Hi Anshiu, when you talk about "environmental factors", you are looking at a lot of variables. Perhaps, if you can narrow it down and look for specific environmental factor(s) individually, it would be easier for you to discuss. For instance, soil pH, average temperature, rainfall etc are some of the common environmental factors.

The question is too broad unless you are trying to write a 1000+ page book.

It depends on the specific herbicide and mode of action: glyphosate, paraquat, etc.. In cases like 2,4-D it might be a plant growth regulator at one dose and an herbicide at another. There are also different salts of the herbicide and each compound has slightly different physical and chemical properties.

It depends on the formulation: The "inert" ingredients are there for a reason.

It depends on how it was applied. This can be wet versus dry, foliar versus soil. It is also a function of application rate and particle size that influence dispersion in the environment and adherence to the target surface. Were adjuvants added to the spray tank?

What plant species is the target and what are the non-target species?

Was the application outdoors or in a protected environment (screenhouse, greenhouse, growth chamber)? Even a semi-protected environment like understory crops will influence the environmental fate of the pesticide.

It may seem like some of these factors do not matter. Yet temperature influences the rate of chemical reactions and water (humidity, dew, rain) and sunlight are two of the major forces in pesticide degradation. Anything that alters exposure or increases penetration rates through the plant cuticle will influence pesticide (herbicide) efficacy.