Abstract

A field experiment was conducted in a silty-loam soil in AL-Saqlawia district, 40 kilometer east the city of Ramadi at the center of AL- Anbar governorate in season 2012, to study the effects of adding phosphogypsum,Irrigation water salinity, cotton cultivars and the interaction among them in some of chemical properties of soil affected with saline. The design used is, the split–split plots design with RCBD. Irrigation treatments occupied the main plots which are, (w1) Irrigation with river water throughout the season; (w2) Irrigation by alternating between river and drainage water; and (w3) Irrigation with drainage water with salinity percentage of 3.55 dS.m-1 throughout the season long. cotton cultivars took sub–plots, and they are, (C1) Coker Welt 310; and (C2) Lashata. Levels of phosphogypsum was under the secondary plots sub–sub plots which are three levels: (GP0) without adding; (GP1) adding an average of 3 t.ha-1 ; and (GP2) adding an average of 6 t.ha-1.
Cotton seeds were planted at 21/3/2012, soil samples representing the depths of the study 0-25,25-50,50-75cm were taken after second reaping at 25/9/2012 to measure; SAR, PH, ECe and dissolved positive ions(Ca+2,Mg+2,Na+) were estimated.The results showed that:
Addition of 6 t.ha-1 of phosphogypsum significantly increased electrical conductivity. The increase at the first depth recorded 25.40%, at the second depth 26.93%, while at the third depth 24.27%. and significantly decreasing soil PH at the first and second depth only, with a declining rate of 3.66% at the first depth, and 2.97% at the second depth, while the third depth recorded an significantly increase in soil PH 1.99%. and significantly decreasing sodium adsorbtion Ratio at the first depth with a declining rate of 3.66% and 2.97% at the second depth. and significantly decreasing soluble sodium in soil at the first depth recording a decline rate of 37.10%, and at second depth 21.65%. and significantly increasing soluble calcium and magnesium for each depth in soil at rates of 37.65% 33.66% and 34.03% for Ca+2. 31.41%, 31.35% and 22.77% for Mg+2 at three depths, respectively compared with control. Irrigation with drainage water significantly increased electrical conductivity by 16.56%. soluble Sodium 28.33% compared with irrigation with river water.