Develop the near-infrared spectroscopy (NIRS) technique to determine N soil supply and plant demand in permanent pasture.

1.- Calibrate and validate the use of NIRS to estimate nitrogen supply from volcanic soils. 2.- Use NIRS to generate dilution curves for high production ryegrass cultivars under different nitrogen fertilization rates and different soil types. 3.- Determine the soil-plant interaction as for N supply and plant demand, as axes to optimize nitrogen fertilization.