Why should you plant soybeans into a fall rye cover crop?

January 18, 2022

There are many good reasons to use fall rye as your cover crop. Fall rye is affordable, easy to kill and helps improve soil structure. This winter-hardy crop also reduces water and wind erosion. But the value of using rye as a cover crop doesn’t stop there.

Let’s dig into the impact and benefits of planting soybeans into a rye cover crop.

When should you terminate the rye crop?

A study was conducted to determine whether there is an ideal time to terminate the fall rye that is used as a cover crop for soybean planting.

Two tests were carried out at several trial sites:

  • Terminating rye 2 weeks before soybean planting
  • Terminating rye the day of planting

These tests showed that when rye was terminated the day of planting, rye biomass increased 3-fold, on average, from 500 lbs/acre to 1500 lbs/acre. At one site in particular, the biomass actually increased 10-fold (view source here).

How does rye affect soybean development?

The extra biomass from the rye builds organic matter, improves soil structure and provides a longer-lasting mulch. However, soybean stands may be reduced when planted into a moderate to thick rye cover. In these cases, a minimum seeding rate of 160,000 soybean seeds/acre is recommended.

How does rye affect weed growth?

The study also looked at the impact of fall rye cover on the weed population.

There was lower weed abundance at the beginning of the critical V1 growth stage. Weed levels were even lower in the later treatments, which is to be expected, given that a glyphosate treatment was initially applied to kill the rye.

Fall rye is not a substitute for other weed control measures. That said, it can be a good tool for improving or complementing existing weed control methods.

How does rye affect soybean yield?

There was no significant impact on soybean yield for crops planted in a fall rye cover, regardless of when the rye was terminated.

However, you should pay close attention to soybean seeding depth because rye can create drier, cooler conditions on the soil surface. Late-terminated rye may also compete with soybeans for soil water reserves.

Benefits of planting soybeans into a fall rye cover: summary

So what makes rye a good choice of cover crop? It adds biomass to the soil, improves soil structure and provides a lasting mulch. Rye also reduces weed abundance when used with other weed control methods.

Are you tempted to give it a t-rye?