化肥对黑土不同粒级碳水化合物的影响

本文采集公主岭市长期定位监测基地不施肥和施用不同化肥的黑土,通过超声波分散-离心分离得到细黏粒(<0.2μm)、粗黏粒(0.2～2μm)、粉粒(2～53μm)、细砂粒(53～250μm)、粗砂粒(250～2000μm)5个颗粒级别,分析全土及不同粒级中土壤碳水化合物并进行含量与分布的比较。结果表明,黑土中不同粒级碳水化合物库的性质差异显著,碳水化合物多集中在粉+黏粒中;长期施用化肥后,黑土全土及各粒级碳水化合物库大小和浓度基本上没有变化;粗砂粒级(Gal+Man)(:Ara+Xyl)下降,表明该粒级中植物来源碳水化合物所占比重有所增加,暗示出粗砂粒级对施肥措施更为敏感。

Effect of Chemical Fertilizer Application on the Carbohydrates in Bulk Black Soil and Particle-size Fractions

The black soil fertilized with different chemical fertilizers for 21 years was sampled from Gongzhuling long-term located station.Fine clay(< 0.2 μm),coarse clay(0.2-2 μm),silt(2-53 μm),fine sand(53-250 μm) and coarse sand(250-2000 μm) fractions were obtained by ultrasonic dispersion,centrifugation and wet sieving separation.Carbohydrates were detected in bulk soil and particle-size fractions.The results showed that there was a large variation among the size separates in black soil carbohydrate pool.Clay plus silt fractions comprised major carbohydrates pool in the soils studied and contained about 70% of the total carbohydrate.In general the application of chemical fertilizers had no clear effect on either neueral sugar accumulation or distribution in size fractions.The decrease of the(Gal+Man):(Ara+Xyl) ratio in coarse fraction after the application of chemical fertilizers indicated a higher contribution of plant sugars to the polysaccharide pool,suggesting that coarse sand fraction was more sensitive to fertilization than the other fractions.