Does Planting Green Into a Rye Cover Crop Affect Corn Growth And Yield?

Apr 07, 2021

By Dr. Alison Robertson and Jyotsna Acharya

As more producers integrate cover crops into their operation, there has been increased interest in planting corn into a green or living cover crop, such as cereal rye, and terminating the cover crop after planting.

To help provide some insight into how “planting green” might affect corn growth and yield, we did an experimental field plot study comparing the effect of termination date of a winter cereal rye cover crop on growth, development, seedling disease and yield of corn in 2019 and 2020. This research project is being funded by USDA-NIFA through the Critical Agricultural Research and Extension program. Below is a summary of what we learned.

We looked at terminating the cereal rye cover crop 18 and 3 days before (DBP), and 6 and 12 days after planting (DAP) corn (Fig. 1.) Cereal rye biomass in 2020 was almost double that of 2019. In both years, corn seedlings were taller and shoot dry weight was less in the treatments where cereal rye was terminated after planting the corn (Table 1). In 2020, the corn seedlings in the treatments where cereal rye was terminated after planting the corn were approximately half a growth stage behind the no cover crop control and the treatments where cereal rye was terminated before planting. Radicle rot was more severe in the treatments where cereal rye was terminated after planting the corn compared to the remaining treatments. Yield was lowest when cereal rye was terminated 12 DAP corn.

field plots

Fig. 1. Photo of field plots to investigate the effect of planting corn into a green cereal rye cover crop near Boone, Iowa.

Table 1. Effect of termination treatments of a winter rye cover crop on corn seedling growth, root disease at growth stage V2 to V3, barren plants at R6, and yield in Iowa.

Effect of termination treatments

These data suggest that planting corn into a green cereal rye cover crop may contribute to seedling disease, and negatively affect corn growth, development and yield. To mitigate risk, we continue to recommend terminating a cereal rye cover crop 10 to 14 days before planting corn.

We are continuing to investigate the effect of planting green on corn. As part of this project, we are working with Practical Farmers of Iowa to collect on-farm data on planting green. In addition, Iowa is one of 15 states investigating the effect of planting green on weeds, insects, diseases, and corn development and yield from 2021 to 2023 as part of a USDA-NIFA CAP project being led by Steven Mirsky at USDA-ARS BARC, Maryland and Chris Reberg-Horton from North Carolina State University.

Source : iastate.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.