EFFECT OF POTASSIUM FERTILIZATION ON WATER ECONOMY AND MAIZE PRODUCTIVITY IN NEWLY RECLAIMED SALINE SOIL OF EGYPT

A field experiment was carried out on saline soil ( loamy sand soil ) at Gelbana Village, El-Tina Plain, North – Western Sinai Peninsula  , Egypt during two successive growing summer seasons of 2011 and 2012 to study the influence of potassium fertilization on the productivity of  maize ( Zea mays  L. , cv. Trible hybrid 310 ) and yield component . The maize was grown on newly reclaimed saline soil of Egypt under different levels of irrigation water. The used irrigation water resource was El-Salam Canal . Potassium fertilization was applied as soil application at rates of  0 , 24 , 36 and 48 kg  K2O / fed. and as foliar application at rates of  0 , 1 , 2  and 4 % K2O, equal to 0, 4 , 8 and 16 kg K2O/ fed., respectively which dissolved in 400 liter water of irrigation and sprayed . The used K fertilizer was K2SO4 ( 48 % K2O ) . Each rate of added K as soil application and foliar application was added on two equal doses after 30 and 65 days  from sowing .  Surface  irrigation  system  was used , where  the soil was irrigated at three levels of  water requirement (WR) of maize plant under saline soil conditions. These levels were 50 , 75 and 100 % of  WR , which equal 4250 m³/ fed. The experiment was carried out in split design with three replicates .
The obtained data show that , K fertilization with either of soil or foliar application resulted in a significant increase of the measured growth parameters .i.e. stover and yield ( ton / fed. ) , grains weight ( g / plant) , ears weight (g / plant) , weight of 100 grains ( g) and biological yield (ton / fed. ) . According to the mean values of RC ( % ) , the grains yield was more than stover yield with foliar application , where the stover yield was more than grains yield with soil application. The increases in these parameters were increased with increasing K rate . At the same irrigation level , the yields of  stover and grains produced from each one  m³ of the added water was increased with the increase rate of added K as soil or foliar application. Under different treatments of K fertilization, the grain content (%) of N , P , K and protein were increased significantly and its become more significant with the increase of added irrigation water. Maize grains contents (mg / kg ) of  Fe , Mn and Zn were increased significantly with the increase of added K fertilization for both soil and  foliar applications . Except K, the contents of  the determined macro and micronutrients resulted from the treatments of  soil application, were higher than those associated the treatments of foliar application . Under saline soil conditions, the best treatment was soil application of  K  fertilization at  rate of  48 kg  K2O / fed. with irrigation  at 100 % WR .
The important conclusion which may be extract from the obtained data is potassium fertilization increased irrigation water use economy . The best value of  water economy were with 48 kg K2O / fed. as  soil application  and  4 %  K2O  as  foliar  application at 50 % WR .