Nitrogen fertilization management in orchards to reconcile productivity and environmental aspects

Nitrogen fertilization in orchards of Emilia-Romagna Region, (Italy) was based in the past on excessive, not split, applications often supplied late in winter; the NUE (Nitrogen Use Efficiency) was therefore low and the risk of nitrate leaching was high. This paper summarizes the studies conducted in the last 10 years at the Department of Horticulture and Forestry of the University of Bologna aimed to develop a more rational use of nitrogen in orchards and vineyards. Root escavation of mature trees revealed that the use of localized irrigation (drip or microjet) causes a concentration of roots in the area wetted by the emitters. In such a situation, band applications of N to the tree row may allow a reduction of amounts of N fertilizer, while widespread applications, especially if the orchard soil is tilled, lead to an accumulation of nitrates in the alley. Results of several field trials where increasing N rates were applied indicate that the kind of response to N supply depends on the presence in soil of natural sources of nitrogen. This fact clearly stresses the necessity of evaluate the N status of an orchard before N fertilization. Rapid estimation of leaf chlorophyll by portable instruments is a promising index of leaf N concentration, only provided that calibration is made for each cultivar. A method, currently under testing in orchards and vineyards of Emilia-Romagna, is proposed here to adjust N fertilizer rates to the demand of the crop and to the level of available N in soil as determined in soil or soil solution samples.

[1]  T. Dejong,et al.  Causes and Consequences of Overfertilization in Orchards , 1992 .

[2]  M. L. van Beusichem,et al.  Optimization of Plant Nutrition , 1993, Developments in Plant and Soil Sciences.

[3]  K. Shaw.  Loss of mineral nitrogen from soil , 1962, The Journal of Agricultural Science.

[4]  O. Löhnertz.  Soil nitrogen and the uptake of nitrogen in grapevines , 1991 .

[5]  G. Velthof,et al.  Ammonia volatilization from compound nitrogen-sulfur fertilizers , 1993 .

[6]  C. J. Clark,et al.  Nutrient dynamics of a kiwifruit ecosystem , 1988 .

[7]  Relationship between chromaticity values and nitrogen content of pear leaves , 1994 .

[8]  B. Bravdo,et al.  32 – IRRIGATION, WATER STATUS AND NUTRIENT UPTAKE IN AN APPLE ORCHARD , 1980 .

[9]  F. Legaz,et al.  Seasonal uptake of 15N-nitrate and distribution of absorbed nitrogen in peach trees , 1993, Plant and Soil.

[10]  Dr. Wolfgang Böhm.  Methods of Studying Root Systems , 1979, Ecological Studies.

[11]  D. Greenham.  Nutrient cycling: the estimation of orchard nutrient uptake. , 1980 .

[12]  Kenneth G. Cassman,et al.  Adjustment for Specific Leaf Weight Improves Chlorophyll Meter's Estimate of Rice Leaf Nitrogen Concentration , 1993 .

[13]  P. Millard,et al.  The Effect of the Autumn Senescence of Leaves on the Internal Cycling of Nitrogen for the Spring Growth of Apple Trees , 1989 .

[14]  M. Tagliavini,et al.  Influence of root pruning and water stress on growth and physiological factors of potted apple, grape, peach and pear trees , 1992 .

[15]  M. Faust,et al.  Nutritional ranges in deciduous tree fruits and nuts. , 2011 .

[16]  K. Mengel,et al.  Relationship between electroultrafiltration (EUF) extractable nitrogen, grain yield, and optimum nitrogen fertilizer rates for winter wheat , 1992, Fertilizer research.

[17]  J. Schepers,et al.  Comparison of corn leaf nitrogen concentration and chlorophyll meter readings , 1992 .

[18]  D. Atkinson,et al.  THE ROOT-SOIL INTERFACE AND ITS SIGNIFICANCE FOR FRUIT TREE ROOTS OF DIFFERENT AGES , 1979 .

[19]  R. Q. Cannell.  Methods of Studying Root Systems . By W. Böhm. Berlin: Springer (1979), pp. 200, DM 69, $38.00. , 1980, Experimental Agriculture.

[20]  M. Watson,et al.  Plant Analysis Handbook: A Practical Sampling, Preparation, Analysis, and Interpretation Guide , 1992 .

[21]  K. Schaller.  Ground water pollution by nitrate in viticultural areas , 1991 .