Characteristics of soil acidification and its influencing factors in Shandong province

Abstract: Soil acidification can change the configuration of soil nutrients, affect soil biological activity, so as to affect the growth and development of crops, and bring a series of ecological environmental problems. Soil acidification was a major problem in intensive Chinese agriculture systems. This research was carried out to investigate the soil acidification in Shandong province and provide scientific basis for improving the soil quality using statistical and spatial analytical methods. The soil data collected from the soil testing formula fertilization program in Shandong province were compared with those collected from the second national soil survey. Soil acidification of Shandong province was showed with pH spatial distribution map using inverse distance weighted in ArcGIS. Soil acidification in different regions, land use types, and soil types was analyzed. Results showed that the soil in Shandong province was mainly weak-acidic, neutral and weak-alkaline. The average of pH value was 7.1 and the acidified soil area was 1.26 million hectares accounted for 8.13% of the province. Compared to the second national soil survey data, the percentage of soil acidification area was increased by 8.07%. The soil pH value of Shandong province decreased from west to east and from north to south gradually. The acidification soil was mainly located in the eastern and southern regions of the province, especially in Weihai, Yantai, Rizhao, Qingdao and Linyi city. The soil acidification of Weihai city was the most serious, accounting for 67.94% of the city's soil area. Under different agricultural land use, the soil pH averages of farmland, garden and forestry decreased in turn. The soil acidification of tea garden was the most serious in garden, while the mulberry garden was the least. The soil acidification of vegetable field was the most serious in farmland, while the cropland was the least. As to different soil groups, the fluvio-aquatic soil was mainly weak-alkaline, accounting for 67.87% of this soil group points. The cinnamon soil, lime concretion black soil, paddy soil were mainly neutral, accounting for 50.66%, 36.54% and 54.07% of these three soil group points, respectively. The skeletal soil and brown earth were mainly weak-acidic, accounting for 38.90% and 41.22% of these two soil group points, respectively. The soil pH averages of fluvio-aquatic soil, cinnamon soil, lime concretion black soil, paddy soil, skeletal soil and brown earth decreased in turn. The soil acidification of brown earth was the most serious, while fluvio-aquatic soil was the least acid. The soil acidification in Shandong province showed an increasingly serious trend may due to the natural geographic and climatic conditions of local environment. Additionally, other possible factors such as different land use types, unreasonable fertilizations and managements were also accountable. By adjusting soil pH value, the contents of soil nutrients could be controlled and the growth of crops could be promoted.