Organic Matter and it's value in crop production was the topic of a recent Direct Seed meeting. I've known about OM since my school days of long ago. I didn't take it seriously until well after the Horse Escaped the Barn -- if any readers are old enough to remember that phrase. Current research puts a little different twist to what I remember from 1960. Organic Matter can now be divided into two basic types -- Stable OM where it is highly decomposed with very little biological activity, and Active OM that is being used, and worked on, by living plants, animals and microbes. Food to feed these communities associated with Active OM needs to be continual and not intermittent. Good soil is alive and needs nourishment. I'm starting to think that production from these soils have the potential for sustainability without costly inputs. Bad soil is dead dirt. These soils will always require massive inputs of fertilizer and chemistry to raise a crop. I use to poo-poo organic farming, but not anymore. Thanks to those people, research on our micro-biological soil life and how to develop and exploit sustainable farming has taken off. Speaking of dead dirt -- is there anything deader than fallow, and we do this intentionally. We need to give more thought to this subject.
When the Palouse Prairie was first put under the plow it was roughly 20% of Stable OM and 80% Active OM. Nutrients were manufactured, and recycled by organisms in the Active OM. Some plants are capable of tapping into a variety of nutrients deep in the soil profile and transport them to the surface where other plants can use them. Today, after a 100 years of cultivation the Active OM and the Stable OM are reversed. The Active OM has been lost primarily through cultivation from two factors. 1)--Cultivation stokes the fire of mineralization. By mixing air, moisture, and residue(fuel), organic matter is converts to nitrogen and carbon dioxide. Nitrogen is released and growing plants use it for food, and Carbon Dioxide is released into the atmosphere. Does Carbon Sequestration and Global Warming strike a bell? Our farming practices are taking us in the wrong direction on these subjects. I include our commonly accepted DS techniques in this statement. 2)--Every cultivation pass breaks down soil structure into ever decreasing particle size. This results in less residue to protect the soil surface, allows soils to seal off when it rains, and increases compaction, and starves the biological communities in the soil. One visual symptom is droughty high ground and waterlogged low ground. There are numerous visual examples east of State Highway 195. Should we lose the technology of fertilizer and chemistry either by availability or price, all our operations would be at risk. In the past, civilizations have disappeared when their political and cultural practices destroyed the soil. Professor, Jared Diamond has written three books on the subject. The book "Collapse" is an interesting read, and a bit sobering.
Where do we go from here? First, move away from farming practices that deplete the soil. A careless practice can cost you an inch of soil in one major weather event. It takes nature approximately 1000 years to replace that one inch. This happened in a major production area in Australia about 20 years ago. Starting with 7"of productive soil, these farmers made a quick change. One year they were tillage based farmers, and the next year, and since, they are DS.
Second, start incorporating practices that will build soil structure and reestablish the soil biological communities. There is a lot of good research on the subject and more in the pipeline. Land Grant Universities and private laboratories are ramping up programs to meet the need.
Third, it appears that we need to get out of fallow. Current research by Oregon State indicates that one fallow year loses more than we gain in the two crop years of a three year rotation. That was a real downer for me. For years I thought I was building soil by DS. A better understanding of soil biology and interaction from/with different crop cultivars is going to be necessary to break traditional mind sets.
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