The future of agriculture

The January 2012 Burleigh County Soil Conservation District's soil health workshop presentations are now online:

These include videos of great presentations by Rudolf Derpsch, Gail Fuller, Jay Fuhrer, Doug Peterson, and Kenny Miller.

These presentations are about the future of agriculture, based on what's already been tried. Essential learning, essential principles for all areas.

Active Carbon, Microbial Biomass, N & P-Mineralization

A new test is available to growers that can save costly nitrogen inputs and tell something important about soil health. In conjunction with Rick Haney (USDA-ARS, Temple TX), Dr. Will Brinton of Woods End Laboratories (Mt Vernon ME) has introduced to the soil-testing market an innovative biological soil test (Solvita®) that reveals soil microbial activity relative to carbon turnover. The significance of the test is twofold: it enables farmers to accurately evaluate the quantity and quality of soil microbial activity and it provides a tool to accurately estimate the amount of nitrogen and phosphorus likely to be released for plant growth, a factor called “mineralization”.

“The Solvita technology is proudly shared with growers, laboratories, and consultants from all over the world,” states Andrew Sparda, Director, Solvita Sales and Customer Relations, Woods End Laboratories, Inc., Mount Vernon, ME.

The nutrient mineralization potential of soil has been recognized since as early as 1919 in America, but measuring it usefully and economically has greatly challenged soil labs. All agree that by better estimating this factor, farmers gain more control of crop nutrient supply requirements, and in many cases, expect to reduce N-inputs, but without any loss of yield. Until now, fairly time-consuming or complicated chemical lab tests have been tried to evaluate potential release of N from the organic pool in the soil. As a result there is an absence of commercial and economical lab tests to aid farmers in making this prediction.

The Solvita® test offers significant advantages over other earlier procedures used to estimate N and P availability. Pre-dried soil is re-moistening to field capacity and a pre-calibrated gel probe inserted in the sample to capture the “CO2-burst” that results from re-wetting. The resulting color change in the probe can be read visually in the field, but a lab digital spectrometer is available which reads the results very precisely to units of ppm CO2 for a 24-hr period. Dr Brinton’s and Dr Haney’s researches over a decade have successfully correlated this burst of CO2 with longer term respiration tests which were previously thought to be essential to accurately measure soil activity. The success of the 24-hr CO2 protocol brings the procedure within the realm of economically viable options for soil labs. The reward to the soil-lab is a procedure that readily handles dozens of samples at a time with relatively little set up and no calibration required. The reward to the grower is a “real-world” measure of actual soil biological activity giving the opportunity to adjust and spare excess or unneeded N fertilization. The overall effort of the two cooperating labs, one government and one private sector, will be the offering of a integrative or holistic protocol called “SQAT” – Soil Quality Adjustment Tool”.

Soil Microbes: Agricultural soils possess significant but very varying levels of microorganisms that inhabit available pore space and plant rootlets and feed on organic materials from crop exudates and residues and applied manures (see image at right). USDA estimates that there are from 1-million to 10-million microbes per gram of soil, which per acre translates into 1,000 to 3,000 lbs of living microbes. These microbes break down dead plants and animals and in the process release CO2, nitrogen and phosphate associated with these residues. In addition, another group of soil bacteria, called free-living nitrogen-fixers, directly take nitrogen from the atmosphere into eventual plant available form. These microbes are also measured by the CO2-test, but are missed in all other procedures. One reason they are so significant is that the nitrogen associated with these symbionts is not necessarily correlated with soil carbon, which has been a crude but traditional means to guess at what potential N-release may be present in any given soil.

The Solvita test therefore provides a direct biological measure of the aggregate of soil microbial activity without the conventional dilemma of extraction chemicals that interfere with direct calibration. Taken as a whole, soil microbes are a “free-army” working in the soil for growers and they release free fertilizer that we do not customarily account for in our fertilizer recommendations. From a business perspective in farming, it is a “win-win” deal when soil labs can measure this factor and farmers can apply it.

One existing lab test for nitrogen mineralization that Woods End and USDA have followed closely is known as “7day N-min” and involves incubating soils anaerobically for a week and measuring the change in ammonium released by biological decay in that time. While this test is time consuming and costly and has not therefore been widely used, it does accurately reflect what microbes are able to do. The graph shows 257 soil samples from across the USA, which have been tested by both Solvita® and 7d-Nmin methods. A very high degree of relationship between the two indicates that both methods are measuring similar microbial characteristics.

Woods End Laboratories staff has in the last few years traveled America meeting with farmers, agronomists and soil testing labs. There is real and genuine interest in this new biological test method that could enable improved targeting of nitrogen and phosphorus fertilizers inputs, which continue to rise in cost. Biologically produced nitrogen and phosphorus in soils is critical since it provides a source of nutrient for plant growth that is “all ready paid for”, is non-polluting and is not dependent on fertilizers manufactured from fossil fuels. In some regions, reduction in net inputs will only be very modest, but in others possessing higher intrinsic fertile soils, the gains may be very measurable.

While pictures may over-simplify, the final graph illustrates the dynamic system in soils that is being measured in which biological testing complements and enhances the value of ordinary nutrient tests.

“The Solvita technology is proudly shared with growers, laboratories, and consultants from all over the world,” states Andrew Sparda, Director, Solvita Sales and Customer Relations, Woods End Laboratories, Inc., Mount Vernon, ME.

Related publications:
Haney, R.L., W.F. Brinton, and E. Evans. 2008 Estimating soil carbon, nitrogen, and phosphorus mineralization from short-term carbon dioxide respiration. Comm. Soil Science and Plant Analysis 39(17):2706 – 2720

Haney, R.L., W.F. Brinton and E. Evans. 2008. Soil CO2 respiration: Comparison of chemical titration, CO2 IRGA analysis, and the Solvita gel system. Renewable Agriculture and Food Systems 23 (02): 171 – 176.

For more information, contact on the development of the technology contact: Andrew R. Sparda, Director, Solvita Customer Relations, Woods End Labs, 207.293.2457