EFFECT OF SOME SOIL MANAGEMENT PRACTICES AND NITROGEN FERTILIZER LEVELS ON SOME SOIL PROPERTIES AND ITS PRODUCTIVITY AT NORTH DELTA

A field experiment was conducted at Sakha Agricultural Research Station Farm, Kafr El-Sheikh Governorate, Egypt to evaluate the effect of subsoiling, sandy mole drains and nitrogen fertilization on improving some soil properties, some water relations and yields of wheat (2008/2009) and maize (2009) in clayey salt affected soils. The design of this experiment was laid in split-split plot design with four replicates. The main plots were assigned to nitrogen fertilizer levels (75, 90 and 110 kg N/fed.). The subplots were devoted to mole drain spacing (2, 4, and 6m), while the mole types (subsoiling and mole drain filled with sand) were allocated in sub-sub plots.                                  
The most important findings could be summarized as follows:        
● The application of subsoiling at 2m spacing with addition of 110 kg N /fed., gave the highest production of wheat (2632 kg grain/fed. and 3680 kg straw /fed.)  and maize ( 3380 kg grain /fed. and 5361 kg straw /fed.).
● The values of ECe and SARe in the top soil layer after harvesting of wheat and maize crops were lower than that in subsoil layers.                                               
● The installation of sandy moles at 2m spacing was more effective in leaching of soil salts comparing to that with or without subsoiling. Therefore, the highest mean values of ECe and SARe after harvesting of wheat (6.35 dSm^-1 and 12.36, respectively) and after harvesting of maize (5.05 dSm^-1 and 11.10, respectively) were achieved with sandy moles at 2 m spacing.               
● The highest values of field water use efficiency for wheat grains 1.14 kg/m³ was achieved from interaction between sandy mole at 6m spacing with 110 kg N/fed. While the highest value of crop water use efficiency (2.03kg/m³) was achieved with sandy mole drains at 2m spacing under 110kg N /fed_.
● The highest values of field water use efficiency for  maize grains (1.0 kg/m³) was obtained from combination between the control treatment and 90 kg N/fed  ,while the highest value of crop water use efficiency (1.52 kg/m³) was achieved from  sandy mole at 6m spacing under 110 kg N /fed.
* The subsoiling followed by sandy mole at 2m spacing were more effective on basic infiltration rate and achieved the highest values of basic infiltration rate.