扬州市耕地土壤速效钾含量30年演变及其驱动因子

Thirty-year variation of soil available K and the driving factors in Yangzhou

调查分析扬州市19843994.2005,2014年4个年份耕地土壤速效钾含量、成土母质、土壤质地以及各年份的耕作制度、施用化肥品种和数量,参照第二次土壤普查的分级标准将耕地土壤速效钾含量分为6级,研究扬州市近30年来耕地土壤速效钾含量变化情况。结果表明:1984、1994、2005、2014年土壤速效钾含量平均值分别为108,63,116和99mg·kg^-1;1984-2014年土壤速效钾含量的空间分布格局均表现为里下河地区、沿江土于区、丘陵地区、通南高沙土区呈递减趋势。1984、2005年速效钾空间分布以II、IH、IV级为主,占总面积95%以上;1994年速效钾空间分布以IV级为主,占总面积的87.27%;2014年土壤速效钾空间分布以DI、IV级水平为主,占总面积的90%以上。30年间土壤速效钾含量呈先下降后上升再下降的趋势;30年间成土母质的速效钾含量整体呈先下降再上升后下降的趋势;30年间不同土壤质地的速效钾含量变化整体趋于一致。1994-2005年间钾肥投入量和土壤速效钾含量呈正相关关系,而2005~2014年间两者呈负相关关系,30年间秸秆还田与土壤速效钾含量呈显著正相关关系。影响土壤速效钾空间分布因素主要为成土母质、土壤质地,影响土壤速效钾时间分布因子主要为施用钾肥、秸秆还田,其中施用钾肥、秸秆还田是土壤速效钾含量变化的主要驱动因子。

This study investigated the soil available K, soil parent material, and soil texture for the year of 1984, 1994, 2005 and 2014. Cultivation system, rainfall, type of fertilizer application and its inputs were also investigated for these years. The data came from 16 996 sampling points in Yangzhou City, including 4 107 agricultural chemical soil samples of the second general soil survey in 1984, 2862 general soil survey points in 1994, 4 018 soil nutrients survey points in 2005 , and 6 009 soil nutrients survey points in 2014. According to the second soil census standard, the soil available K content of cultivated land in Yangzhou was divided into six grades: ClassⅠ(>200mg·kg^-1 ), ClassⅡ(150-200 mg o kg-1), Class Ⅲ(100-150 mg·kg^-1), Class IV (50-100 mg·kg^-1), Class V (30-50 mg·kg^-1), Class VI (<30 mg·kg^-1). The results showed that the average soil available K was 108 mg·kg^-1, 63 mg·kg^-1 , 116 mg·kg^-1 and 99 mg·kg^-1 in 1984, 1994, 2005 and 2014, respectively. The spatial layouts of soil available K content in the last 30 years from high to low were Lixiahe area, Yangtze River diked area, Sandy soil area in Tongnan, and Hilly region. In 1984 and 2005, the soil available K mainly belonged to Class Ⅱ,Ⅲ and IV , which accounted for more than 95% of total area. In 1994, the soil available K mainly belonged to Class IV, which accounted for 87.27% of total area. In 2014, the soil available K mainly belonged to Class Ⅲ and IV , which accounted for more than 95% of total area. In these 30 years, the soil available K decreased first, and then increased. The available K in different kinds of soil-forming parent materials showed a trend of decreased first, then increased and then decreased as a whole and the overall available K in different kinds of soil textures tended to be uniform. From 1984 to 1994, there was a positive correlation between the input of potash fertilizer and the soil available K. From 1994 to 2014, there was a negative correlation between ?the input of potassium fertilizer and the soil available K. There was a significant positive correlation between straw returning and soil available K in 30 years. The spatial distribution of soil available K in the study area was mainly influenced by the parent materials of soil, soil tex-ture, chemical potash fertilizer and straw incorporation. The chemical potash fertilizer and straw incorporation were the main driving factors soil available K change.