DOWN on the FARM
with Tom Willey
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Organic Farm | Madera, California
DOWN on the FARM
with Tom Willey
What sort of inquiry might defuse controversy over whether compost-loving organic farmers like the Kaisers and Willeys are indeed “worst nitrate polluters” or responsible soil nutrient managers? Conclusive proof is only evidenced by employing a lysimeter. What’s that? Think underground, open-topped terrarium, buried beneath a farm soil’s growing crop. Researchers install lysimeters as catchment systems to intercept rain or irrigation water percolating through plant root zones towards an aquifer. That liquid is easily drawn off and accurately analyzed for nitrate and other soluble nutrients threatening water quality. So, has anyone utilized lysimeters to compare composted crop systems to those chemically fertilized? Arduous internet search turned up just two such studies, both unsurprisingly from Europe where biological agriculture garners more respect. For each of 11 years, Austrian experimenters applied a standard chemical nitrogen dose to one cropped plot while another received a compost equivalent of four times that amount of nitrogen. Lysimetric data compiled by Institute for Organic Research and Austrian federal scientists determined that while both treatments lost nitrogen beneath plant root zones in some years, composted soil’s quadruple nutrient load posed no increased threat to the environment. This long-term Austrian trial and another just underway in the Czech Republic suggest a soil nutrient dynamic unique to biologically influenced systems. Raw compost ingredients are blended for specific carbon to nitrogen ratios – carbon provides energy for legions of bacterial and fungal decomposers while nitrogen builds protein. After a fortnight of digestive frenzy plus a critical six-week curing process, compost is mature, at which stage all nitrogen is now sequestered into living and dead microbe anatomies. Soil-applied compost functions like an interest-bearing savings account. Biological farmers expect compost deposits will convert 10% to 20% of insoluble organic nitrogen into plant-available form the first year, followed by 5% to 10% returns for years thereafter. Complex compost nitrogen is slowly liberated (mineralized) through secondary microbial degradation of organic matter and nutrient release from intricate predator-prey soil foodweb interactions. Mineralized, nitrogen’s fate is determined by farm management, which, like all politics, is local. In Singing Frogs Farm’s case, Sebastopol’s mild climate enables year-round vegetable production. Paul Kaiser’s quintuple crop rotation could be nicely mopping up all the soluble nitrogen his sixty tons of surface-applied compost mineralizes annually, opines Cornell Cooperative Extension’s Emily Cook. What’s more, Kaiser’s no-till practice fosters a larger soil microbial community that can safeguard more nitrogen. Rock throwers best grab their shovels and a lysimeter.–Tom Willey
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