IRRIGATION AND FERTILIZATION PROGRAMS FOR "WASHINGTON NAVEL" ORANGE TREES IN SANDY SOIL UNDER DESERT CLIMATIC CONDITIONS. 1- EFFECT ON SOIL PROPERTIES, VEGETATIVE GROWTH AND YIELD

Document Type : Original Article

Abstract

This study was carried out during the two successive growingseasons of 2013 and 2014 on seven years old "Washington Navel'' orangetrees budded on Volkamer lemon grown at a commercial orchard near El-Nubaria city, Beheira Governorate, Egypt, to evaluate the effect of differentkinds of fertilizers with using the organic and bio-fertilization partially instead
of completed mineral fertilizers as applied at 33.33 to 100 % out of therecommended NPK rate. Organic fertilizers (compost) with three natural rocks(rock phosphate , feldspar and mixed mineral ore) were applied with orwithout bio-fertilizers (Azospirillum lipoferum for N, Bacillus megaterium for PandBacillus circulans for K) at 25g/tree on soil properties, vegetative growthand fruit yield under three different irrigation levels (1- Actual irrigation
practiced in the orchard (control) 100%, 2- Irrigation at 75% of control and 3-Irrigation at 50% of control) in sandy soil under drip irrigation system. Theresults indicated that use of moderate irrigation (2919.34 - 3157.88m3/fed./year) and the fertilization program/fed./year (33.33% mineral NPK +33.33% organic NPK + 33.33% mixed mineral ore + bio-fertilizer NPK)followed by (50% organic NPK + 50% mixed mineral ore + bio-fertilizers NPK)exhibited decrease in pH and increased (EC, O.M., available macronutrients(NPK), soil microorganisms content and dehydrogenase activity) and improvemost of vegetative growth parameters particularly trunk cross-sectional area(TCSA), canopy volume (CV), number of shoots, average shoot length, averageshoots diameter and number of leaves/shoot at the spring growth cycle, leaf area,leaf dry weight and specific leaf weight in both seasons and achieving the best fruityield with its components as number of fruits/tree, kg/tree, ton/fed. and yieldefficiency (YE). While the deficit irrigation treatment (level 3) with the samefertilization program resulted in an increase field water use efficiency (FWUE)and water productivity (WP). Therefore, both two programs are recommended fororange farmers to save about 25% of irrigation water and replaced about
66.66% of chemical fertilizers by others of natural source and safe for humanand environment without any negative responses on soil properties,vegetative growth and yield assuring higher profit for "Washington Navel"orange trees growers under conditions of this study.

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