Combining two different coding program into one sketch
The simplest way of combining two programs is this:


Copy the content of the two programs into a single new .ino (program) file 
Rename the first setup function setup_one 
Rename the first loop function loop_one 
Rename the other setup and loop functions setup_two and loop_two 
Add the following code to the bottom of that file.


Code:

void setup()
{
  setup_one();
  setupr_two();
}
void loop ()
{
  loop_one();
  loop_two();
}


This is a very simplistic approach and it won't work for all cases.  It will work in this case, but you will find it will do program one then program two.  It will work because your constants don't clash (at the top of the program) you aren't using the same pin in the different programs, etc.

You need to learn what the code does though to really merge the programs, you will see better ways of doing it.  The best way to learn is to right down, in your native language, what each line of code does, so in the case of program one:

turn on the motor
turn on the LED
wait for 'watertime' seconds
turn off the motor
turn off the LED
wait for 'waittime' minutes


For program 2:

  read the state of the pushbutton value:
  If the button is in state low
    Turn off the LED -- Not sure  this might be on
  else  
    Turn on the LED -- Not sure this might be off


Hopefully you should recognise those descriptions (they are the comments) and when you read through the descriptions you will realise why the code you put together using the above method "doesn't work".  It does, you just need to wait for 'waittime' minutes before you get a few microseconds to press the button.

If you want the motor to respond to the button then rearrange the natural language description to do what you want and then replace the English with the code and you should have a program that is close to working.  (Hopefully)