OPTICAL CHARACTERISTICS OF SPRING WHEAT LEAVES DEPENDING ON NITROGEN USE EFFICIENCY AND RESPONSIVENESS TO FERTILIZER APPLICATION

Sustainable crop production systems can be attained by using inputs efficiently and nitrogen use efficiency (NUE) parameters are indirect measurements of sustainability of production systems. The objective of this study was to investigate the effect of selected nitrogen (N) management treatments on wheat yields, grain and straw N concentration, and NUE parameters, under conservation agriculture (CA). The present study was conducted at the International Maize and Wheat Improvement Center (CIMMYT), in northwest, Mexico. Seventeen treatments were tested which included urea sources, timing, and methods of fertilizer application. Orthogonal contrasts were used to compare groups of treatments and correlation and regression analyses were used to look at the relationships between wheat yields and NUE parameters. Contrasts run to compare wheat yields or agronomic efficiency of N (AEN) performed similarly. Sources of urea or timing of fertilizer application had a significant effect on yields or AEN (p > 0.050). However, methods of application resulted in a highly significant (p < 0.0001) difference on wheat yields and agronomic efficiency of N. NUE parameters recorded in this study were average but the productivity associated to NUE levels was high. Results in this study indicate that wheat grew under non-critically limiting N supply levels, suggesting that N mineralization and reduced N losses from the soil under CA contributed to this favorable nutritional condition, thus minimizing the importance of N management practices under stable, mature CA systems.

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PAPER PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Reduced nitrogen and improved farm income for irrigated spring wheat in the Yaqui Valley, Mexico, using sensor based nitrogen management

The Journal of Agricultural Science ◽

10.1017/s0021859607006995 ◽

2007 ◽

Vol 145 (3) ◽

pp. 215-222 ◽

Cited By ~ 41

Author(s):

J. I. ORTIZ-MONASTERIO ◽

W. RAUN

Keyword(s):

Technology Transfer ◽

Spring Wheat ◽

Nitrogen Use Efficiency ◽

Nitrogen Management ◽

Farm Income ◽

Wheat Crop ◽

Nitrogen Use ◽

Yaqui Valley ◽

Crop Cycle ◽

Use Efficiency

Wheat nitrogen-use efficiency in the Yaqui Valley has been estimated at about 0·31. The nitrogen that is not recovered by the crop has important environmental costs that have regional and global consequences. In addition, these nitrogen losses represent an important reduction in farm income. The objective of the present work was to validate a technology that includes the use of N-rich strips together with the GreenSeeker™ sensor and a crop algorithm in farmers' fields with the ultimate goal of improving nitrogen-use efficiency through site-specific nitrogen management in irrigated spring wheat. During the wheat crop cycle 2002/03 and 2003/04, 13 validation experiments of c. 1 ha each were established in farmers' fields in the Yaqui Valley. After the validation phase, during the wheat crop cycle 2005/06, eight technology transfer trials were established in farmers' fields; these had on an average an area of 10 ha each. Both the validation and technology transfer trials compared the farmers' conventional nitrogen management use v. the use of the N-rich strip together with the Green Seeker™ sensor and a crop algorithm to derive N recommendations for each individual field. The results of the validation trials showed that on an average over all locations, farmers were able to save 69 kg N/ha, without any yield reduction. At the price of US$0.9 per unit of N in the valley when these experiments were established, this represented savings to the farmers of US$62/ha. The technology transfer trials demonstrated that, in large commercial areas with an average size of 10 ha, farmers could improve their farm income by US$50/ha, when using sensor based N management. The combination of the N-rich strip, together with the use of the sensor and a crop algorithm to interpret the results from the sensor, allowed farmers to obtain significant savings in N use and thus in farm profits. Farm income was increased by US$56/ha, when averaged over all trials in all years.

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