Optimizing intercrop success through row orientation and crop management

Overview

This research program addresses a critical gap in intercropping success by demonstrating how row orientation, combined with row spacing, planting density, and cultivar choice, can dramatically improve the performance of inter-row crops. The work focuses on two practical systems: interseeded cover crops in corn and relay-intercropped soybeans in winter wheat. The core insight is that row orientation directly controls how much light reaches the inter-row space, which in turn shapes the micro-environment for the intercrop. A North-South orientation allows more light penetration, favoring warm-season and C4 species, while an East-West orientation creates shading that benefits cold-tolerant species. By optimizing these variables, growers can shift intercrop outcomes from failure to success.

Technical specifications

Key research factors:

• Row orientation (North-South versus East-West) as the primary variable for light interception management
• Row spacing comparisons (30 inches versus 60 inches) for corn-cover crop systems
• Wheat planting density (low versus normal) and cultivar type (erect versus floppy) for wheat-soybean relay systems
• Cover crop mix including oats, triticale, radish, and red clover interseeded at the V5-V6 corn stage
• Soybeans relay-intercropped into wheat at the Zadoks 50-59 growth stages

Measured outcomes:

• Light interception by the main crop and inter-row space
• Soil temperature and moisture dynamics between rows
• Crop development staging and biomass accumulation
• Inter-crop biomass and final crop yields
• Weed population shifts driven by micro-environmental changes (validated in prior 2017-2018 Elora trials showing wild mustard dominance under East-West orientation and C4 species preference under North-South)

Technology readiness level

The concept has been validated through an exploratory field trial at the Elora Research Station in Ontario during 2017-2018, which confirmed that row orientation significantly alters inter-row weed communities and micro-conditions. Full multi-site validation is currently underway at three Ontario research locations (Woodstock, Ridgetown, and Harrow) during the 2024 and 2025 growing seasons, using randomized complete block designs with four replications. Results from these trials will determine the agronomic recommendations for row orientation, spacing, density, and cultivar selection across both corn-cover crop and wheat-soybean intercropping systems.