Evaluation of soil quality and land suitability in different management systems

Figures & data

Figure 1. The location of the soil profile and management system in Neyshabur plain, northeastern Iran.

Figure 2. The illustrated procedure of study including date base preparation, data analyses (land suitability and soil quality calculation) and validation the result.

Table 1. The number of depth sections and weight coefficients for soils with different depths (Sys et al. 1991).

Soil profile depth (cm)	The number of equal parts with 25 cm intervals	Weight coefficients from top to depth
25	1	1
50	2	1.25–0.75
75	3	1.5-1-0.5
100	4	1.75-1.25-0.75-0.25
125	5	1.5-1.75-1- 0.5-0.25
150	6	2-1.5-1-0.75-0.5-0.25

Table 2. Descriptive statistics of the soil properties in the study area.

	Surface				Profile
Soil indicator	Mean	Std.dev	Range	CV (%)	Mean	Std.dev	Range	CV (%)
Naaq (mmol l^−1)	6.5	4.2	13-5.1	53	8.1	5.3	8.2-13.60	37
EC (dS m^−1)	4.2	6.4	9.31 -3	69	4.4	1.1	7.6 -3.3	24
TN (mg kg^−1)	31	5	40- 20	50	23	3	10 -35	8
Pav (mg kg^−1)	9	5.5	15-3	51	6	2.17	2- 10.5	27
Kav (mg kg^−1)	140	5.50	280-70	56	70	533	50-225	34
Silt (%)	22.70	7.3	38-11	58	21.84	5.80	13-38	26
Sand (%)	68	7.9	82-50	67	58.15	11.75	34-78	20
Clay (%)	9.5	6.4	25-2	53	18.96	9.4	7-45	44
SOC (%)	0.30	5.1	0.37-0.30	58	0.18	4.8	0.28 -0.18	31
CCE (%)	17.6	2.50	22– 12	14	15.87	2.3	13-21	14
SAR	2.1	1.70	5.40 -0.2	51	2.82	1.65	1.15-6.20	42
pH	7.80	0.12	8 – 7.50	9	7.7	0.36	8.4-6.7	4

CV: Coefficient of variance, Std.dev: Standard deviation, Na_aq: Soluble sodium, EC: Electrical conductivity, TN: Total nitrogen, P_av: Available phosphorous, K_av: Available potassium, SOC: Soil organic carbon CCE: Calcium carbonate equivalent, and SAR: Sodium absorption ratio.

Table 3. Mean values properties of the representative soil profiles in different management systems.

Surface					Profile
Soil profile	P10	P13	P12	P2	P10	P13	P12	P2
Management system	Rangeland	Smallholder	Total owner	Binaloud company	Rangeland	Smallholder	Total owner	Binaloud company
Naaq (mmol l^−1)	11	5.65	5.4	6.1	7.6	6.40	5.4	6
EC (dS m^−1)	9.3	4.50	4.1	3.6	4.7	5.3	4.13	3.3
TN (mg kg^−1)	13	21	28	36	13	16	20	30
Pav (mg kg^−1)	2	4	12	10	5	6	7	8
Kav (mg kg^−1)	63	66	215	230	60	67	180	178
Silt (%)	10	8	13	18	12	12	10	12
Sand (%)	30	34	40	68	40	38	44	53
Clay (%)	60	58	47	14	50	48	46	35
SOC (%)	0.37	0.30	0.35	0.36	0.28	0.18	0.20	0.20
CCE (%)	21.25	18.5	16.8	15	16.30	15.5	14.30	16.40
SAR	5.45	1.8	1.65	0.9	0.5	0.30	0.20	0.2
pH	8	7.9	7.7	7.7	7.7	7.65	7.75	7.7

Na_aq: Soluble sodium, EC: Electrical conductivity, TN: Total nitrogen, P_av: Available phosphorous, K_av: Available potassium, SOC: Soil organic carbon CCE: Calcium carbonate equivalent, and SAR: Sodium absorption ratio.

Table 4. Results of four principal component analysis of the surface soil properties affecting soil quality.

Principal components	PC1	PC2	PC3	PC4
Eigenvalue	4.067	2.29	1.77	1.23
Variance (%)	33.88	19.100	14.79	10.24
Cumulative variance (%)	33.88	49.65	64.43	74.69
Factor loadings (Rotated component matrix)
Naaq (mmol l^−1)	0.607	-0.689	0.185	0.192
EC (dS m^−1)	0.878	-0.388	-0.104	0.063
Silt (%)	0/779	0.131	-0.571	-0.056
Sand (%)	- 0.870	-0.251	-0.005	0.363
Clay (%)	0.216	0.189	0.782	-0.456
TN (mg kg^−1)	0.050	0.762	0.100	0.354
Kav (mg kg^−1)	0.619	0.125	0.197	-0.399
Pav (mg kg^−1)	-0.452	0.567	0.398	0.116
SOC (%)	0.414	0.769	0.106	0.070
CCE (%)	0.779	0.250	0.137	0.208
SAR	0.209	-0.623	0.603	0.316
pH	0.505	0.235	0.120	0.627

Bold face factor loadings were considered highly weighted and underlined were retained in MDS, Na_aq: Soluble sodium, EC: Electrical conductivity, TN: Total nitrogen, P_av: Available phosphorous, K_av: Available potassium, SOC: Soil organic carbon CCE: Calcium carbonate equivalent and SAR: Sodium absorption ratio.

Table 5. Results of five principal component analysis of the soil profile properties (weighting factor) affecting soil quality.

Principal components	PC1	PC2	PC3	PC4	PC5
Eigenvalue	3.66	2.29	1.77	1.23	1.13
Variance (%)	30.55	19.100	14.79	10.24	9.43
Cumulative variance (%)	30.55	49.65	64.43	74.69	84.12
Factor loadings (Rotated component matrix)
Naaq (mmol l^−1)	0.830	0.201	-0.296	0.256	-0.180
EC (dS m^−1)	0.555	0.492	-0.392	0.037	0.254
Silt (%)	0.808	-0.121	0.162	-0.226	-0.053
Sand (%)	-0.656	0.680	-0.135	0.081	-0.096
Clay (%)	0.239	-0.842	-0.022	0.044	0.133
TN (mg kg^−1)	0.444	0.344	0.555	0.286	-.0399
Kav (mg kg^−1)	0.626	0.110	0.205	-0.485	-0.464
Pav (mg kg^−1)	-0.344	0.684	0.127	0.132	0.497
SOC (%)	0.124	0.225	0.892	-0.107	-0.208
CCE (%)	0.546	0.148	0.259	0.285	0.427
SAR	0.688	0.220	-0.448	0.293	-0.236
pH	-0.121	-0.381	0.243	0.768	0.318

Bold face factor loadings were considered highly weighted and underlined were retained in MDS, Naaq: Soluble sodium, EC: Electrical conductivity, TN: Total nitrogen, Pav: Available phosphorous, Kav: Available potassium, SOC: Soil organic carbon CCE: Calcium carbonate equivalent and SAR: Sodium absorption ratio.

Table 6. Results of four principal component analysis of the soil profile properties (weighted mean) affecting soil quality.

Principal components	PC1	PC2	PC3	PC4
Eigenvalue	4.63	2.19	1.41	1.22
Variance (%)	38.58	18.28	11.80	10.23
Cumulative variance (%)	38.58	56.87	68.67	78.91
Factor loadings (Rotated component matrix)
Naaq (mmol l^−1)	0.867	0.278	0.270	-0.046
EC (dS m^−1)	0.672	0.333	0.351	-0.055
Silt (%)	0.783	-0.277	0.173	-0.113
Sand (%)	-0.528	0.800	0.038	-0.035
Clay (%)	0.146	-0.821	0.243	0.255
TN (mg kg^−1)	0.558	0.049	-0.384	-0.638
Kav (mg kg^−1)	0.616	-0.292	-0.241	-0.441
Pav (mg kg^−1)	-0.553	0.398	0.037	0.319
SOC (%)	0.681	0.084	-0.339	0.546
CCE (%)	0.659	0.457	-0.291	-0.175
SAR	0.787	0.391	0.215	-0.078
pH	0.019	0.044	0.823	0.326

Bold face factor loadings were considered highly weighted and underlined were retained in MDS, Na_aq: Soluble sodium, EC: Electrical conductivity, TN: Total nitrogen, P_av: Available phosphorous, K_av: Available potassium, SOC: Soil organic carbon CCE: Calcium carbonate equivalent and SAR: Sodium absorption ratio.

Table 7. Soil quality index of the different management units in the MDS.

PCA							EO
	Profile						Profile
	Weighted factor		Weighted mean		Surface		Weighted factor		Weighted mean		Surface
Mnagement system	Add	Wi	Add	Wi	Add	Wi	Wi	Add	Wi	Add	Add	Wi
Range lands	0.58	0.59	0.53	0.56	0.45	0.56	1.03	0.46	0.69	0.58	0.58	1.01
Binaloud company	0.57	0.56	0.49	0.53	0.49	0.53	0.89	0.56	0.88	0.52	0.52	0.86
Total owner	0.59	0.59	0.57	0.61	0.52	0.61	1.05	0.58	0.93	0.56	0.56	0.90
Smallholder	0.55	0.54	0.48	0.52	0.47	0.52	0.90	0.56	0.90	0.50	0.50	0.75

Table 8. Land suitability for alfalfa in the study area.

Soil profile	Management system	Land index	Predicted yield (kg ha^−1 a^−1)	Observed yield (kg ha^−1 a^−1)	Subclass	Management index
P1	Range lands	73.56	9320	-	S2 d	-
P17		70.04	9160	-	S2 d	-
P4		71.23	9280	-	S2 d	-
P10		69.45	9001	-	S2 da	-
P2	Binaloud company	81.67	9210	8700	S2 da	0.94
P3		80.96	9180	8500	S2 da	0.92
P16		80.65	9150	8400	S2 da	0.91
P18		71.06	9170	8300	S2 d	0.90
P20		69.81	9080	7500	S2 d	0.94
P7	Total owner	60.51	7780	6500	S2 da	0.83
P8		53.06	6890	6250	S2 da	0.90
P12		70.05	9170	7200	S2 d	0.78
P6	Smallholder	60.43	7750	5100	S2 d	0.65
P9		60.45	7150	5200	S2 da	0.72
P11		69.23	9120	6500	S2 da	0.71
P13		55.87	7100	5200	S2 da	0.73
P14		68.21	8900	5700	S2 d	0.64
P15		69.01	9030	6300	S2 d	0.69

Figure 3. Relationship between the observed yield and predicted yield in the management systems.

Table 9. Regression relationship between surface and profile soil quality index with observed yield of alfalfa in the MDS.

		EO				PCA
Depth	Management system	Weighted		Additive		Weighted		Additive
Surface	Binaloud company	0.49		0.46		0.17		0.12
	Total owner	0.52		0.50		0.20		0.13
	Smallholder	0.35		0.32		0.14		0.09
		Weighted factor		Weighted mean		Weighted factor		Weighted mean
Profile		Weighted	Additive	Weighted	Additive	Weighted	Additive	Weighted	Additive
	Binaloud company	0.44	0.40	0.43	0.40	0.44	0.42	0.31	0.27
	Total owner	0.66	0.65	0.66	0.63	0.56	0.53	0.62	0.60
	Smallholder	0.63	0.56	0.60	0.50	0.36	0.38	0.34	0.33

Figure 4. Relationship between the observed yield and land index in the management systems.

Sys C., Van Ranst E., Debaveye J. 1991. Land evaluation. Part 1: principles in land evaluation and crop production calculation. General Administration for Development Cooperation, Agric. Publ. No. 7, Brussels.

 Google Scholar