Spatial Variability of Soil Organic C, Inorganic N and Extractable P in a Mediterranean Grazed Area

2012 ◽  
Vol 26 (2) ◽  
pp. 103-109 ◽  
Author(s):  
C. Costa ◽  
E. M. Papatheodorou ◽  
N. Monokrousos ◽  
G. P. Stamou
Keyword(s):  
Spatial Variability ◽  
Soil Organic C ◽  
Inorganic N ◽  
Organic C ◽  
Extractable P

scholarly journals Effects of broad-leaf crop frequency in various rotations on soil organic C and N, and inorganic N in a Dark Brown soil

2012 ◽  
Vol 03 (06) ◽  
pp. 854-864
Author(s):  
Sukhdev S. Malhi ◽  
R. L. Lemke ◽  
S. A. Brandt
Keyword(s):  
Soil Organic C ◽  
Inorganic N ◽  
Organic C ◽  
Brown Soil ◽  
Broad Leaf ◽  
C And N

scholarly journals Rhizosphere priming of two near-isogenic wheat lines varying in citrate efflux under different levels of phosphorus supply

2019 ◽  
Vol 124 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Qiao Xu ◽  
Xiaojuan Wang ◽  
Caixian Tang
Keyword(s):  
Microbial Biomass ◽  
Root Exudates ◽  
Root Exudation ◽  
Mineral Dissolution ◽  
Microbial Biomass C ◽  
Inorganic N ◽  
Organic C ◽  
Extractable P ◽  
Water Extractable ◽  
Citrate Efflux

Abstract Backgrounds and Aims The rhizosphere priming effect (RPE) has been explained from the perspective of microbial responses to root exudates and nutrient availability. This study introduced a chemical process that could also contribute to RPE: root exudates (organic acid ligands) could liberate mineral-protected carbon (C) in soil for microbial degradation. Methods Wheat (Triticum aestivum L.) near-isogenic lines varying in citrate efflux were grown for 6 weeks in a C4 soil supplied with either low (10 μg g–1) or high P (40 μg g–1). Total below-ground CO2 was trapped and partitioned for determination of soil organic C decomposition and RPE using a stable isotopic tracing technique. Mineral dissolution was examined by incubating soil with citric ligand at a series of concentrations. Key Results High P increased RPE (81 %), shoot (32 %) and root biomass (57 %), root-derived CO2-C (20 %), microbial biomass C (28 %) and N (100%), soil respiration (20 %) and concentrations of water-extractable P (30 %), Fe (43 %) and Al (190 %), but decreased inorganic N in the rhizosphere. Compared with Egret-Burke, wheat line Egret-Burke TaMATE1B with citrate efflux had lower inorganic N, microbial biomass C (16 %) and N (30 %) in the rhizosphere but greater RPE (18 %), shoot biomass (12 %) and root-derived CO2-C (low P 36 %, high P 13 %). Egret-Burke TaMATE1B also had higher concentrations of water-extractable P, Fe and Al in the rhizosphere, indicating the release of mineral-protected C. In addition, citrate ligand facilitated Fe and Al release from soil, with their concentrations rising with increasing ligand concentration and incubation time. Conclusions While high P supply increased microbial growth and RPE possibly due to higher total root exudation, citrate efflux from the root might have facilitated the liberation of mineral-bound C, leading to the higher RPE under Egret-Burke TaMATE1B. Mineral dissolution may be an important process that regulates RPE and should be considered in future RPE research.

scholarly journals Novel Proximal Sensing for Monitoring Soil Organic C Stocks and Condition

2017 ◽  
Vol 51 (10) ◽  
pp. 5630-5641 ◽  
Author(s):  
Raphael A. Viscarra Rossel ◽  
Craig R. Lobsey ◽  
Chris Sharman ◽  
Paul Flick ◽  
Gordon McLachlan
Keyword(s):  
Soil Organic C ◽  
Proximal Sensing ◽  
Organic C ◽  
C Stocks

Characterization of basaltic clay soils (vertisols) from the Oxford land system in central Queensland

Soil Research ◽  
1990 ◽  
Vol 28 (6) ◽  
pp. 841 ◽  
Author(s):  
AA Webb ◽  
AJ Dowling
Keyword(s):  
Clay Soils ◽  
Total N ◽  
Organic C ◽  
Land System ◽  
Group Position ◽  
Dominant Soil ◽  
Extractable P ◽  
General Decline ◽  
Close Proximity ◽  
Native Pasture

Morphological, chemical and physical properties of basaltic clay soils (Vertisols-Usterts and Torrerts) from the Oxford Land System in central Queensland are described and compared over their geographical range of occurrence and also their position in the landscape. These soils are derived from undifferentiated basic lavas and interbedded pyroclastics of Tertiary age. Black earths are the dominant soil group. Position on slope had the biggest influence on depth of soil, with crest and mid-upper slope positions having more shallow (<0.9 m) soils than mid-lower and footslope positions. Soils have very high CEC and clay contents throughout the profile, are mildly alkaline at the surface and strongly so at depth, are non-saline and non-sodic (except in some footslope positions), and have an exchange complex dominated by calcium and magnesium. In the surface 0.1 m, extractable P and Zn, and total N and S levels are low and crop responses to fertilizer are probable. In comparison of 26 paired sites, where areas of native pasture and cultivation occur in close proximity, cultivated soils have lower organic C and total N, P, K and S levels than native pasture soils. This reflects a general decline in soil fertility under cultivation, and has implications for soil management and long-term soil stability.

Landscape position, sampling time and tillage, but not legume species, affect labile carbon and nitrogen fractions in a four-year-old rejuvenated grazed pasture

2021 ◽  
Author(s):  
Gazali Issah ◽  
Jeff Schoenau ◽  
J. Diane Knight
Keyword(s):  
Sampling Time ◽  
Microbial Biomass C ◽  
Legume Species ◽  
Inorganic N ◽  
Organic C ◽  
Substrate Quality ◽  
Pasture Legumes ◽  
C Storage ◽  
Grazed Pasture ◽  
Over Time

Termination by tillage is one strategy used for regenerating pasture stands. Yet, research gaps exist on how tillage affects carbon (C) and nitrogen (N) forms and amounts in western Canadian soils. We measured total soil organic C (SOC), dissolved organic C (DOC), total dissolved N (TDN), light fraction organic C (LFOC) and N (LFON), microbial biomass C (MBC) and N (MBN), and inorganic N as indicators of soil organic matter (SOM) dynamics. After tillage termination in fall 2018, we sampled soils (0‒10cm; 0‒15cm) under three legume species (alfalfa, cicer milkvetch and sainfoin) three times (spring, summer and fall of 2019) across three landscape positions. Legume species did not affect the measured parameters. Over time, tillage affected DOC, TDN, and inorganic N. Averaged across three pasture legumes and three landscape positions, tillage increased DOC 29% by summer. Fall-applied tillage led to 59% and 33% higher TDN in the succeeding summer and fall. Inorganic N increased by 14% and 40% across landscape positions and sampling after tillage. Averaged across landscape positions, MBC decreased by 31% from spring to summer and increased by 51% from summer to fall. However, MBN increased by 53% and decreased by 5% within the same period. The seasonal fluctuations in MBC/MBN reflected variations in moisture, temperature, and substrate quality. Total SOC, LFOC, and LFON increased on the upper slopes and fall sampling time. Although single intensive tillage did not affect total SOC, several tillage operations could accelerate SOM loss and reduced total C storage over time.

Warming increases soil carbon input in a Sibiraea angustata-dominated alpine shrub ecosystem

2021 ◽  
Author(s):  
Mei Liu ◽  
Jia-Hao Wen ◽  
Ya-Mei Chen ◽  
Wen-Juan Xu ◽  
Qiong Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Root Exudates ◽  
Climate Warming ◽  
Root Exudate ◽  
Soil Organic C ◽  
Organic C ◽  
Root Litter ◽  
C Stocks ◽  
Alpine Shrub ◽  
Key Drivers

Abstract Aims Plant-derived carbon (C) inputs via foliar litter, root litter and root exudates are key drivers of soil organic C stocks. However, the responses of these three input pathways to climate warming have rarely been studied in alpine shrublands. Methods By employing a three-year warming experiment (increased by1.3 ℃), we investigated the effects of warming on the relative C contributions from foliar litter, root litter and root exudates from Sibiraea angustata, a dominant shrub species in an alpine shrubland on the eastern Qinghai-Tibetan Plateau. Important Findings The soil organic C inputs from foliar litter, root litter and root exudates were 77.45, 90.58 and 26.94 g C m -2, respectively. Warming only slightly increased the soil organic C inputs from foliar litter and root litter by 8.04 and 11.13 g C m -2, but significantly increased the root exudate C input by 15.40 g C m -2. Warming significantly increased the relative C contributions of root exudates to total C inputs by 4.6% but slightly decreased those of foliar litter and root litter by 2.5% and 2.1%, respectively. Our results highlight that climate warming may stimulate plant-derived C inputs into soils mainly through root exudates rather than litter in alpine shrublands on the Qinghai-Tibetan Plateau.

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