The adoption of precision agriculture technologies is probably one of the greatest challenges and opportunities of the 21st century to expand the horizons of soil and plant analysis by matching the spatial variability of soil properties and crop demand with a variable input of agro-resources in the field. The high cost of soil sampling and chemical and physical analysis by conventional laboratories has restricted the full implementation of this technique at field level. Near Infra Red (NIR) analysis could be a cost-effective solution, but a whole paradigm shift in philosophy is needed to move away from the traditional approach in soil testing of taking a 'perceived' representative sample in which all the spatial variation is lost, to using a combination of grid soil sampling at a sample intensity of 4 to 10 cores per ha, in which the sub samples are analysed separately using rapid but less accurate methods such as NIR. Agricultural industries worldwide are showing increasing interest in the potential applications of near infrared (NIR) analysis in the fields of soil fertility, cane nutrition, cane quality testing and screening for resistance to certain pests and diseases. Recent investigations in the sugar and wheat industries have demonstrated the feasibility of using NIR scanning techniques for mapping spatial variability of important soil properties on a field scale. Soil properties that have been calibrated include gravimetric soil water, clay, buffer capacity, pH, electrical conductivity, titratable acidity, organic matter, mineralizable nitrogen, potential ammonia volatilization from urea, potential nitrification rate, and urease activity. Mapping spatial variability in this way will enable better utilization of resources such as the application of fertilizers.
source: http://www.cababstractsplus.org/google/abstract.asp?AcNo=20053159362
