A natural weed killer is a weed killer that is not chemically made. This means that many natural weed killers come the items found in your kitchen pantry or grown from your garden as well as cultural practice s that can lead to the death of a weed. Since man has been killing weeds long before he was mixing chemicals, natural weed killers have been around for a very long time.
Long before laboratory-engineered chemical weed killers were invented, mankind used natural weed killers to prevent weeds from growing. Biblical records state that certain cities were razed and then plowed with salt so that nothing would ever grow there again. Although this act was partially symbolic, it contained elements of revenge along with psychological warfare by ensuring that survivors of a razed city would not be able to rebuild.
During and after the Vietnam war, there was concern over the widespread use and aftereffects of Agent Orange, a herbicide used to defoliate the jungle so that enemy troop movements would be more visible. Tests on Agent Orange revealed that illnesses linked to the herbicide were caused by dioxins created as a byproduct of the process used to make one of the chemicals in Agent Orange. Because of this, some consumers mistrust synthetic chemical herbicides.
Chemical herbicides and natural herbicides have different means of killing weeds. Chemical herbicides attack the biological systems of plants, blocking their ability to function. Most natural herbicides contain some element of poison that will kill the plant. For example, sodium herbicides raise the sodium level in the soil around a plant. This prevents any plant in that soil from absorbing nutrients and water. Alcohol-based herbicides cause the water in a plant to evaporate, which will kill the plant. An herbicide made of boiling water that is poured over a weed parboils the weed.
According to the University of Florida IFAS extension, some natural herbicides may actually be more toxic than several synthetic chemical herbicides. This is because synthetic chemical herbicides are formulated specifically to attack plant biological systems and are not harmful to mammals. While many herbicides can harm mammals, sodium too can harm a mammal that gets too much of it. Additionally, If you apply too much of certain natural herbicides such as salt to a plant, it can change the balance of sodium in the soil and prevent plants from growing in the soil.
Because of consumer demand for natural herbicides, some herbicide manufacturers have attempted to create herbicides with natural ingredients. Several pre-emergent herbicides on the market contain corn gluten meal. There are also a few post-emergent herbicides that use acetic acid as an ingredient.