Predicting Sugarcane Response to Nitrogen Using a Canopy Reflectance-Based Response Index Value
- J. Loftona,
- B. S. Tubana *a,
- Y. Kankea,
- J. Teboha and
- H. Viatorb
In Louisiana, sugarcane (Saccharum officinarum L.) N rate recommendations are established based on N response trials and further refined for specific crop age and soil type. Without accounting for current growing conditions and soil N levels, these recommendations can potentially lead to under- or over-application of N fertilizers. The objective of this study was to determine if N response index at harvest (RIHarvest) can be predicted using normalized difference vegetative index (NDVI) response index value (RINDVI). Sensor and yield data were collected from different N field trials from 2008 to 2010 in St. Gabriel and Jeanerette, LA. Nitrogen fertilization treatments ranged between 0 to 201 kg N ha−1. A GreenSeeker Hand Held Optical Active Sensor (Trimble Navigation, Ltd., Sunnyvale, CA) was used to obtain NDVI readings for each of three consecutive weeks beginning 3 wk after fertilization. There was a strong relationship between RINDVI and RIHarvest using the traditional method of determining RI, comparing plots that received high N rates to check plots, with coefficient of determination (r2) values of 0.92 for cane tonnage and 0.81 for sugar yield (P < 0.05). When using a modified RI value, which compared all N rates to the check plot, relationships between RINDVI and RIHarvest were comparable, with r2 values of 0.85 and 0.81 for cane tonnage and sugar yields, respectively (P < 0.05). Our results suggest that NDVI collected 4 wk after N fertilization can be used to predict sugarcane yield response to fertilizer N using the relationships established by either the traditional or modified RI methods.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © 2012 by the American Society of Agronomy, Inc.