the mixture when added after the nitrogen and phosphoric acid finally the potash is added for safety reasons it is preferable to add the potash slowly because if it is added too fast to the mixture an explosive reaction may occur adding the potash also increases heat of the compound and causes a strong odor to be emitted the potash neutralizes the ph of the mixture balancing out the phosphoric acid once the potash is added the compound should be mixed for approximately twenty minutes once the product is done with the mixing steps it is then ready for filtration the product is preferably slowly added to a filter screen and preferably filtered by gravity flow the preferred filter size is a between 20 and 70 mesh a majority of the product will pass through the filter but a small amount will not pass through the product that does not pass through should be discarded once the compound has been filtered it may be appropriately packaged for distribution to field sites when packaging it is preferable to add a small amount of defoaming agent before filling so that foam is minimized and containers do not have to be refilled after the foam produced in the filling process settles out the containers may then be sealed and stored for shipment for application this method of production is preferable to previous methods used in several ways for example by adding the water later in the process the lignite stays suspended more completely in the solution thereby reducing clumping in the final product which can cause clogging in the equipment used to spray the compound onto fields further the use of gravity flow through the filter as opposed to a pumping procedure results in a superior product because.