if something provides something else then that something conducts the unit of that something else & an increase in the amount of something causes there to be more of something ->  if something provides something else then that something causes there to be more of something else  if something provides something else then that something ability there to be more of something else & growing legumes provide nitrogen for other plants -> growing legumes causes there to be more nitrogen for other plants growing legumes causes there to be more nitrogen for other plants  decreasing filter angle there to be more antinitrogen for other animal & if something causes something else then that something else is an effect of that something -> more nitrogen for other plants is an effect of growing legumes