吉林西部不同开发年份盐碱水田土壤有机碳和碳酸盐的季节动态

水稻土是中国主要的耕作土壤，在陆地土壤碳循环研究中具有重要现实意义。针对吉林西部水田土壤的特征，将无机碳库纳入土壤碳库研究，以典型灌区前郭县为例，野外采集盐碱地和已开发5、15、25、35、55年的5种不同水田表层土壤，建立实验样地，在水稻生长的幼苗期、分蘖期、长穗期和结实期采集土壤样品，用TOC仪分别测试表层土壤有机碳和碳酸盐含量，分析其季节动态规律和开发年份特征。结果表明：吉林西部盐碱水田土壤有机碳呈现“减-增-减”的季节变化规律，水稻生长的幼苗期和分蘖期有机碳含量下降，长穗期含量上升，结实期含量下降，碳酸盐季节变化规律与其相反，二者季节变化呈显著负相关；经历一个生长季后，开发5、15、25、35、55年的土壤有机碳含量分别增加了2.98%、3.53%、3.66%、2.72%、2.30%，碳酸盐含量分别增加了4.07%、2.15%、1.08%、1.61%、11.36%，说明研究区水田生长期具有碳汇作用；与未开发盐碱地相比，开发的5、15、25、35、55年生长季土壤平均总碳量分别增加了89.81%、121.03%、137.22%、188.28%，有机碳含量分别增加了284.28%、392.00%、456.37%、559.08%、666.06%，碳酸盐含量分别降低了13.49%、22.84%、32.23%、43.53%、62.40%；开发年份越长，水田土壤总碳和有机碳含量越高，碳酸盐含量越低；总碳的增加来自有机碳的增加；盐碱地开发有利于土壤碳汇。水稻生长期温度和降雨量影响土壤有机碳和碳酸盐季节变化。

Seasonal variation of soil organic carbon and carbonate in saline-sodic paddy soils at different development years in western Jilin province

As a significant cultivated land paddy soil plays an important practical role in carbon cycle of terrestrial soil in China. According to characteristics of the paddy soil in Western Jilin Province, inorganic carbon was included in the study of soil carbon pool in the paper, taking Qianguo County a typical irrigation area as a study area. The saline-sodic and paddy soils of five different development periods from five to 55 years were collected to build experimental plots. The soil samples were collected in seedling, tillering, tassel formation and fructicative stages. Organic carbon and carbonate were tested to analyze the seasonal variations in dif-ferent development years. The results show that organic carbon decreases in seedling and tillering stages, then increases in tassel formation stages, finally decreases in fructicative stages with obvious seasonal variation. However carbonate shows an opposite sea-sonal variation. There was a significant negative correlation between organic carbon and carbonate. After the growing season, soil organic carbon of five different developed years has increased by 3%, 3.5%, 3.7%, 2.7%and 2.3%respectively;and carbonate in-creased by 4.1%, 2.2%, 1.1%, 1.6%, 11.4%respectively, indicating the function of carbon sink of the paddy soil in the study area during the growing season. Compared with the undeveloped saline-sodic soil, the average total carbon of five different developed years increases by 89.8%, 121%, 137.2%, 188.3%respectively during the growing season;soil organic carbon increases by 284.3%, 392%, 456.4%, 559.1%, 666.1% respectively, but carbonate decreases by 13.5%, 22.8%, 32.2%, 43.5%, 62.4% respectively. The longer the development year is, the higher in total carbon and organic carbon is and, the less carbonate is. The increase of total car-bon resulted from the increase of organic carbon. Development of the saline-sodic soil led to the soil carbon sink. The temperature and rainfall during the growing season influenced the seasonal variation of organic carbon and carbonate in soils.