Corn Management Following Cereal Rye Cover Crop with Strip Tillage and In-Row Fertilization
Cover crop adoption is a key practice promoted to reach the Iowa Nutrient Reduction Strategy (INRS) goals of 45% nitrogen and 29% phosphorus reduction in surface waters. It is estimated 12 million acres of cover crops are needed in Iowa to meet INRS goals, yet only 720,000 acres were planted in 2017, about 3% of the corn and soybean acres planted in Iowa annually. Farmer evaluations show corn yield drag and poor return on investment are the biggest barriers to adoption. Most cover crop research for corn production systems is focused on the management of the cover crop. This research focuses on management of the corn crop following winter cereal rye.
Evaluate the effects of a winter rye cover crop-free zone and starter fertilizer to improve seedling vigor and eliminate yield drag associated with winter cereal rye. This objective will be reached by determining treatment effects on corn growth and development throughout the growing season; disease, insect and weed incidence, severity, and prevalence; and winter cereal rye biomass growth and nutrient uptake.
This project includes a field trial at the ISU Agricultural Engineering and Agronomy Farm, supplemented by companion trials at one outlying research farm. Eight treatments will be used. Cover crops will be broadcast seeded in the fall, and terminated 10-14 days ahead of corn planting for all treatments. Cover crop biomass and nitrogen uptake will be determined with two fall and two spring biomass sampling periods each year. Corn growth and development will include stand establishment; root and shoot biomass, nutrient uptake, and staging at approximately 10 and 20 days after emergence; date of silking and physiological maturity; and grain yield and moisture at harvest. Corn roots will be evaluated for root rot pathogens, and stand establishment observations will be used to detect noticeable seedling death. Insect incidence and weed density/community notes will be determined in every plot. These data will help researchers develop improved management recommendations for corn production following winter cereal rye cover crops.
For the 2019 growing season, crop growth and development, disease incidence, weed community and insect incidence were collected as planned. Data is being summarized and will be discussed at a project meeting in early 2020. Preliminarily, seedling disease, insect presence and weed populations were not significantly different between strip-tillage and starter N treatments. In fact, disease, insect and weed pressure was found to be at very low levels. This comes as no surprise because cover crop biomass was very low following drill seeding in the fall of 2018 (no biomass samples were taken).
There were corn grain yield differences between treatments. At Kanawha, the no-rye and no starter N check and cereal rye, and no starter N treatments had similar yields (mean of 184 bu/ac) which was higher than the cereal rye treatments with 35 and 70 lbs N/acre (mean of 171 bu/ac). At Ames, the no-tillage treatments averaged 11.5 bu/ac less than the strip-tillage treatments. Additionally, the cereal rye with 70 lb N/ac was the lowest yielding treatment by nearly 25 bu/ac.
For the 2020 growing season, the cover crop plots were broadcast seeded at Kanawha and Ames the first week of October. The fall strip-tillage treatment occurred at Ames Nov. 4, 2019. Wet weather delayed strip-tillage at Kanawha to spring. Fall 2019 cover crop growth was determined at both locations via stand counts and biomass collection in early November.
Outreach included 2 field days and 2 presentations
Plots were laid out, and cover crops were drilled seeded Oct. 19, 2018, in Ames and Oct. 30, 2018, in Kanawha. Cover crop seeding and lack of fall biomass and stand counts collection was due to cold, wet fall conditions, delayed soybean harvest and lack of cover crop emergence. Cover crop biomass, stand counts and soil samples were collected in the spring of 2019 as planned. Cereal rye was terminated on 5/3/19, however, soybean planting was delayed by rain that continued through 5/16/19. This resulted in a longer time frame between termination and planting than intended. Soil sampling, corn biomass and stand counts, crop reflectance, disease, insect and weed assessments were conducted as planned.
Cover crop plots were seeded at Kanawha (October 30) and Ames (October 29). The fall strip-tillage treatment occurred at Kanawha and Ames (November 16). Soil samples were taken for baseline fertility at the Ames site (November 16). No soil samples were collected from Kanawha because of wet conditions followed by frozen soil. Neither site had cover crops emerge so fall cover crop biomass and stand counts were not able to be determined.
A post-doc has been placed on the project. The field locations have been identified at the ISU Northern Research and Demonstration Farm, Kanawha, and at the Ag Engineering Agronomy Research Farm, Boone. Plot layouts have been generated and Elbon cereal rye has been secured. The cereal rye will be drill seeded-soon after the soybean are harvested; weather permitting by mid-October.
The project was discussed at a September 2018 field day at the ISU Southeast Research and Demonstration Farm, Crawfordsville.