الفهرس 
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Abstract
The present study was conducted in Soil Science Dept., Faculty of Agriculture, Minia University during 1994, 1995 and 1996 seasons, to study the effect of K. Mg and moisture levels and their interactions on some growth parameters of sorghum grown in four different soils in terms of dry matter yield and K. Mg and Ca concentration and uptake by plants.
To perform the above mentioned three parts of Lab. and cultivation work was carried out as following:
Part 1:
A. Potassium fractionation in the studied soils before cultivation:
The main values of K fractions in the studied soils were varied from
0.12 to 0.25, 1.2 to 3.75, 2.25 to 6.94, 0.79 to 3.39 and 0.19 to 3.39 me./100 g soil of soluble water. exchangeable. reserve, total step and constant rate potassium, respectively. The higher values were recorded in fine textured soils, whereas, the lower ones were recorded coarse textured soils.
R. Magnesium status in the studied soils before cultivation:
The main values of Mg content in the different soils were varied from
0.17 to 0.42, 1.4 to 3.48. 2.0 to 4.2 and 1.0 to 7.75 me./ 100 g soil of water soluble, exchangeable, 0.01 M CaCl2 and 0.5 M Nacl extractants, respectively. Also, as the case of K fractions, the higher mean values were recorded in fine textured soil and the lower ones in coarse textured soils.
Part If: Cultivation experiments
A greenhouse experiment was carried out to study K and Mg supplying power of four soils tinder two moisture levels. Sorghum (Giza 15)
was grown for three seasons successively (1994, 1995 and 1996) in 2.75 Kg of the treated soils and for a period of 45 days for each season. The tested treatments (72 ones) were two levels of K (50 and 100 Kgs of K20/fed.), two levels of Mg (25 and 50 Kgs of MgO/fed.), two moisture levels (50 and 75% of F.C.) and their interactions in four soils. The obtained foliage in each season was recorded as dry matter yield and analysed for K, Mg and Ca conc. and their uptake by plants were calculated.
1. Dry matter production (DM):
The data about DM of sorghum in the three seasons as affected by the studied treatments could be summarized in three broad lines as following: 1.1. Effect of the soils:
The obtained results indicated that the different soils could be arranged according to their performances in DM production in the three seasons in the following order:
non saline clay > saline clay > sandy > sandy calcareous soil. 1.2. Effect of K and Mg levels and their interactions:
1.2.1. Effect of K levels:
The results clearly indicated that DM of sorghum markedly increased with increasing K levels over control regardless of the studied soil or moisture level. Furthermore, the increase in dry matter production over control due to K treatments showed a decreasing trend from season to season.
1.2.2. Effect of Mg levels:
Data clearly show the marked increase in DM of sorghum grown in Mg treated soils as compared to control and the increase was proportional to
the increase in Mg levels. Moreover, the increase in DM showed a
decreasing trend from season to season.