The smock mill Goliath in front of the wind farm Growind in Eemshaven in the Netherlands. A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades. Centuries ago, windmills usually were used to mill grain (gristmills), pump water (windpumps), or both.
When bat guano is harvested, it is in a powdered form. Plants that can benefit from the use of bat guano fertilizer include vegetables, herbs, ornamentals, and fruit and nut trees.
Definition of guano for English Language Learners. : waste material from birds and bats that is used to help plants grow.