By Orvin Bontrager
Servi-Tech, Inc.I finished reading the book, Dirt: the Erosion of Civilizations, in the past week by David R. Montgomery, professor earth and space science at University of Washington. Although I personally believe there are additional factors in causing civilizations to collapse, Mr. Montgomery certainly makes valid points on the importance of conserving our soil resources to adequately feed our growing population.
He is critical of the modern “American industrial farming” methods. I am not going to debate whether we should be promoting or subsidizing more organic production instead of the more conventional agriculture. I believe the market system will sort out the desired methods of production.
Much evidence is cited to promote his thesis that more organic production with more “labor-intensive systems” will sustain our soil longer without the high cost of fertilizer and pesticide inputs. Undoubtedly returning more manure back into the fields will be beneficial. The uneven distribution of large feedlots across the High Plains and western Corn Belt doesn’t allow manure to be placed economically back on many fields now.
My experience in the past 26 years in south-central Nebraska has shown a plateauing of organic matters in the soil tests. This is on both a long term certified organic farm I have been checking since 1989 as well as the surrounding conventional produced land with the same silt loam soil types. The soil tests are done yearly on all the fields. It is very important to compare some soil sample depths and even same soil labs for long term results.
I haven’t seen an increase of organic matter on the organic fields with an alfalfa-corn-soybean-wheat-alfalfa rotation compared to the conventionally farmed corn-soybean or continuous corn rotation in the area. The phosphorous levels have increased somewhat more on the organic fields due to 2-3 tons per acre composted manure applications on selected areas of the farm each year. The organic matters have stabilized in the 2.5-3% range on a 9-10 inch soil sample depth on both organic and conventional fields.
The organic farm has to be tilled for weed control. The other surrounding fields are more modified ridge till to even no till. Less organic matter destroying tillage is done on the corn-soybean rotations than on the organically farmed ground.
These are my observations of walking and routinely checking fields on a weekly basis as well as yearly composted soil samples. They are not replicated small plots or strips that most published research projects entail.
I am going to discuss this issue more next time.
