Corn production response to tillage and nitrogen application in dry-land environment

Tillage system and N fertilization management are important factors in corn production. Optimizing these factors can help improve corn production in southeastern Corn Belt under rain-fed environment. A 3-yr study was conducted to determine the effects of three tillage systems (conventional tillage, CT; strip tillage, ST; and no tillage, NT) and five N rates (0, 45, 90, 135, and 180 kg N ha−1) on corn (Zea mays L.) plant characteristics at R1 growth stage (the first reproductive stage, silk stage) and grain yield in dryland rain fed environment. Tillage systems had no significant effect on plant height, NO3–N concentration in plant, and relative chlorophyll content (SPAD) at R1 growth stage, but CT and ST increased normalized difference vegetation index (NDVI) and leaf area index (LAI) at R1 stage compared with NT system. Increasing N rate generally increased plant height (193–209 cm), SPAD (34.8–41.7), NDVI (0.53–0.64), LAI (1.47–1.72) at R1 growth stage and corn grain yield (2.85–4.55 Mg ha−1,2.45–4.51 Mg ha−1, and 2.27–3.77 Mg ha−1 for CT, ST, and NT, respectively) as N rate did not exceed specific amount. SPAD and NDVI values did not increase with N rates above 90 kg ha−1. The rates above 45, 90, and 90 kg N ha−1 did not significantly increase grain yield under CT, ST, and NT system, respectively. There was no statistical difference between CT and ST system for grain yields, and CT and ST generally produced greater yields than NT system. Water availability at corn early reproductive stages significantly influenced corn grain yield. Relatively higher precipitation at corn reproductive stages in 2007 contributed to greater corn grain yields compared with 2008 and 2009 under all these three tillage systems (151 mm, 44 mm, and 54 mm in June, respectively). In 2 out of 3-yr study the ST system contributed to generally higher yields compared to other systems; therefore, it would be a preferable tillage system for planting corn in this area.

► Tillage and N fertilization should be further optimized in dryland corn production.
► Increasing N rate generally increased corn grain yield.
► CT and ST generally produced greater yields than NT system.
► ST system is more stable for corn production under variable growing environments compared with CT and NT systems.
► ST would be a preferable tillage system for planting corn in this area under rainfed environment.