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Tag Archives | soil testing

Farming the CO2 Factor

In a rare moment in an early Rover reconnaissance mission to Mars, carbon dioxide (CO2) was released from a soil sample during a scientific test and was thought to indicate the presence of microbes. Excitement quickly faded to puzzlement, then dismay, as it was realized that a glitch in the expensive on-board lab had produced inorganic CO2. Chemicals used for the soil extract triggered release of inorganic CO2, perhaps from the ubiquitous magnesite (MgCO3) found in Martian soil.

Will Brinton and Odette Menard (MAPAQ Quebec) speak at an on-farm event in Pennsylvania as part of the No-Till Alliance Field Days,

On Earth, the release of carbon dioxide from moist soil due to microbial activity is so pervasive that it is difficult not to observe it. We don’t have the problem they do on Mars trying to distinguish biological CO2, in an atmosphere containing 96 percent CO2, from non-living sources. In science we call this dilemma “distinguishing small differences between large numbers.” Here on Earth, CO2 in the atmosphere is only 0.04 percent, and climbing just barely perceptibly, making it relatively easy to distinguish biological CO2. Curiously, almost nobody is doing it.

Borrowing From the Past

I learned about soil CO2 respiration working on a graduate program in Sweden investigating fertilizer and crop effects on soil biology. Agronomists in the 1950s set up farm plots and maintained them for decades, enabling later researchers such as myself to observe the long-term effects of differing soil management.

In the process, I discovered a trove of even earlier Swedish work on soil respiration. Continue Reading →

Minerals for Healthy Soil & High-Quality, Top Yields

It’s a new century, and there is more knowledge about farming and the role of minerals, and there are more farmers paying attention to it. When it comes to farming, we know what the “base” is: putting all the pieces together including minerals, biology and soil structure — and using crop fertilizers that provide above and  beyond what the soil can dish out in terms of nutrients and biology.

A fall mixed cover the author grew after rye was harvested. He used the cover crop to capture nutrients in a biological form and to cycle nutrients to get more minerals into the following cash crop.

Even though there’s a lot of discussion about soil health, no-till and soil structure in farming right now, not enough attention is paid to minerals.

It seems like so much of agriculture is spending its time and money chasing magic biologicals, foliars or plant protection and not focusing on doing everything you can to feed your crop a balance of minerals and prevent the problems in the first place.

So what is your limiting factor or constraint that interferes with plant production and plant health? You need to understand that your farming practices have a lot of influence on plant health, and plants that are healthy protect themselves — just as you have an immune system that functions well if you are healthy. Reduce stress; eat a balanced diet with a balance of nutrients; eat a variety of foods that are clean without foreign compounds to fight and a good biological balance. If you get all that right do you need to take supplements?

It’s not farming the same way it was in grandpa’s day because there was a lot he didn’t know. He didn’t understand nutrients, soil health or soil fertility, and didn’t have the tools we have. He was stuck with a “plow.” If I asked you to do everything you could to get your soils healthy and mineralized, what would you do? Continue Reading →

Soil Lab Selection

Soil lab selection: How does anyone choose the right laboratory? Aren’t they all the same? Should you send a sample to several different labs and average the results? How do you get the samples to a lab and what is the turnaround time? Some homework needs to be done here.

These are all questions that I hear on almost a daily basis. All labs are not the same. This does not mean that one laboratory is better than another. They all provide a different “menu” of services. It is important to find a lab that provides all of the services that you require. Are you just looking for a soil analysis, or do you also need an irrigation water test or tissue analysis?

Laboratories can also choose from a number of methods or “recipes” to obtain results. Which method would be best for your soil type or crop? “Presentation” of results can also vary greatly from one laboratory to another. It is important that you can read the report and make use of the information it provides. These are all questions that you should consider before choosing a laboratory.

Menu of Services

Packages with various soil parameters are usually available, plus some a la carte choices. This will vary greatly from one laboratory to another. I think we all agree now that there is a lot more to soil than pH. Therefore, look at what is included in the soil package you are requesting. Continue Reading →

Soil Testing: The Need for Total Testing

What many farmers probably don’t know about soil testing is that most soil tests only tell us what is soluble in the soil. They do not tell us what is actually there in the soil, no matter what fertilizer salesmen might like to imply. To find out what is actually there requires a total acid digest similar to what is used for plant tissue analysis. Mining labs run these total acid di­gests on ore samples which are crushed, ground and extracted with concentrated nitric and hydrochloric acid solutions, but a mining assay does not determine total carbon, nitrogen and sulfur as a plant tissue analysis would. These ele­ments need a separate procedure essen­tial for evaluating soil humic reserves.

Total soil testing is key to understanding your soils’ needs.

Most soil tests measure total carbon, which then is multiplied by 1.72 to calcu­late soil organic matter. This assumes that most of the carbon in the soil is humus of one form or another. While this may or may not be true, determining the car­bon to nitrogen, nitrogen to sulfur, and nitrogen to phosphorus ratios is a good guide for evaluating organic matter, and this requires testing total nitrogen, sulfur and phosphorus as well as carbon.

While carbon in almost any form is a benefit to the soil, it helps enormously if it is accompanied by the right ratios of ni­trogen, sulfur and phosphorus. Though these ratios are not set in stone, a target for carbon to nitrogen is 10:1, for nitro­gen to sulfur is 5.5:1 and for nitrogen to phosphorus is 4:1. This works out to an ideal carbon to sulfur ratio of 55:1, and a carbon to phosphorus ratio of 40:1. Because soil biology is very adjustable these targets are not exact, but achieving them in soil total tests is a good indica­tion of humus reserves that will supply the required amounts of amino acids, sulfates and phosphates whenever the soil food web draws on them. Continue Reading →

More Accurate Soil Testing

soil testingSoil testing that determines needed fertilizer will measure nitrate in the soil, but tests don’t sufficiently account for soil microbes, which mineralize organic nitrogen and make more of it available to a crop. As a result, farmers often apply more fertilizer than necessary.

Richard Haney, a U.S. Department of Agriculture soil scientist in Temple, Texas, has developed soil test that replicates some of the natural processes that occur in a field and accounts for microbial activity, along with measuring nitrate, ammonium (NH4) and organic nitrogen.

The new soil test is known as the Soil Health Tool. It involves drying and rewetting soil to mimic the effects of precipitation. It also uses the same organic acids that plant roots use to acquire nutrients from the soil. The testing tool measures organic carbon and other nutrients, accounts for the effects of using cover crops and no-till practices and works for any crop produced with nitrogen or other types of nutrient fertilizer. For more information visit http://www.ars.usda.gov/is/pr/2014/140710.htm

This article appears in the September 2014 issue of Acres U.S.A.