ESTIMATE OF THE CRITICAL LEVEL OF AVAILABLE ZINC IN SOME MIDDLE EUPHRATES SOILS BY USING ANALYSIS OF VARIANCE METHOD OF TWO CLASSES SUM SQUARES

Abstract

Abstract A biological experiment was carried out to evaluate zinc soil fertility status by estimating critical level of both available zinc in soil and its content in plant using wheat (cv. Mexipak L.) as an economical test crop in twenty locations of Middle Euphrates. Two levels of zinc as ZnSO4.7H2O (23% Zn) (0 and 5 mg Kg-1 soil) were used for estimation critical level of plant available zinc. Factorial randomized complete block design with three replicates was used in this study.The results revealed the following: Critical level of available zinc in all tested soils was 0.76 mg Kg-1 soil and the statistical method was more efficient than graphical method for estimation plant Zn availability as depending on two classes sum squares, coefficient of determination (r2) and t value as statistical indexes. Using relative yield was superior criterion for evaluation plant available Zn as compared with maximum yield according to the three statistical parameters. The values of these parameters were 891.89, 0.787 and 8.156 for relative yield and 69.101, 0.737 and 7.103 for maximum yield respectively. The results also showed that the critical level of zinc plant content before blooming stage was estimated as 17.86 mg Kg-1 dry weight. The response percentage of soils for zinc fertilization was recorded about of 45% from the used soils.