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Phoenix, AZ

I was able to get LOTS of compost for my little patch. It looks as if I will have the capability to put upwards of 9" of compost into the soil. The guy I bought the compost from said it is normally about 1-1/2% nitrogen and seems to be made up of highly composted sawdust.

So my question to you all is: would 9" be too much?

My intent is to till in every 3" layer. Another thing to consider is our soil here NEVER gets below 50 F and I will be planting sometime in mid Feb. Also, I estimate I have somewhere around 5% OM now but it is humus by this point and not much nitrogen left.

Just don't want to overdo my nitrogen and have problems setting a pumpkin next spring.

Thanks all.

11/18/2004 3:16:51 PM

Ctpumpkin@optonline.net

Your concerns are valid. There is a reasom southern soils aren't usually high OM. Pert of the reason is the type of native flora. But likewise raw organic materials don't last long in the long-warm soil. If they liberate N quickly enough, we have trouble.

I'd like to resaerch the weight of that material, calculate the total weight in N, & then estimate the total impact before commenting further.

How deep can you realistically till?

11/18/2004 3:28:51 PM

Phoenix, AZ

Steve,

I can till 9" deep.

As for the weight, shoot, I don't know dry weight of this stuff. Was pretty light (compared to dirt).

Ben

11/18/2004 6:44:39 PM

Ctpumpkin@optonline.net

Ben,

I knew I had seen this somewhere. Everything we need is here:

http://www.soiltest.psu.missouri.edu/compostguide.htm

Here we see that 1 inch of compost at 1% Nitrogen adds 4.4 lbs of Nitrogen per 1000 sq. ft. when the compost weighs 800 lbs per yard.

Add the compost into the patch over time if you can. It's always nice to have some loose in a pile for vine burying if you hase a place to keep it. Watch for tree roots that like to grow into piles!

It's no wonder then that adding 4 yards/1000 of manure last fall to my own patch yielded very high Nitrogen on the summer tissue analysis. Manure is more than 1% Nitrogen.

11/18/2004 9:26:15 PM

Phoenix, AZ

OMG, I have 4 yards for my 200 SF patch!

LOL I just bought what I thought would be enough. Everyone always says add as much OM as possible.

Oh, I do remember them telling me the compost weighed somewhere over 1000 lb per yard.

So again, when is there too much nitrogen?

Bottom line: Where should I stop adding? Currently, I have 3" added.

What I think I will do is double till it in so I can go farther down than 9". 200 SF should not be too much to work with.

Steve, you are helpful that is for sure.

11/18/2004 10:55:51 PM

Ctpumpkin@optonline.net

We do waqnt as much Organic MATTER as possible. To get there we add Organic MATERIAL. Bacteria, Worms, oxidation, etc will in time convert Material into Matter liberating nutrients (including Nitrogen early in the process) along the way.

So in theory you have added at least 13.2 lbs of Nitrogen/M. You can till that down to 9" or 3/4 of a foot. So in rough numbers, we have about 766 lbs Nitrogen per Acre Foot.

This isn't awful. That N is in the organic complex form. The same amount of soluble urea Nitrogen would kill everything green. But the dynamic nature of soils will keep things more or less in line.

Some N will volatilize over winter. Some will leach. Much more will remain in nonavailable forms all summer. These are low salt forms & shouldn't be a problem.

The key here is to read the plants well in the spring. You now have nutrient rich soil. If growth looks adequate once warm soil conditions arrive, then don't use any synthetic Nitrogen. The mistake some people make is spending years building up humus & nutrient richness, only to continue the use of synthetics at the same rates & then things go awry.

Stockpile some for vine burying & breath easy.

For your comfort, take a couple pot fulls inside & grow some "germination experiments". Some as amended patch soil & some as straight compost. The plants in compost will do well but won't require as much supplemental fertility to maintain growth as the amended soil.

11/19/2004 7:15:38 AM

Phoenix, AZ

Great idea on the testing thing. Currently I have a few growing, testing the addition of phosphrus - as you know I am low on.

Yea, I will do some straight compost germination and some amended soil tests.

I think a lot of this will make my wife happy and go into the grass. For sure, I will leave myself at least a yard for future use.

11/19/2004 8:09:02 AM

On top of Brush Mountain, Pa.

There is compost and there is compost. Not all compost is the same. Compost made from just sawdust is not likely to have lots of nitrogen in it. This depends on how long the compost sat and whether or not anything else was added to it other than sawdust. If the guy who sold it to you says it contained a certain amount of nitrogen, he must have had it tested. Ask to see that test result and when it was done. If you are going to put 9 inches of this compost on your garden, you might consider getting it tested yourself or to at least get a soil test early in the spring to see what you have done to your soil by having added it. If the compost is made of just sawdust the testing of it can reveal results that can be quite variable depending on how long and how it was composted.

11/19/2004 8:35:48 AM

Phoenix, AZ

Thanks for that input. I for sure will have Tremor do my test again in January so I have consistency.

For sure no idea what compost I have but a few plant tests will tell a bit.

11/19/2004 2:55:43 PM