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Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor
Abstract:
Plants demonstrate visual and physiological signals that are reflective of their growing conditions. These signals are being used to guide development of early season variable-rate fertilizer nitrogen (N) applications to corn (Zea mays, L.) using optical sensors. This project is examining whether monitoring these signals in-season can quantify residual soil nitrate following corn harvest. Corn was monitored in-season at growth stages R2, R3-R4 and R5 using a SPAD meter, an optical sensor and by green leaf counts. Data from all three measurement techniques was significantly correlated with corn relative yield and with each other. However, the relationship with residual soil nitrate for all three techniques was weak, reflecting the inability of these tools to characterize N fertility status of corn beyond the deficient to optimum range. Nevertheless, monitoring these signals late in the growing season could provide a simple and useful on-farm tool to assess nitrogen management. For example, a producer could easily evaluate new N management practices in on-farm field strips that include either a standard practice or a high N fertility strip and use a simple green leaf count to help answer the question of whether the new N management practice was adequate.
Corn will luxury accumulate nitrate in the corn stalk, forming the basis for the corn stalk nitrate test (CSNT), a post-season test. The CSNT can characterize corn N fertility status in the above optimum range. A second objective of this project is examining the CSNT to characterize residual soil nitrate and corn performance. Although much work has been done that relates CSNT results to corn relative yield, little information has been published relating CSNT results to residual soil nitrate. This poster will present the relationships observed for the three in-season plant-based measurements that were assessed plus the CSNT with corn performance and residual soil nitrate.
Corn will luxury accumulate nitrate in the corn stalk, forming the basis for the corn stalk nitrate test (CSNT), a post-season test. The CSNT can characterize corn N fertility status in the above optimum range. A second objective of this project is examining the CSNT to characterize residual soil nitrate and corn performance. Although much work has been done that relates CSNT results to corn relative yield, little information has been published relating CSNT results to residual soil nitrate. This poster will present the relationships observed for the three in-season plant-based measurements that were assessed plus the CSNT with corn performance and residual soil nitrate.