Effect of Land Use on Organic Carbon Storage Potential of Soils with Contrasting Native Organic Matter Content

Table 3

Mean values of organic carbon (OC), nitrogen (N) and C  : N ratio in physical fractions of soils from four agroecological zones under four land use types.

Agroecological zone	Land use	OC (%)		N (%)		C : N ratio
		POM	MOM	POM	MOM	POM	MOM
7	Crop land	0.42^Cb	0.78^Ba	0.02^Cb	0.04^Ba	18.3^Ba	17.9^Bb
	Orchard	0.92^Aa	0.53^Cb	0.05^Ab	0.03^Ca	19.1^Aa	17.3^Bb
	Grassland	0.75^Bb	0.81^Ba	0.04^Bb	0.06^Aa	19.6^Aa	13.2^Cb
	Fallow	0.91^Ab	1.12^Aa	0.05^Ab	0.06^Aa	19.0^Aa	18.7^Aa
3	Crop land	0.40^Db	0.70^Ba	0.02^Bb	0.05^Aa	17.5^Da	13.0^Cb
	Orchard	0.71^Ba	0.61^Cb	0.04^Ab	0.05^Aa	19.5^Ba	11.3^Db
	Grassland	0.60^Cb	0.72^Ba	0.03^Bb	0.04^Ba	20.7^Aa	16.1^Ab
	Fallow	0.81^Aa	0.81^Aa	0.04^Ab	0.05^Aa	18.4^Ca	14.9^Bb
9	Crop land	0.62^Cb	1.30^Ca	0.05^Cb	0.11^Ba	12.4^Ca	12.0^Bb
	Orchard	1.85^Aa	0.90^Db	0.11^Aa	0.07^Cb	16.5^Aa	12.4^Ab
	Grassland	1.44^Bb	1.58^Ba	0.09^Bb	0.14^Aa	16.2^Aa	11.0^Cb
	Fallow	1.35^Bb	1.78^Aa	0.10^Ab	0.14^Aa	13.6^Ba	12.7^Ab
5	Crop land	1.41^Cb	1.61^Ba	0.10^Bb	0.12^Ba	14.0^Ca	13.9^Ba
	Orchard	1.91^Aa	1.51^Bb	0.11^Ab	0.12^Ba	17.9^Aa	13.0^Cb
	Grassland	1.84^Ab	1.81^Aa	0.11^Ab	0.13^Aa	17.2^Aa	13.5^Bb
	Fallow	1.61^Bb	1.91^Aa	0.10^Bb	0.12^Ba	16.3^Ba	15.9^Aa

Here, POM (particulate organic matter) ≥ 53 µm and MOM (mineral associated organic matter) ≤ 53 µm. Standard error (S.E.) for OC = 0.00–0.09, N = 0–0.01 and C : N ratio = 0.01–0.65. Uppercase letters indicate significant differences () among land uses at corresponding fraction size for each AEZ and lowercase letters indicate significant differences () between fractions at corresponding land use for each AEZ.