From this chart that certain nutrients move in the soil while others are limited mobility and some are considered immobile.
Nitrogen is prone to leaching in the nitrate form but not in the ammonium form.
Sulphur is mobile and Boron is very mobile in the soil. Others that are less important that are mobile, are chlorine and Manganese.
This is a very important to know because if you are placing the entire needs of the crop at seeding time and you have rain, you may not be using much of or any of that spring applied fertilizer as leaching can move those nutrients away from the root zone. Especially early in the growing season when the crop is small and not using much or any of the applied nutrients.
If you zero til this section is important because over the years your crop trash stays on the top of the soil and decomposes. As that happens the mobile nutrients are moving back into the soil, the immobile nutrients are not. So copper, zinc, magnesium, iron and phosphate are sitting in the top couple of inches of the soil away from the root zone. So your fertility strategy must include looking at this issue and over coming these hurdles.
