In western Kansas, our dryland cropping systems tend to have long fallow periods between cash crops. The original reason behind these systems is to basically “bank” moisture in the soil profile for the next crop, thus reducing the risk of a failure.
This seems to make sense in a semi-arid area that receives an average of 15 to 22 inches of rainfall annually. In dry years this could be the difference of having a crop or not.
One of the issues with these systems is that they are not very efficient at capturing and storing soil moisture during those fallow periods.
Depending on how much tillage is done around 70 to 85% of the moisture is lost from runoff, evaporation and in some cases deep percolation below the crop’s root zone.
In other words, if you receive 16 inches of moisture during a fallow period at best you are only gaining about 2.5 to 5 inches of additional moisture depending on how much tillage is used in the system.
In a dry year that little bit of extra moisture might be difference from a failed crop and a decent crop. But in average or wet years we are greatly under utilizing the moisture Mother Nature has provided us.
Another concern with these systems is that for extended periods the soil surface is nearly bare and vulnerable to both wind and water erosion. It doesn’t make much difference whether it is a tillage or no-till system.
No-till fields, without cover on the soil surface, can blow and wash away just as easily as a tilled field. With every erosion event the soil becomes more degraded and less productive.
So, the question becomes can we utilize all of that lost moisture in a more positive way. I believe that we can.
One way is just to intensify the cropping system with less fallow and more cash and/or cover crops. I think this has real merit in those 18 to 22-inch rainfall areas and possibly further north and west where our evaporation rates are less due to the cooler climate and higher elevations.
This doesn’t have to be an all or none scenario and should be flexible. As an example, if in the spring after a fall harvested crop there is a good soil moisture profile and the long- term weather forecast is favorable I would plant another fall harvested crop rather than fallow those acres.
If soil moisture is a little iffy but the weather forecast is neutral, I would lean towards planting a cover crop that can be terminated if conditions turn dry.
In the drier areas of the state just using cover crops to bridge that time between the cash crops may be a better option. This would provide a lot more flexibility than trying to incorporate more cash crops because you don’t need to worry about getting a crop to maturity so you can harvest it. You can always terminate a cover crop early if conditions become dry.
Or, if conditions are extremely dry and the weather forecast is unfavorable when a cover crop needs to be planted you may decide not to plant it, at least for that season.
At the end of the day the one question that you really need to ask is will changing my current system be more profitable for my operation? Can I get enough economic gain from that extra cash or cover crop to make it worthwhile. Just don’t look at it from the short term but also consider long-term costs
and benefits. If there is a lot of soil erosion with your current system eventually it will cost more money to maintain the productively of those fields.
Cover crops are not a silver bullet that will fix all soil health issues. They are just another tool in the toolbox that may work for some producers but not for others.
There are other soil health practices, like nutrient management, no-till, crop rotation and others that may be a better fit for some producers.
If you are new to using cover crops, I suggest that you start small and experiment to figure out what might work for you before implementing it on a large scale.
Seek out others in your area that are using cover crops and ask what they are doing to make it work for them.
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