Files
Abstract
A three-year study (2016-2018) was conducted to evaluate the effects of high fertility management strategies on maize in the southeastern Coastal Plain of Georgia, USA. UGA Extension Service and Georgia Maize Growers recommended the CE (yield goal: 22 Mg ha-1) and CG (yield goal: 28 Mg ha-1) high fertilization treatments, respectively. The tillage changed from conventional the first year to conservation the following two years. During the season hourly soil water tension (SWT) data was collected in addition to tissue data at several vegetative and reproductive stages for avoiding water and nutrient stresses. Additionally, soil, phenology, and meteorological data were collected. No statistical differences were observed between the treatments, which shows increased fertilizer rates did not result in higher yields. The yield results were lower than the expected due to low soil pH and CEC. The 2016 yields were higher than the 2017 and 2018 due to lower minimum temperatures and higher solar radiation. The data collected throughout the field study were used in DSSAT CERES-Maize model for simulating the growth and development of maize. The 2018 observed data of leaf number per stem, leaf weight, vegetative N concentration, and yield were used for calibrating the CERES-Maize cultivar coefficients P1, P2, P5, G2, G3 and PHINT, and the 2016 and 2017 datasets were used for the model’s evaluation. The model was successfully calibrated with high correlation values and d-stat (>0.8). The calibrated model was used for evaluating yields under different management scenarios regarding planting date and depth, row spacing, plant density, N fertilizer rates, number and timing of side-dress N applications, and irrigation method. The model showed that the optimum planting date varied from year to year due to the different meteorological conditions; scenarios of 4-6 cm planting depths were ideal for increasing yields; the narrower the row spacing the higher the yield; a plant density of 120K plants ha-1 resulted in higher yields; the higher the fertilizer rate the higher the yield but the lower the efficiency; higher yields were predicted with the sensor-based irrigation method compared to the UGA Extension Checkbook and rainfed.