GB795805A - Improvements in or relating to fertilisers - Google Patents

Abstract

Water soluble fertilizing materials and/or trace elements are incorporated in a highly porous carrier material which is a mixture of diatomaceous earth with calcined diatomaceous earth, plastic clay or fuller's earth. Trace elements specified are iodine, manganese, copper, iron, zinc, magnesium, cobalt, boron and bromine. The fertilizer or trace elements compounds may be incorporated in the carrier either by providing a saturated solution of the compounds to be incorporated and introducing dry carrier material thereinto and subjecting the suspension to alternating pressure and rarification. Sodium or potassium silicate or glues such as casein may be added to decrease the solution rate of the fertilizer. The suspension may then be sprayed under pressure into a quantity of the same carrier material in a dry pulverized state in a mixing machine. Alternatively the carrier material may be broken down mechanically in a mill and the fertilizing compounds added partly in solid form and partly in solution in the mill. The plastic mixture may then be fed to an extrusion pressure to provide granules having a length of 1/4 in. to 1/2 in. and a diameter of about 3/4 in. The granules so obtained are dried to about 10 per cent moisture content. Examples refer to carrier material in the form of a mixture of diatomaceous clay, with calcined diatomaccous clay and fuller's earth with diatomite. In such carriers are incorporated ammonium sulphate, potassium nitrate and chloride, and urea together with soluble compounds of trace elements.