Effect of Tillage and Cover Crops on Corn Yield

TRIAL OBJECTIVE

  • Different tillage practices are utilized by farmers for various reasons including to:

    • Enhance residue decomposition
    • Control pests
    • Conserve soil moisture
    • Deliver fertilizer to the root zone
    • Relieve compaction
  • Farmers also utilize cover crops in their crop production system. Potential benefits of cover crops are:

    • Soil conservation (erosion control) 
    • Soil moisture conservation
    • Weed suppression
    • Improved organic matter
    • Improved soil structure
    • Improved nutrient cycling
  • In 2019, the Monmouth Learning Center established a trial to evaluate the interaction of certain tillage practices with the presence of a cover crop and the effect on corn yield. This is intended to be a long-term trial to monitor both yield and soil quality over time.

     

RESEARCH SITE DETAILS

Location Monmouth, IL Planting Date 4/23/19
Soil Type Silt loam Harvest Date 10/14/19
Previous Crop Corn  Potential Yield (bu/acre) 250
Tillage Type Various Seeding Rate (seeds/acre) 36K

 

  • Five zones were established in the fall of 2018 (Figure 1):
    • Conventional tillage without a cover crop
    • No-till without a cover crop
    • No-till with a cover crop 
    • Strip tillage without a cover crop
    • Strip tillage with a cover crop
  • Cereal rye was sown in the relevant zones and respective tillage operations were performed in the fall of 2018.

  • Following cover crop termination, a 114-day RM SmartStax® RIB Complete® corn blend product was planted in all plots. 

  • Grain was harvested and adjusted to 15% moisture.

Figure 1. Map of tillage and cover crop plots. CC = cover crop.

UNDERSTANDING THE RESULTS

Figure 2. Average corn yield after being planted in various combinations of tillage with or without a cover crop.
  • In this trial, no-till plots had the lowest corn yield (Figure 2). Prolonged cold temperatures prior to planting likely hindered residue decomposition and seedling emergence, potentially affecting yields in those plots.1 Rising temperatures after planting likely promoted rapid residue decomposition, which could reduce the amount of nitrogen available during the early season as microbes utilize soil nitrogen when decomposing crop residue.2

  • Yields were similar between the strip-tilled plots and the conventionally-tilled plot.

     

KEY LEARNINGS

  • This was the first year of this trial; establishing tillage zones and improving soil structure and quality takes time.

  • Cover crops may have other benefits beyond yield: moisture conservation, weed suppression, and nutrient cycling. These benefits are less tangible but may have an effect on profit potential.

  • The Monmouth Learning Center has committed to conducting this study on a long-term basis to monitor the effects on yield and soil quality over time.

Sources:

1Archontoulis, S. and Castellano, M. 2018. Soil water, residue, and nitrogen status entering the 2018 growing season. Iowa State University. https://crops.extension.iastate.edu/.

2University of Nebraska – Lincoln. 2017. Crop residue removal: impacts on yield. No-Till Farmer. https://www.no-tillfarmer.com.

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