Assessment of the nitrogen management strategy using an optical sensor for irrigated wheat - 2011
Peer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=1774-0746
Blanket fertilizer nitrogen (N) recommendations for large irrigated wheat tracts lead to low N-use efficiency due to field-to-field variability in soil N supply and seasonal variability in yield. To achieve high N use efficiency, a site-specific N management strategy using GreenSeeker? optical sensor was evaluated. We conducted seven field experiments during 2004?2006 at three locations to define relationships between in-season sensor measurements and yield of wheat and to know whether response of wheat to fertilizer N can be estimated by sensor measurements. During 2005?2007, four field experiments were conducted to assess the sensor-based N management strategy and to work out prescriptive N management to be followed prior to applying sensor-guided fertilizer dose. We observed robust relationships between in-season sensor-based estimates of yield at Feekes 5?6 and 7?8 stages and actual wheat yields. Response of wheat to fertilizer N defined by the sensor was highly correlated with harvest response index. Sensor-guided fertilizer N applications resulted in high yield levels and high N-use efficiency. Application of 90 kg N ha-1 at planting or in two equal doses at planting and crown root initiation stage was the appropriate prescriptive fertilizer N management. This study reveals that high N-use efficiency in irrigated wheat can be achieved by replacing blanket fertilizer recommendation by an optical sensor-based N management strategy consisting of applying moderate amount of fertilizer N at planting and crown root initiation stages and sensor-guided fertilizer N dose at Feekes 5?6 or 7?8 stages of wheat.
1773-0155 (Revista en electrónico) 1774-0746
GreenSeeker optical sensor