eventually the soil will become amended so to speak.

I do agree with John that cow manure is less hot than chicken manure. The chicken manure I have compared to the cow manure smells much more potent and burns my nose if I smell for too long where as the cow manure is like sweet music to my nose. Maybe I have a strange bag of chicken poo? I do know the cow manure has been in the bag for a long time compared to the chicken manure. I have heard with time in the bag cow poo becomes less hot? Either way I used the cow poo mixed with native soil.

Excellent posts everyone:)


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RE: Need advice on soil amendment for citrus tree

John and Patty are discussing about the practice of amending the soil DURING the planting process and Blaze is talking about his established tree....right? You CANNOT amend the soil in which a tree is already growing, blaze. You're on the right track there. But I do have to tell you...I worry a bit about your 2X2 space you've cleared for your tree. We call that a 'tree coffin'!

The most important part of the root system consists of a very far reaching network of VERY fine roots. We need to foster that shallow soil/root system by allowing our trees as much root growth space as possible. You cut through lots of those roots without even knowing it.

When applying mulch, try to remember that a healthy tree's root system will extend 3 to 4 times the spread of the crown. Now, I know that we aren't going to 'donate' that much real estate to a tree, especially as it grows and develops, but we should find some happy medium. Grass, by the way, is the ultimate competitor for root space, water, and nutrients. Grass usually wins the battle under ground. Many turfgrass species are allelopathic, as well.

The practice of using amendments to 'improve' the existing soil in a planting hole has long been discredited for woody plants of all kinds, sizes and species. This is true in nearly all soil types. Trees (and woody shrubs) simply establish more rapidly when planted into an unamended planting hole.

However, if one is incorporating the tree as part of a whole landscape bed, that entire large area can be tilled up and amended. Native soil can certainly be modified by breaking up clods, removing stones, etc.


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RE: Need advice on soil amendment for citrus tree

I was describing an existing tree from my first thread. I agree that trees planted in the soil directly grow better. Like you said if I plan on planting over a large area I usally create a nice bed so to speak but for single planting Ill let the tree grow in th natural soil and feed from the top. But I have only really begun to create "beneficial" zones around my trees. The grass is so agressive that this year alone it over took my trees in the little areas that I thought would be OK but am learning now it is not..hehe

Ive seen healthy trees around here that are grown in the smallest of plot with grass surrounding but they are also large some what established trees. Would that help with competing for the grass? They are large mid aged to older fruit trees but grow nice and green and full in a grass yard with lass space than what I have created for my little tree.

Ill try to post pics by Saturday.


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RE: Need advice on soil amendment for citrus tree

Okay, to back up rhizo's excellent post, one of the challenges, blaze, is with citrus specifically and grass. Both are big nitrogen users, which is why a lawn and a citrus tree rarely do well together :-) It is recommended not to plant citrus trees in a lawn. Besides the lawn robbing the citrus tree of nitrogen, lawns are also frequently sprinkled, another thing citrus trees really do not like. They don't like their trunks to get wet. It can kill a young citrus tree. Other trees can compete with the grass that do not demand as much nitrogen, but citrus are a little more unique in their requirements. Not unlike avocados, that can be killed by raking up their messy leaf drop (which they need to shade and feed their very shallow feeder roots). Now, that being said, an older, established tree that was "there first" can manage in a lawn that comes later. The other way around, though, is a poor combination for citrus.

And, more info regarding the amending of tree holes for John. John, I had an opportunity to chat with Robin Rivet. Here is her response, again, that confirms my and Rhizo's statement about the amending of holes. Yes, you might see this in large commercial orchard practice - old habits die hard - but it's not the going theory at this time, especially for backyard orchard culture or for ornamental trees in a backyard setting:

From Robin Rivet:

In an educational orchard setting, it may be common practice to
till and amend a large area before planting the citrus or other fruit trees,
rather than digging and amending small holes. This can be fine, and actually
may be the best practice - it's just usually impractical for most people.

Of course there is always a "gray" area when answering such questions in public
places.

Here is a paper from UC Davis that basically reinforces the tenet not to amend,
plus it has lots of other useful tips. http://ucce.ucdavis.edu/files/datastore/391-272.pdf

I also found this article and basically agree with where he goes, although the
guy is from a region with very different soils than ours. http://www.sustainable-gardening.com/plants/shrubs-and-trees/time-to-bust-this-myth-do-not-amend-soil-when-planting-trees
Keep in mind that few people are willing to till and amend a 10 ft. radius of
compacted soil. And, it's good to note that many tree's roots will grow
considerably past 10 feet out.

Here are some more CA and related professional tree resources. The bottom line
is to avoid creating a hole where the tree roots are so content, they never want
to leave. It takes awhile to kill a tree this way, so few folks ever realize
this was the problem.
http://www.treesaregood.com/treecare/tree_planting.aspx
http://ucipm.ucdavis.edu/PMG/GARDEN/ENVIRON/sitepreparation.html
http://www.ftpf.org/resources.htm
www.sandiegotrees.org - http://energycenter.org/index.php/trees/tree-and-landscape-management/2876-proper-planting?catid=569%3Aplanting-a-tree

The links are broken, so you'll have to make sure to copy and paste the entire link, but you'll see this concept of planting in native soil is the philosophy now, based on good research here in California and actually across the country.

Patty S.


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RE: Need advice on soil amendment for citrus tree

I cant believe how much Im learning:) Thanks everyone


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