Vízügyi Közlemények, 1956 (38. évfolyam)
2. füzet - VII. Kisebb közlemények
(27) жат магнезий. Они могут быть использованы для орошения при увеличении кальциево-ионной концентрации воды с незначительным количеством сухих остатков. Применяемый кальциевый раствор может определяться из эквивалентной величины соды (s). Это вычисляется таким образом, что из щелочности (I.) вычитается эквивалентная величина кальция + магнезия (S 1) : s = L — S v Так напр. если у воды, которая должна быть обработана сухой остаток составляет 300 мг/л, щелочность (L) 13,6 мг/л и эквивалентная величина Ca . + Mg (S,) равна 8,8 мг/л, то эквивалентная величина соды (s) = 4,8 мг/л. Если это умножим эквивалентной величиной гипса (CaS0 4 + 2 Н 20) т. е. числом 86,1, то необходимое для обработки воды количество гипса в приведенном примере равно 86,1 • 4,8 = = 413,28 мг/л. В 1954 году приведенный способ обработки воды в практике с успе хом применялся на 330 га площади. В связи с обработкой воды однако необходимы дальнейшие исследования. FITNESS OF SURFACE WATERS FOR IRRIGATION IN THE TISZALÖK SYSTEM S. Arany, 1). of Agricultural Sc. (Figures and tables on pp. 197 — 214 of Hungarian text) 626.810 : 631.41 : 54 For successful irrigation-farming and ricegrowing, features of soil and water must be known. In the Tiszalök irrigation system high water losses have to be reckoned with for water that does not infiltrate into the soil. Every drop of water available, thus water drained from the surface too, has to be used for irrigation: however, no matter how irrigation is necessary, the quantity oj water is о/ secondary importance in comparison to its quality. From the Tiszalök irrigation land about 76 000 hectares are covered with shallow humus, and about 3/, of these are alkali soils. Therefore a large part of the soil of the area is not capable of storing an adequate quantity of water, even if the storage capacity of the surface layer is high. If the soil is alkaline and cannot therefore store sufficient water for plant-growing, the infiltration capacity can be raised only by soil reclamation. In the determination of the fitness of surface waters for irrigation the following requirement is of importance : Water which is not silt у is suitable for irrigation as long as it takes up alkali soil forming sodium ions from the soil and does not release such ions into the soil. The given definition does not exclude alkaline waters from irrigation in specific cases. But the case when such waters can be used without the danger of alkali soil formation cannot always be stated, not even with joint examination of water and soil. According to experience the solid residue of good irrigation water is less than 500 mg per liter, such water does not show phenolphtalein alcalinitv, and the proportion of other anions especially of chlorides is very low. From the theoretical as well as practical viewpoint it is very important to ascertain whether the water is alkaline, and if so. to what degree. In the investigation of this both the quality and quantity of the cation and anion components are to be taken into consideration. If the compound sodium -f anion activités hydroxyl — OH — ions, its presence even in minute quantities in irrigation water is undesirable. Such anions are the carbonate (COV), the silicate (SiO, ), the aluminate (AlOV ). Alkali salts of these are destructive to the soil and poisonous to plants. So far we have not ascertained what minimum quantities of these anions are harmless in irrigation water. For the time being water can be used for irrigation safely only after their removal or neutralization. In surface waters of the Tiszalök system chlorides (CI ) and sulphates (S() 4 ) are very frequent anions, but chlorides are more poisonous than sulphates. In surface waters of this irrigation system anions may be classed practically in relation to their poisonous effect according to the following equivalent proportions in mg per liter : 0,01 C0 3 : 0,1 CI : 0,5 S0 4
