Soil structural development in a rehabilitated open-cast mine site in south-east Australia

Rehabilitated soils from post mining fields are considered to have poor soil structure, low nutrient content and microbial activity. Soil development during rehabilitation is a complex biogeochemical process influenced by the inherent properties of the substrate used for the rehabilitation. Besides disturbed soil properties, in Australia soil rehabilitation success is also influenced by climatic conditions like high evaporation rate which affects rebuilding of soil system functions. There are several studies looking into the development of soil properties post rehabilitation in temperate climates, however, the intertwined development of soil structure, quality and quantity of soil organic matter (SOM) after the rehabilitation under water stressed environment is not clear until now.In this study, we used a space-for-time chronosequence approach in the rehabilitated open-cast mine site at Yallourn (Victoria, Australia) to elucidate the development of soil structure and soil organic matter after rehabilitation. We selected five different fields with increasing rehabilitation ages (2, 3, 10, 21 and 39 years) and two mature soils that are used as grazing land. In each field, we sampled 6 independent locations with stainless steel cylinders (100 cm3) at two depths of 0-4 cm and 10-14 cm. &#160;All samples were analysed for bulk density, organic carbon (OC) and total nitrogen (TN) concentration. Selected samples were wet sieved into four aggregate size classes of <63 &#181;m, 63-200 &#181;m, 200-630 &#181;m and >630 &#181;m. Each aggregate size class was characterized by OC and TN concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.The studied soils have a strong temporal dynamic and variability as determined for the soil properties bulk density and SOM stocks. Aggregate fractionation showed that large macroaggregates (>630 &#181;m) were the most abundant size class fractions in each rehabilitation field, representing 95-75% of the total soil mass. SOM played an important role in the formation of large macroaggregates, where the highest contribution to total OC content was observed. It became evident that plant derived carbon had a decisive role in the structural formation, because O/N-alkyl-C and alkyl-C chemical shift regions represented the highest relative intensities throughout the chronosequence.

Download Full-text

Descriptors for soil development in a water limited environment of a rehabilitated open-cast mine site in south-east Australia

10.5194/egusphere-egu2020-8114 ◽

2020 ◽

Author(s):

Evelin Pihlap ◽

Franziska Bucka ◽

Tiia Haberstok ◽

Emily Scholes ◽

Tabea Klör ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Properties ◽

Bulk Density ◽

Microbial Activity ◽

Soil Structure ◽

Aggregate Size ◽

Water Infiltration ◽

Soil System ◽

Open Cast

Soil structure and soil organic matter (SOM) are closely linked characteristics describing the status of development of a soil. Their interactions affect various physical, chemical and biological soil properties and functions like water holding capacity, water infiltration, composition of the carbon pool and microbial activity. Rehabilitated soils from post mining fields are considered to have poor soil structure, low nutrient content and microbial activity. Besides disturbed soil properties, in Australia soil rehabilitation success is also influenced by climatic conditions like high evaporation rate which affects rebuilding of soil system functions. Although there are several studies looking into the development of soil properties post rehabilitation in temperate climates, the intertwined development of soil structure and quality and quantity of SOM during soil formation under water stressed environment is not clear until now.In this study we used a space-for-time chronosequence approach in the rehabilitated open-cast mines at Yallourn Mine (Victoria, Australia) to elucidate the development of soil structure and soil organic matter after rehabilitation in a water limited environment. We selected five different fields with different rehabilitation ages (40, 22, 11, 4 and 3 years) and two mature soils that are used as grazing land. In each field we sampled 6 independent locations with stainless steel cylinders (100 cm3) at two depths of 0-4 cm and 10-14 cm. &#160;All samples were analysed for bulk density, organic carbon (OC) and total nitrogen (TN) concentration. Selected samples were wet sieved into four aggregate size classes of <63 &#181;m, 63-200 &#181;m, 200-630 &#181;m and >630 &#181;m. For detecting OC contribution to aggregate formation, OC and TN was measured from each aggregate size fraction. This system is temporarily highly dynamic and shows different developments for bulk density and SOM stocks, which had an effect on the structure of the microbial communities. Along the space-for-time chronosequence we can observe soil structure formation with ageing and a build-up of a OM, which has a positive effect on recovering soil functionality.

Download Full-text

The role of SOM and CaCO3 on soil aggregate development in reclaimed soils

10.5194/egusphere-egu2020-13644 ◽

2020 ◽

Author(s):

Evelin Pihlap ◽

Markus Steffens ◽

Ingrid Kögel-Knabner

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Extracellular Polymeric Substances ◽

Aggregate Size ◽

Soil Aggregate ◽

Parent Material ◽

Size Class ◽

Aggregate Formation ◽

Structural Formation ◽

Size Classes

Soil organic matter (SOM) and extracellular polymeric substances (EPS) from biological processes are considered to be major contributors in aggregate formation. But there is limited knowledge on soil structural formation after reclamation &#8211; the step when SOM content is low and soil properties are mostly controlled by the parent material. In our study we used a chronosequence approach in the reclaimed open-cast mining area near Cologne, Germany to elucidate the development of soil structure and soil organic matter during initial soil formation in a loess material. We selected six plots with different ages of agricultural management after reclamation (0, 1, 3, 6, 12, and 24 years after first seeding). In each reclaimed field 12 spatially independent locations were sampled with stainless steel cylinders (100 cm3) at two depths in the topsoil (1-5 cm and 16-20 cm). Samples were wet sieved into four aggregate size classes of <63 &#181;m, 63-200 &#181;m, 200-630 &#181;m and 630-2000 &#181;m. Each aggregate size class was characterized by organic carbon (OC), total nitrogen (TN) and CaCO3 concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.Wet sieving into aggregate size classes showed different trends along the chronosequence. Contradicting relation between CaCO3 and OC contribution to aggregate size classes display two different mechanisms on soil aggregate formation in young loess derived soils. CaCO3 influenced aggregation predominantly in finer aggregate size classes, where the highest concentration and contribution was measured. SOM, on the other hand, played an important role on formation of large macro-aggregates after organic manure application in year 4. Furthermore, the loss of total OC after year 12 was connected with the loss of OC contributing to the largest aggregate size class. Our findings reveal that SOM and CaCO3 role on stabilizing aggregates is not equally distributed and is aggregate size class dependent.

Download Full-text

Underneath it All: Soil Differences May Explain Contrasting Outcomes of Adjacent Prairie Restorations in Madison, Wisconsin

American Journal of Undergraduate Research ◽

10.33697/ajur.2018.024 ◽

2018 ◽

Vol 15 (3) ◽

Author(s):

Krista Marshall ◽

Nick Balster ◽

Alex Bajcz

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Spatial Heterogeneity ◽

Soil Properties ◽

Bulk Density ◽

Total Nitrogen ◽

Native Species ◽

Prairie Restoration ◽

Significant Difference ◽

Prairie Restorations

The evaluation of prairie restorations tends to focus on aboveground properties such as changes in plant diversity and the encroachment of non-native species. As a result, knowledge gaps persist concerning belowground controls of restoration success. To address these gaps at a 13-year-old prairie restoration site in Madison, Wisconsin, we spatially compared soil chemical, physical, and hydrological properties in two adjacent parcels that differed markedly in response to a tallgrass prairie restoration. We hypothesized that soil properties and their heterogeneity would differ significantly between the two parcels and that these differences would help explain the divergent response. In support of this hypothesis, soil organic matter, pH, and total nitrogen were significantly lower (p = 0.007, p < 0.001, and p = 0.006, respectively) in the restored parcel compared to the parcel that has yet to respond to any restoration efforts. Moreover, despite no significant difference in soil average bulk density between the two parcels, the restored parcel had significantly lower sand and silt fractions overall (p = 0.039 and p = 0.040, respectively). In contrast, except for total nitrogen, there were no apparent differences in the spatial heterogeneity of the measured soil properties between the restored and unrestored parcels, which did not support the second hypothesis of this study. These results demonstrate the utility of measuring belowground properties when assessing unexpected outcomes of prairie restorations as well as inform future hypothesis-driven experiments to determine which soil properties impede restoration and under what circumstances. KEYWORDS: Prairie Restoration; Bulk Density; Soil Organic Matter; Soil Properties; Soil Texture; Spatial Heterogeneity

Download Full-text

Obtaining more benefits from crop residues as soil amendments by application as chemically heterogeneous mixtures

10.5194/soil-2020-9 ◽

2020 ◽

Author(s):

Marijke Struijk ◽

Andrew P. Whitmore ◽

Simon R. Mortimer ◽

Tom Sizmur

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Properties ◽

Nutrient Availability ◽

Soil Structure ◽

Crop Residues ◽

Soil Amendments ◽

Aggregate Stability ◽

Available N ◽

Nitrogen Levels

Abstract. Crop residues are valuable soil amendments in terms of the carbon and other nutrients they contain, but incorporation of residues does not always translate into increases in nutrient availability, soil organic matter (SOM), soil structure, and overall soil fertility. Studies have demonstrated accelerated decomposition rates of chemically heterogeneous litter mixtures, compared to the decomposition of individual litters, in forest and grassland systems. Mixing high C : N ratio with low C : N ratio amendments may result in greater carbon use efficiency and non-additive benefits in soil properties (i.e. mixture ≠ sum of the parts). We hypothesised that non-additive benefits would accrue from mixtures of low-quality (straw or woodchips) and high-quality (vegetable-waste compost) residues applied before lettuce planting in a full-factorial field experiment. Properties indicative of soil structure and nutrient cycling were used to assess benefits from residue mixtures, including soil respiration, aggregate stability, bulk density, SOM, available and potentially mineralisable N, available P, K and Mg, and crop yield. Soil organic matter and mineral nitrogen levels were significantly and non-additively greater in the straw-compost mixture compared to individual residues, which mitigated the N immobilisation occurring with straw-only applications. Addition of compost significantly increased soil available N, K and Mg levels. Together, these observations suggest that greater nutrient availability improved the ability of decomposer organisms to degrade straw in the straw-compost mixture. We demonstrate that mixtures of crop residues can influence soil properties non-additively. Thus, greater benefits may be achieved by removing, mixing, and re-applying crop residues, than by simply returning them to the soils in situ.

Download Full-text

Obtaining more benefits from crop residues as soil amendments by application as chemically heterogeneous mixtures

SOIL ◽

10.5194/soil-6-467-2020 ◽

2020 ◽

Vol 6 (2) ◽

pp. 467-481

Author(s):

Marijke Struijk ◽

Andrew P. Whitmore ◽

Simon R. Mortimer ◽

Tom Sizmur

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Properties ◽

Nutrient Availability ◽

Soil Structure ◽

Crop Residues ◽

Soil Amendments ◽

C:N Ratio ◽

Mineral N ◽

Available N

Abstract. Crop residues are valuable soil amendments in terms of the carbon and other nutrients they contain, but the incorporation of residues does not always translate into increases in nutrient availability, soil organic matter (SOM), soil structure, and overall soil fertility. Studies have demonstrated accelerated decomposition rates of chemically heterogeneous litter mixtures, compared to the decomposition of individual litters, in forest and grassland systems. Mixing high C:N ratio with low C:N ratio amendments may result in greater carbon use efficiency (CUE) and nonadditive benefits in soil properties. We hypothesised that nonadditive benefits would accrue from mixtures of low-quality (straw or woodchips) and high-quality (vegetable waste compost) residues applied before lettuce planting in a full factorial field experiment. Properties indicative of soil structure and nutrient cycling were used to assess the benefits from residue mixtures, including soil respiration, aggregate stability, bulk density, SOM, available N, potentially mineralisable N, available P, K, and Mg, and crop yield. Soil organic matter and mineral N levels were significantly and nonadditively greater in the straw–compost mixture compared to individual residues, which mitigated the N immobilisation occurring with straw-only applications. The addition of compost significantly increased available N, K, and Mg levels. Together, these observations suggest that greater nutrient availability improved the ability of decomposer organisms to degrade straw in the straw–compost mixture. We demonstrate that mixtures of crop residues can influence soil properties nonadditively. Thus, greater benefits may be achieved by removing, mixing, and reapplying crop residues than by simply returning them to the soils in situ.

Download Full-text

Slope position and management practices as factors influencing selected properties of topsoil

Soil Science Annual ◽

10.2478/ssa-2019-0012 ◽

2019 ◽

Vol 70 (2) ◽

pp. 137-146

Author(s):

Vladimír Šimanský ◽

Martin Juriga ◽

Łukasz Mendyk

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Properties ◽

Soil Structure ◽

Management Practices ◽

Soil Management ◽

Slope Position ◽

Structure Parameters ◽

Slope Gradient ◽

Mean Weight Diameter

Abstract An interaction between the slope position and type of soil management practices could be one of the most important factor affecting several soil properties including soil structure. Therefore, we evaluated selected soil properties including soil structure parameters in relation to slope gradient and soil management practices between Trakovice and Bučany villages (western Slovakia). The sampling sites were located in two adjacent, gently sloping fields with a NW-SE orientation. The sites also differ in soil management type: Field No. 1 was used as arable land with intensive cultivation (IC) of crops, while a greening system (GS) had been established on Field No. 2. Soil samples were taken from five geomorphological zones at each slope: summit, shoulder, back-slope, toe slope and flat terrain under the slope. Results showed that soil pH, content of soil organic matter (SOM) and carbonates depended on land use of the slopes. In GS, the water-stable macro-aggregates (WSAma) 0.5–3 mm (favourable size fraction) displayed statistical significant quadratic polynomial trend along the slope gradient. In IC the values of mean weight diameter of dry sieved aggregates (MWDd) decreased significantly along the slope gradient, while in GS the opposite trend was observed. In IC significant correlations between carbonates content (r=-0.775, P<0.01), humic acids (HA) content (r=0.654, P<0.05), colour quotients of humic substances (r=-0.706, P<0.05), colour quotients of HA (r=-0.723, P<0.05) and MWDd were determined. In GS higher content of carbonates was followed by a decrease in content WSAma, MWDd, mean weight diameter of wet sieved aggregates (MWDw) and stability index of aggregates. At the same time stabile and labile soil organic matter improved soil structure parameters in GS.

Download Full-text