(1)  The level of a characteristic of a fertilizer listed in column 1 of Schedule 3 as stated in a label, invoice or delivery docket is to be within the tolerance listed in column 2 of that Schedule.

(2)  In determining whether a characteristic of a sample of a fertilizer, of which phosphorus is a constituent, is within the tolerance –

(a) an excess of water-soluble phosphorus may be set off against a deficiency of citrate-soluble phosphorus; and

(b) an excess of citrate-soluble phosphorus may be set off against a deficiency of water-soluble phosphorus, if the percentage of citrate-soluble phosphorus is not more than 25% of the sum of the percentages of citrate-soluble phosphorus and water-soluble phosphorus.