The aim of this research is to study CO2 released in vertical and horizontal developing directions of rhizosphere (0-5 and 5-10) cm . The plots experiment is performed in college of Agriculture / Al-Qadissiya University for the spring season 2013 ,the loamy sand soil has been used and cultivated Tomato (Lycopersicon Esculentum mill) and Bean (Phaseolus Vulgaris L.) plants under salinity levels (without salted (the natural salinity) , 6 , 8 and 10) ds.m-1 and compost levels (0,10 ,20)T.h-1 , and their interactions randomized complete design (RCD) is used with three replicates as compared with L.S.D test 5% level .
The soil has been incubated under the same treatments and the interactions in vertical and horizontal developing directions of rhizosphere for both plants under incubated periods (2 , 4 ,7 and 14) day for calculated the CO2 released .
The results are summarized as follows :
1- The highest quantities of CO2 released are in salinity level 6ds.m-1 and decreases with the increasing of salinity levels and the lowest in the 10ds.m-1 level for both plants .
2- The adding compost levels leads to an increase of CO2 released , the CO2 released quantities are varied in vertical and horizontal rhizosphere developing and the CO2 released quantities in horizontal rhizosphere developing are highest than the vertical direction for both plants .