Investigating soil quality in cold highland agricultural fields with different soil types

Figures & data

Figure 1. Overview map of the study area.

Table 1. Differences in soil physical properties across different soil types.

Indicator	Agrotype
	Cold calcic soil	Luvic chernozem	Calcareous meadow soil	Calcareous gray cinnamon soil
SWC (%)	22.08±0.71ab	24.14±1.01a	18.65±1b	23.89±0.89a
BD (g cm^−3)	1.01±0.01ab	0.95±0.03b	1.05±0.03a	0.92±0.03b
pH	7.88±0.06a	8±0.03a	8.09±0.04a	8.01±0.01a
EC (μS cm^−1)	153±10.06ab	222.75±17.36a	184.53±15.31ab	129.85±2.88b
Clay particle (%)	4.5±0.16a	5.29±0.25a	3.27±0.26b	4.47±0.37a
Silt particle (%)	66.31±2.02ab	75.26±1.43a	54.04±3.8c	61.01±3.78bc
Sand particle (%)	29.19±2.15bc	19.45±1.67c	42.69±4.04a	34.52±4.09ab

Note: The data are expressed as mean ± standard error. Different lowercase letters within the same row indicate statistically significant differences in soil indices under different soil types (p < 0.05). The same letters indicate no significant differences within this level of analysis. The same convention applies to subsequent tables.

Table 2. Differences in soil chemical properties across different soil types.

Indicator	Agrotype
	Cold calcic soils	Luvic chernozem	Calcareous meadow soil	Calcareous gray cinnamon soil
TN (g kg^−1)	5.82±0.13bc	6.75±0.16a	5.18±0.22c	6.3±0.26ab
TC (g kg^−1)	35.38±1.09b	42.72±1.54a	29.81±2.15b	35.45±0.91b
TP (g kg^−1)	2.55±0.07a	2.42±0.13a	2.25±0.13a	2.57±0.14a
TK (g kg^−1)	22.07±0.21ab	19.89±0.69c	21.37±0.58b	22.79±0.44a
SOC (g kg^−1)	28.54±1.49b	38.33±0.93a	20.7±2.47c	29.4±1.01b
AN (mg kg^−1)	171.19±9.28b	226±16.51a	134.83±16.37b	167.9±9.91b
AP (mg kg^−1)	32.2±2.41a	46.93±9.26a	31.83±4.31a	32.22±5.98a
AK (mg kg^−1)	139.26±13.46a	130.17±18.51a	143.67±27.1a	122.8±8.39a

TN: Total nitrogen; TC: Total carbon; TP: Total phosphorus; TK: Total potassium; SOC: Soil organic carbon; AN: Alkaline–hydrolyzable nitrogen; AP: Available phosphorus; AK: Available potassium.

Table 3. PCA results of soil quality indices for cold calcic soil.

Indicator	Principal component (PC)				Grouping	Norm value
	PC1	PC2	PC3	PC4
SWC	0.19	0.854	−0.277	−0.046	2	1.865
BD	−0.217	−0.764	−0.248	−0.022	2	1.692
pH	−0.723	0.32	0.356	0.146	1	1.747
EC	0.183	0.245	0.615	−0.307	3	1.191
Clay particle	−0.254	0.854	−0.072	0.132	2	1.857
Silt particle	−0.393	0.883	0.058	−0.035	2	2.008
Sand particle	0.387	−0.892	−0.049	0.022	2	2.02
TN	0.923	0.176	−0.196	0.057	1	1.988
TC	0.858	0.327	−0.167	−0.003	1	1.934
TP	0.504	−0.323	0.719	0.08	3	1.675
TK	−0.029	−0.005	0.131	0.956	4	1.029
SOC	0.776	0.248	−0.222	0.201	1	1.749
AN	0.843	0.407	0.051	−0.076	1	1.957
AP	0.45	−0.085	0.656	0.046	3	1.397
AK	−0.04	0.196	0.815	−0.028	3	1.33
Eigenvalue	4.368	4.296	2.403	1.109
Variance contribution rate (%)	29.12	28.64	16.02	7.39
Cumulative contribution rate (%)	29.12	57.76	73.78	81.17

Table 4. PCA results of soil quality indices in luvic chernozem soils.

Indicator	Principal component (PC)			Grouping	Norm value
	PC1	PC2	PC3
SWC	0.025	0.488	0.853	3	1.682
BD	0.838	−0.294	−0.317	1	2.364
pH	0.025	−0.902	0.364	2	2.059
EC	0.13	0.908	−0.393	2	2.111
Clay particle	0.973	−0.102	0.082	1	2.593
Silt particle	0.952	0.194	0.178	1	2.575
Sand particle	−0.962	−0.151	−0.165	1	2.585
TN	−0.699	0.681	0.208	1	2.403
TC	−0.264	0.689	0.673	2	1.956
TP	0.66	0.696	−0.222	2	2.349
TK	0.728	−0.082	0.616	1	2.152
SOC	−0.347	0.754	0.115	2	1.904
AN	−0.739	0.54	−0.328	1	2.345
AP	0.813	0.517	−0.12	1	2.444
AK	0.826	0.492	−0.25	1	2.472
Eigenvalue	7.033	4.832	2.301
Variance contribution rate (%)	46.89	32.22	15.34
Cumulative contribution rate (%)	46.89	79.11	94.45

Table 5. PCA results of soil quality indices for calcareous meadow soil.

Indicator	Principal component (PC)			Grouping	Norm value
	PC1	PC2	PC3
SWC	−0.363	0.346	0.738	3	1.494
BD	−0.652	0.137	−0.551	1	2.047
pH	−0.853	−0.254	0.407	1	2.596
EC	0.495	0.8	−0.101	2	1.933
Clay particle	0.831	−0.237	−0.111	1	2.484
Silt particle	0.827	−0.448	−0.056	1	2.542
Sand particle	−0.832	0.437	0.059	1	2.551
TN	0.799	0.363	0.299	1	2.453
TC	0.935	0.25	0.061	1	2.788
TP	0.639	−0.385	0.102	1	1.985
TK	0.412	−0.671	0.408	2	1.684
SOC	0.82	0.382	0.268	1	2.515
AN	0.87	0.417	0.033	1	2.651
AP	0.866	0.103	−0.228	1	2.576
AK	0.918	−0.252	−0.094	1	2.741
Eigenvalue	8.711	2.478	1.446
Variance contribution rate (%)	58.07	16.52	9.64
Cumulative contribution rate (%)	58.07	74.59	84.23

Table 6. PCA results of soil quality indices for calcareous gray cinnamon soil.

Indicator	Principal component (PC)		Grouping	Norm value
	PC1	PC2
SWC	0.827	−0.206	1	2.21
BD	−0.566	0.589	2	1.927
pH	−0.928	−0.209	1	2.471
EC	0.004	0.709	2	1.48
Clay particle	0.833	−0.335	1	2.293
Silt particle	0.856	−0.433	1	2.419
Sand particle	−0.867	0.431	1	2.444
TN	0.244	0.264	2	0.844
TC	0.083	0.965	2	2.026
TP	0.871	0.325	1	2.382
TK	0.731	0.131	1	1.935
SOC	0.069	0.953	2	1.997
AN	0.924	0.075	1	2.427
AP	0.637	0.476	1	1.943
AK	0.449	0.821	2	2.079
Eigenvalue	6.87	4.357
Variance contribution rate (%)	45.8	29.05
Cumulative contribution rate (%)	45.8	74.85

Table 7. Common factor variance and index weight of total data set (TDS).

Indicator	Cold calcic soils		Luvic chernozem		Calcareous meadow soil		Calcareous gray cinnamon soil
	Communality	Weight	Communality	Weight	Communality	Weight	Communality	Weight
SWC	0.845	0.069	0.966	0.068	0.825	0.060	0.828	0.064
BD	0.693	0.057	0.889	0.063	0.847	0.062	0.809	0.063
pH	0.774	0.064	0.947	0.067	0.958	0.070	0.946	0.074
EC	0.566	0.046	0.995	0.070	0.902	0.066	0.911	0.071
Clay particle	0.817	0.067	0.965	0.068	0.869	0.063	0.916	0.071
Silt particle	0.939	0.077	0.976	0.069	0.989	0.072	0.92	0.072
Sand particle	0.948	0.078	0.976	0.069	0.989	0.072	0.94	0.073
TN	0.924	0.076	0.997	0.070	0.904	0.066	0.176	0.014
TC	0.87	0.071	0.996	0.070	0.949	0.069	0.957	0.075
TP	0.881	0.072	0.97	0.068	0.818	0.060	0.958	0.075
TK	0.931	0.076	0.916	0.065	0.918	0.067	0.738	0.057
SOC	0.754	0.062	0.702	0.050	0.927	0.068	0.943	0.073
AN	0.885	0.073	0.944	0.067	0.933	0.068	0.936	0.073
AP	0.643	0.053	0.942	0.066	0.959	0.070	0.927	0.072
AK	0.706	0.058	0.987	0.070	0.916	0.067	0.935	0.073

Table 8. Common factor variance and index weight of MDS.

Indicator	Cold calcic soils		Luvic chernozem		Calcareous meadow soil		Calcareous gray cinnamon soil
	Communality	Weight	Communality	Weight	Communality	Weight	Communality	Weight
SWC	–	–	0.516	0.103	0.964	0.357	–	–
BD	–	–	–	–	–	–	0.971	0.338
pH	–	–	–	–	–	–	0.948	0.330
EC	–	–	–	–	0.876	0.324	–	–
Clay particle	–	–	0.965	0.193	–	–	–	–
Silt particle	–	–	–	–	–	–	–	–
Sand particle	0.594	0.224	–	–	–	–	–	–
TN	0.439	0.166	0.973	0.195	–	–	–	–
TC	–	–	–	–	0.862	0.319	–	–
TP	0.674	0.255	–	–	–	–	–	–
TK	0.939	0.355	–	–	–	–	–	–
SOC	–	–	–	–	–	–	–	–
AN	–	–	0.737	0.148	–	–	–	–
AP	–	–	0.941	0.188	–	–	–	–
AK	–	–	0.863	0.173	–	–	0.951	0.331

Figure 2. Correlation analysis of soil quality indices between MDS and TDS.