MANAGEMENT OF DRIP IRRIGATION AND PHOSPHORUS FERTILIZATION OF SOME FIELD CROPS GROWN ON SANDY CALCAREOUS SOILS

Abstract

Global concern about the increasing water scarcity for agriculture purposes due to increasing world population. the deterioration of water quality and increasing competition among sectors rose up during the past decades. The newly developed irrigation and fertilization systems (i.e. sprinkler and drip-macro and micro irrigation systems) arc generally recognized as the most water efficient irrigation method Water efficiency in these systems can reach 80-90 % while it only averages 40- 50 %) under surface irrigation.

In l:gypt using the newly developed i rrigation and fertilization systems became obligatory. widely accepted. and more and more day-to­ day agricultural practices especially in newly reclaimed desert soils. In the sprinkler and drip irrigation systems, fertilizers are injected v.rith irrigation water. Therefore. water solubility and compatibility of the fertilizers are critical parameters. Fertilizers applied through drip irrigation systems must be water-soluble. do not react with the irrigation water. and not clog the irrigation equipments. Many N and K fertilizers are easily applied through drip irrigation systems. Phosphorus fertilizers. however. are more difficult to apply and obtain proper distribution in soiL

Because P has limited mobility in soil and may form insoluble precipitates with Ca and Mg in irrigation water, and chemically and physically react · with soil constituents fanning less available P forms. the use of traditional P fertilizers has not generally been recommended for injection in drip irrigation system. In that respect. special care should be taken with phosphate fertilizers injected in alkaline and high calcium containing irrigation waters.

For these reasons. finding practical solutions, and adopting better management for P fertigation received a great com:ern all over the world.