Slow-release fertilizer spike having high crush-resistance

Claim 1

The composition of claim 1, additionally comprising about 0.1 to 2.0 weight percent fertilizer trace elements.

Claim 2

A method for the manufacture of homogeneous, crush-resistant, slow-release fertilizer compositions, shaped in the form of a spike having a beveled end portion and having a crushing strength of at least 2,000 p.s.i., comprising the steps of: a. preparing a dry powder mixture comprising, in parts by weight, about 45 parts magnesia, and about 405 parts of a urea-formaldehyde resin containing about 35 to 40 weight percent nitrogen; b. converting the dry powder mixture to a uniform paste by agitating the powder mixture with about 110 parts of 75 percent phosphoric acid diluted with sufficient water to reduce the acid strength to about 50 percent; c. blending into the paste about 200 parts ground coke; d. extruding the blended paste through a die having an opening whose counter edge configuration is shaped to define the length of a spike having a beveled end portion, said length being within the range from 5 to 8 inches, the cross-sectional area of the said spike extrudate along the said beveled end portion diminishing to determine the same; e. cutting the shaped spike extrudate of d into strips to define the cross sectional area of the beveled spike at its top end and above the beveled portion thereof, said cross sectional area being at least 1 square inch but no greater than required to provide a top cross-sectional area of the spike of about 3 square inches, the combined surface areas of the obverse beveled faces of the spike being at least 4 times the surface area of the top end; and f. drying the extruded spike at ambient temperature for about 10 days, to provide a cured fertilizer composition comprising a spike having a beveled end portion.