Page 230 - PC2019 Program & Proceedings

PLANT CANADA 2019

P33. Improving corn N fertilizer recommendations using rainfall effects on crop N demand
*
Niemeyer, C. ; J. Nasielski; K. Janovicek; B. Deen
University of Guelph

Adequate Nitrogen (N) is critical in high yielding and profitable corn production systems. However,
efficiency decreases when N fertilizer application exceeds crop N requirement resulting in significant
environmental and economic costs. Data from a long-term N response trial at the Elora Research Station
(Elora, Ontario) demonstrates large annual variation (140kg/ha to 260+kg/ha) in the Maximum Economic
Rate of N (MERN) and suggests that precipitation is a significant source of variability in N response. We
hypothesize that the existing Ontario corn N Decision Support System (DSS) can be improved by
accounting for soil moisture effects on potential sink size and corn N demand. To test this hypothesis, we
used over 120 N response curves and supporting data (weather, management, soil) generated from 1975-
2017 on silt-loam soils at the Elora Research Station. Regressions between sums of rainfall during various
growing periods over the season and MERN were conducted. Rainfall during June 15th to July 15th (the
one month period before silking) was the most predictive of MERN while other time periods (i.e. early
spring, grainfill) were non-predictive. Inclusion of a rainfall correction factor in the Ontario Corn N DSS
significantly improved predictions of MERN. This rain-corrected DSS has significant potential to
improve the economic and environmental sustainability of Ontario corn production.

Caleb Niemeyer (cniemeye@uoguelph.ca)

P34. Abiotic and biotic responses to cover crops and soil amendments in a vineyard
1*
2
Vanvolkenburg, H. ; F. Guinel ; L. Vasseur 1
1 Brock Universit
2 Wilfrid Laurier Universit

Soil is the foundation of all agricultural systems and how it is managed can have implications on the
structure and productivity of the entire agroecosystem. Agrominerals may have the potential to support
soil systems in similar ways as synthetic fertilizers. In combination with cover crops, they may have
synergistic benefits enhancing productivity. This study was conducted on an existing commercial
vineyard in the Town of Lincoln, Ontario, to determine what effects a specific agromineral, Spanish River
Carbonatite, and cover crops (either monoculture or mixture) would have on both biotic and abiotic
variables such as soil nutrients, plant communities, and soil invertebrate community) over two growing
seasons. While amendment type did not affect invertebrate community structure, cover crop combination
mattered with monoculture of ryegrass resulting in higher plant species richness but mixtures having
higher overall plant species diversity. Soil nutrients and plant and invertebrate diversities varied
temporally, both seasonally and annually. Management techniques used by the grape grower most likely
influenced amendment efficacy. To properly determine system effects of amendment and management
technique, it is recommended that fields are monitored over a longer period considering the perennial
nature of this agroecosystem and its complexity.

Heather VanVolkenburg (hvanvolkenburg@brocku.ca)

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