Abstract:
It is of great significance to carry out soil quality assessment for the delimiting of the permanent basic farmland and overall optimization of agricultural production layout. Nemerow comprehensive pollution index, grading, cumulative frequency and integrated decision method were adopted in this paper, and Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018 ) and Green Food- Environmental Quality for Production Area (NY/T391-2013) were chosen as reference. The heavy metals, pH values, beneficial elements abundance-deficiency and producing area suitability for green agricultural products were evaluated in Yangtze River Economic Zone. The land quality of the study area is generally good, and the clean land area is 348 400 km
2. The heavy metals content of the soil inherits the characteristics of natural background. The land area of and below the third stage is 69 400 km
2, distributed in star-shaped plaques in Northeast and South Jiangxi, Changsha-Chenzhou area of Hunan, along the river and Guiyang, Kunming and other places. Their heavy metals enrichment was caused by natural factors or mining development, combustion of coal and oil and industrial three wastes emission. Acidic soil area is 335 600 km
2, mainly distributed in Jiangxi, Hunan, Ningbo-Taizhou coastal region and Jinhua-Quzhou Basin. Alkaline soil area is 156 900 km
2, mainly distributed in North Jiangsu Plain, around Dongting Lake area, Chengdu Plain and the area along the Yangtze River. Soil acidity and alkalinity is related to soil type. Abundance-deficiency of beneficial elements in soils is related to the soil parent material of Quaternary sediments, and the moderate-high area of beneficial elements is 344 400 km
2, mainly distributed in Sichuan Aba, Chengdu Basin, around Dongting Lake, around Poyang Lake, Anhui Province along Yangtze River, North Jiangsu coastal region and Hangzhou-Jiaxin-Huzhou Plain. Deficiency area of beneficial elements is 138 900 km
2, distributed in South Jiangxi, Jianghuai, Northeast Hubei and Yunnan Yuxi and other places. The most suitable area, suitable area and unsuitable area for green agricultural products are about 224 900 km
2, 187 800 km
2 and 182 800 km
2 respectively. According to the producing area suitability for green agricultural products, cultivated land quality and site condition in the region, 7 pieces of permanent farmland protection proposal areas are established.