Intensive tillage was the method that supported the expansion of agriculture in the United States to the point that our country exports more farm products than any other. There is no denying that fact, but today we face many new challenges that require solutions. We can’t afford to simply say “this is the way we have always done it and this is the way we will continue”. The soil is a natural resource that can be depleted by erosion and loss of nutrients and organic matter as the result of too much tillage.
As the younger generation says “back in the day” tillage in one form or another was the only way to manage weeds. Now we control weeds with herbicides so well that traditional cultivators are essentially obsolete. However many growers still hold to the practice of thoroughly tilling the soil for a wide range of reasons from fairly good ones such as destroying perennial weeds and incorporating lime or fertilizers to less logical ones like “it just needed a good plowing”.
In fact there are very few farms where the level of tillage is as intensive as it was as recently as the 1960’s, but there are a few that approach it. We more commonly see the old beds re-hipped in the fall and then burned down and harrowed prior to planting. The core of the row remains intact, allowing plants to produce their roots in undisturbed soil. When a field is reworked for some reason the soil is vulnerable to erosion until it has time to settle and reestablish its structure or better still be covered by vegetation.
Tillage has its place in agriculture, but we need it much less today than in the past. All of the organisms that inhabit the soil from mycorrhizae to earthworms are damaged by tillage. The pores that allow water and air to enter the soil profile are closed by tillage and must be reestablished. Organic matter levels as high as four percent in forest soil can drop to around one percent after a few years of intensive tillage. Soil aggregates are broken down and we see problems with clodding and crusting, not to mention that crop yields may suffer.
Trafficability, or the capability of soil to support equipment, is another big issue as many can attest following the heavy rainfall of recent weeks. No-till fields can be planted much quicker following rain, and they also support equipment for in-season tasks like spraying and fertilizing. The harvest is critical as any farmer can attest who has harvested subsoiled fields in a wet fall.
I realize that soils that have been tilled for generations produce good yields with tillage. These soils are in fact “addicted” to tillage, and may require years of winter cover and high biomass crops like corn to “wean” them off the plow. The economics of today’s agriculture demand maximum yield, but the rest of the story is that the combination of soil loss, wasted nutrients and water, nematodes which are more active in tilled soils, and other issues may bring no-till, reduced tillage, conservation tillage, or whatever you want to call it into practicality.
This debate is complex, combining issues of economics, peer pressure, appearance, and a score of other issues that would confound a busload of soil professors. However the bottom line is that tillage is destructive to the soil that the generations following us will require to produce their food. We are forced by economics to take the short view on many of the things we do in order to keep farming from one year to the next, but we must keep the future in mind as well.