长期施肥条件下棕壤无机硫组分时空变异特征

Temporal and Spatial Variation of Inorganic Sulfur Forms under Long-term Fertilization in Brown Earth

为合理施用含硫肥料,以沈阳农业大学棕壤肥料长期定位试验为依托,研究了长期(32年)不同处理(不施肥、单施化肥、有机肥配施化肥等)条件下,土壤不同层次无机硫时间和剖面分布的特征。本研究选取1979~2011年间的13年收获期0~100cm土壤样本进行无机硫组分分析,利用连续提取法提取土壤水溶态硫、吸附态硫和酸溶态硫,提取液采用ICP-AES进行硫浓度测定。结果表明:经过32年长期施肥,化肥区中不含硫素投入处理(CK,N1,N2)水溶态硫、吸附态硫、酸溶态硫含量都处于降低趋势。不施肥处理下降幅度最大,3种形态无机硫含量分别降低34.1%,29.3%和51.7%;单纯施入化学氮肥,土壤无机硫降低1.2%~15.2%,随着氮肥用量的增加,下降幅度增大;含有硫素投入处理(N1P,N1PK)土壤中水溶态硫含量处于增加趋势,与原始土相比分别增加10.7%和46.6%;吸附态硫含量分别增加3.3%和19.8%;酸溶态硫含量处于降低趋势,降低幅度分别为4.1%和18.2%。采用低量有机肥配施化肥或高量有机肥配施化肥均可有效提高3种形态无机硫含量,提升幅度为2.3%~81.0%,随着有机肥用量的增加,3种形态无机硫含量提升效果更好。水溶态硫、吸附态硫、酸溶态硫剖面分布呈现出明显"V"型,随着土层加深,含量降低;在40~60cm层次其含量降到最低。长期施用不含硫素的化肥会导致土壤中硫素有效性降低;施用含硫化肥会增加水溶态和吸附态无机硫含量、而酸溶态硫含量降低;采用有机肥、有机肥配施化肥均可以提高不同土层无机硫各组分含量,提高了硫素有效性并增大了土壤硫库。

A field experiment was established in 1979 in the long-term fertilization of brown earth to investigate soil fertility and nutrient use efficiency. In this paper, the inorganic sulfur contents of soil（0-100 cm） were tested under different fertilization treatments（no fertilization, chemical fertilization, manure et.al）. The soil samples of 13 years were chosen from 1979 to 2011, and were successively extracted to determine the contents of H_2O-S, absorbed-S and HCl-S with the ICP-AES. The results showed that the H_2O-S, absorbed-S and HCl-S contents decreased in no sulfur input treatments（CK, N1 and N2）..The contents of inorganic sulfur decreased by 34.1%, 29.3% and 51.7% in CK. With the application of chemical nitrogen fertilizer, the contents of soil inorganic sulfur were reduced by 1.2% to 15.2%. However, the contents were different in in N1 P and N1 PK. The contents of H_2O-S in soil were increasing by 10.7% and 46.6% compared with the original soil. The absorbedS was increased by 3.3% and 19.8%. The contents of HCl-S decreased by 4.1% and 18.2 %. With low levels of organic fertilizer and chemical fertilizer or high amount of organic fertilizer could effectively increase the three forms of inorganic sulfur content（2.3%-81.0%）. The distribution of inorganic sulfur was presented obvious ＂V＂ type. The minimum value was observed in soil layer of 40-60 cm. The long-term fertilization without sulfur could significantly decrease availability of sulfur in brown earth.The use of S-containing chemical fertilizers will increase the contents of H_2O-S and absorbed-S, while the HCl-S acid decreases. Manure or manure plus chemical fertilizer is in favor of sulfur accumulation in soil.