Grasses Stunt Fruit Tree Growth?

[SoCalDan]

I was reading an older book recently and the author mentioned in passing about planting grasses (fountain, etc.) near fruit trees.  He didn't go into any detail but wrote kind of "matter of fact" that it was a bad idea. 

I am in South Florida (zone 10) and my wife loves grasses.  Are there any reasons to not plant grasses near my fruit trees.  Are grasses considered anti-companion? 

Thanks in advance.     

[FrankDrebinOfFruits]

I plant zoysia grass specifically around trees to help retain water. The grass helps with rain water run off (slows the runoff and allows more absorption), soil erosion, and shades the soil allowing for longer water retention and less evaporation.

If I don't plant grass then its weeds, like guinea grass, which will grow to be 8 feet tall and shade a tree in under under a year. I envy people who will grow nothing if they plant nothing. Here, its a daily battle against a jungle.

[Cookie Monster]

Grasses will reduce the amount of available moisture and nutrients, since the feeder roots of your fruit trees share the same soil space. Just provide extra water and fertilizer if you wish to have both.

[skhan]

I was curious about this as well. I agree 100% with the moisture part but not with the fertilizer.

It seems like this statement doesn't take into consideration that in most of our cases the competing weeds/grasses will be cut back and decompose right under the tree.
Releasing those same nutrients to be taken up by trees or more grass.

Seems like if you are constant in you fertilizing (and mowing) it shouldn't be to much of a problem.

[fruitlovers]

When a tree is very small, and newly transplanted, there is going to be a lot more competition than with older plants. For new plants there should be no grasses around the perimeter of tree. Full grown trees are not going to suffer at all as their tap roots are way below surface and the areas where grasses are feeding. Moisture may also be a concern in very dry areas, as grasses will suck up a lot of moisture.

[Finca La Isla]

I think grass is not the best. Ideally you have just mulch under the fruit trees. There are ground covers that help with erosion and moisture retention without the aggressive competition of grass. Good ground covers, once established, can choke out tall weeds.
Something to consider is whether your fruit tree roots are going to be feeding superficially or tend to have a deeper root system.
Peter

[bsbullie]

Certain grasses, such as St. Augustine, that have aggressive running root systems, can choke a young fruit tree.  This is especially critical with citrus trees as they have surface feeder roots where the grass could virtually kill the tree.

[Cookie Monster]

The only flaw with that theory is that grass mulch and fertilizer don't provide the same nutrition. Depending on environmental conditions, some (most?) of the nitrogen that the grass used dissipates into the atmosphere after the grass is cut. Also, compost can actually make some nutrients less available -- which I found out via experience after trying to feed my garden exclusively with mulch (LOTS of it).

On an intuitive level, one would assume that if all fertilizer were simply dumped back into the soil after mowing, then the soils where grass has been mowed for decades would be incredibly rich storehouses of nutrients. However, this is not true. In my neighborhood, for example, a new tree will typically exhaust the supply of copper (one example) in about 2 years, despite grass growing in those areas for around 50 years. I don't know how long mulching mowers have been used by our HOA, but I know it's been at least 12 years (the time I've lived here).

I was curious about this as well. I agree 100% with the moisture part but not with the fertilizer.

It seems like this statement doesn't take into consideration that in most of our cases the competing weeds/grasses will be cut back and decompose right under the tree.
Releasing those same nutrients to be taken up by trees or more grass.

Seems like if you are constant in you fertilizing (and mowing) it shouldn't be to much of a problem.

[Cookie Monster]

Aside from the fert / moisture issues, grass / weeds also carry other problems. Examples:

• Cuban may beetle larvae thrive on grass roots. Removing the food source causes them to die out (personal experience).
• Garden pests, such as leaf hoppers (which are very destructive to annonas) thrive on certain weeds. Populations increase significantly when they have weed food sources.

[skhan]

The only flaw with that theory is that grass mulch and fertilizer don't provide the same nutrition. Depending on environmental conditions, some (most?) of the nitrogen that the grass used dissipates into the atmosphere after the grass is cut. Also, compost can actually make some nutrients less available -- which I found out via experience after trying to feed my garden exclusively with mulch (LOTS of it).

On an intuitive level, one would assume that if all fertilizer were simply dumped back into the soil after mowing, then the soils where grass has been mowed for decades would be incredibly rich storehouses of nutrients. However, this is not true. In my neighborhood, for example, a new tree will typically exhaust the supply of copper (one example) in about 2 years, despite grass growing in those areas for around 50 years. I don't know how long mulching mowers have been used by our HOA, but I know it's been at least 12 years (the time I've lived here).

I was curious about this as well. I agree 100% with the moisture part but not with the fertilizer.

It seems like this statement doesn't take into consideration that in most of our cases the competing weeds/grasses will be cut back and decompose right under the tree.
Releasing those same nutrients to be taken up by trees or more grass.

Seems like if you are constant in you fertilizing (and mowing) it shouldn't be to much of a problem.

Thanks for the clarifying that Jeff. I always assumed that when plants decompose they are releasing nitrates and nitrites back into the soil.
I guess that is what you get for assuming

[zands]

You go to a nursery and buy a mango tree in  a three gallon pot or another fruit tree in a three gallon pot. Plant this and definitely mulch to a three foot diameter or more, which will not allow grass to grow nearby. I know people who are anti-mulch but who none the less  maintain a three ft diameter of bare soil for their newly planted fruit tree.

Older fruit trees are not effected as much by grass near their trunks due to an extensive root system. But young trees have trouble competing with grass growing up to their trunks. They will grow much slower.
Even so, I maintain a 3-4ft diameter of mulch around older mango and fruit trees

[greenman62]

my house was biult on a swamp
they had to truck in sand... LOTS of sand.

now, after 30yrs the soil isnt just sand.
grass clippings going back into the soil absolutely helped it.

i take grass clippings, leaves, and lots of yard waste, old vines, sunflower stalks etc...
all chopped up and put under the fruit trees.
its 6 in thick in some spots.

when i move back the mulch, there is a ton of life.
it teams, it moves...
springtails, worms, little bugs jumping and crawling
all of them eat, and hence, all of them excrete waste. (fertilizer)

the soil has been transformed in 3 years.
its very rich, and i have lots of healthy trees...

[Cookie Monster]

I think the organic material from grass clippings is good, but it's not a perfect closed loop. If you plow the grass under, then the nitrogen loss would be a lot lower (but obviously that's not practical :-). Also, Har taught me the trick of composting grass clippings in a black plastic bag to avoid nitrogen evaporation loss. The other thing to be wary of though is -- organic material doesn't provide nutrients in the right ratios for plants and it makes some nutrients less available.

The only flaw with that theory is that grass mulch and fertilizer don't provide the same nutrition. Depending on environmental conditions, some (most?) of the nitrogen that the grass used dissipates into the atmosphere after the grass is cut. Also, compost can actually make some nutrients less available -- which I found out via experience after trying to feed my garden exclusively with mulch (LOTS of it).

On an intuitive level, one would assume that if all fertilizer were simply dumped back into the soil after mowing, then the soils where grass has been mowed for decades would be incredibly rich storehouses of nutrients. However, this is not true. In my neighborhood, for example, a new tree will typically exhaust the supply of copper (one example) in about 2 years, despite grass growing in those areas for around 50 years. I don't know how long mulching mowers have been used by our HOA, but I know it's been at least 12 years (the time I've lived here).

I was curious about this as well. I agree 100% with the moisture part but not with the fertilizer.

It seems like this statement doesn't take into consideration that in most of our cases the competing weeds/grasses will be cut back and decompose right under the tree.
Releasing those same nutrients to be taken up by trees or more grass.

Seems like if you are constant in you fertilizing (and mowing) it shouldn't be to much of a problem.

Thanks for the clarifying that Jeff. I always assumed that when plants decompose they are releasing nitrates and nitrites back into the soil.
I guess that is what you get for assuming

[Cookie Monster]

I thought you were the one who had chlorotic jaboticabas.

Organic material is great, but it doesn't provide nutrients in the right ratios, and it can make some nutrients less available. A funny example of this -- even though I'm on calcareous soil, many of my trees showed symptoms of Ca deficiency (soft, low brix fruit, leaf symptoms). This is because the top 9 - 12 inches of my soil is black compost (the result of a decade worth of tree trimmer mulch application), and the feeder roots of most of my trees prefer that portion of the soil. However, compost is notoriously low in Ca. A couple thousand pounds of gypsum solved the problem :-).

I also had chlorotic jabos that got worse and worse as I added more compost. Now that I've started using fertilzer, they've all greened up.

my house was biult on a swamp
they had to truck in sand... LOTS of sand.

now, after 30yrs the soil isnt just sand.
grass clippings going back into the soil absolutely helped it.

i take grass clippings, leaves, and lots of yard waste, old vines, sunflower stalks etc...
all chopped up and put under the fruit trees.
its 6 in thick in some spots.

when i move back the mulch, there is a ton of life.
it teams, it moves...
springtails, worms, little bugs jumping and crawling
all of them eat, and hence, all of them excrete waste. (fertilizer)

the soil has been transformed in 3 years.
its very rich, and i have lots of healthy trees...

[greenman62]

I thought you were the one who had chlorotic jaboticabas.

Organic material is great, but it doesn't provide nutrients in the right ratios, and it can make some nutrients less available. A funny example of this -- even though I'm on calcareous soil, many of my trees showed symptoms of Ca deficiency (soft, low brix fruit, leaf symptoms). This is because the top 9 - 12 inches of my soil is black compost (the result of a decade worth of tree trimmer mulch application), and the feeder roots of most of my trees prefer that portion of the soil. However, compost is notoriously low in Ca. A couple thousand pounds of gypsum solved the problem :-).

I also had chlorotic jabos that got worse and worse as I added more compost. Now that I've started using fertilzer, they've all greened up.

my house was built on a swamp
they had to truck in sand... LOTS of sand.

now, after 30yrs the soil isnt just sand.
grass clippings going back into the soil absolutely helped it.

i take grass clippings, leaves, and lots of yard waste, old vines, sunflower stalks etc...
all chopped up and put under the fruit trees.
its 6 in thick in some spots.

when i move back the mulch, there is a ton of life.
it teams, it moves...
springtails, worms, little bugs jumping and crawling
all of them eat, and hence, all of them excrete waste. (fertilizer)

the soil has been transformed in 3 years.
its very rich, and i have lots of healthy trees...

the Jabo that looked chlorotic is likely the result of being transplanted,
 then dug up , and planted again.

something like Pine in abundance is low in calcium.
(Oak and Birch also are BTW)
but, my mulch is from a very diverse set of plants.
all compost is not made equal.
Linden, Hawthorn, Elm, maple and most weeds are high in calcium.

i would worry about a lot of grass as a fertilizer because it is mainly bacterial
as opposed to woody mulch which is more fungally dominant.
"chop and drop" as termed in Permaculture means to use plant matter as mulch
if you use stems and twigs, and leaves, and grass etc...
there is a mix of fungi and bacteria. There is also a higher diversity of species
each one having different mineral ratios.

For your place Jeff,
1ft of woody mulch could easily have been anaerobic, which would have made it acidic.
certain plants may have a hard time uptaking Ca.
also you need a lot of nitrogen to break down that much woody mulch.
adding greens would have balanced it out. giving it nitrogen and bacteria, and different minerals.

I tend to look at things through natures lens first.
True, most of us are planting trees that have been selected by man
and not grown in their natural environment.
 and this will lead to the need for amendments, or, other solutions.
But, i would rather add calcium by using plant matter that is high in Ca

[Cookie Monster]

I suggest you take some time to research the issue. It's common knowledge that compost (whatever the source) is short on calcium. It "has" calcium, but the ratio to other cations is out of whack. Here are a couple of references:

https://highbrixgardens.com/victory-gardens/putting-compost-in-its-place.html
http://www.soilminerals.com/compost_manure_humus.htm

Here's one quote in case you don't want to read the entire article:

Even a sandy loam requires at least 2,000 lbs of Calcium per acre for best growth.  What if we measured the minerals and found that we needed to add 1,000 lbs of Calcium?  How much compost would that take, at 11 grams per 100 lbs?  I'll spare you the arithmetic:  It would take about 4,000,000 lbs:  Four million pounds of that 75% moisture content compost per acre to add 1,000 lbs of Calcium.  Wait, it gets worse:  While we were adding that 1,000 lbs of Calcium we were also adding almost 4,000 lbs of Potassium, far too much.  Well balanced soils need about 1/7th as much Potassium as Calcium, so this soil would call for about 280 lbs of  Potassium per acre; we would be adding over 3,700 lbs too much, assuming that we were crazy enough to try adding four million pounds of compost anyway.

Putting that in terms a backyard gardener could relate to, one would need 90,000 lbs of compost per 1,000 square feet of garden just to bring the Calcium level up to par.

Good luck.

the Jabo that looked chlorotic is likely the result of being transplanted,
 then dug up , and planted again.

something like Pine in abundance is low in calcium.
(Oak and Birch also are BTW)
but, my mulch is from a very diverse set of plants.
all compost is not made equal.
Linden, Hawthorn, Elm, maple and most weeds are high in calcium.

i would worry about a lot of grass as a fertilizer because it is mainly bacterial
as opposed to woody mulch which is more fungally dominant.
"chop and drop" as termed in Permaculture means to use plant matter as mulch
if you use stems and twigs, and leaves, and grass etc...
there is a mix of fungi and bacteria. There is also a higher diversity of species
each one having different mineral ratios.

For your place Jeff,
1ft of woody mulch could easily have been anaerobic, which would have made it acidic.
certain plants may have a hard time uptaking Ca.
also you need a lot of nitrogen to break down that much woody mulch.
adding greens would have balanced it out. giving it nitrogen and bacteria, and different minerals.

I tend to look at things through natures lens first.
True, most of us are planting trees that have been selected by man
and not grown in their natural environment.
 and this will lead to the need for amendments, or, other solutions.
But, i would rather add calcium by using plant matter that is high in Ca

[Finca La Isla]

I'm surprised by the notion that you need 2000lbs per acre of calcium.  That doesn't make any sense to me.  many tropical trees are acid loving, it depends on what you are starting with in terms of soil.
When I look at the forest and natural growth in the area of my farm it is growing quite well, and nobody is out there in the forest slinging calcium and chemical fertilizers around.  So why should we have to do that?
Perhaps the difference is in the balance of microorganisms that occur naturally.  We don't apply compost in the field but do mulch around the trees and apply biochar with microorganisms.  Mostly, that's all I use.  I do use calcium in certain cases but not as a general program on my 6.1ph soil.
Peter

[Cookie Monster]

Acid soil can be high in calcium. Don't confuse calcium carbonate (which raises pH) with other forms of calcium which don't affect pH. Here's a study showing the effects of adding nearly 10,000 pounds of gypsum (calcium carbonate) -- roughly 2,000 pounds of pure calcium -- per acre to acid soil. The change in pH was not statistically significant. Moreover, the quality and production of the mango trees increased: http://fshs.org/proceedings-o/1965-vol-78/369-375%20(YOUNG).pdf

Calcium is a macro-nutrient, and a grower will typically want the calcium to potassium ratio to be north of 10 to 1, meaning that for every 1 pound of potassium, there should be at least 10 pounds of calcium present in the soil. So, while 250ppm of K would be ideal for most crops, 2,500ppm - 5,000ppm would be the ideal calcium counterpart. And if you do the math, 0.5% calcium in an acre-foot of soil is quite a lot!

Trees will grow quite well with less, but for optimum production, flavor (brix), and consistency (crunch), calcium is vital.

In sum, compost is absolutely awesome. There are myriad benefits to having a soil that has adequate organic matter. However, growing top notch tropical fruits requires more than just dumping compost in the garden -- which I found out after a decade of trial and error (and some help from giants like Har :-).

I'm surprised by the notion that you need 2000lbs per acre of calcium.  That doesn't make any sense to me.  many tropical trees are acid loving, it depends on what you are starting with in terms of soil.
When I look at the forest and natural growth in the area of my farm it is growing quite well, and nobody is out there in the forest slinging calcium and chemical fertilizers around.  So why should we have to do that?
Perhaps the difference is in the balance of microorganisms that occur naturally.  We don't apply compost in the field but do mulch around the trees and apply biochar with microorganisms.  Mostly, that's all I use.  I do use calcium in certain cases but not as a general program on my 6.1ph soil.
Peter