USE OF A CROP MODEL TO STUDY THE RESPONSE OF ARTICHOKE TO DIFFERENT LEVELS OF SOIL MINERAL NITROGEN
Traditional nitrogen fertilization practices are associated with the increase of nitrate concentration in the groundwater in the intensive horticultural areas of the Mediterranean coast of Spain. In spite of this, there are only few studies on the actual needs of soil mineral N (Nmin) of artichoke, which is an important vegetable crop in several Mediterranean areas. In this work, we study the response of artichoke (Cynara scolymus L.) to different soil mineral nitrogen levels using the crop model N_ABLE (Horticulture Research International, UK). The crop was grown during two seasons on a sandy loam soil in an area near Valencia (Spain). Four fertilizer rates were applied in order to obtain four levels of soil available Nmin in the 0-60 cm layer (N0, N1, N2 and N3) that ranged from 113 kg N/ha to 416 kg N/ha. Available mineral N in soil includes the soil Nmin at planting time in the 0-60 cm layer plus the N applied as fertilizer, and that contained in the irrigation water and in the rain. During the two growing seasons soil and plants were sampled six times. Soil mineral N (ammonium + nitrate) was determined in soil and irrigation water, whereas total N was measured in plants. No increase in plant dry matter with available mineral N was observed, although the N3 treatment had a higher yield (p<0.05). N_ABLE does not include artichoke in its database and, therefore, mean values of the parameters of similar crops included in the model were used. Two of these parameters (PNINF and B0) define the curve that establishes the plant critical N content as a function of plant dry matter. Simulations were also made using values for PNINF and B0 that were derived from several N artichoke field experiments in this area. The model simulated reasonable well dry matter production and plant-N content but predictions improved when the PNINF and B0 values obtained from previous artichoke experiments were used. Simulated and calculated drainage at 90 cm were also very similar. However, N leaching was only well predicted in the second growing cycle while in the first cycle it was highly overestimated. An example of how the model can be used for fertilization management is shown. More testing of the model appears necessary to determine its usefulness for nitrate leaching prediction under Mediterranean conditions.
Doltra, J., Carpintero, J.M., Berbegal, F., Khayyo, S. and Ramos, C. (2007). USE OF A CROP MODEL TO STUDY THE RESPONSE OF ARTICHOKE TO DIFFERENT LEVELS OF SOIL MINERAL NITROGEN. Acta Hortic. 730, 257-264
Cynara scolymus L., fertilization, plant critical N, nitrate leaching, N_ABLE, modeling