Error_log files is occupied fully with errors given below the total size of the error_log file is more than 2gb, i don't understand why this happens, and let me know how to rectify this.

Thank you

Error_log:

[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxPluginManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajax.inc.php on line 269
[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxLanguageManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajax.inc.php on line 272
[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxArgumentManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajax.inc.php on line 273
[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxResponseManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajax.inc.php on line 274
[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxResponseManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajaxResponse.inc.php on line 104
[01-Sep-2014 12:09:11 America/Chicago] PHP Strict Standards: Non-static method xajaxPluginManager::getInstance() should not be called statically, assuming $this from incompatible context in /home/tvmalai/public_html/libs/ajax/xajax_core/xajaxResponse.inc.php on line 109
[01-Sep-2014 22:39:12 Asia/Kolkata] PHP Strict Standards: Declaration of rlTestimonials::getOne() should be compatible with rlDb::getOne($field = false, $where = NULL, $table = NULL, $prefix = false) in /home/tvmalai/public_html/plugins/testimonials/rlTestimonials.class.php on line 214
[01-Sep-2014 22:39:12 Asia/Kolkata] PHP Strict Standards: Only variables should be assigned by reference in /home/tvmalai/public_html/libs/ajax/xajax_core/xajaxPluginManager.inc.php on line 268...........