Evaluation on Cultivated Land Soil Quality in Western Qinghai-Tibet Plateau

doi:10.11924/j.issn.1000-6850.casb2022-0729

Abstract

Abstract:

To scientifically evaluate the soil environment of cultivated land in western Qinghai-Tibet Plateau and improve the quality of cultivated land according to local conditions, the soil fertility (organic matter, total nitrogen, available phosphorus, available potassium, slow-release potassium etc.) and heavy metal pollution (As, Hg, Cr, Pb, Cd) of cultivated land were analyzed in four counties of western Ngari (Burang, Zanda, Gar, Rutog). Standard comparison method, single factor index method and Nemerow comprehensive index method were used to evaluate the soil environmental quality of the cultivated land. The results showed that the Nemero comprehensive fertility index of the cultivated land in the study area was 1.74, which belonged to grade 3, and soil fertility was average. The soil was deficient in organic matter and total nitrogen, rich in phosphorus and potassium, relatively rich in medium and trace elements except available zinc and available molybdenum. And the Nemero comprehensive pollution index was 0.71, which reached the warning line. The pollution was mainly concentrated in Burang and Gar. As and Cr exceed the heavy metal risk control value by 27.5% and 2.5%, respectively. In addition, Cd was 95% higher than the background value of the Qinghai-Tibet Plateau. In conclusion, the cultivated land of Rutog is fertile and pollution-free, which can be developed as the key cultivated land planting area. But organic matter and nitrogen should be properly supplemented during cultivation to ensure crop growth. Furthermore, it is necessary to pay attention to As pollution in Burang to ensure food safety.

Key words: Qinghai-Tibet Plateau, cultivated land, soil fertility, soil heavy metals

XU Tao, SHI Weigang, LIU Kuolong, XU Xiaofei, FAN Jiaxue. Evaluation on Cultivated Land Soil Quality in Western Qinghai-Tibet Plateau[J]. Chinese Agricultural Science Bulletin, 2023, 39(21): 75-82.

Figures/Tables 12

References 29

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土壤养分	1	2	3	4	5	6
土壤养分	很丰富	丰富	适量	缺乏	很缺乏	极缺乏
有机质/(g/kg)	>40	30 ~40	20~30	10~20	6~10	<6
全氮/(g/kg)	>2	1.5~2	1~1.5	0.75~1	0.5~0.75	<0.5
有效磷/(g/kg)	>40	20~40	10~20	5~10	3~5	<3
速效钾/(g/kg)	>200	150~200	100~150	50~100	30~50	<30
缓效钾/(g/kg)	>500	400~500	300~400	200~300	100~200	<100
有效硫/(mg/kg)	>30	16~30	<16	—	—	—
有效铜/(mg/kg)	>1.8	1.0~1.8	0.2~1.0	0.1~0.2	<0.1	—
有效锌/(mg/kg)	>3.0	1.0~3.0	0.5~1.0	0.3~0.5	<0.3	—
有效铁/(mg/kg)	>20	10~20	4.5~10	2.5~4.5	<2.5	—
有效锰/(mg/kg)	>30	15~30	5~15	1~5	<1	—
有效钼/(mg/kg)	>0.3	0.2~0.3	0.15~0.20	0.1~0.15	<0.1	—
有效硼/(mg/kg)	>2.0	1.0~2.0	0.5~1.0	0.2~0.5	<0.2	—

土壤养分	1	2	3	4	5	6
土壤养分	很丰富	丰富	适量	缺乏	很缺乏	极缺乏
有机质/(g/kg)	>40	30 ~40	20~30	10~20	6~10	<6
全氮/(g/kg)	>2	1.5~2	1~1.5	0.75~1	0.5~0.75	<0.5
有效磷/(g/kg)	>40	20~40	10~20	5~10	3~5	<3
速效钾/(g/kg)	>200	150~200	100~150	50~100	30~50	<30
缓效钾/(g/kg)	>500	400~500	300~400	200~300	100~200	<100
有效硫/(mg/kg)	>30	16~30	<16	—	—	—
有效铜/(mg/kg)	>1.8	1.0~1.8	0.2~1.0	0.1~0.2	<0.1	—
有效锌/(mg/kg)	>3.0	1.0~3.0	0.5~1.0	0.3~0.5	<0.3	—
有效铁/(mg/kg)	>20	10~20	4.5~10	2.5~4.5	<2.5	—
有效锰/(mg/kg)	>30	15~30	5~15	1~5	<1	—
有效钼/(mg/kg)	>0.3	0.2~0.3	0.15~0.20	0.1~0.15	<0.1	—
有效硼/(mg/kg)	>2.0	1.0~2.0	0.5~1.0	0.2~0.5	<0.2	—

土壤养分	土壤属性
土壤养分	x_a	x_c	x_p
有机质	10	0.5	30
全氮	20	1.0	1.5
有效磷	5	10	20
速效钾	100	150	200
缓效钾	200	400	500

土壤养分	土壤属性
土壤养分	x_a	x_c	x_p
有机质	10	0.5	30
全氮	20	1.0	1.5
有效磷	5	10	20
速效钾	100	150	200
缓效钾	200	400	500

肥力等级	肥力系数范围
Ⅰ级（很肥沃）	≥2.7
Ⅱ级（肥沃）	1.8~2.7
Ⅲ级（一般）	0.9~1.8
Ⅳ级（瘦瘠）	<0.9