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Author Topic: Growing avocado in sandy soil  (Read 486 times)

jbclem

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Growing avocado in sandy soil
« on: November 02, 2018, 05:27:16 AM »
I have a two year old Fuerte that I recently planted in soil that's classified as sandy silt or silty sand.  The problem seems to be either that it drains too fast or just doesn't retain enough moisture for the roots to take in.  Even now, in daytime 70-80F fall weather(S. Calif zip 90290), I need to water every two or three days or the leaves will start to droop.  They pick up after I water, but I'd like to know what I can do to lengthen the watering interval.

I'm also concerned about root rot (from watering so much) even though the soil is sandy.

And for the next avocado I plant, I'd like to add to the sandy soil to try to alleviate this problem.  I'm thinking of peat moss, and compost, but also worried that too much organic matter might increase the chances of root rot.

Any opinions and suggestions for me?

John

pineislander

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Re: Growing avocado in sandy soil
« Reply #1 on: November 02, 2018, 07:47:48 AM »
Some questions.
How long has the tree been in ground?
Is it on flat ground, slope or hill?
Has the tree developed an extensive root system, of has there been some restriction, damage or dieback?
What is the subsoil profile down several feet through the B&C horizons?
Have you amended the soil or mulched?
What is the sun and wind exposure?
What vegetation or trees are nearby?
Some photos might help.

All of the above might be influences on what you are seeing and are pertinent to a solution.

Frog Valley Farm

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Re: Growing avocado in sandy soil
« Reply #2 on: November 02, 2018, 08:34:31 AM »
Your. Soil needs structure. The best way to accomplish that is with organic matter, specifically with roots in the ground of a legume cover crop like hairy vetch.  To accomplish this on sand without a cover crop, mulch heavilly with alfalfa hay and add some fresh raw manure or earthworm castings and keep moist.  Shouldn’t worry about root rot.

Jack, Nipomo

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Re: Growing avocado in sandy soil
« Reply #3 on: November 02, 2018, 08:53:17 AM »
We are in dune sand.  300 ft of just sanddune sand.  Water is not retained by the "soil".  Avocados do fine here, but need to be watered frequently.  Used to use micro sprayers, but converted to drip with water costs.  Each avocado tree has multiple drippers.  Frequent watering, every other day, hour to hour 1/2 during the summer.  Our summers are mild, but getting warmer each year.  Looks like a bit or rain in a week or so, hope so.

pineislander

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Re: Growing avocado in sandy soil
« Reply #4 on: November 02, 2018, 04:19:48 PM »
Some questions.
How long has the tree been in ground?
Is it on flat ground, slope or hill?
Has the tree developed an extensive root system, of has there been some restriction, damage or dieback?
What is the subsoil profile down several feet through the B&C horizons?
Have you amended the soil or mulched?
What is the sun and wind exposure?
What vegetation or trees are nearby?
Some photos might help.

All of the above might be influences on what you are seeing and are pertinent to a solution.
Another question, how are you applying water?

spaugh

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Re: Growing avocado in sandy soil
« Reply #5 on: November 02, 2018, 06:46:39 PM »
I would fertilize with slow release and top dress with a foot of compost and water with a sprinkler that waters the entire area.  Worms will move the compost down and fix your soil.
Brad Spaugh

pineislander

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Re: Growing avocado in sandy soil
« Reply #6 on: November 03, 2018, 06:38:47 AM »

How long has the tree been in ground?
I now see two years so young but the roots should be spreading out 3 feet or so.

Is it on flat ground, slope or hill?
If not on flat ground probably no possibility of standing water in root zone. On flat ground if standing water was ever possible during some high water event even a few hours root system could have been damaged.

Has the tree developed an extensive root system, of has there been some restriction, damage or dieback?
It's possible that during the tree's life some damage may have come to the root zone which has resulted in a reduced root mass.
 
What is the subsoil profile down several feet through the B&C horizons?
You may have sand on top but solid rock or an impermeable profile underneath. Maybe just a big rock or ledge you don't know about. You could use a post hole digger or steel rod to check that.

Have you amended the soil or mulched?
If you haven't mulched you need to recognize that avocado root system is shallow feeder roots which really need mulch to keep roots cool, reduce evaporation, maintain a soil food web and eventually build topsoil. If you pull mulch back under a healthy avocado tree you should be able to see fine feeder roots coming into the mulch. If not, get that started.

What is the sun and wind exposure?
If in full California sun or high wind exposure you might try a windbreak or something to give only afternoon sun protection but realize this tree needs enough sun to conduct photosynthesis.

What vegetation or trees are nearby?
I've seen lawn grass grown right up to avocado. The grass was absorbing almost all water and nutrients, the tree hardly grew and was starving. Same with a large tree, nearby trees can send roots out seeking water. Some can travel 20 feet and emerge into your avocado tree's root zone robbing it of everything. You could check by digging outside the avocado tree's root zone searching for small or large roots invading the tree's space.

How are you watering?
A two year old tree probably should have a root zone 3 feet wide maybe twice that if you have mulched well. As the tree grows you need to add mulch and expand the root zone by expanding mulching outside the drip zone. Water needs will increase as the tree grows so a single dripper needs to change to 4-6 drippers or better a microsprayer which will maintain healthy soil throughout the root zone.

There's a  slight chance some animal like mole or ground squirrel has a burrow or gopher has eaten roots?

Good luck.

PS, this guy's channel discusses lots of California specific tree information.
https://www.youtube.com/watch?v=fBMvGhHuXxU

jbclem

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Re: Growing avocado in sandy soil
« Reply #7 on: November 05, 2018, 03:43:33 AM »
Thanks everyone for the ideas.  This Fuerte was kept in the container (a deep 9x16" black plastic from Stuewe) for at least two years.  It flushed and bloomed(a bit) last year but didn't set any fruit.  The tree came from C&M Nursery in Nipono.  It's planted on the side of a steep hill on a 8'x4' ledge behind a small retaining wall I built. About 5 feet below it is an Oak tree (probably scrub Oak) that shades the tree from the hot late afternoon sun...that's why I planted the Fuerte in this spot.

Soil tests were done five years ago, the holes dug 4-5' deep,  and showed silty sand and sandy silt.  No mention of organic matter.  And when I've done the settling soil test in a jar of water, there is very little organic matter, and usually just one layer of what I'd guess is sandy silt. Or silty sand.

When I planted it in June this year 2018 (on a small mound but it's settled now to ground level.) the root system looked good and there was a lot of it in the middle and lower part of the container.  There is a 2-3' diameter stucco wire (high quality chicken wire 1" holes) cage around the roots because this is a gopher hill it's planted on.  Right now there are no gophers present in the hill and no sign of tunnels pointed at this tree.  I believe I added some compost to the soil but judging by how often I have to water, not enough.  A few months after I planted it I spread bark mulch around the base, but not up to the base.  A month ago I pulled some o it back because I couldn't see the ground when I was watering the tree.

The trunk is protected from the sun by the cardboard that came with the tree and a piece of shade cloth I draped in front of the trunk.  The tree itself is inside a five foot high, 4 foot diameter deer cage.  Since I planted the tree I've had some 60% shade cloth hug on the front of the deer cage so most of the summer sun has been filtered through the shade cloth.  Windwise, on the north side of the tree there are some thick trees that block a lot of the common Santa Ana winds we get this time of the year.  The sea breeze (from the S and SW) usually isn't very strong up here (1100 ft elevation) in Topanga Canyon.  The strong winds are the NE-NW Santa Ana's and they haven't affected the tree at all so far.  Grasswise, grass does not grow in this sandy soil without lot's of water.  So the only things that grow are native weeds and plants I've planted and watered.  I water by hand.  Yesterday I let the hose run for 15 minutes to the base of the tree, filling the mulch basin I built around it. Previous watering was three days ago, and yesterday the tree was drooping before I watered it.  It had picked up when I checked it today.

This tree hasn't flushed any new growth since I planted it, but the leaves look healthy and I don't think it's dropped any.  It just droops if I don't water every 2 or 3 days.  And the soil feels moist even when it's drooping, so the soil isn't drying out that much in the interval.

I like the idea of planting some hairy vetch if the roots would put organic matter into the soil...did I understand that correctly?

Jack from Nipono...do you know how many gallons of water each day you give each avocado trees in the summer, and how hot does it get there?  Summer's here give us 90-95F weather sometimes until Sept-Oct.  It's been cool-ish lately, the days 80-85F, nights in the low 50's this week but low 60's the past two weeks.

Top dress with a foot of compost?  That's a lot of compost...there are no worms in this dry soil, but I have red worms in my compost pile.  Will they really move the compost down into the soil?  That would be worth trying.

I haven't fertilized the tree since I planted it, and I did so sparingly when it was in the container.  I'd like to hear some suggestions about this.  I do have Osmocote Plus which is slow release.  I also have Jack's Citrus fertilizer, and Miracle Gro, and Ammonium Sulfate, and Mir-Acid.

I hope I've covered all the questions...


Jack, Nipomo

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Re: Growing avocado in sandy soil
« Reply #8 on: November 05, 2018, 08:55:12 AM »
In response to your questions: each avocado tree that is about 4 ft in height has approx 6 1 gal per hour emitters. More for larger trees.  Timer runs 4X a week for 1 1/2 hours.  We have temps similar to yours, but 10 degrees less daytime and nighttime. In July we had two days of 107 degrees.  We used to get morning and evening fog.  We do get Santa Anas in the fall.  I will manually water trees somewhat with the Santa Anas to gain some humidity in the canopy.  I used to have minisprinklers for each tree, but converted to drip due to water costs (my water bill is about $525 for a two month period...no lawn but extensive plantings on 1 1/2 acre).  I have about 50 different avocado trees from 3 ft to 45 ft in addition to mature macadamias (50), cherimoya, etc.  Macadamias don't care much about less water, avocados do. Problem here in the sand is water retention, 6 years of drought.  Subsoil is so dry that it competes for applied water with the plant roots.  Used to be that winter rains kept the subsoil damp....now deeply rooted trees are dying, like the extensive eucalyptus planted all over the Nipomo Mesa in 1906.  Hopefully we will return to normal winter rains, but does not look good.  We do get water from the State Water Project ($) as wells are dropping, but that depends on winter snow in the Sierra Mountains.  As far as mulching, that would be great, if it rained or you had minisprinklers, and lots of water.  Not happening.  So fertilizer is applied with winter rains.  Nevertheless, avocados are doing well and just present a challenge.  Glad I am not a farmer.

spaugh

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Re: Growing avocado in sandy soil
« Reply #9 on: November 05, 2018, 11:54:45 PM »
Thanks everyone for the ideas.  This Fuerte was kept in the container (a deep 9x16" black plastic from Stuewe) for at least two years.  It flushed and bloomed(a bit) last year but didn't set any fruit.  The tree came from C&M Nursery in Nipono.  It's planted on the side of a steep hill on a 8'x4' ledge behind a small retaining wall I built. About 5 feet below it is an Oak tree (probably scrub Oak) that shades the tree from the hot late afternoon sun...that's why I planted the Fuerte in this spot.

Soil tests were done five years ago, the holes dug 4-5' deep,  and showed silty sand and sandy silt.  No mention of organic matter.  And when I've done the settling soil test in a jar of water, there is very little organic matter, and usually just one layer of what I'd guess is sandy silt. Or silty sand.

When I planted it in June this year 2018 (on a small mound but it's settled now to ground level.) the root system looked good and there was a lot of it in the middle and lower part of the container.  There is a 2-3' diameter stucco wire (high quality chicken wire 1" holes) cage around the roots because this is a gopher hill it's planted on.  Right now there are no gophers present in the hill and no sign of tunnels pointed at this tree.  I believe I added some compost to the soil but judging by how often I have to water, not enough.  A few months after I planted it I spread bark mulch around the base, but not up to the base.  A month ago I pulled some o it back because I couldn't see the ground when I was watering the tree.

The trunk is protected from the sun by the cardboard that came with the tree and a piece of shade cloth I draped in front of the trunk.  The tree itself is inside a five foot high, 4 foot diameter deer cage.  Since I planted the tree I've had some 60% shade cloth hug on the front of the deer cage so most of the summer sun has been filtered through the shade cloth.  Windwise, on the north side of the tree there are some thick trees that block a lot of the common Santa Ana winds we get this time of the year.  The sea breeze (from the S and SW) usually isn't very strong up here (1100 ft elevation) in Topanga Canyon.  The strong winds are the NE-NW Santa Ana's and they haven't affected the tree at all so far.  Grasswise, grass does not grow in this sandy soil without lot's of water.  So the only things that grow are native weeds and plants I've planted and watered.  I water by hand.  Yesterday I let the hose run for 15 minutes to the base of the tree, filling the mulch basin I built around it. Previous watering was three days ago, and yesterday the tree was drooping before I watered it.  It had picked up when I checked it today.

This tree hasn't flushed any new growth since I planted it, but the leaves look healthy and I don't think it's dropped any.  It just droops if I don't water every 2 or 3 days.  And the soil feels moist even when it's drooping, so the soil isn't drying out that much in the interval.

I like the idea of planting some hairy vetch if the roots would put organic matter into the soil...did I understand that correctly?

Jack from Nipono...do you know how many gallons of water each day you give each avocado trees in the summer, and how hot does it get there?  Summer's here give us 90-95F weather sometimes until Sept-Oct.  It's been cool-ish lately, the days 80-85F, nights in the low 50's this week but low 60's the past two weeks.

Top dress with a foot of compost?  That's a lot of compost...there are no worms in this dry soil, but I have red worms in my compost pile.  Will they really move the compost down into the soil?  That would be worth trying.

I haven't fertilized the tree since I planted it, and I did so sparingly when it was in the container.  I'd like to hear some suggestions about this.  I do have Osmocote Plus which is slow release.  I also have Jack's Citrus fertilizer, and Miracle Gro, and Ammonium Sulfate, and Mir-Acid.

I hope I've covered all the questions...

You can top dress a lot, maybe use tree trimmer mulch instead of compost if you are going to put down a lot on a small tree.  A foot of mulch is not a problem at all.  Compost might stay too wet if you use that much.  Worms will absolutely show up where none existed and work your soil.  They just need compost or mulch to work on.  Osmocote would work well also.  A fist full spread around the tree and worked into the mulch.  Dont use jacks on it until its large and established, you will burn the tree. 

I have very well draining decomposed granite soil.  Its basically sandy silt type composition.  This is how I do all my avocados.  Top dress really heavy with compost and mulch.  Mostly corse tree trimmer mulch.  Each tree gets 3 or 4 tradh cans full. 

Your tree should start flushing by late spring.  It may not do much over winter.  Maybe some blooms but not much leaf growth.  Just be patient and work on the mulch and it will start growing.
« Last Edit: November 05, 2018, 11:57:20 PM by spaugh »
Brad Spaugh

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Re: Growing avocado in sandy soil
« Reply #10 on: November 07, 2018, 06:30:37 AM »
If you are having to use a slow release fertilizer on top of your compost, your compost quality must be very poor.  Seems redundant as compost is a slow release fertilizer.  Can someone please explain the need to add a slow release fertilizer on top of compost?

spaugh

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Re: Growing avocado in sandy soil
« Reply #11 on: November 07, 2018, 09:55:38 AM »
Sure, "compost" "quality" can vary a lot.  I should have been more specific and said recycled yard waste compost.  Not animal manures or table scraps or other rich composts.  The stuff you get truck loads at the dump for free.  They are low in nitrogen.  Avocado trees need nitrogen.

Do you have to use fertilizer with it?  No, you can do whatever you want.  Not everyone is an organic purist though.  Some of us like to use organic inputs as well as comercial fertilizer. 
Brad Spaugh

laidbackdood

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Re: Growing avocado in sandy soil
« Reply #12 on: November 09, 2018, 08:59:59 AM »
well i grow both citrus and avo's here in Perth.......I know a guy who grafts and sells avo's........we get temps to 40C plus in the summer......I went to his house......he had a tree planted in pure sand........it looked like it was on the beach !.......around that he had a circle of compost out about 3 or 4 inches from the trunk........with citrus there are no feeder roots within a 6 inch circle of the trunk....I used to put food in that area and it killed my trees....loads of them.....avo's need good drainage and hate wet feet...........sand provides the perfect drainage for winter.......so the roots dont stay wet......even if it rains hard....my papaya has gone through winter nicely because i just stuck it in pure sand.......nothing added to the planting hole at planting time.......then compost out 6 inch from trunk with slow release fert.........I have two avo's in grow bags...they are difficult in pots or bags ........both citrus and avos......do well in ground but you need to adjust to the seasons........in winter......you remove all mulch and let any sun that comes help dry out the soil.......if the rootball is surrounded by sand that will happen............when it  gets hot.........compost with slow release around to the drip line and then a thick coat of mulch.......lupin or licerne is good......i did that today to 6 trees because we were 33C today ...36C tomorrow.........the avo's need their surface roots kept moist.....so water often and stick a thick layer of mulch on your pot.......i wouldnt go with compost because it will clog up the air spaces in your potting mix and you will get root rot........move them so they only get morning sun.......thats what i have done to mine....i am getting drooping leaves as well....water often to wet those surface roots but you dont need to water deeply........in ground you have create raised beds with leaf litter etc....thats very free draining..........since i have been putting plants in the ground ...straight into sand with no added stuff .....then do compost and feed when i see new growth and also food around the outside of the pot and not above the rootball.......things have improved dramatically.........the analogy i would use.....is to tease the roots....like the smell of kfc from a distance.......let the roots smell water and food over there and go looking for it....dont just give it to them.......then they will send out roots and develop bigger root systems......bigger and healthier roots = good top growth...Young trees are most at risk until they establish their root systems........citrus grow in peoples back yards here and nobody bothers with them,,,,,i ate some mandarins from a rental here a few years ago and they were yummy.....a big tree in pure sand and from nov to feb its evil hot with very very little rain but because they are so bloody big the roots have spread every where.....thery never get fed or water in this time !....i saw a huge lemon tree in a concrete pot on the side of the road.........nobody ever bothered with that.....it produced lemons !.........its all about establishment my friend...hope this helps.
« Last Edit: November 09, 2018, 09:06:55 AM by laidbackdood »

 

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