help needed

[Medbury Gardens]

Ive had a soil test done and it shows my Calcium is low and a PH of 6.4 which is about what i want,how can i increase the calcium with out altering the PH?

Thanks
Richard

[ireilly]

Hi Richard,

Most sources say the use of gypsum (commonly made into sheetrock or wallboard) will contribute Ca++ ions, and is not a liming agent (will not raise pH). The home centers sell it pelletized as a lawn amendment.

The liming agent chart at the very end of this link bears this out.

http://hubcap.clemson.edu/~blpprt/acidity2_review.html

Of course, there is rarely "something for nothing" as it were, and while the use of gypsum will not change pH directly, it does change the chemistry of the soil via its binding with sodium, reducing available sulfur, so you might look at your sulfur levels also - maybe that's why calcium is low in your soils. The table at the end of this link shows common soil amendment reactions.

http://cesonoma.ucdavis.edu/files/27200.pdf

Walter

[fortyonenorth]

Don't worry too much about your pH. It is simply one indicator of soil health and balance. If your soil is properly balanced, the pH will be right for your soil type and climate. Conversely, even if the pH is spot on, you could still have an imbalance. That's why trying to manipulate your pH by liming or adding sulfur is seldom the right course - it's like trying to bring down a high fever by taking an ice bath. It may work, in the short term, but it does nothing to treat the underlying cause.

How low is your Calcium and what does the rest of your soil test look like? What are the levels of the other major cations (i.e. Magnesium, Potassium, Sodium) and anions (i.e. Phosphorus and Sulfur?

My guess is that, in addition to a C deficiency, there's something else at play.

[ContainerTed]

My county extension agent actually mentioned using Nonfat Dry Milk Powder. I had to think about it for a few minutes, but it really does make sense. Milk is very high in Calcium.

Anyhow, if true (and I think it could be), that's a good use for "spilt milk". It would be kinda expensive to buy just for that use, but any good bone meal or dolomite lime would help with your calcium numbers.

Ted

[Medbury Gardens]

Thanks for the replies guys,as you can see by the reams test i'm also lacking in Magnesium also,what i wasnt sure about was if i was to use dolomite lime would the PH be affected at all.

Ammonum is also low,what could i add to bring this up??

The humus levels are low because the garden was double dug 5 years ago so the soil i'm growing in now would have been 0% so after,i'm green cropping and adding compost so this level will continue to rise

[dice]

Why would ammonium levels matter? It gets converted to nitrate
by soil bacteria, and that is what most veggies use. It goes up
and down as you amend soil with manures, grasses, etc. (Fresh
manures give off a lot of ammonia.)

Anyway, you can add di-ammonium phosphate in spring. The phosphorus will dissociate from the ammonium in solution and
attach to other things in the soil. The ammonium will either be
converted to nitrates by bacteria or leached down below the
root zone by rain. Or you can add rock phosphate and ignore
the ammonium, assuming that your fertilizer will raise the
levels up in spring and summer. (This will also add some
calcium, quite slow release.)

Cover crops can also extract phosphorus from the soil
and make it more available, and manures re-supply it
in the spring. This article from Small Farmer's Journal
discusses phosphate management:
http://smallfarmersjournal.com/follow-up-on-phosphorus

It does not say what your sulfur levels are, but you could add
gypsum and epsom salts. Those are calcium sulfate and
magnesium sulfate. I would add the gypsum in fall, the
epsom salt in spring. Gypsum will not have any dramatic
effect on pH. Epsom salts might, depending on how much
sulfur your soil already has.

This is all going to change dynamically as you add manures
and other organic materials (compost, etc) to your soil.

The only fertilizer sources of magnesium that I know about are
dolomite lime (raises pH) and magnesium sulfate (effect on
pH varies with the soil), but perhaps there are others. I am not
a farming or horticulture professional, and I do not know what
all might be available for magnesium supplementation.

I would think one might need three soil tests when fertilizing
with manures, composts, and cover crops: one in spring,
one in mid-summer, and one in fall. That tells you how the
nutrient balance in your soil changes over a summer as
organic fertilizers are added and break down. What you see
in spring and fall are not going to be what the plants see in
mid-summer.

(Or you can spy on some neighbor who has it down and has
the same soil you have.:-)

[fortyonenorth]

Ignoring the pH takes a leap of faith - it's what we've all been taught for many years. But, it's the right thing to do. Dolomite lime could raise your pH slightly but since you need both C and Mg, it would be the appropriate amendment for your soil. Calcium is of singular importance as a soil nutrient, so the tradeoff (with soil pH) is advisable.

The Ammonium on your soil test is a form of nitrogen. Ammonium sulfate fertilizer is an acidifier, which would offset the Dolomite. If you have access to cottonseed meal, it is another nitrogen option that is acidic.

If you add soft rock phosphate as your P source, it also contains 30% calcium. The Ca is bound tightly to the phosphorus and won't be immediately available to plants (i.e. you can't use this is a sole source of Ca), but with an active organic soil, it will become available over time. Our domestic source of SRP comes from Florida. I'm not sure if this is exported to NZ or, perhaps there is a more localized source. For a number of reasons, it's a much better source of P than hard rock phosphate, which is more commonly available.

Hope this helps!

[Medbury Gardens]

I buy one 25kg sack of soft rock phosphate per year which is imported from Florida,this is added to the compost in layers as it builds up over the season,i only started buying this two seasons ago.The compost is made with no animal manures but 2 tons seaweed per year is added,so that should add the sulfur hopefully dice,but you are right,sulfur is not on that test,i'll ask them when i do the next one.

So it sounds like it should be ok for me to spread Dolomite lime now that we are moving in to winter,come spring i'll get another test done and also see how the Calcium&PH looks.

Thanks again guys,ive got a better understanding now

[organichris]

Originally Posted by ContainerTed

My county extension agent actually mentioned using Nonfat Dry Milk Powder. I had to think about it for a few minutes, but it really does make sense. Milk is very high in Calcium.

Anyhow, if true (and I think it could be), that's a good use for "spilt milk". It would be kinda expensive to buy just for that use, but any good bone meal or dolomite lime would help with your calcium numbers.

Ted

Yeah, I think you could absolutely use dry milk, and though I'd never heard of anyone doing it, I have actually considered it before. Anytime I have spoiled milk I give it to my plants diluted in water. They seem to like it alright.

[dice]

There is also sul-po-mag, which has sulfur, potassium, and
magnesium, but your potassium is already high (likely supplied
by the seaweed), and sul-po-mag is mined from a mineral
deposit in the US (langbeinite). It would at best be fairly
expensive in NZ if it is available at all. Dolomite lime,
magnesium sulfate, and other sources are probably all better
choices on price for a magnesium source and fit better with
your soil profile.

(The mineral langbeinite was created by evaporation of an
ancient ocean. It is found in few places in the world, and
I do not know of any other commercial deposits than
the one in New Mexico in the US.)

A good general analysis of magnesium in the soil:
http://www.spectrumanalytic.com/supp.../Mg_Basics.htm

[ireilly]

Wow, two tons of seaweed? That's impressive!

[wmontanez]

Comfrey. I have been reading about it...adds Calcium, phosphorous, good compost activator but the roots are the propagating mechanism should be controlled. You can use it as mulch in the fall to add extra calcium etc.

[dice]

Actually, whether plants prefer nitrate or ammonium as
their nitrogen source depends on the soil pH where they
evolved. According to the document below, plants that
prefer acid soils prefer ammonium, while plants that grow
in higher pH soils (like garden vegetables, on average) prefer
nitrate.

http://ag.arizona.edu/pubs/crops/az1359/az13592f.pdf

(The abstract basically discusses mesquite and jojoba, which
were the focus of the study. The information above is in the
first paragraphs of the introductory text of the document.)

[Medbury Gardens]

Originally Posted by wmontanez

Comfrey. I have been reading about it...adds Calcium, phosphorous, good compost activator but the roots are the propagating mechanism should be controlled. You can use it as mulch in the fall to add extra calcium etc.

A great plant Wendy,ive got truck loads of it growing in my orchard,but i would imagine that adequate Calcium & phosphorous levels would need to be present in the subsoil to start with.

Originally Posted by dice

Actually, whether plants prefer nitrate or ammonium as
their nitrogen source depends on the soil pH where they
evolved. According to the document below, plants that
prefer acid soils prefer ammonium, while plants that grow
in higher pH soils (like garden vegetables, on average) prefer
nitrate.

http://ag.arizona.edu/pubs/crops/az1359/az13592f.pdf

(The abstract basically discusses mesquite and jojoba, which
were the focus of the study. The information above is in the
first paragraphs of the introductory text of the document.)

So looking at my soil test then the N levels look good in relation to the PH

[wmontanez]

I wonder if pulverized bones, seashells, rock dust, egg shells etc can contribute enough Ca to the soil around your Comfrey, since Comfrey is a bioacumulator it will trap it and you till into your soil with the rest of your green manures. I know you have a farm so you need plenty!