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Category: Agricultural Events, Acres USA 2015
Texas Plant & Soil Lab – featuring Dr. Larry Zibilske and Noel Garcia, CCA – has been invited to give another Acres U.S.A. pre-conference workshop this year in Pittsburg. This year it will be a one-day-only, extremely concentrated session, again designed for well-experienced field consultants and growers. The workshop will focus upon not only post-session […]
Mon, 27 Jul 2015 19:01:47 +0000

Category: Blog, Fresh Fruit Analysis
Fresh Fruit Elements Analysis With Silicon Option is the latest test from Texas Plant & Soil Lab for 2015. This test is intended especially for Fertilizer / Adjuvant / Inoculant Manufacturers who want to track the effectiveness of their products and Food Processors who wish to monitor the levels of produce Nutrient Density by their […]
Mon, 22 Jun 2015 22:03:50 +0000

Category: Blog, plant testing
It’s the first week of June and while some of Texas is still waist-deep in water, Texas Plant and Soil Lab is waist-deep in plant tissue samples from all over these United States. Farmers that were fortunate enough to get crops in the ground amid the unusually heavy rains that engulfed Texas and most of […]
Mon, 08 Jun 2015 23:18:26 +0000

Category: Blog, ACRES USA
Be sure and check out our ads in this month’s Acres USA Magazine!
Tue, 02 Jun 2015 15:36:57 +0000

Compost Testing

Order Compost Testing Online
You can now order Compost Testing online. Ordering your compost testing online streamlines the process and provides online order status tracking.

Compost Testing Online Category Page
For the entire Compost Testing Category Page Click Here.

Compost Test Direct Links
To Click Through directly to the Compost Test you wish to order, choose from the list below:

Compost Testing Forms Download Links
To Download and Print forms for ordering Compost Testing, choose from the list below:

U.S. Composting Council

TP&S Lab is the 11th approved US Composting Council Seal of Testing Assurance ( USCC STA ) laboratory for all participating STA composters in the U.S. and Canada! You can find us listed at

Compost Testing and Organic Mix Testing

Composting testing is important for characterizing the beneficial physical and chemical properties of a compost as well as for identifying potential problems with compost use. TP&S Lab employs testing procedures from the U.S. Compost Council’s Test Methods for the Examination of Composting and Composts as well as some proprietary testing methodology that is also essential to measure the quality of your compost.

For example, TP&S Lab measures the humus fraction of the compost as well as the total organic matter to verify that the compost is fully mature. An indicator of compost maturity is high OM (humus) and Nitrate (NO3) > 30 ppm which indicates well matured (cured) compost by biologically active microbes releasing Nitrate (NO3). High OM (humus) and Nitrate (NO3) < 10 ppm indicates a very active to moderately active (curing stage) compost. Adjusting C : N ratio with fertilizer N or biologically with energy (molasses, fish, vegetable meals, etc.) will aid maturity. Just like a conventional fertilizer bag that comes with a guaranteed analysis and a label rate, we must also know the guaranteed analysis of composts to make sure that we apply safe rates to avoid accumulation of excessive mineral salts over time.

See Explanation of Soil Organic Matter here.

General Guidelines of Compost Testing and Organic Mix Testing

pH is a measure of active acidity in the feedstock or compost. Most finished composts will have pH values in the range of 5.0 to 8.5. Ideal pH depends on compost use. A lower pH is preferred for certain ornamental plants while a neutral pH is suitable for most applications. pH is not a measure of the total acidity or alkalinity and cannnot be used to predict the compost effect on soil pH.

Soluble salts are determined by measuring Electrical Conducity (EC) in a 1:5 (compost:water, weight ratio) slurry. Electrical Conducity (EC) is related to the total soluble salts dissolved in the slurry and is measured in units of millimhos/cm (mmho/cm). Composts typically range from 1 to 10 mmhos/cm. High salinity may be toxic to plants. Ideal soluble salt levels will depend on the end use of the compost. Final compost blends with soil or container media/potting mixes should be tested for soluble salts.

The ideal moisture content for composting will depend on the water holding capacity of the materials being composted. In general, high organic matter materials have a high water holding capacity and a higher ideal moisture content. A typical starting compost mix will have an ideal 65-45 % mositure. Finished compost should have a 50-40 % moisture.

Compost Testing Protocols

Review our Online Ordering Page for Compost Testing for a complete list of test descriptions and protocols.

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TP&S Lab is proud to be a member of the Texas Ag Industries Association.
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TP&S Lab is proud to be a member of the Texas Wine and Grape Growers Association.
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TP&S Lab is proud to be an approved Lab by the U.S. Composting Council for Seal of Testing Assurance.
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