Yield‐Based Corn Planting Date Recommendation Windows for Iowa

Abstract

Core Ideas• Three distinct site-groupings resulted, with different recommended planting windows.• Two planting windows were developed for each site-grouping: 98-100% grain yield or 95-100% grain yield.• The north-central and northeast grouping had the earliest recommended planting window to maximize grain yield. Three distinct site-groupings resulted for Iowa, which is different than previous statewide research: north-central (NC) and northeast (NE); northwest (NW) and central (C); and southwest (SW) and southeast (SE). Two planting windows were developed for each site-group based on the maximum yield on the response curve and a subtraction of 2 or 5% relative yield to develop yield windows of 98-100% or 95-100%, respectively. The response curves for each site-grouping identify locations that exhibit a stronger grain-yield response to planting date, especially in the northern and southern locations. The NC-NE grouping had the earliest 98-100% planting window (12-30 April) whereas the NW-C grouping (15 April-9 May) and SW-SE grouping (17 April-8 May) were later. Impact of Planting Date in Corn SystemsGrain yield potential is maximized with the earliest spring planting dates for a particular region, assuming that other abiotic and biotic stresses are minimized (Gaile, 2012). Specific calendar dates that produce the optimum grain yields for a particular location vary due to differences in climate and the length of the growing season (Bruns, 2003). A trend toward earlier corn planting during the past several decades has occurred and is due to improvements in technology, along with temperature and precipitation shifts from climate change (Pryor et al., 2014;Urban et al., 2015). Technological advancements include the increased early-season stress tolerance of hybrids, use of improved seed treatments, increased herbicide use, reduction in tillage operations, larger equipment, tile drainage, and mechanical improvements in planters that distribute seed more uniformly in suboptimal conditions (Shaw, 1988;Kucharik, 2006;Lenhart et al., 2012). Increased farm size also necessitates

Sowing Date Affects Maize Development and Yield in Irrigated Mediterranean Environments

“…Timely sowing is critical for maximizing yield for both grain and biomass in maize [1,2] and therefore, growers are concerned about the yield response of maize to sowing date (SD) [3][4][5]. However, optimum maize SD may vary from area to area due to differences in climate and the length of the growing season where the crop is produced [6].…”

“…It is known that maize needs warm soil to germinate and grow [5,7]. However, the practice of sowing as soon as possible to take advantage of the solar radiation [8] is nowadays more adopted by farmers.…”

“…Bruns and Abbas [6] reported technological improvements in maize hybrids such as better early season vigor and tolerance to germination in cool wet soils, better seed treatments to guard against damping off diseases and seedling insect pests, or the advent of herbicides. These factors have contributed to planting maize earlier than it was 30 years ago [5].…”

“…Also, SD must be late enough to avoid late spring frosts. As a rule, maize should not be sown until the soil temperature approaches 10 • C. Under cold soil conditions (below 10 • C), seeds will readily absorb water but will not initiate root or shoot growth, which leads to seed rot and poor emergence [5,14].…”

“…The highest yields generally occur where the growing season is longest and soil moisture is not a limiting factor [17]. Yield reductions due to early or late planting have been well documented in the literature [4,5,9,11,16,18]. Early planting results in reduced cumulative intercepted photosynthetically active radiation (IPAR) because of delayed leaf area development.…”