username = driver.find_element_by_name('_username')
username.send_keys('username')

password = driver.find_element_by_name('_password')
password.send_keys('Password')

submit_button = driver.find_element_by_id('buttonSubmit__login')
submit_button.click()

submit_Sutability_and_Potential_Yield = driver.find_element_by_name('_targetfieldmain=main_py&_passChanged=true&_eventtype')
submit_Sutability_and_Potential_Yield.click()

submit_AgroEco_Suitability_and_Productivity = driver.find_element_by_name('&fieldmain=main_py&idPS=0&idAS=0&idFS=0&_targetfieldmain=main_py_six&_passChanged=true&_eventtype')
submit_AgroEco_Suitability_and_Productivity.click()

selenium.common.exceptions.NoSuchElementException: Message: no such element: Unable to locate element: {"method":"name","selector":"fieldmain=main_py_six_qdns&idPS=0&idAS=0&idFS=0&_passChanged=true&_eventtype"}
  (Session info: chrome=59.0.3071.115)
  (Driver info: chromedriver=2.30.477700 (0057494ad8732195794a7b32078424f92a5fce41),platform=Windows NT 6.1.7601 SP1 x86_64)

<input id="buttonSubmit__type_fieldmain=main_py_six_qdns&idPS=0&idAS=0&idFS=0" name="fieldmain=main_py_six_qdns&idPS=0&idAS=0&idFS=0&_passChanged=true&_eventtype" value="Total production capacity (t/ha)" onclick="return wf_click(this);" type="submit" class="linksubmit linksubmitfalse" style="font-size: 80%;">

//*[@id="buttonSubmit__type_fieldmain=main_py_six_qdns&idPS=0&idAS=0&idFS=0"]