Dissolved organic nitrogen fluxes and crop yield after long-term crop straw incorporation

The present study aims to assess the influences of long-term crop straw returning and recommended potassium fertilization on the dynamic change in rice and oilseed rape yield, soil properties, bacterial and fungal alpha diversity, and community composition in a rice–oilseed rape system. A long-term (2011–2020) field experiment was carried out in a selected paddy soil farmland in Jianghan Plain, central China. There were four treatments with three replications: NP, NPK, NPS, and NPKS, where nitrogen (N), phosphate (P), potassium (K), and (S) denote N fertilizer, P fertilizer, K fertilizer, and crop straw, respectively. Results showed that long-term K fertilization and crop straw returning could increase the crop yield at varying degrees for ten years. Compared with the NP treatment, the long-term crop straw incorporation with K fertilizer (NPKS treatment) was found to have the best effect, and the yield rates increased by 23.0% and 20.5% for rice and oilseed rape, respectively. The application of NPK fertilizer for ten years decreased the bacterial and fungal alpha diversity and the relative abundance of dominant bacterial and fungal taxa, whereas continuous straw incorporation had a contradictory effect. NPKS treatment significantly increased the relative abundance of some copiotrophic bacteria (Firmicutes, Gemmatimonadetes, and Proteobacteria) and fungi (Ascomycota). Available K, soil organic matter, dissolved organic carbon, and easily oxidized organic carbon were closely related to alterations in the composition of the dominant bacterial community; easily oxidized organic carbon, dissolved organic carbon, and slowly available K were significantly correlated with the fungal community. We conclude that long-term crop straw returning to the field accompanied with K fertilizer should be employed in rice-growing regions to achieve not only higher crop yield but also the increase in soil active organic carbon and available K content and the improvement of the biological quality of farmland.

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Dissolved organic matter in the subterranean estuary of a volcanic island, Jeju: Importance of dissolved organic nitrogen fluxes to the ocean

Journal of Sea Research ◽

10.1016/j.seares.2012.12.009 ◽

2013 ◽

Vol 78 ◽

pp. 18-24 ◽

Cited By ~ 34

Author(s):

Tae-Hoon Kim ◽

Eunhwa Kwon ◽

Intae Kim ◽

Shin-Ah Lee ◽

Guebuem Kim

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Dissolved Organic Nitrogen ◽

Organic Nitrogen ◽

Volcanic Island ◽

Subterranean Estuary ◽

Nitrogen Fluxes

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Forest detritus and cycling of nitrogen in a mountain lake

Canadian Journal of Forest Research ◽

10.1139/x91-136 ◽

1991 ◽

Vol 21 (7) ◽

pp. 990-998 ◽

Cited By ~ 8

Author(s):

Robert C. Wissmar

Keyword(s):

Total Nitrogen ◽

Dissolved Organic Nitrogen ◽

Organic Nitrogen ◽

Inorganic Nitrogen ◽

Mountain Lake ◽

Dissolved Inorganic Nitrogen ◽

Microbial Oxidation ◽

Nitrogen Fluxes ◽

Nitrogen Concentrations ◽

Definition Of

Small lakes of forested watersheds can receive large subsidies of forest matter, but little is known about the material's role in the cycling of nutrients within these ecosystems. This paper examines the influence of detritus and dissolved nitrogen from a forest on the nitrogen cycle of a small subalpine lake in the Cascade Mountains of Washington during the ice-free period (98 days). Relationships between changing detrital microbial biomass, oxygen uptake rates, and water conditions indicate that dissolved inorganic nitrogen concentrations and water temperatures control the decomposition of the nitrogen-depleted detritus. The microbial respiration rates suggest the probable co-occurrence of several microbial oxidation and reduction reactions that could be cycling nitrogen in oxic–anoxic interfaces of detrital deposits, sediments, and riparian areas. Estimates of nitrogen gains and losses (3 and 7%, respectively) by forest detritus are low in comparison with total nitrogen uptake and releases within the lake during the study period (378 and 347 mg•m−2, respectively) and point to the need to examine other methods for measuring detrital nitrogen fluxes. The total nitrogen input to the lake (2600 mg•m−2 for the study period) from the watershed exceeds the lake output (2120 mg•m−2 for the study period). The low output of total nitrogen appears to be due to retention of dissolved inorganic nitrogen and particulate organic nitrogen within the lake. Most dissolved inorganic nitrogen retained is nitrate suggesting possible losses through denitrification. Dissolved organic nitrogen is the major proportion of the total nitrogen fluxes, but related mass balance errors indicate the need for further definition of both the sources and fates of dissolved organic nitrogen for the ecosystem.

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