Ammonia Application in a Drought
A common question that farmers have in seasons of dry soil conditions is whether ammonia will be lost if the soil is too dry.
A dry soil in our environment still has about 10% water in it; it is just held more tightly onto clay and organic matter due to a thinner film and prevents crops from taking it up. However, ammonia can certainly be held by it. The problem of ammonia in dry soils is not the water in the soil restricting rate, but the tilth of the soil. If the soil flows around the ammonia application band and the band is placed at least 4 inches deep in the soil then the ammonia should be safe from loss. In the fall, dry soil often translates into cloddier soil because there has not been enough freeze-thaw to break up the soil into fine particles. Therefore, dry soils are much more a problem in the fall because if the soil is cloddy, there are gaps between the clods that would allow ammonia to escape not only the day of application, but in the days following. In spring, and this spring is no exception, all the soils I have investigated so far are very fine at and near the soil surface, and would provide good coverage of the ammonia band.
If ammonia is to be applied at planting there needs to be at least 3 inches distance from the intended seed row. In moist springs, farmers have skated by with less distance because there is more water to trap the ammonia before it reaches the seed, but not this year. If the ammonia will be applied in a separate preplant trip before planting, it should be applied at an angle to the intended planting row. Some seeds will be damaged and stand reduced, but it will not leave large gaps within a row, just a plant missing once in a while, which increasing seeding rate about 10% will take care of.
Extension Soil Specialist