Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping. 2. Total and labile nitrogen

Soil Research ◽  
2005 ◽  
Vol 43 (2) ◽  
pp. 179 ◽  
Author(s):  
R. C. Dalal ◽  
B. P. Harms ◽  
E. Krull ◽  
W. J. Wang ◽  
N. J. Mathers
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Light Fraction ◽  
Organic N ◽  
Soil N ◽  
Organic Matter Quality ◽  
Organic C ◽  
Total Soil ◽  
Acacia Aneura

Mulga (Acacia aneura) woodlands and open forests occupy about 150 Mha in Australia, and originally occupied 11.2 Mha in Queensland. Substantial areas (1.3 Mha) of the mulga vegetation have been cleared in Queensland, mostly for pasture production, but some areas are also used for cereal cropping. Twenty years after mulga clearing we found a significant loss of total soil organic C (28–35% from the 0–0.05 m depth) and light fraction C (>50% from the 0–1 m depth) from soil under pasture and cropping at a site in southern Queensland. We report here the changes in soil N and labile N pools in a paired-site study following conversion of mulga to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for more than 20 years. Conversion from mulga forest to pasture and cultivation resulted in greater losses of soil N than organic C in the top 0.1 m depths. As a result, C/N ratios in soil under both pasture and cropping were higher than soil under mulga, indicating a decline in soil organic matter quality after mulga clearing. Although land-use change had no significant effect on 15N natural abundance (δ15N) values of total soil N down to a depth of 1 m, δ15N values of wheat tops and roots indicated that the primary source of N under cropping was soil organic N, while that of buffel pasture was a mixed source of soil N and decomposed litter and root N. Light fraction N (<1.6 Mg/m3) declined by 60–70% throughout the 1 m soil profile under pasture and cropping, but it was 15N-enriched in these 2 land-use systems. The δ15N values of mulga phyllodes, twigs, and fine roots, indicated an input of atmospheric fixed N2 that was estimated to be about 25 kg N/ha.year. However, the source and magnitude of this N resource needs to be confirmed. Soil N losses were estimated to be 12 kg N/ha.year under pasture and 17 kg N/ha.year under cropping over a 20-year period. These findings raise the issue of the long-term sustainable use of cleared mulga areas for pasture and/or cropping. The labile C and N pools and N mineralised also declined, which would have an immediate adverse effect on soil fertility and plant productivity of cleared Mulga Lands, as well as reducing their potential as a soil sink for greenhouse gases.

Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping 1. Total and labile carbon

Soil Research ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 13 ◽  
Author(s):  
R. C. Dalal ◽  
B.P. Harms ◽  
E. Krull ◽  
W.J. Wang
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Land Use Change ◽  
Soil Organic C ◽  
Organic Matter Quality ◽  
Organic C ◽  
Soil C ◽  
Acacia Aneura ◽  
Soil Organic Matter Quality

Mulga (Acacia aneura) dominated vegetation originally occupied 11.2 Mha in Queensland, of which 12% has been cleared, mostly for pasture production, but some areas are also used for cereal cropping. Since mulga communities generally occupy fragile soils, mostly Kandosols and Tenosols, in semi-arid environments, clearing of mulga, which continues at a rate of at least 35 000 ha/year in Queensland, has considerable impact on soil organic carbon (C), and may also have implications for the greenhouse gas emissions associated with land use change in Australia. We report here the changes in soil C and labile C pools following mulga clearing to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for 20 years in a study using paired sites. Soil organic C in the top 0.05 m of soil declined by 31% and 35% under buffel pasture and cropping, respectively. Land use change from mulga to buffel and cropping led to declines in soil organic C of 2.4 and 4.7 t/ha, respectively, from the top 0.3 m of soil. Using changes in the δ13C values of soil organic C as an approximate representation of C derived from C3 and C4 vegetation from mulga and buffel, respectively, up to 31% of soil C was C4-derived after 20 years of buffel pasture. The turnover rates of mulga-derived soil C ranged from 0.035/year in the 0–0.05 m depth to 0.008/year in the 0.6–1 m depths, with respective turnover times of 29 and 133 years. Soil organic matter quality, as measured by the proportion/amount of labile fraction C (light fraction, < 1.6 t/m3) declined by 55% throughout the soil profile (0–1 m depth) under both pasture and cropping. There is immediate concern for the long-term sustainable use of land where mulga has been cleared for pasture and/or cropping with a continuing decline in soil organic matter quality and, hence, soil fertility and biomass productivity. In addition, the removal of mulga forest over a 20-year period in Queensland for pasture and cropping may have contributed to the atmosphere at least 12 Mt CO2-equivalents.

Impact of long-term cultivation on the status of organic matter and cadmium in soil

2001 ◽  
Vol 81 (3) ◽  
pp. 349-355 ◽  
Author(s):  
D. F. E. McArthur ◽  
P M Huang ◽  
L M Kozak
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Significant Positive Correlation ◽  
Soil Organic C ◽  
Organic C ◽  
Total Soil ◽  
Total Organic C ◽  
Soil Cd ◽  
Cultivated Soils

Research has suggested a link between the bioavailability of soil Cd and total soil organic matter. However, some research suggested a negative relationship between total soil organic matter and bioavailable soil Cd while other research suggested a positive relationship. This study investigated the relationship between soil Cd and both the quantity and quality of soil organic matter as influenced by long-term cultivation. Two Orthic Chernozemic surface soil samples, one from a virgin prairie and the other from an adjacent cultivated prairie, were collected from each of 12 different sites throughout southern Saskatchewan, Canada. The samples were analyzed for total organic C, total Cd, Cd availability index (CAI), and pH. The nature of the soil organic matter was investigated with 13C Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy (13C CPMAS NMR). The total soil Cd, CAI, and total soil organic C of the cultivated soils were significantly lower than those of the virgin soils whereas the opposite trend was observed for the soil pH and the aromaticity of the organic C. The reduced CAI in the cultivated soils was related to the increase in both the soil pH and the aromaticity of the organic C. No relationship was found between the CAI and the soil organic C content, but a significant positive correlation was found between total organic C and total Cd in both the virgin and the cultivated soils. As well, a significant positive correlation was found between the fraction of total Cd removed from the soil after long-term cultivation and the corresponding fraction of organic C removed. Key words: Long-term cultivation, soil organic matter, 13C CPMAS NMR, cadmium

scholarly journals Role of Crop Rotations in the Dynamic of Soil Organic Matter Pools

2018 ◽  
Vol 10 (8) ◽  
pp. 341
Author(s):  
Rodrigo Santos Moreira ◽  
Marcio Koiti Chiba ◽  
Isabella Clerici De Maria ◽  
Caio César Zito Siqueira ◽  
Aildson Pereira Duarte ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Crop Rotation ◽  
Light Fraction ◽  
Crop Rotations ◽  
Organic Matter Quality ◽  
Humification Index ◽  
No Till ◽  
C And N ◽  
Soil Organic Matter Quality

Soil organic matter is considered a key attribute for a sustainable agricultural production and is influenced by the quantity and quality of the crop residue deposited on the soil surface. Therefore, different crop rotations could change the soil organic matter pools. The objectives of this study were to evaluate the soil carbon pools obtained by chemical and physical fractionation methods and the humification index under different crop rotations in a no-till system. We test the following hypothesis: a) the distribution of C and N among the soil organic matter fractions depends on plant species rotation schemes and; b) labile fractions are more sensitive to the input of crop residues and therefore, more suitable for evaluating the impact of different crop rotations in the soil organic matter quality. We evaluated four crop sequences (corn/corn/corn; corn/wheat/corn; soybean/wheat/corn and soybean/corn/corn) in a no-till system. A five-year reforested area was used as reference. We determined the total C and N contents, the mineral-associated C and N, the light fraction of C and N, the labile carbon extracted with KMnO4 and the soil organic matter humification index. We found narrow differences between the crop rotation systems in the total C and N levels, the mineral-associated C and N fractions and the labile C extracted with KMnO4. The diversification of the agricultural system with soybean in crop rotation favored the accumulation of light fraction C and N in the soil that were more efficient to provide information about the changes in the soil organic matter quality.

Land use effect on microbial growth and respiration under future climate

2020 ◽  
Author(s):  
Vusal Guliyev ◽  
Melissa Pfeiffer ◽  
Maria Udovenko ◽  
Christina Fasching ◽  
Thomas Reitz ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Growth ◽  
Microbial Respiration ◽  
Growth Parameters ◽  
Vegetation Type ◽  
Interactive Effect ◽  
Organic Input ◽  
Organic C

&lt;p&gt;Fresh input of organic material in soil is continuously transformed and processed by growing microorganisms using this organic input as a substrate. Therefore, the quality and quantity of soil organic C stock is strongly dependent on the intensity of mineralization processes through microbial respiration and growth. We aimed to prove the sensitivity of microbial respiration and growth parameters to indicate an interactive effect of land use and climate warming. For this we used Global Change Experimental Facility in Bad Lauchst&amp;#228;dt, UFZ, Halle, Germany. This long-term experiment is designed in 5 land use strategies (Organic Farming, Conventional Farming, Intensive Meadow, Extensive Meadow, and Extensive Pasture) and 2 climate scenarios (ambient and future). We determined basal respiration by CO&lt;sub&gt;2&lt;/sub&gt; emission, microbial growth parameters by substrate-induced growth respiration (SIGR), and the quality of soil organic matter by Fourier-transformed infrared spectroscopy (FTIR). The effect of biotic (vegetation type) and abiotic (temperature and moisture) factors on microbial attributes and on chemical composition of soil organic matter will be compared.&lt;/p&gt;

Free light fraction carbon and nitrogen, a physically uncomplexed soil organic matter distribution within subtropical grass and leucaena–grass pastures

Soil Research ◽  
2018 ◽  
Vol 56 (8) ◽  
pp. 820 ◽  
Author(s):  
K. A. Conrad ◽  
R. C. Dalal ◽  
D. E. Allen ◽  
R. Fujinuma ◽  
Neal W. Menzies
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Depth ◽  
Light Fraction ◽  
Grass Species ◽  
Pasture Grass ◽  
Total N ◽  
Δ13c And Δ15n ◽  
Organic C ◽  
C And N

Quantifying the size and turnover of physically uncomplexed soil organic matter (SOM) is crucial for the understanding of nutrient cycling and storage of soil organic carbon (SOC). However, the C and nitrogen (N) dynamics of SOM fractions in leucaena (Leucaena leucocephala)–grass pastures remains unclear. We assessed the potential of leucaena to sequester labile, free light fraction (fLF) C and N in soil by estimating the origin, quantity and vertical distribution of physically unprotected SOM. The soil from a chronosequence of seasonally grazed leucaena stands (0–40 years) was sampled to a depth of 0.2m and soil and fLF were analysed for organic C, N and δ13C and δ15N. On average, the fLF formed 20% of SOC and 14% of total N stocks in the upper 0.1m of soil from leucaena rows and showed a peak of fLF-C and fLF-N stocks in the 22-year-stand. The fLF δ13C and fLF δ15N values indicated that leucaena produced 37% of fLF-C and 28% of fLF-N in the upper 0.1m of soil from leucaena rows. Irrespective of pasture type or soil depth, the majority of fLF-C originated from the accompanying C4 pasture-grass species. This study suggests that fLF-C and fLF-N, the labile SOM, can form a significant portion of total SOM, especially in leucaena–grass pastures.

scholarly journals Labile and stable fractions of soil organic matter under management systems and native cerrado

2010 ◽  
Vol 34 (3) ◽  
pp. 907-916 ◽  
Author(s):  
Cícero Célio de Figueiredo ◽  
Dimas Vital Siqueira Resck ◽  
Marco Aurélio Carbone Carneiro
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Particulate Organic Matter ◽  
Block Design ◽  
Management Systems ◽  
Total N ◽  
Organic C ◽  
Randomized Block Design ◽  
Stable Organic Matter

Soil organic matter can be analyzed on the basis of the different fractions. Changes in the levels of organic matter, caused by land use, can be better understood by alterations in the different compartments. The aim of this study was to evaluate the effect of different management systems on the labile and stable organic matter of a dystrophic Red Latosol (Oxisol). The following properties were determined: total organic C and total N (TOC and TN), particulate organic C and particulate N (POC and PN), organic C and N mineral-associated (MOC and NM) and particulate organic C associated with aggregate classes (POCA). Eight treatments were used: seven with soil management systems and one with native Cerrado as a reference. The experiment was designed to study the dynamics of systems of tillage and crop rotation, alternating in time and space. The experimental design was a randomized block design with three replications. The soil samples were collected from five depths: 0-5, 5-10, 10-20, 20-30 and 30-40 cm. Changes in organic C by land use occurred mainly in the fraction of particulate organic matter (> 53 mm). Proper management of grazing promoted increased levels of particulate organic matter by association with larger aggregates (2-8 mm), demonstrating the importance of the formation of this aggregate class for C protection in pasture.

DYNAMICS OF SOIL MICROBIAL BIOMASS AND WATER-SOLUBLE ORGANIC C IN BRETON L AFTER 50 YEARS OF CROPPING TO TWO ROTATIONS

1986 ◽  
Vol 66 (1) ◽  
pp. 1-19 ◽  
Author(s):  
W. B. McGILL ◽  
K. R. CANNON ◽  
J. A. ROBERTSON ◽  
F. D. COOK
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Environmental Conditions ◽  
Management Practices ◽  
Water Soluble ◽  
Turnover Rates ◽  
Organic Matter Quality ◽  
Organic C ◽  
Microbial N

Amounts and turnover rates of biomass and water-soluble organic C (WSOC) were measured at the Breton plots where records of long-term management of a Gray Luvisolic soil are available. Plots (control, manure, and NPKS) which had been cropped to either a wheat-fallow or a wheat-oats-barley-forage-forage rotation for 50 yr were sampled 13 times during 1981 and 1982. Biomass C and flush of microbial N were measured using the chloroform fumigation technique. Long-term crop yields were used to derive C supply to the plots. Regression analyses were used to relate seasonal fluctuations in environmental conditions to biomass and WSOC dynamics. Reinoculation with soil was unnecessary but Lysobacter sp. formed a greater proportion of isolates following incubation of fumigated soil than of unfumigated samples. Reinoculation with Lysobacter sp. is suggested to provide a more standardized biological assay. The 5-yr rotation contained 38% more N but 117% more microbial N than did the 2-yr rotation, and manured treatments contained twice as much microbial N as did NPKS or control plots. A management effect on soil organic matter quality is indicated. Averge turnover rates of biomass were 0.2–3.9 yr−1; being 1.5–2 times faster in the 2-yr rotation than in the 5-yr rotation. Replenishment of the WSOC component would have to occur 26–39 times yr−1 to supply microbial turnover. Most of the biomass must be dormant because annual C inputs are two orders of magnitude less than maintenance energy requirements. Seasonal variations in biomass were most consistently related to losses during desiccation and regrowth upon moistening. Regrowth appears to be at the expense of native soil organic matter. Management practices and environmental conditions therefore affect amount of organic matter by controlling both input of C and biomass turnover. Key words: Crop rotations, Luvisol, organic matter, biomass, soluble C, Breton plots

Sensitivity of total, light fraction and mineralizable organic matter to management practices in a Lethbridge soil

1994 ◽  
Vol 74 (2) ◽  
pp. 131-138 ◽  
Author(s):  
E. Bremer ◽  
H. H. Janzen ◽  
A. M. Johnston
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Depth ◽  
Crop Management ◽  
Light Fraction ◽  
Yield Response ◽  
Native Grass ◽  
Organic C ◽  
Total Light ◽  
Light Fraction Organic Matter

Crop management influences the quantity and quality of organic matter in agricultural soils. A crop rotation study established at Lethbridge, Alberta in 1951 was sampled in September 1992 to determine the effect of crop management on total, light fraction and mineralizable (10-wk) organic matter contents. Spring wheat was the dominant cropping system; treatments examined include fallow frequency, forage hay production in rotation, manure amendment, N fertilizer application, and native grass. The two latter treatments were introduced in 1985. Total and light fraction organic matter did not vary among phases of the rotation whereas mineralized C tended to be lowest during and shortly after a fallow phase. When averaged across rotation phases, total, light fraction, and mineralized organic matter were enhanced by reduced fallow frequency, manure additons, hay production and native grass. Highest concentrations of total and labile organic concentrations in the 0- to 7.5-cm soil depth were generally found in the continuously-cropped wheat and native grass treatments. Hay production significantly increased soil organic matter in the 15- to 30-cm soil depth. Nitrogen fertilization did not increase soil organic matter in this study, likely because of minimal yield response over the treatment period. Sensitivity of the various indicators to treatment [(highest–lowest)/lowest] was 0.2 for total, 2.5 for light fraction, and 1.5 for mineralized soil organic C. Light fraction organic matter was the most robust indicator of management-induced effects on soil organic matter. Key words: Labile organic matter, fallow frequency, forage hay production, manure, native grass

scholarly journals Effect of land use and soil organic matter quality on the structure and function of microbial communities in pastoral soils: Implications for disease suppression

PLoS ONE ◽  
2018 ◽  
Vol 13 (5) ◽  
pp. e0196581 ◽  
Author(s):  
Bryony E. A. Dignam ◽  
Maureen O’Callaghan ◽  
Leo M. Condron ◽  
George A. Kowalchuk ◽  
Joy D. Van Nostrand ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Communities ◽  
Structure And Function ◽  
Disease Suppression ◽  
Organic Matter Quality ◽  
And Function ◽  
Soil Organic Matter Quality
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