Table 2. δ¹⁵N values of organic and inorganic fertilizers.

Type	Fertilizer	Fertilizer δ15N (‰, AIR)	Reference
Organic	Blood	6.0±1.3	[191]
	Bonemeal	4.9±0.3	[191]
	Cattle manure	5.0±0.8	[192]
	Cattle manure	2.9±0.5	[193]
	Cattle manure	4.5	[133]
	Cattle manure	3.1±0.2	[85]
	Chicken manure	6.2±1.9	[191]
	Fishmeal	7.1±3.6	[191]
	Hoof and horn	6.4±0.2	[191]
	Livestock manure	8.8±4.4	[191]
	Livestock manure	8.7±0.2	[132]
	Pig manure	13.9	[102]
	Pig manure	16.9	[194]
	Pig manure	11.3	[133]
	Pig manure	6.5	[133]
	Pig manure	16.4	[195]
	Poultry manure	8.6±0.3	[132]
	Poultry manure	2.7	[133]
	Seabird guano	26.7±0.6	This study
	Seaweed	2.5±1.5	[191]
	Various composts	17.4±1.2	[196]
Inorganic	(NH4)2H2PO4	−0.6±0.4	[191]
	(NH4)2SO4	1.7±3.4	[191]
	(NH4)2SO4	−1.6	[133]
	(NH4)2SO4	−2.6	[197]
	KNO3	−1.2±0.3	[191]
	NH4NO3	−1.3	[128]
	NH4NO3	−0.6±1.7	[191]
	NH4NO3	−1.7	[133]
	Urea	−2.4±2.1	[191]
	Urea	−1.7	[133]
	Urea	−0.7	[195]