By DALE YOUNKER
Natural Resources Conservation Service
Many Kansas dryland cropping systems tend to have long 9–15-month fallow periods between cash crops. This 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 semi-arid regions that receives an average of 15 to 22 inches of rainfall annually.
Unfortunately, these systems are typically not very efficient at capturing and storing moisture. Roughly around 15-25% of the rain and snow received during the fallow period is captured and stored in the soil for the next crop. The rest is lost from runoff, evaporation, and in some cases deep percolation below the crop’s root zone. 16 inches of moisture during a fallow period will only gain about 2.5 to 4 inches of additional soil moisture. The more tillage in the system the less moisture you will be able to capture and store. Granted, in dry years that extra moisture, as small as it is, might be the difference between a failed crop and a harvested crop. But in average or wet years we are greatly under utilizing the moisture mother nature has provided us.
Many times, these systems leave the soil surface nearly bare making the soil susceptible to both wind and water erosion. This is true in both tillage and no-till systems. No-till fallow 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.
Can we utilize that lost moisture in a more positive way? In many situations I believe that we can. One way is to add more cash crops to the cropping system. This doesn’t have to be an all or none scenario and should be flexible. If there is a good soil moisture at planting time, and the long- term weather forecast is favorable, a cash crop could replace a fallow period. If soil moisture is sketchy and the long-term weather forecast is dry to neutral, you may forgo planting a cash crop and plant a cover crop, or just continue with the traditional fallow period.
Cover crops could also be used to bridge the time between the cash crops. They provide a lot more flexibility than trying to add more cash crops, because you don’t need to worry about getting a crop to maturity to harvest it. They can always be terminated early if gets dry, or not planted at all if moisture conditions are not favorable at planting.
Intensifying the crop rotation or adding cover crops are not a silver bullets 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 practices, like nutrient management, no-till, crop rotation and others that may be a better fit for some producers.
At the end of the day every producer needs to ask, is changing my current system going to put more money in my pocket? Both short term and long-term costs and benefits need to be considered, including the long-term productivity of the soil. For more information you can contact me at [email protected] or any local NRCS office.