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National Key Research and Development Program of China

No abstract is provided for this article.

Long-term fertilization is considered as the most effective practice in organic C accrual in intensively managed paddy soils. However, the contribution and mechanism of microbial necromass C for soil organic C accrual, and the effective incremental component in paddy soils under the different fertilization remain unclear. To address the knowledge gap, we collected soils from a 31-year long-term fertilization paddy field including no fertilization (control), mineral fertilizers alone (NPK), mineral fertilizers plus rice straw incorporation (NPK + S), and mineral fertilizers plus manure incorporation (NPK + M). Living microbial biomass and their necromass were quantified by the biomarker analysis of phospholipid fatty acids and amino sugars, respectively. Results showed that the three fertilization treatments significantly increased the bacterial and fungal biomass in both 0–10 and 10–20 cm layers, which were universally greatest in NPK + M. The microbial necromass C was little affected by 31-year mineral fertilization; however, mineral combined organic fertilizers incorporation greatly stimulated microbial necromass C accumulation. Besides, soil treated with NPK + M showed 3.55 ± 0.12 g kg−1 higher accumulation of microbial necromass C than NPK + S, because manure application increased the abundance of Gram-positive r-strategy bacteria (mainly Firmicutes and Actinobacteria), and enriched filamentous fungi (Ascomycota). Compared to the control, the increase in the microbial necromass C contribution to SOC was lowest in NPK and highest in NPK + M, mainly derived from the variation in the contribution of bacterial necromass. Consequently, this study suggested long-term mineral combined manure application in subtropical paddy fields could effectively increase soil C sequestration by strengthening microbial necromass accumulation. Bacterial and fungal necromass C accrual was closely associated with living microbial biomass and their community structure. Given the C sequestration potential of manure in paddy soil, as the crucial resource of livestock and poultry waste in this region, it should be incorporated into subtropical agricultural ecosystems.

Unforested sandy areas near flood plains and riverbed plains formed by dunes, barchans, and accumulative berms are well common in northern Eurasia and Alaska indicating the complex history of climate periods in the Holocene and modern eras. Active dunes with simple plant communities are surrounded by stable dunes overgrown with taiga forests, and are predestined for investigation of initial vegetation and soil development. Based on climatic, geomorphological, vegetation and soil properties including soil microbiome, we analyzed the cyclic and linear development of ecosystems in a typical sand area in the lower part of the Nadym River, 100 km south of the Arctic Circle. Shift of wind direction during Holocene, as well as very slow vegetation development under these harsh climatic conditions, lead to circular ecosystem development without to reach a steady state. Arenosols with extremely sparse vegetation and undifferentiated horizons are typical for this circular ecosystem development. In contrast, faster development of vegetation on slightly stabilized soils in wind protected areas (enclaves) stabilize sand movement, and lead to soil formation in the direction of Podzols. Based on soil acidification by litter input and succession of microbial communities we concluded about the carbon and nutrient limitations during soil development. Summarizing, detailed analysis of initial ecosystem development chains on sand dunes in taiga allowed to elucidate the common phases of vegetation and soil succession, and clarify their cyclic and linear development.

Microbial volatile organic compounds (VOCs) can suppress plant pathogens. Although fertilization strongly affects soil microbial communities, the influence of fertilization on microbial VOC-mediated suppression of pathogens has not been elucidated. Soil was sampled from a paddy field that had been subjected to the following treatments for 30 years: a no-fertilizer control, mineral fertilization (NPK), NPK combined with rice straw (NPK + S), NPK combined with chicken manure (70% NPK + 30% M). Then, within a laboratory experiment, pathogens were exposed to VOCs without physical contact to assess the impact of VOCs emitted from paddy soils on in vitro growth of the fungal rice pathogens: Pyricularia oryzae and Rhizoctonia solani. The VOCs emitted from soil reduced the mycelial biomass of P. oryzae and R. solani by 36–51% and 10–30%, respectively, compared to that of the control (no soil; no VOCs emission). Overall, the highest suppression of P. oryzae and R. solani was in the NPK and NPK + S soils, which emitted more quinones, phenols, and low alcohols than NPK + M soils. The abundances of quinones and phenols in the soil air were maximal in the NPK-fertilized soil because the low ratio of dissolved organic carbon and Olsen-P increased the population of key species such as Acidobacteriae, Anaerolineae, and Entorrhizomycetes. The abundance of alcohols was minimum in the NPK + S fertilized soil because the high SOC content decreased the population of Sordariomycetes. In conclusion, mineral fertilization affects bacterial and fungal VOC emissions, thereby suppressing the growth of R. solani and P. oryzae.

Soil organic carbon (SOC) has various pools with different stabilization mechanisms. It is unclear how these SOC pools respond to various mineral and organic amendments depending on a large climate-soil gradient. Here, we studied in three zonal soils: Ferralic Cambisol (subtropic), Calcaric Cambisol (warm-temperate) and Luvic Phaeozem (mid-temperate) under 23-year mineral, straw and manure amendments. Six SOC sub-pools were isolated: unprotected, physically, chemically, biochemically, physico-chemically and physico-biochemically protected pools. Compared to initial level, SOC and most sub-pools increased in the three soils under manure application ( p < 0.05), but little under straw and mineral amendments. The Luvic Phaeozems had much higher sequestration efficiencies of bulk SOC (27%) and its five sub-pools (5–7%) more than the Calcaric Cambisol (9%, 1–2%) and Ferralic Cambisol (9%, 0.5–1%). In contrast, Ferralic Cambisol had highest sequestration efficiency of unprotected pool (7%). The Calcaric Cambisol had divergent patterns of the six SOC pools compared with Luvic Phaeozems and Ferralic Cambisol, due to the low clay content. With the build-up of bulk SOC, the building-up abilities of non-protected, physically-, chemically- and biochemically-protected pools depended on soil type, while the building-up abilities of physico-chemically- and physico-biochemically-protected pools were convergent (12–19%) among soils. In conclusion, the Luvic Phaeozems had much higher build-up ability of bulk SOC and most sub-pools than the other two soils. With the build-up of SOC, the physico-chemically- and physico-biochemically-protected pools (most stable) had convergent response rates among soils, while the other pools had divergent response rates. Graphical Abstract

No abstract is provided for this article.

No abstract is provided for this article.

The study examines the early medieval paleosol (4th–6th centuries AD) and background soil at the fortified settlement of Ust-Utyak-1 located in the forest-steppe area of the Middle Tobol region. Differences in soil type were discovered. In the last 1300–1500 years, the development of forest-steppe chernozems shows a tendency towards exceeding aridity, resulting in the evolvement of leached chernozems into typical chernozems. Comparative analysis of the morphological structure and chemical properties of the soils under study gives reason to believe that the environmental conditions of the 4th–6th centuries were marked by greater humidity and heat supply than the present day. According to the historical and archaeological data, this time coincides with the flourishing of the Bakal Culture which declined at the end of that period.