Mechanical spreaders are available but fertiliser can be broadcast very effectively by hand. Probably the best method is to divide the total quantity of fertiliser into halves. Then spread the first half in one direction (say, north/south) and the other half at right angles to it (east/west). This way you cover the area twice.
You can be even more accurate if you divide the area into strips with garden twine stretched between pegs at 2 m intervals. This is a convenient width for scattering fertiliser by hand. Calculate the quantity of fertiliser for each strip. After spreading the first half of the fertiliser, move the twine and pegs to make strips at right angles for spreading the second lot.
After spreading, water well.