Use of1H NMR to identify nitrogen and carbon metabolites associated with mineralizable N in grassland soil

Effects of rotation length, fallow-substitute crops, and N and P fertilizer on some physical and biological properties of a Brown Chernozemic loam in southwestern Saskatchewan were determined over a period of 16 yr. After 12 yr, the erodible fraction in the top 15 cm of soil (i.e., < 0.84 mm) was inversely related to trash conserved and thus rotation length. Soil organic N (in the top 15 cm) increased from 0.18 to 0.20% in continuous-type rotations receiving an average 32 kg N∙ha−1∙yr−1 and adequate P, but it did not increase in continuous wheat receiving P only, nor in fallow rotations, except the one that included fall rye (Secale cereale L.). This N increase was credited partly to fertilizer and partly to more efficient use and cycling of subsoil NO3-N via plant roots and crop residues. After 10 yr, well-fertilized continuous-type rotations had a 13% greater C content than fallow rotations and continuous wheat receiving only P. In the top 7.5 cm of soil under the four rotations examined in detail, bacterial numbers were lowest in fallow-wheat, intermediate in fallow-wheat-wheat, higher in continuous wheat receiving N and P, and highest in continuous wheat receiving only P. Similarly, microbial biomass C in these four rotations was 180, 226, 217 and 357 kg∙ha−1; biomass N was 52, 65, 54 and 72 kg∙ha−1; and biomass C/N ratios were 3.4, 3.5, 4.1 and 5.1, respectively. Differences in biomass C/N, respiration rates and numbers of bacteria, actinomycetes and yeasts indicated both quantitative and qualitative microbial changes and reflected increasing rotation length and differences in fertility. Potentially mineralizable N (No) was 192 kg∙ha−1 for adequately fertilized continuous wheat, and exceeded No in fallow-wheat by 45%, in fallow-wheat-wheat by 17% and in continuous wheat receiving only P by 25%. The latter rotation contained a large but fairly inactive microbial population. We concluded that land degradation caused by frequent summerfallowing can be arrested and the decline in amount and quality of organic matter reversed by use of available agronomic technology. Key words: Microbial biomass, microbial activity, potentially mineralizable N, respiration, soil erodibility

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<i>Grassland soil-root complex and its research methods</i>

10.13031/aim.202100370 ◽

2021 ◽

Author(s):

Xuening Zhang ◽

Yong You ◽

Decheng Wang

Keyword(s):

Research Methods ◽

Grassland Soil

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Amerosporium concinnum. [Descriptions of Fungi and Bacteria].

IMI Descriptions of Fungi and Bacteria ◽

10.1079/dfb/20093210585 ◽

2009 ◽

Author(s):

V. P. Hayova

Keyword(s):

Vitis Vinifera ◽

Geographical Distribution ◽

Conservation Status ◽

Cichorium Intybus ◽

Foeniculum Vulgare ◽

Grassland Soil ◽

Stenotaphrum Secundatum ◽

Ephedra Distachya

Abstract A description is provided for Amerosporium concinnum, which is found on dead remains of various plants, but it has also been isolated from grassland soil in Spain. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Mexico, USA (Texas), China (Shaanxi), Iran, Turkey, Georgia, Greece, Portugal, Spain, and Ukraine) and hosts (Ceratocladium purpureogriseum, Phomopsis brunaudiana, Torula herbarum f. quaternella, Acer oliverianum, Alhagi pseudalhagi, Arundo phragmitis, Bambusa sp., Cichorium intybus, Citrus sp., Echinops sp., Ephedra distachya, Foeniculum vulgare, Stenotaphrum secundatum, Vitis vinifera, and Ziziphora serpyllaceae).

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THE ORGANIC PHOSPHORUS COMPOSITION OF AN IRISH GRASSLAND SOIL

Biology & Environment Proceedings of the Royal Irish Academy ◽

10.1353/bae.2008.0018 ◽

2008 ◽

Vol 108B (1) ◽

pp. 17-28

Author(s):

David Bourke ◽

Paul Dowding ◽

Hubert Tunney ◽

John E. O'Brien ◽

David W. Jeffrey

Keyword(s):

Organic Phosphorus ◽

Grassland Soil

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Incubation methods for assessing mineralizable nitrogen in soils under sugarcane

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832013000200016 ◽

2013 ◽

Vol 37 (2) ◽

pp. 450-461 ◽

Cited By ~ 11

Author(s):

Eduardo Mariano ◽

Paulo Cesar Ocheuze Trivelin ◽

José Marcos Leite ◽

Michele Xavier Vieira Megda ◽

Rafael Otto ◽

...

Keyword(s):

N Mineralization ◽

Standard Technique ◽

Extraction Methods ◽

N Fertilization ◽

Chemical Extraction ◽

Net N Mineralization ◽

Anaerobic Incubation ◽

Aerobic Incubation ◽

Mineralizable N

Considering nitrogen mineralization (N) of soil organic matter is a key aspect for the efficient management of N fertilizers in agricultural systems. Long-term aerobic incubation is the standard technique for calibrating the chemical extraction methods used to estimate the potentially mineralizable N in soil. However, the technique is laborious, expensive and time-consuming. In this context, the aims of this study were to determine the amount of soil mineralizable N in the 0-60 cm layer and to evaluate the use of short-term anaerobic incubation instead of long-term aerobic incubation for the estimation of net N mineralization rates in soils under sugarcane. Five soils from areas without previous N fertilization were used in the layers 0-20, 20-40 and 40-60 cm. Soil samples were aerobically incubated at 35 ºC for 32 weeks or anaerobically incubated (waterlogged) at 40 ºC for seven days to determine the net soil N mineralization. The sand, silt and clay contents were highly correlated with the indexes used for predicting mineralizable N. The 0-40 cm layer was the best sampling depth for the estimation of soil mineralizable N, while in the 40-60 cm layer net N mineralization was low in both incubation procedures. Anaerobic incubation provided reliable estimates of mineralizable N in the soil that correlated well with the indexes obtained using aerobic incubation. The inclusion of the pre-existing NH4+-N content improved the reliability of the estimate of mineralizable N obtained using anaerobic incubation.

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