首页期刊导航|Geoderma: An International Journal of Soil Science
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Geoderma: An International Journal of Soil Science
Elsevier Science Publishers
Geoderma: An International Journal of Soil Science

Elsevier Science Publishers

0016-7061

Geoderma: An International Journal of Soil Science/Journal Geoderma: An International Journal of Soil Science
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    Aggregate stability and size distribution regulate rainsplash erosion: Evidence from a humid tropical soil under different land-use regimes

    Chen, ChunfengZhu, KaiZhang, WanjunYang, Bin...
    12页
    查看更多>>摘要：Soil erosion by water is a serious global ecological issue that leads to land degradation and threatens ecosystem sustainability. Splash erosion resulting from raindrop impact is the first stage of the erosion process and is mainly responsible for the detachment and migration of soil surface aggregates. In humid tropical regions, however, there has been little quantitative analysis of the relations between splash erosion and variable aggregate characteristics such as stability, particle size distribution and organic matter content. The objective of the current study was to determine how rain splash erosion is related to soil aggregate characteristics under land-use change, i.e., the conversion of tropical rainforest (TR) into rubber plantation (RP). Splash cups containing dry-sieved aggregate samples with eight size classes were exposed to natural rainfall to measure the splash erosion rate. The results showed that the initial aggregate organic carbon, water-stable aggregate index (WSA) and mean weight diameter (MWD) decreased by 31%, 9% and 48%, respectively, after 32 years of rubber cultivation. These degenerations in aggregate properties increased the susceptibility of soil aggregates to erosion and mutually contributed to a higher average splash erosion rate in RP (1.20 kg m-2) than in TR (1.09 kg m-2), regardless of aggregate size fractions. Splash erosion rates for all aggregate sizes were significantly positively correlated with rainfall kinetic energy, rainfall amount and intensity during the study period. The average splash erosion rate of aggregates first increased and then decreased with a decline in aggregate size in both TR and RP. The minimum and maximum splash rates were observed within 10-8 mm and 0.5-0.25 mm size fractions, respectively. In particular, the proportion of small-sized aggregates (i.e., 1-0.15 mm) with a relatively high splash erosion rate increased remarkably after land-use change. This exerted a negative impact on splash erosion control as well as on the sustainable development of rubber cultivation. Increasing the additional input of organic materials (e.g., intercropping cash crops with rubber trees) may help to enhance large aggregate formation and stabilization, which could minimize the risk of splash erosion at the aggregate scale for eroded rubber plantation ecosystems.
      原文链接:
    • NSTL
    • Elsevier

    Earthworms exert long lasting afterlife effects on soil microbial communities

    Wang, HongjuanQian, ShenhuaZhao, LiangYang, Yongchuan...
    9页
    查看更多>>摘要：Earthworms dominate the invertebrate biomass in soils. Although the effects of living earthworms on soil functioning have been extensively studied, the ecological impacts of earthworm cadavers on soil microbiota remain unclear. In a 10-weeks laboratory incubation experiment, we monitored the influence of decomposing earthworm cadavers on the diversity and composition of soil bacterial, fungal and protistan communities. We found that the decomposition of earthworm cadavers decreased alpha diversity and changed the composition of microbial communities in comparison to control soil and soil with living earthworms. Although the functional composition of bacterial communities was not significantly influenced by the presence of dead earthworms, both fungal and protistan communities significantly shifted toward r-selected copiotrophic strategists; fungal com-munities were significantly enriched in molds and yeasts while protistan communities were enriched in sapro-trophs. Our results suggest that dead earthworms play a distinct role in influencing soil microbial communities and associated functioning compared to their living counterparts. They further highlight that there is an increasing need to consider the afterlife effects of soil biota to better predict soil biogeochemical cycling in terrestrial ecosystems.
      原文链接:
    • NSTL
    • Elsevier

    Belowground plant inputs exert higher metabolic activities and carbon use efficiency of soil nematodes than aboveground inputs

    Zhang, ZhiyongWang, HanDing, FanWilschut, Rutger A....
    9页
    查看更多>>摘要：Soil nematodes are key components of soil food web and, through their metabolic activities, play a crucial role in soil carbon (C) cycling. Aboveground and belowground plant C inputs can directly, or indirectly via soil microbes, modify nematode abundance and community composition. Aboveground and belowground C inputs differ in chemical composition, amounts, and frequency, so we hypothesized that the two input pathways affect nematode communities differently. To assess the relative contributions of aboveground versus belowground inputs to nematode community composition and activity, we subjected grassland soils to four plant input pathways over two consecutive years: no input, only aboveground input (+A), only belowground input (+B), and both aboveground and belowground inputs (+A + B). Nematode metabolic footprints, as estimates of C used in growth/reproduction and C lost by respiration, and C use efficiency (C used/(C used + C lost)) were calculated. We predicted that soils with belowground inputs, which are more directly linked to the soil biota, and which contain a more labile blend of molecules, would support richer and more complex nematode communities, and also favor a bacterial-driven decomposition channel. Accordingly, we showed that + B soils supported higher nematode numbers than + A soils, and that the bacterial decomposition channel was dominant in + B soils, while the fungal decomposition channel dominated in + A soils. Compared with + A soils, +B input system increased nematode structure footprints (the metabolic footprints of nematodes in upper functional guilds) rather than enrichment footprints (the metabolic footprints of enrichment opportunistic nematodes). Moreover, we observed that, compared to + A soils, +B soils had higher growth and respiration rates of bacterivores, omnivores predators, and total nematodes. Finally, we found higher C use efficiency values for omnivores-predators and total nematodes in + B than in + A soils. We thus conclude that belowground plant-derived resources, by changing the ratio between fungivores and bacterivores, induce a faster carbon turnover rate, and higher metabolic activity of soil nematodes within soil food web, ultimately spurring richer and more efficient soil food web than aboveground inputs.
      原文链接:
    • NSTL
    • Elsevier

    Nitrous oxide production pathways in Australian forest soils

    Pan, BaobaoZhang, YushuXia, LonglongLam, Shu Kee...
    5页
    查看更多>>摘要：Forest soils are a major source of N2O emissions from terrestrial ecosystems. However, the magnitude and contribution of N2O production from different pathways in Australian forest soils remain uncertain. We conducted a N-15 tracing laboratory incubation experiment on 13 forest soils sampled from subtropical, temperate and arid regions across Australia and found that forest soils in temperate areas had the highest N2O emission rate (19.5 mu g N kg-1 soil d-1), followed by subtropical and arid soils (3.84 and 3.80 mu g N kg-(-1)soil d(-1), respectively). N2O production in Australian forest soils was mainly derived from the organic nitrogen (N) pool; its contribution followed the order of arid (78%) > subtropical (69%) > temperate (59%). N2O emission potentially from heterotrophic nitrification was negatively correlated with latitude (p < 0.05) and the contribution of soil organic N to N2O production was negatively correlated with soil total N and total carbon (C) content (p < 0.01). Our study improves the understanding of N2O production pathways from warm arid to cool temperate regions in Australian forest soils.
      原文链接:
    • NSTL
    • Elsevier

    Determining the hot spots and hot moments of soil N2O emissions and mineral N leaching in a mixed landscape under subtropical monsoon climatic conditions

    Zhou, ZhiwenLiao, KaihuaZhu, QingLai, Xiaoming...
    12页
    查看更多>>摘要：Identification of hot spots and hot moments (HSHMs) in regard to soil nitrogen (N) losses has received public attention. Soil nitrous oxide (N2O) emissions and mineral N leaching under varied annual precipitation were simulated with the DayCent model in a mixed landscape (tea garden, bamboo forest and coniferous and broadleaved mixed forests). Their HSHMs were further quantified using the 3rd quartile value of all data as the baseline. Results showed that the hot moments of soil N2O emissions were the dry year, summer, and months with high air temperature (July to September) and months after fertilization (April or May) at inter-annual, seasonal and monthly time scales, respectively. The hot moments of mineral N leaching at these time scales were the normal year or the wet year, spring or rainy seasons after drought, and rainy months after fertilization or drought, respectively. The main factors controlling the formation of hot moments on N losses were temperature, precipitation and fertilization. In addition, the hot spots of N2O emissions and mineral N leaching in the mixed landscape were both distributed in the tea garden (TG). When the entire study area was assumed to be under the same land-use type (i.e., TG), the hot spots of these two kinds of N losses were mainly distributed in the areas with rock fragment content < 0.16 cm3 cm-3, field capacity > 0.24 cm3 cm-3, bulk density > 1.29 g cm-3, soil carbon (C)/N ratio < 13.26, and slope < 12 degrees. These results indicated that fertilizer management, climate factors, soil properties and topography need to be comprehensively considered to alleviate the formation of HSHMs of N losses in mixed landscape mountainous areas.
      原文链接:
    • NSTL
    • Elsevier

    Contrasting effects of siderophores pyoverdine and desferrioxamine B on the mobility of iron, aluminum, and copper in Cu-contaminated soils

    Gaudin, P.Ouedraogo, F.Sourzac, M.Parlanti, E....
    11页
    查看更多>>摘要：Siderophores are biogenic metallophores that can play significant roles in the dynamics of a range of metals, including Cu, in the soil. Understanding the impact of siderophores on the mobility and the availability of metals in soil is required to optimize the efficiency of soil remediation processes such as phytoextraction. This study compared the ability of siderophores desferrioxamine B (DFOB) and pyoverdine (Pvd) to mobilize metals in a series of Cu-contaminated soils, and investigated the extent their metal mobilization efficiency changed over time and with the level of Cu contamination of the soil. Siderophores were supplied (or not) to Cu-contaminated soils and metal mobility was assessed through their total concentration in 0.005 M CaCl2 extract. DFOB selectively mobilized Fe and Al while Pvd also mobilized Cu and Ni, Co, V and As but to a lesser degree. The 1:1 relationship between DFOB in the CaCl2 extract and Fe + Al mobilized from the solid phase suggests that DFOB mobilized metals by ligand-controlled dissolution. The accumulation of Cu in soil enhanced the adsorption of DFOB and Pvd at the surface of soil constituents and the mobilization of Fe to the detriment of Al by the two siderophores. The metal mobilization efficiency of DFOB and to a lesser extent of Pvd decreased over 22 days. According to N-15-Pvd analyses, Pvd degradation at least partly contributed to the progressive reduction in the metal mobilization efficiency of Pvd. The processes behind these results and the relevance of these results for manipulating the availability of Cu (and Fe) in soil are discussed.
      原文链接:
    • NSTL
    • Elsevier