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.
Negative Aspects. Some critics say that the harvesting of bat guano from caves has certain detrimental effects. The process, which is also called mining, disturbs the bats' habitat and can cause them to panic, which can result in the bats dropping their young, not eating or not getting enough rest. It has been blamed for bat populations decreasing in areas where guano is harvested.