The long tale of prevent plant: Fallow syndrome reduces yields after a prevent plant year

In any given year for most regions the risk of prevent plant is possible. In some areas, such as the Red River valley, the central Corn Belt, the Mississippi Delta, and the Great Lakes it seems prevent plant is not only possible, but likely under normal weather scenarios. Not only does prevent plant create immediate production and cash flow challenges, there is a lingering issue that could lead to further yield and productivity problems the year following prevent plant.

Called fallow syndrome, research has revealed that fields coming out of prevent plant the previous year are likely to experience yield declines or struggle to reach typical production. So what exactly is the fallow syndrome? Simply put, it is a sudden decline in soil biology that is key to helping plants obtain key plant growth nutrients. This decline in soil biology is caused by the lack of plant roots that feed soil biology. If a field is left fallow for an entire growing season, the soil biology that works with plants will die back. A period of saturated or flooded conditions only compounds the loss of soil biology. Research has found that the main cause of loss is by far the starving of soil biology, with drowning a secondary cause. 

Some crops fare better than others in overcoming fallow syndrome following prevent plant. Corn, with its coarse roots, has a higher dependence on soil biology to find and deliver phosphorus. Wheat and sorghum are also susceptible to fallow syndrome. Soybean, however, seems to fare better.

So what can growers do to help ensure a rapid bounce back in productivity following prevent plant? Research shows that prevent plant fields planted to a cover crop may help avoid the fallow syndrome. Some details matter here. In particular, brassica crops are not good hosts for the Vesicular Arbuscular Mycorrhizae that work so well with cash crops. This means that while brassicas can be useful for improving soil infiltration and drainage, they should not contribute more than 50% of any prevent plant cover crop mix. Additionally, including some grasses in the mix will ensure happy and populated mycorrhizae. 

What won’t help? Tillage. Bare soil. Increasing N fertilization. Broadcasting Phosphorus. While each of those attempts to create pore space vital to soil biology or increase overall soil fertility, they not only do not help soil biology, they further contribute to its degradation. 

As if you need more justification to plant a cover crop on every prevent plant acre, here are some additional benefits:

• Cover crops can improve soil structure which in turn improves natural drainage of excess moisture while increasing pore space for improving water holding capacity. They are a small step toward making your fields more resilient to saturated weather.

• Cover crops can significantly manage weeds, especially on prevent plant acres, reducing management costs.

• Legume cover crops can provide a sizeable nitrogen credit. Red Clover or Hairy Vetch can earn a 100 pound nitrogen credit if given a reasonable amount of time to grow such as in a prevent plant year.

• Adding a cover crop to prevent plant acres may qualify for carbon credits, earning a new revenue stream. 

By Ryan Stockwell, Indigo Grower Engagement Senior Manager and Wisconsin farmer