Influence of Spatial Planting Arrangement of a Winter Cereal Rye Cover Crop on Corn Productivity

Date: 
Oct 2018

Issue

Winter rye is one of the most widely used and successful cover crops in the Upper Midwest because of its adaptability to the corn-soybean rotation, late fall planting window, superior winter hardiness, growth at cool temperatures in both fall and spring, and documented soil health and water quality benefits. Yet many farmers are reluctant to try winter rye for various reasons, including reports of possible yield reductions in the following corn crop. This project will evaluate the effect of cover crop spacing on disease, and growth and development of corn, to improve understanding of yield decline that may occur in corn planted after rye.

Objective

Conduct growth chamber experiments to investigate the effect of proximity of corn to rye crowns on early corn growth and seedling disease. Compare corn seedling diseases, growth, development, and yield following a winter rye cover crop seeded in different spatial arrangements in a field trial. Compare rye cover crop shoot growth and N accumulation with different spatial planting arrangements in a field trial. Document nitrate availability in the corn seed row and cover crop rows at planting in a field trial.

Approach

This project includes both a growth chamber study and a field trial. The field trial will involve four treatments over two years. There will be a control plot with no rye; broadcast rye with shallow incorporation; three rows of rye planted into the middle of future corn interrows; and a single row of rye planted in the center of future corn interrows. Soil and cover crop biomass samples will be collected, corn stand counts and seedling vigor assessed, disease levels will be monitored, and yield and grain moisture at harvest recorded. This data will improve understanding of the effect of cereal rye on corn growth and development, and risk of disease.

Project Updates

December 2019

Plant growth and disease data were analyzed. Corn dry weight at V3/V4 was larger/more vigorous in 15” compared to 7.5” and broadcast treatments and was not different from the check plot with no cover crop. Plant height at V12 was shorter in broadcast and 7.5” treatment compared to no cover crop and 15” treatments. Corn was greener, as detected using a SPAD meter, in the 15” treatment compared to 7.5” and broadcast treatments but was less green than the no cover crop check. Yields were lower in broadcast (204.8 bu/A) and 7.5” treatment (203.5 bu/A) compared to no cover crop (233.0 bu/A) and 15” treatments (225.7 bu/A)(P=0.0002).

Very little seedling disease was observed, with no difference detected between treatments. Researchers are quantifying pathogen populations among treatments. Cover crops for Year 2 of the project were planted 09/18/2019.

The hypothesis is that the closer corn is planted to the rye crown and roots, the greater the chance that corn will be infected by pathogens from the dying rye, resulting in more seedling disease and reducing growth and yield. The first year of data suggests that planting the corn at a distance from rye will reduce the negative effect of rye on corn growth and yield. A manuscript detailing the growth chamber studies is in progress for submission to “Plant Disease.”

A master’s student also collected data from two on-farm trials evaluating the effect of rye spacing on corn growth in collaboration with the Iowa Soybean Association On-Farm Network, with funding from NC-SARE. These data are currently being analyzed.

Outreach this period included 2 presentations.

July 2019


Root rot on a V3 corn seedling sampled from a cover crop field trial.  
    Credit: A. Robertson, Iowa State University

Rye biomass samples were collected in spring immediately prior to cover crop termination. Rye biomass dry weight varied between treatments. Biomass was lowest in the broadcast treatment, greatest in the 30" rye treatment with 7.5" rye biomass in between. Rye biomass samples are currently being processed for carbon and nitrogen content. Rye was sprayed with glyphosate on April 26 and corn was planted May 4. This was later than planned but precipitation delayed planting. Corn seedlings were collected at growth stage V3 and assessed for root rot. Data are being captured and analyzed. DNA is currently being extracted from root samples and Q-PCR will be used to quantify Pythium clades in the tissues. Corn shoots are being processed for carbon and nitrogen content. Soil samples were also collected from each treatment when seedlings were sampled. DNA is currently being extracted from the soil samples and Pythium in the rhizosphere is being quantified using Q-PCR.  

Graduate student researcher Sarah Kurtz has been awarded an NC-SARE grant (~$12,000) to compliment this work. She is also collecting data from two on-farm trials in collaboration with the Iowa Soybean Association On-Farm Network. These trials are comparing different spatial planting arrangements and termination date of the rye. She presented a poster with data from this project at the Annual American Phytopathological Society meeting in August.  

December 2018

Mean stand counts of rye planted in mid-September 2018 varied from 217 to 131 to 59 plants per square meter (m-2) in the broadcast, 15” and 30” drilled treatments, respectively. In the two drilled treatments, the number of rye plants per meter of row were similar (47.6 and 45 plants m-1 row, respectively).

A growth chamber experiment to compare the distance planted from rye on corn seedling growth, seedling disease, and pathogen populations was established. Data were inconclusive due to temperature variation throughout the growth chamber. The experiment is being repeated.

A growth chamber experiment to compare soil temperature fluctuation on corn seedling disease and pathogen populations after planted to rye was established.

A method to quantify pathogen populations in soil using Q-PCR was optimized.

September 2018

  • Plot layouts were generated and Elbon cereal rye secured. 
  • Broadcast and drilled cereal rye treatments were planted in mid-September after soybean harvest.
  • Mean stand counts of rye varied from 217 to 131 to 59 plants per square meter in the broadcast treatments. In the two drilled treatments (15” and 30”), the number of rye plants per meter of row was similar (47.6 and 45 plants per m-1row, respectively).
  • A growth chamber experiment was established to compare the distance planted from rye on corn seedling growth, seedling disease, and pathogen populations.
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