scholarly journals Estimating Soil Organic Carbon Under Different Land-Use Types in Australia’s Northern Grains Region Using Mid-Infrared Spectroscopy

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 141
Author(s):  
Alwyn Williams ◽  
Ryan Farquharson ◽  
David Lawrence ◽  
Jeff Baldock ◽  
Mike Bell
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Native Vegetation ◽  
Land Use Type ◽  
Short Term ◽  
Mid Infrared ◽  
Land Use Types ◽  
Soc Fractions

Land-use type is known to affect levels of soil organic carbon (SOC). However, the degree to which SOC is affected by land-use type over the short—(<10-years) and long—(≥10-years) term remains relatively uncertain. Moreover, there is limited data on the distribution of SOC across particulate (POC), humus (HOC) and resistant (ROC) fractions, and the responses of these fractions to land-use. Using mid-infrared spectroscopy (MIR) coupled with partial least squares regression (PLSR) algorithms generated from the Australian Soil Carbon Research Program (SCaRP), soil organic carbon (TOC, POC, HOC and ROC) was estimated across 280 paired samples across Australia’s Northern Grains Regions. Our analysis covered five land-use types: remnant native vegetation, long-term pasture (≥10-years), short-term pasture (<10-years), short-term cropping (<10-years) and long-term cropping (≥10-years). All land-use types except long-term pasture generated significant declines across all SOC fractions compared with native vegetation. Long-term cropping resulted in the greatest declines, with an average decrease of 6.25 g TOC/kg soil relative to native vegetation. Long-term cropping also reduced POC (−0.71 g/kg) and HOC (−3.19 g/kg) below that of short-term cropping. In addition, the ROC fraction responded to land-use type, with native vegetation and long-term pasture maintaining greater ROC compared with other land-use types. The results demonstrate substantial reductions across all SOC fractions with long-term cropping. The ability of long-term pastures to maintain levels of SOC similar to that of native vegetation indicates the importance of limiting soil disturbance and maintaining more continuous living plant cover within cropping systems.

scholarly journals Effects of Management and Hillside Position on Soil Organic Carbon Stratification in Mediterranean Centenary Olive Grove

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 650
Author(s):  
Jesús Aguilera-Huertas ◽  
Beatriz Lozano-García ◽  
Manuel González-Rosado ◽  
Luis Parras-Alcántara
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Quality ◽  
Management Practices ◽  
Soil Management ◽  
Olive Grove ◽  
No Tillage ◽  
Short Term ◽  
Degradation Degree

The short- and medium—long-term effects of management and hillside position on soil organic carbon (SOC) changes were studied in a centenary Mediterranean rainfed olive grove. One way to measure these changes is to analyze the soil quality, as it assesses soil degradation degree and attempts to identify management practices for sustainable soil use. In this context, the SOC stratification index (SR-COS) is one of the best indicators of soil quality to assess the degradation degree from SOC content without analyzing other soil properties. The SR-SOC was calculated in soil profiles (horizon-by-horizon) to identify the best soil management practices for sustainable use. The following time periods and soil management combinations were tested: (i) in the medium‒long-term (17 years) from conventional tillage (CT) to no-tillage (NT), (ii) in the short-term (2 years) from CT to no-tillage with cover crops (NT-CC), and (iii) the effect in the short-term (from CT to NT-CC) of different topographic positions along a hillside. The results indicate that the SR-SOC increased with depth for all management practices. The SR-SOC ranged from 1.21 to 1.73 in CT0, from 1.48 to 3.01 in CT1, from 1.15 to 2.48 in CT2, from 1.22 to 2.39 in NT-CC and from 0.98 to 4.16 in NT; therefore, the soil quality from the SR-SOC index was not directly linked to the increase or loss of SOC along the soil profile. This demonstrates the time-variability of SR-SOC and that NT improves soil quality in the long-term.

Spatial variability of soil organic carbon in a typical watershed in the source area of the middle Dan River, China

Soil Research ◽  
2013 ◽  
Vol 51 (1) ◽  
pp. 41 ◽  
Author(s):  
Guo-Ce Xu ◽  
Zhan-Bin Li ◽  
Peng Li ◽  
Ke-Xin Lu ◽  
Yun Wang
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spatial Variability ◽  
Spatial Heterogeneity ◽  
Spatial Variation ◽  
Soil Depth ◽  
Source Area ◽  
Soil Layers ◽  
Land Use Types

Soil organic carbon (SOC) plays an important role in maintaining and improving soil fertility and quality, in addition to mitigating climate change. Understanding SOC spatial variability is fundamental for describing soil resources and predicting SOC. In this study, SOC content and SOC mass were estimated based on a soil survey of a small watershed in the Dan River, China. The spatial heterogeneity of SOC distribution and the impacts of land-use types, elevation, slope, and aspect on SOC were also assessed. Field sampling was carried out based on a 100 m by 100 m grid system overlaid on the topographic map of the study area, and samples were collected in three soil layers to a depth of 40 cm. In total, 222 sites were sampled and 629 soil samples were collected. The results showed that classical kriging could successfully interpolate SOC content in the watershed. Contents of SOC showed strong spatial heterogeneity based on the values of the coefficient of variation and the nugget ratio, and this was attributed largely to the type of land use. The range of the semi-variograms increased with increasing soil depth. The SOC content in the soil profile decreased as soil depth increased, and there were significant (P < 0.01) differences among the three soil layers. Land use had a great impact on the SOC content. ANOVA indicated that the spatial variation of SOC contents under different land use types was significant (P < 0.05). The SOC mass of different land-use types followed the order grassland > forestland > cropland. Mean SOC masses of grassland, forestland, and cropland at a depth of 0–40 cm were 5.87, 5.61, and 5.07 kg m–2, respectively. The spatial variation of SOC masses under different land-use types was significant (P < 0.05). ANOVA also showed significant (P < 0.05) impact of aspect on SOC mass in soil at 0–40 cm. Soil bulk density played an important role in the assessment of SOC mass. In conclusion, carbon in soils in the source area of the middle Dan River would increase with conversion from agricultural land to forest or grassland.

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