长期化肥有机替代对黑土颜色及腐殖物质的影响

基于30年长期定位试验,通过测定黑土光谱反射率和不同腐殖质组分含量,探究了不同施肥对黑土土壤腐殖质含量、土壤颜色及二者之间的关系。试验设置5个处理:(1)休耕(Fallow);(2)不施肥处理(CK);(3)单施化肥(NPK);(4)有机肥部分替代化肥(NPKM);(5)秸秆部分替代化肥处理(NPKS)。结果表明:与NPK处理相比,Fallow、NPKS、NPKM分别显著提高49.7%,74.3%,27.0%的土壤有机碳含量(p<0.05)。NPKM处理中胡敏酸(HA)含量最高为3.9 g/kg,随后依次为CK、NPKS、NPK、Fallow。NPKM、NPKS和Fallow处理中土壤富里酸(FA)含量为2.2~2.3 g/kg,显著高于NPK和CK。NPKM处理中胡敏素(HM)含量为18.6 g/kg,显著高于其他处理(p<0.05)。不同处理间土壤光谱反射率由高到低依次为NPK>Fallow、CK>NPKS>NPKM,与CK处理相比,NPK土壤光谱反射率在平均提高6.5%,NPKS和NPKM则分别降低11.1%和15.1%。根据线性相关分析结果,黑土土壤光谱反射率与土壤HAHM均呈显著负相关关系(p<0.01),相关系数(r)分别为-0.858,-0.681。综合上述结果,长期有机物料投入可以显著提高黑土腐殖物质含量,降低黑土光谱反射率,使黑土颜色加深,而长期化肥施入则使黑土光谱反射率提高,出现"褪色"现象,有机粪肥在黑土中对土壤有机质和腐殖质含量的提升效果优于秸秆。

Effects of Organic Substitution Chemical Fertilizer on Color and Humic Substances of Black Soil

Spectral reflectance and humic substances components were determined aiming at studying the effects of different fertilization on humic substances content and color of black soil based on 30 years long-term location trial. A total of 5treatments were included in this study: (1) Fallow; (2) No fertilizer application (CK); (3) Only chemical fertilizer (NPK); (4) Organic fertilizer partly replaced chemical fertilizer (NPKM); (5) Straw partly replaced chemical fertilizer (NPKS). Results indicated that soil organic carbon content in Fallow, NPKM, NPKS were significantly increased by 49.7%, 74.3%, 27.0% in contrast with NPK (p<0.05). The highest content of humic acid (HA) was 3.9 g/kg observed in NPKM, and following was in order of CK, NPKS, NPK, Fallow. Soil fulvic acid (FA) contents in NPKM, NPKS and Fallow were in range of 2.2 to 2.3 g/kg, significantly higher than NPK and CK. Soil humin (HM) content in NPKM was 18.6 g/kg, significantly higher than other treatments (p<0.05). The order of soil spectral reflectance from high to low was as following NPK > Fallow, CK > NPKS > NPKM. In contrast with CK, soil spectral reflectance in NPK was increased by 6.5% on average, while in NPKS and NPKM were decreased by 11.1% and 15.1% in average, respectively. According to the linear correlation analysis results, the spectral reflectance of black soil was significantly negatively correlated with soil HA and HM contents (p<0.01), and the correlation coefficient (r) were -0.858 and -0.681, respectively. Summing up the results above, it can be concluded that long-term organic materials application could significantly enhance soil humic substance content, lower soil spectral reflectance, and make black soil darker. Oppositely, long-term chemical fertilizer application increased soil spectral reflectance, and made black soil "faded". The effects of organic manure on improving soil organic materials and humic substances were better than straw.