Skip to content

Optimizing crop management decisions in early and late-planted soybean and corn

Principal Investigator: David Hooker

Research Institution: University of Guelph

Timeline: January 2021 – February 2024  


  • Determine how optimal maturity selection (CHUs to maturity) in corn and soybean varies across a gradient of planting dates (from mid-April to late June) to provide Ontario farmers with profitable, data-backed Ontario-specific recommendations on appropriate maturity selections in early and late planting scenarios (planting date by maturity rating interaction).
  • Compare the profit response functions (corn and soybean) in early/late planting scenarios to assist farmers when deciding a) which crop to prioritize, b) at what point in late planting scenarios does it make sense to switch from corn to soybean.
  • At the earliest and latest planting date, identify economically optimum soybean seeding rates across relative maturities for Ontario.
  • Discover physiological mechanisms underlying corn grain yield response to planting date across relative maturity ratings in Ontario.


  • Farmer-members: To our knowledge, there is no Ontario dataset that provides guidance on when to switch soybean maturity for (early or late) planting dates. In corn, the dataset used in the OMAFRA agronomy guide has only one Ontario location (Chatham). A cross-Ontario dataset that characterizes the planting date by maturity rating interaction in both corn and soybean will assist farmers and farm advisors with decisions related to time to switch varieties.
  • Farmer-members: In early and late-planting situations, Ontario farmers often face a trade-off and prioritize either soybean or corn, in terms of which crop to plant first, or which crop to invest in and purchase seed with a different maturity rating. By investigating planting date by maturity rating interactions in both corn and soybean simultaneously, we will be able to provide farmers with profitable recommendations that incorporate this real-world trade-off.
  • Environment: By the end of May and into June, there is a large incentive to plant ‘unfit ground’ (wet soils that would typically not be planted into) because of the yield penalties and associated loss of income due to late plantings. But by planting into overly wet soils, destruction of soil structure and long-term compaction damage is likely to have long-term repercussions on crop productivity.). By quantifying the profitability of different crop management factors (which crop to prioritize, when it pays to switch varieties), we hope to increase the profitability of late planting situations and reduce the incentive and perceived need to plant into overly wet soils come June.

Scientific Summary:

Similar to optimizing management according to spatial precision in precision agriculture, corn and soybean growers need information to optimize management according to the “temporal position” of planting time that can vary widely from year-to-year. The shortcomings of the Ontario dataset for making decisions were highly apparent in 2019. In Ontario, corn and soybean planting typically occurs during the first week or two of May, with an adapted hybrid or variety expected to mature before a killing frost. However, most years are not typical; there are opportunities in some years to plant ultra early, and weather may delay planting to ultra late in other years. There is a high probability of planting ultra late or ultra early in at least some regions of Ontario in every year. In either situation, growers need to be better informed: for example, which crop should be prioritized in terms of economic returns – corn or soybean — and second, when does it make economic sense to move to a longer or shorter season hybrid or variety? At very early or late planting dates, there is evidence that seeding rates should change in soybean.

Robust datasets relevant to Ontario are desperately needed to help farmers and farmer advisors make more confident and profitable decisions in early and late planting scenarios. These datasets would compare yields, grain moisture concentrations and phenology, across different planting dates, CHU ratings and plant populations. Currently, most of the data available in Ontario to inform early and late planting decisions are sourced from the U.S.A. We propose to develop Ontario datasets by conducting two paired experiments representing the major corn and soybean regions in Ontario (Ridgetown, Elora, Winchester) over 3 years. One experiment will test the effect of different planting dates, CHU maturity ratings, and seeding rates on yield (and related parameters) in corn and soybean. A paired experiment in soybean will evaluate, at the earliest and latest planting date, the effect of seeding density. Economic analyses of the data generated will enable a profitability analysis for crop selection, planting date and maturity rating.

External Funding Partners:

The project is funded in part by the Ontario Ministry of Agriculture, Food and Rural Affairs.