1 Mechanical digestion is evident, where one can see the breaking down of large food particles into smaller ones after being ground by the teeth. 2  While the chemical changes that take place happen within the body and are not visible.
Using a pre-emergent herbicide around your property could stop these territorial plants from overtaking your home's most valued green space. Pre-emergent herbicide is a type of weed killer that prevents weed seeds from sprouting. Unlike normal herbicide, it is meant to stop weeds from growing in the first place by spraying or spreading a chemical onto the soil so that weeds have difficulty placing down their roots.
Sum it up. To sum it up, pre-emergent fertilizer is the best option when to prevent crabgrass and other weeds within your lawn but keep in mind, that while it does stop the germination of those pesky eye-sores, it will also stop the germination of anything else you may be trying to grow such as grass seed.owever, with the right pre-emergent application at the right time, the germination of this and other unsightly weeds will be dramatically reduced. Pre-emergent alone is not a fertilizer; it is an herbicide which helps to prevent weed seeds from germinating by blocking an essential enzyme.