Pushing the Early Corn Planting Envelope in No-till On High-Clay Soils.

Early planting is key to successful corn production in drought-prone areas where yields are frequently limited by available soil moisture. Surface residue associated with no-till cropping systems conserves soil moisture but also can slow soil warming in the spring, potentially delaying emergence. Experiments conducted in central and eastern Kansas in 2004 to 2008 tested three hybrids of differing maturities at planting dates ranging from mid-March to mid-April. Each hybrid-by-planting date combination was evaluated at three populations. Corn was no-till planted following a soybean crop in the respective experiments. The objective was to identify optimum combinations of hybrid maturity and populations for early planting dates in no-till, dryland cropping systems on shallow topsoils. Greater plant density usually resulted in greater yields within the range of populations compared in these experiments, regardless of planting date. The positive yield response to increasing populations was larger in environments that supported greater yields. Exceptions occurred if planting was delayed until May or June, when yield decreased with greater plant density, or in a drought situation, when there was no response to plant population. Yield response to planting date varied with year and location but tended to decline slightly with later planting dates on average. The earliest planting dates posed a greater degree of risk from damage to corn by freezing temperatures. Medium- or full-season hybrids produced the greatest yields in almost every planting date – population combination. Early-season hybrids were superior only in drought conditions or if planting was delayed into mid-May or June. Although pushing the planting date as early as possible improved yield in some years, results indicated that with existing weather patterns, the risk of freeze damage is significant and may offset that benefit.