长期不同施肥黑土碳氮库的组分特征

Component characteristics of carbon and nitrogen pools in black soil under long term fertilization

土壤有机质因组成和稳定机制等差异,具有很大的分解异质性,研究其分组特征,对于了解土壤有机质的质量具有十分重要的意义。本文利用物理分组法,对于土壤有机质组分性质影响少的优点,比较了长期不同施肥黑土不同组分碳氮库的数量变化。结果发现,23年后化肥(NPK)处理和化肥配施秸秆(NPKS)处理土壤有机碳、全氮含量波动不大。化肥配施有机肥(NPKM)处理土壤有机碳、全氮含量显著增加(P<0.01)。进一步碳氮分组发现,有机无机配施(NPKS和NPKM)显著降低了有机质与矿质结合组分(>150μm MF)的含量;NPKM处理显著增加了黑土粗有机质组分(>150μm MOM)的比例。将大于150μm组分中有机质与矿质结合部分去除作为易分解库,剩余组分作为耐分解库,比较3种处理发现,与NPK处理相比,NPKS和NPKM处理易分解有机碳比例增加0.9和5.9个百分点;耐分解有机碳比例分别为下降14.2和18.8个百分点。易分解有机氮比例增加1.8和9.9个百分点;耐分解有机氮下降2.7和5.3个百分点。上述研究表明,NPKS和NPKM可以改善黑土土壤有机氮和土壤有机碳的数量和品质,且NPKM的效果显著优于NPKS处理。

Soil organic matter is a heterogeneous material because of its different components and stability mechanisms, so the changes of soil organic carbon （ SOC） and nitrogen （ SON） fractions over time were different in their turnover rates. There-fore, physical fractionation procedure was adopted to study three fertilizer treatments, namely NPK （ inorganic fertilizer ） , NPKS （ inorganic fertilizer ＆straw） and NPKM （ inorganic fertilizer ＆manure） on labile and recalcitrant organic C and N pool in black soil. The results showed SOC and TN contents under NPK and NPKS treatments changed little over past 23 years. While NPKM treatment significantly increased SOC and TN contents by 0. 28 g/kg and 0. 04 g/kg per year, respectively. NPKS and NPKM treatments significantly reduced the proportion of 〉150 μm MF fraction. NPKM treatment significantly in-creased the proportions of total C and N stored in the 〉150 μm MOM fraction. Comparing with NPK treatment, labile carbon pools under NPKS and NPKM treatments increased by 0. 9 percent and 5. 9 percent, respectively. Labile nitrogen pools in-creased 1. 8 percent and 9. 9 percent for NPKS and NPKM treatments, respectively. In all, NPKS and NPKM treatments im-prove SOC and SON amount and quality among fractions. And NPKM treatment was significantly better than NPKS treatment in improving quantity and quality of SOC and SON in different fractions.