Last week I mentioned no-till in regards to the 2011 wheat crop. Some thought the comments rather negative but that wasn’t my intention. My point was while no-till has many positive benefits, it usually isn’t as easy as deciding to no-till. Often when producers decide to no-till after using tillage for years or decades, it is under adverse conditions like drought and/or heat stress. This is the absolute worse time to eliminate tillage and count on success. In fact, as is evident by much of this year’s wheat crop planted into first time no-till ground, the crop fares worse than it would under tillage. The full benefits of eliminating tillage take years or even decades to happen, especially under the climate typical of the western half of Kansas.
Very briefly, the benefits include improved soil structure, infiltration rate, water holding capacity, nutrient levels, organic matter levels, microbial and overall biological activity. Wind and water erosion as well as evaporation and soil temperature fluctuations decrease. No-till was developed in the eastern part of the country in states like Ohio, Virginia, and Kentucky. Not only are the soils often different, the climate is more humid; rainfall is more dependable, more evenly distributed and more evenly distributed over the year; and yearly evapotranspiration rates are much lower as a result. Also the cropping systems used as a result of the climate are much different.
Although producers in this part of the state have largely moved away from continuous wheat, our primary crops are all grass crops – wheat, corn, cereal grains and feed crops such as forage sorghums and sorghum-sudan hybrids. This makes sense since our climate and soils are better suited to grass crops than most broadleaf crops. And these crop choices have and will continue to work well as long as we manage the residue, normally through tillage.
The benefits of reducing tillage result from two factors, allowing soil structure development and the accumulation of crop residues on the soil surface. The surface residues provide several benefits; they help prevent wind and water erosion; water infiltration rates increase while runoff decreases; and the accumulation of organic matter at the soil surface results in better nutrient cycling and increased microbial activity. When crops are rotated, especially grass with broadleaf crops, the system will eventually be quite successful for most soils. However, under continuous cropping of a single crop or planting only grass or only broadleaf crops, problems can rapidly arise. These problems involve pest pressures. While you may not link corn, sorghum and wheat together, they are all grass crops sharing some common disease and insect pests. When residues accumulate on the soil surface they serve as habitat for these common pests and can create above normal insect and disease pressure. While these can be controlled chemically, the costs tend to grow higher over time and eat into profits. And when planting only grass crops, even with glyphosate resistant crops, grass weeds tend to increase in abundance without intensive weed management. And the same would hold true if you only planted broadleaf crops.
Farmers here and in other areas help no-till to succeed by rotating between grass and broadleaf crops, helping interrupt pest cycles and manage residue. Even if pest pressures weren’t a problem under continuous grass cropping and no-till, the level of residue generated, especially under irrigation, can become almost impossible to manage. These heavy residues affect soil warming and are extremely difficult to plant into. Broadleaf crops overall produce much less residue and residue that breaks down more rapidly. Most importantly they interrupt pest cycles.
So while producers need to no-till where practical, they need the reliable crops to rotate to which can be difficult in this region. Next week an exploration of what broadleaf crops may fit into our area.