Need some help with soil analysis report

[Tworivers1]

I just received my soil analysis results back from the University of Missouri Extension office and was hoping someone could help me understand what I should do based the results.

Below is what I believe to be the pertinent information from the analysis

salt ph 7.4
cation exchange capacity 11.2 meq/100g
nutrient requirements: lb/1000 sq ft
nitrogen - 1.0
phosphorus - .5
potassium - 0

I have two raised beds about 9 inches deep, 4ft by 28ft and live just outside St Louis.

The weather looks like I will be able to plant out in the middle of next week and I have a few questions.

Is it too late to apply the fertilizer, if not what should I use & how serious is my soil condition - do I really need to worry about it.

I'll probably call the extension office tomorrow to see what they say but was just wondering what everyone's experience was with this.

Thanks for any help.

Mark

[Hotwired]

Originally Posted by Tworivers1

salt ph 7.4
cation exchange capacity 11.2 meq/100g
nutrient requirements: lb/1000 sq ft
nitrogen - 1.0
phosphorus - .5
potassium - 0

I would definitely contact your Cooperative Extension ASAP. Make sure that you talk to someone who knows what Cation Exchange Capacity (CEC) is. My experience has been that the person answering the questions are repeating info from their training session, rather than truly understanding it themselves. I add 4" of pure organic compost each Fall, mix it in and then have everything tested. I don't think that adding dry fertilizer at this stage will help your situation. With a CEC of 11.2, your beds have an extremely high content of sand, so any nutrients are going to wash out really quickly. To put things into perspective, the CEC in my raised beds is consistently over 85 meq/100g.

Salt ph of 7.4 is slightly above the 6.7 to 7.3 acceptable Ph for most vegetable crops. Crops susceptible to iron and zinc deficiencies may be affected as pH levels approach 7.5, and higher Ph usually is accompanied with higher sodium (salt) content which is detrimental to most vegetables. You can treat the soil with sulphur to lower it, except with a CEC of 11.2 the sulfur will wash away quickly meaning the lower Ph is temporary.

over 8.5 strongly alkaline
7.9-8.5 moderately alkaline
7.3-7.9 slightly alkaline
6.7-7.3 neutral
6.2-6.7 slightly acid
5.6-6.2 moderately acid
3.0-5.6 strongly acid

Cation Exchange Capacity (CEC) of 11.2 meq/100g is way too low. It means you have extremely sandy soil that doesn't hold water or nutrients well. You need an infusion of organic material. If I had that reading, I would invest in a truckload of good quality compost. At the very least I would add a lot of peat to hold moisture and nutrients, then fertilize. If you're growing peppers, they don't do well in heavy peat soil.

3-5 meq/100g = Sands (light-colored)
6-12 meq/100g = Sands (dark-colored)
13-18 meq/100g = Loams
19-25 meq/100g = Silt loams
26-50 meq/100g = Clay and clay loams
51-100 meq/100g = Organic soils

The NPK shows that you are very low on Nitrogen (N), slightly low on Phosphorous (P), and have good levels of Potassium (K). This is in line with your CEC levels of 11.2, meaning you are extremely low on organic soil content.

nutrient requirements: lb/1000 sq ft
nitrogen - 1.0
phosphorus - .5
potassium - 0
-------------------
There's a lot more you should be concerned with based on the 11.2 CEC measurement.

Electrical Conductivity (salt): ## E.C. x 10^3 signifies electrical conductivity (salt levels in your soil) Vegetables (other than beets and Asparagus) can tolerate moderate salt levels 4-8 E.C. x 10^3 . There is not an easy fix for a high number other that massive amounts of good compost.

< 2 very low
2-4 low
4-8 moderate
8-16 high
> 16 very high
--------------------
We have very similar sized raised beds. I have eleven of them at 24 foot long and two at 40' long, except mine are only 36" wide.



As I said, I have my soil tested regularly, and adjust nutrient levels as needed. I also add about 6 yards of compost every Fall. I'm a bit anal about my soil and nutrients. Here's my most recent test results:
Ph 6.8
CEC 89.4 meq/100g
Electrical Conductivity 3.8 E.C. x 10^3
Nitrate nitrogen 38 ppm
Phosphorous 29 ppm
Soluble Potassium 67 ppm
Extractable Iron 4.8 ppm
Extractable Zinc 1.1 ppm
Extractable Copper 1.2 ppm
Extractable Manganese 2.7 ppm

[Tworivers1]

Thanks. I will make the call tomorrow morning and see what they have to say. At least now I will have an idea of what I'm talking about.

[BennB]

I'm not a soil scientist, but I took a few soil science courses and some chemistry in college and deal with soil issues for work a bit, so I'll chime in too.

I agree that adding chemical fertilizer is not what you need at this point and it would be good to talk to an extension agent so they can explain the results to you, but all and all these results don't appear too problematic.

The cation exchange capacity is a little low compared to a highly enriched organic soil, but it falls within the category for "loam" or "sandy loam" soils. It is the clay (and organic matter in the soil) that has negatively charged surfaces that can help hold positively charged ions (cat ions), particularly magnesium, calcium, and potassium, all things tomatoes need.

I would not say your soil is too bad since you don't need any potassium, so I am going out on a limb and assume that sufficient amounts are already bound in your soil, which seem probablle due to the slightly basic pH.

I'd follow the advice of the extension agent first, but if you can't get through to one, you may want to consider amending your soil with something that will increase the cation exchange capacity and that will also help with water retention and add some nitrogen.

Normally you don't go adding clay to your soil to increase the cation exchange, so you'd want to add some organic matter. I'd recommend some composted bark fines, peat moss, and some prepared composted steer manure. If you have some relatively weed free fresh grass clippings, you may want to add those too (they will add nitrogen and organic matter quickly). The reason I recommend three (or four if you count the grass clippings) types of organic matter is that they will decompose at different rates during the year and will condition your soil throughout the season.

How much of each is kind of guesswork, but given that your beds are roughly 100 sf, I'd start with about 10 CF of bark fines (well composted fir or pine bark mulch will work and may be easier to find and less expensive), 3 CF of peat moss (about one bale), and about 2 CF of fully composted steer manure per bed. I'd also add about 4 to 5 lbs of dolomite lime per bed, which will add magnesium and calcium without adding salt ions and the carbonate component will help buffer the soil along with the organic matter. You want to do any amendments a week before you plant, if possible.

A month or so into your planting season, you can fertilize with kelp extract, which is mostly organic nitrogen and then throughout the year you could use water soluble fish or standard chemical fertilizers since your soil should be able be bind the cations better by then.

Let us know what you hear back from the extension agent.

Good luck!

Benn