Global Maize Project in the United States: West Lafayette, Indiana

IPNI-2010-USA-GM27

01 Jun 2018

2017 Annual Interpretive Summary


We established our first field experiments in this international effort at Purdue’s Agronomy Center for Research and Education (West Lafayette, IN) in 2012. Like other ongoing studies, our research involved a comparison of traditional farmer practices (FP) versus ecological intensification (EI) practices for rain-fed maize in a conventional maize-soybean rotation. Unlike other studies, we employed a fall strip-till, three management levels, and six reps. The FP plots involve a normal plant density (approximately 31,000 plants/A), sidedress nitrogen (N) application with rates of 0, 100, and 160 lb of N/A following a starter application of 20 lb N/A at planting. The EI plots used the same hybrid (P1498 from 2012-2014, and P1417AMX from 2015-2017), but at a higher plant density (approximately 38,000 plants/A), with sidedress N rates of 0, 160, and 220 lb N/A plus an inhibitor (Instinct™) and ammonium sulfate (thiosulfate) in the coulter-banded UAN. The EI plots are now also receiving broadcast P2O5 (MESZ starting 2017) and K2O (Aspire® starting 2015), despite soil-test phosphorus (P) and potassium (K) that are well above Tri-State critical levels in all treatments.

Maize yields were highly responsive to N rates in all six years, and were significantly higher with EI management compared to FP management in 2015 and 2017. Grain yields in 2017 with EI averaged 249 bu/A at 220 N, and 233 bu/A at 160 N, relative to just 202 bu/A at the comparable 160 lb N rate with FP. Zero N treatments averaged approximately 100 bu/A in 2012-2017. Fertilizer N recovery efficiency (NRE) by whole-plant biomass at maturity averaged 62% (maximum = 80%) from 2012-2017 with the 160 N in the EI treatment. Ear-leaf nutrient concentrations at flowering were highest with the 220 N EI treatment. Total plant nutrient uptakes by maturity (R6) for N, P, K, sulfur, zinc, copper, and boron were also significantly higher for the 220-N EI treatment.

With support from the 4R Research Fund, we added intensive greenhouse gas measurements during the 2015 and 2016 growing seasons. Cumulative N2O losses (per unit grain yield) were no higher in EI than in FP at comparable N rates. Another 2017 development was sampling conducted by Olmedo-Pico (Ph.D. student) for kernel weight and nutrient uptake progression at weekly intervals during grain fill. These samples confirmed the EI system provides benefits to achieve longer filling period durations and final kernel weights similar to those in the FP system (despite having more kernels/unit area via higher populations). We anticipate achieving further yield and nutrient efficiency gains in EI systems.