Low Soil Moisture Planting of Cotton for Optimum Emergence

Abstract

A row crop planter field study was conducted to optimize cotton seed emergence. The depth of moist soil scraped off below the drying front (the interface between the air-dry and initially moist soil) was varied from 1.3 to 5.1 cm to determine the moist soil scraping depth that produced optimum emergence. Next, the effect of seed planting depth below this scraped moist soil surface was varied from 2.5 to 5.1 cm to determine optimum planting depth. Finally, the V-closing/press wheel force was varied from 89 to 356 N to determine optimum press wheel force. A planter automatic seed depth control system (Weatherly and Bowers, 1997) was modified to sense the drying front depth and then scrape off a set depth of moist soil below the drying front. The field study planter was a two row unit with each row consisting of a drying front sensor, an automatic scraper depth control system, a V-wing scraper blade, and a John Deere MaxEmerge planter unit. The moist soil scraping depth that gave the highest emergence was 3.8 cm below the drying front. The V-trench seed depth with the highest emergence ranged from 3.8 to 5.1 cm. The V-closing/press wheel force for highest cotton seed emergence ranged from 178 to 267 N. Setting these three planter functions, in the ranges stated above, produced cotton seed emergence as high as 80% in low soil moisture conditions.