Mustafa Adnan, Frouz Jan, Naveed Muhammad, Ping Zhu, Nan Sun, Minggang Xu, Núñez-Delgado Avelino
National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China; Biology Centre, SOWA RI, Czech Academy of Sciences, 37005, Ceske Budejovice, Czech Republic.
Biology Centre, SOWA RI, Czech Academy of Sciences, 37005, Ceske Budejovice, Czech Republic.
Environ Res. 2022 Apr 1;205:112476. doi: 10.1016/j.envres.2021.112476. Epub 2021 Dec 1.
Long-term fertilization has shown a high relevance as regards soil organic carbon (SOC) sequestration, but the degree of stability of the sequestered SOC has not been widely studied up to now. Using physical fractionation combined with laboratory incubation and NMR spectroscopy, we evaluated the differences in SOC stability caused by long-term fertilization. Four SOC fractions were isolated and examined for contents and chemical composition and cumulative amount of CO-C respired from the fractions under six fertilization treatments: control (CK); balanced inorganic fertilization (NPK); NPK combined with pig manure (MNPK); NPK combined 1.5 times of pig manure (1.5MNPK); and NPK combined with high amount of manure (M2NPK). The highest contents of SOC were recorded for the coarse particulate organic carbon (cPOC) fraction, ranging from 17.25 to 30.47 g kg under CK and M2NPK. The highest cumulative amount of CO-C was released from the cPOC fraction under manure treatments (M2NPK and 1.5NPKM), which was 56 and 43% higher than that from CK, whereas the lowest amount of CO-C was released from the mineral associated-C (MOC) fraction under the same treatments, being 65 and 49% higher than that released from CK, suggesting low SOC stability in cPOC and high SOC stability in MOC fractions. However, manure treatments (M2NPK and 1.5NPKM) greatly lowered the specific amount of C-mineralized (C-mineralized per unit total SOC) in fractions and whole soil, suggesting the ability of manure to accumulate more SOC by reducing SOC losses. Moreover, carbonyl-C was found to be the form of SOC experiencing major degree of sequestration under current fertilization practices. The SOC stability indices; aromaticity index (AI), hydrophobicity index (HI) and alkyl-C/O-alkyl-C were found to be higher in manure treated plots further suggesting higher stability of SOC under manure addition. Thus, long-term manure combined with mineral fertilizers would enhance SOC stability through minimizing SOC losses and promoting accumulation of stable C forms in a Chinese Mollisol.
长期施肥已显示出与土壤有机碳(SOC)固存高度相关,但迄今为止,固存的SOC的稳定性程度尚未得到广泛研究。我们采用物理分级结合实验室培养和核磁共振光谱法,评估了长期施肥导致的SOC稳定性差异。在六种施肥处理下,分离出四个SOC组分,并检测其含量、化学组成以及各组分释放的CO-C累积量:对照(CK);平衡无机施肥(NPK);NPK配施猪粪(MNPK);NPK配施1.5倍猪粪量(1.5MNPK);NPK配施大量猪粪(M2NPK)。粗颗粒有机碳(cPOC)组分的SOC含量最高,在CK和M2NPK处理下,范围为17.25至30.47 g/kg。在施用猪粪的处理(M2NPK和1.5NPKM)下,cPOC组分释放的CO-C累积量最高,分别比CK高56%和43%,而在相同处理下,与矿物结合的碳(MOC)组分释放的CO-C量最低,分别比CK高65%和49%,这表明cPOC中SOC稳定性低,而MOC组分中SOC稳定性高。然而,施用猪粪的处理(M2NPK和1.5NPKM)极大地降低了各组分和整个土壤中C矿化的特定量(每单位总SOC的C矿化量),表明猪粪有通过减少SOC损失来积累更多SOC的能力。此外,发现羰基-C是当前施肥实践下经历主要固存程度的SOC形式。在施用猪粪的地块中,SOC稳定性指标;芳香性指数(AI)、疏水性指数(HI)和烷基-C/O-烷基-C更高,进一步表明添加猪粪后SOC稳定性更高。因此,长期将猪粪与矿物肥料结合使用,将通过最大限度减少SOC损失并促进中国软土中稳定C形态的积累来提高SOC稳定性。