近40年来吉林省农田耕层土壤pH的时空变化特征

Spatial and temporal characteristics of soil pH in the cultivated layer of farmland in Jilin province in the past 40 years

土壤pH是土壤在其形成过程中受生物、气候、地质、水文等因素综合作用产生的重要属性,是土壤化学与肥力的重要指标。通过空间插值分析2008(2005—2008)年和2018(2015—2018)年两个时间段中大量的吉林省土壤样品数据,明确了吉林省农田耕层土壤pH的时空变异特征,并与第二次土壤普查数据(1978年)进行对比,分析了土壤pH的变化趋势。时间上看,从1980年至今的近40年间,土壤平均pH从pH_(1978)-pH_(2008)的每年下降0.03个单位变化至pH_(2008)-pH_(2018)的每年下降0.02个单位,2008—2018年的10年间虽然农田土壤的平均pH仍有一定程度的下降,但与前30年(1978—2008年)时间相比较,酸化趋势有一定的减缓。不同类型的农田土壤的pH下降程度不同,草甸土、水稻土的pH下降较大,降低了1.3、1.6个单位;黑土的pH下降了大约0.4个单位;白浆土和暗棕壤酸化程度相对较小;而盐碱土pH却上升了1.5个单位,从pH_(1978)-pH_(2008)的每年增长0.01个单位变化为pH_(2008)-pH_(2018)的每年增长0.12个单位,盐碱耕地盐碱化有加重趋势。在空间上,吉林农田各耕层土壤pH整体上呈现自西向东逐渐降低。酸性土壤占耕地总面积的5.7%,弱酸性土壤占36.9%,中性土壤占32.4%,弱碱性占24.3%,碱性土壤占0.7%。与2008年相比较,酸性土壤下降了1.6个百分点,弱酸性土壤上升了2.9个百分点,中性土壤上升了2.5个百分点,弱碱性土壤下降了4.2个百分点,碱性土壤上升了0.4个百分点。在农业上应该积极地控制化肥的过量施用并合理添加有机物料如秸秆和有机肥,从而缓解土壤酸化和碱化的趋势,以实现吉林省土壤肥力的提高和养分平衡的稳定供应。

Soil pH is an important attribute of soil produced by the combination of biological,climatic,geological and hydrological factors during its formation,and it is an important indicator of soil chemistry and fertility.Though the spatial interpolation analysis of a large number of soil sample data from Jilin province in the two time periods of 2008(2005—2008)and 2018(2015—2018),the spatial and temporal variability characteristics of soil pH in the cultivated layer of Jilin farmland were clarified,and compared with the data from the 2nd national soil survey data(1978)to analyze the trend of soil pH changes.From 1980 to present,the average soil pH changed from 0.03 units per year in pH_(1978)-pH_(2008) to 0.02 units per year in pH_(2008)-pH_(2018).Although the average soil pH still decreased to some extent during the period from 2008 to 2018,the acidification trend slowed down to a certain extent compared with the previous 30 years(1978—2008).The pH of different soil types decreased differently,the pH of meadow and rice soil decreased significantly by 1.3 and 1.6,respectively;the pH of black soil decreased by 0.4;While the change of pH in albic bleached soil and dark brown soil was relatively small.However,the pH of saline soil increased by 1.5,the average pH changed from 0.01 per year in pH_(1978)-pH_(2008) to 0.12 in pH_(2008)-pH_(2018),which showed that salinization of saline fields increased.Spatially,the soil pH in Jilin farmland decreased from west to east.Acidic soils accounted for 5.7%of the total arable land area,weakly acidic soils accounted for 36.9%,neutral soils accounted for 32.4%,weakly alkaline accounted for 24.3%,alkaline soils accounted for 0.7%.Compared with in 2008,acidic soil decreased by 1.6%,weakly acidic soil increased by 2.9%,neutral soil increased by 2.5%,and weakly alkaline soil decreased by 4.2%,alkaline soil increased by 0.4%.We should control the excessive application of chemical fertilizers and reasonably add organic materials such as straw and organic fertilizers to alleviate the trend of soil acidification and alkalization,and achieve the improvement of soil fertility and stable supply of nutrient in Jilin province.