- Location
- Cornwall
'Sore on land' How so? I was always led to believe it was less acidifying and kinder to soil microbes, than AN. I'm back on AN this year, after 2 years of urea, the decision being made purely on price. I'm already wondering if I'm made the right decision though.
Without going too deeply into the biochemistry of it all... The process of converting Urea to Ammonium increases pH and then the process of converting Ammonium to Nitrate reduces pH, just the same as AN. So at the end of the day there isn't a huge amount of difference, some but not much.
It is fair to say that Urea is kinder to soil and plant than AN. As the plant can't utilise Urea, it has to wait for he conversion to ammonia and Nitrate in order to be able to use the N. this takes time so the plant takes it up slowly.
Because AN is immediately useable the plant takes it up very quickly. However, it can only process N at a certain rate, so it stores it as a salt in solution. This means it has to take up large amounts of water. The perceived rapid growth rates associated with AN are usually just this process of taking up water to dilute the Nitrate. The water fills the cells, which then expand and stretch giving the plant the appearance of growth. The cell walls become thinner as they stretch meaning the chlorophyll becomes more visible and the plant looks greener.
This also has implications for plant health as the thin cell walls are more susceptible to disease.