Seed Zone Soil Temperature and Early Corn Growth with Three Conservation Tillage Systems

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Abstract
Detailed data are needed to quantify the effect of conservation tillage (CT) on corn (Zea mays L.) emergence and early growth in the Northern Corn Belt. Corn was grown using three CT systems: till‐plant (TP), chisel (CH), and no‐till (NT) and conventional moldboard plow (CN) on a Griswold silt loam soil (Typic Argiudoll) during the 1982 to 1984 growing seasons. Soil temperature at the seed depth (5 cm) was measured hourly. Daily means and cumulative growing degree days (GDD) based on seed zone temperatures were calculated. Corn emergence was monitored. Leaf area and dry matter per hectare were measured at different growth stages. Relative growth rates (RGR) were calculated from daily measured plant heights. Soil temperature at the 5‐cm depth ranked CN > TP > CH > NT. Initial corn emergence rates with the NT system were depressed compared to CN; the emergence rate ranked CN > TP = CH > NT. However, time to 100% emergence was delayed by 8, 2 to 3, and 2 d for NT compared to CN in 1982, 1983, and 1984, respectively. All tillage systems started to emerge at 40 to 55 GDD and reached a maximum emergence at 70 to 80 GDD. During the first 5 weeks after emergence, corn growth parameters (plant height, leaf area, dry matter) of NT were consistently lower, and in some cases significantly lower than CN. These growth parameters were highly correlated with GDD. The RGR fluctuated in the same manner as the daily 5‐cm soil temperature during the first 5 weeks after emergence. The correlation coefficients of log RGR vs. daily mean soil temperatures were highly significant and followed the soil temperature trends. Thus, the lower soil temperature associated with CT systems, especially NT, is one of the main factors affecting emergence and seedling growth and development.
Funding Information
  • College of Agricultural and Life Sciences
  • College of Agriculture and Life Sciences, Mississippi State University