Management effects on the dynamics and storage rates of organic matter in long-term crop rotations

2004 ◽  
Vol 84 (1) ◽  
pp. 49-61 ◽  
Author(s):  
E. A. Paul ◽  
H. P. Collins ◽  
K. Paustian ◽  
E. T. Elliott ◽  
S. Frey ◽  
...  

Factors controlling soil organic matter (SOM) dynamics in soil C sequestration and N fertility were determined from multi-site analysis of long-term, crop rotation experiments in Western Canada. Analyses included bulk density, organic and inorganic C and N, particulate organic C (POM-C) and N (POM -N), and CO2-C evolved during laboratory incubation. The POM-C and POM-N contents varied with soil type. Differences in POM-C contents between treatments at a site (δPOM-C) were related (r2= 0.68) to treatment differences in soil C (δSOC). The CO2-C, evolved during laboratory incubation, was the most sensitive indicator of management effects. The Gray Luvisol (Breton, AB) cultivated plots had a fivefold difference in CO2-C release relative to a twofold difference in soil organic carbon (SOC). Soils from cropped, Black Chernozems (Melfort and Indian Head, SK) and Dark Brown Chernozems (Lethbridge, AB) released 50 to 60% as much CO2-C as grassland soils. Differences in CO2 evolution from the treatment with the lowest SOM on a site and that of other treatments (δCO2-C) in the early stages of the incubation were correlated to δPOM-C and this pool reflects short-term SOC storage. Management for soil fertility, such as N release, may differ from management for C sequestration. Key words: Multi-site analysis, soil management, soil C and N, POM-C and N, CO2 evolution

2000 ◽  
Vol 80 (3) ◽  
pp. 429-435 ◽  
Author(s):  
D. Curtin ◽  
F. Selles ◽  
H. Wang ◽  
R. P. Zentner ◽  
C. A. Campbell

Planting of cultivated land with perennial forages may increase C sequestration in soil organic matter and contribute to atmospheric CO2 mitigation strategies. However, little is known of the effectiveness of introduced grasses in restoring organic C in cultivated soils of the Canadian prairies. Our objective was to evaluate the C sequestration potential of crested wheatgrass (CWG) (Agropyron cristatum L. Gaertn.), a widely introduced, early-season grass. In 1995 and 1996, we measured soil CO2 fluxes, C inputs in plant material and total soil C under CWG and a fallow-wheat (Triticum aestivum L.)-wheat rotation (F-W-W). These were two of the treatments in a replicated crop rotation experiment initiated in 1987 in southwestern Saskatchewan on a medium-textured soil that had previously been under long-term wheat production. Average to above-average growing season (1 May to 31 July) precipitation in 1995–1996 resulted in annual inputs of C in wheat residues of 3000–4500 kg ha−1. Growth of CWG, which was hayed and removed, was relatively poor in both years, but especially in 1995 when dry matter yield was only 1300 kg ha−1. For the 1988–1996 period, there was a strong correlation (R2 = 0.81; P < 0.001) between CWG yield and precipitation received in May, showing the importance of early spring rains determining CWG yield and C inputs to the soil. Carbon inputs under CWG (1200 kg ha−1 in 1995 and 2400 kg ha−1 in 1996) were less than under wheat but CO2-C emissions were similar under CWG and wheat. Soil C measurements in fall 1996 confirmed that CWG did not gain C relative to the F-W-W rotation. Although failure of CWG soil to store more C than cultivated soil may be partly because weather conditions during the experiment were more favourable for wheat than CWG, our results cast doubt on the ability of CWG to restore C stocks in prairie soils degraded by long-term cropping. Key words: Carbon sequestation, carbon dioxide emissions, wheat, crested wheatgrass, fallow


2014 ◽  
Vol 94 (6) ◽  
pp. 1025-1032 ◽  
Author(s):  
F. L. Walley ◽  
A. W. Gillespie ◽  
Adekunbi B. Adetona ◽  
J. J. Germida ◽  
R. E. Farrell

Walley, F. L., Gillespie, A. W., Adetona, A. B., Germida, J. J. and Farrell, R. E. 2014. Manipulation of rhizosphere organisms to enhance glomalin production and C-sequestration: Pitfalls and promises. Can. J. Plant Sci. 94: 1025–1032. Arbuscular mycorrhizal fungi (AMF) reportedly produce glomalin, a glycoprotein that has the potential to increase soil carbon (C) and nitrogen (N) storage. We hypothesized that interactions between rhizosphere microorganisms, such as plant growth-promoting rhizobacteria (PGPR), and AMF, would influence glomalin production. Our objectives were to determine the effects of AMF/PGPR interactions on plant growth and glomalin production in the rhizosphere of pea (Pisum sativum L.) with the goal of enhancing C and N storage in the rhizosphere. One component of the study focussed on the molecular characterization of glomalin and glomalin-related soil protein (GRSP) using complementary synchrotron-based N and C X-ray absorption near-edge structure (XANES) spectroscopy, pyrolysis field ionization mass spectrometry (Py-FIMS), and proteomics techniques to characterize specific organic C and N fractions associated with glomalin production. Our research ultimately led us to conclude that the proteinaceous material extracted, and characterized in the literature, as GRSP is not exclusively of AMF origin. Our research supports the established concept that GRSP is important to soil quality, and C and N storage, irrespective of origin. However, efforts to manipulate this important soil C pool will remain compromised until we more clearly elucidate the chemical nature and origin of this resource.


2002 ◽  
Vol 139 (3) ◽  
pp. 231-243 ◽  
Author(s):  
A. J. A. VINTEN ◽  
B. C. BALL ◽  
M. F. O'SULLIVAN ◽  
J. K. HENSHALL

The effects of ploughing or no-tillage of long-term grass and grass-clover swards on changes in organic C and N pools and on CO2 and denitrified gas emissions were investigated in a 3-year field experiment in 1996–99 near Penicuik, Scotland. The decrease in soil C content between 1996 and 1999 was 15·3 t/ha (95% confidence limits were 1·7–28·9 t/ha). Field estimates of CO2 losses from deep-ploughed, normal-ploughed and no-tillage plots were 3·1, 4·5 and 4·6 t/ha over the sampling periods (a total of 257 days) in 1996–98. The highest N2O fluxes were from the fertilized spring barley under no-tillage. Thus no-tillage did not reduce C emissions, caused higher N2O emissions, and required larger inputs of N fertilizer than ploughing. By contrast, deep ploughing led to smaller C and N2O emissions but had no effect on yields, suggesting that deep ploughing might be an appropriate means of conserving C and N when leys are ploughed in. Subsoil denitrification losses were estimated to be 10–16 kg N/ha per year by measurement of 15N emissions from incubated intact cores. A balance sheet of N inputs and outputs showed that net N mineralization over 3 years was lower from plots receiving N fertilizer than from plots receiving no fertilizer.


Soil Research ◽  
2001 ◽  
Vol 39 (3) ◽  
pp. 435 ◽  
Author(s):  
R. C. Dalal ◽  
K. Y. Chan

The Australian cereal belt stretches as an arc from north-eastern Australia to south-western Australia (24˚S–40˚S and 125˚E–147˚E), with mean annual temperatures from 14˚C (temperate) to 26˚C (subtropical), and with annual rainfall ranging from 250 mm to 1500 mm. The predominant soil types of the cereal belt include Chromosols, Kandosols, Sodosols, and Vertosols, with significant areas of Ferrosols, Kurosols, Podosols, and Dermosols, covering approximately 20 Mha of arable cropping and 21 Mha of ley pastures. Cultivation and cropping has led to a substantial loss of soil organic matter (SOM) from the Australian cereal belt; the long-term SOM loss often exceeds 60% from the top 0–0.1 m depth after 50 years of cereal cropping. Loss of labile components of SOM such as sand-size or particulate SOM, microbial biomass, and mineralisable nitrogen has been even higher, thus resulting in greater loss in soil productivity than that assessed from the loss of total SOM alone. Since SOM is heterogeneous in nature, the significance and functions of its various components are ambiguous. It is essential that the relationship between levels of total SOM or its identif iable components and the most affected soil properties be established and then quantif ied before the concentrations or amounts of SOM and/or its components can be used as a performance indicator. There is also a need for experimentally verifiable soil organic C pools in modelling the dynamics and management of SOM. Furthermore, the interaction of environmental pollutants added to soil, soil microbial biodiversity, and SOM is poorly understood and therefore requires further study. Biophysically appropriate and cost-effective management practices for cereal cropping lands are required for restoring and maintaining organic matter for sustainable agriculture and restoration of degraded lands. The additional benefit of SOM restoration will be an increase in the long-term greenhouse C sink, which has the potentialto reduce greenhouse emissions by about 50 Mt CO2 equivalents/year over a 20-year period, although current improved agricultural practices can only sequester an estimated 23% of the potential soil C sink.


Soil Research ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 254 ◽  
Author(s):  
Eva Erhart ◽  
Harald Schmid ◽  
Wilfried Hartl ◽  
Kurt-Jürgen Hülsbergen

Compost fertilisation is one way to close material cycles for organic matter and plant nutrients and to increase soil organic matter content. In this study, humus, nitrogen (N) and energy balances, and greenhouse gas (GHG) emissions were calculated for a 14-year field experiment using the model software REPRO. Humus balances showed that compost fertilisation at a rate of 8 t/ha.year resulted in a positive balance of 115 kg carbon (C)/ha.year. With 14 and 20 t/ha.year of compost, respectively, humus accumulated at rates of 558 and 1021 kg C/ha.year. With mineral fertilisation at rates of 29–62 kg N/ha.year, balances were moderately negative (–169 to –227 kg C/ha.year), and a clear humus deficit of –457 kg C/ha.year showed in the unfertilised control. Compared with measured soil organic C (SOC) data, REPRO predicted SOC contents fairly well with the exception of the treatments with high compost rates, where SOC contents were overestimated by REPRO. GHG balances calculated with soil C sequestration on the basis of humus balances, and on the basis of soil analyses, indicated negative GHG emissions with medium and high compost rates. Mineral fertilisation yielded net GHG emissions of ~2000 kg CO2-eq/ha.year. The findings underline that compost fertilisation holds potential for C sequestration and for the reduction of GHG emissions, even though this potential is bound to level off with increasing soil C saturation.


2006 ◽  
Vol 86 (1) ◽  
pp. 141-151 ◽  
Author(s):  
A. F. Plante ◽  
C. E. Stewart ◽  
R. T. Conant ◽  
K. Paustian ◽  
J. Six

Agricultural management affects soil organic matter, which is important for sustainable crop production and as a greenhouse gas sink. Our objective was to determine how tillage, residue management and N fertilization affect organic C in unprotected, and physically, chemically and biochemically protected soil C pools. Samples from Breton, Alberta were fractionated and analysed for organic C content. As in previous reports, N fertilization had a positive effect, tillage had a minimal effect, and straw management had no effect on whole-soil organic C. Tillage and straw management did not alter organic C concentrations in the isolated C pools, while N fertilization increased C concentrations in all pools. Compared with a woodlot soil, the cultivated plots had lower total organic C, and the C was redistributed among isolated pools. The free light fraction and coarse particulate organic matter responded positively to C inputs, suggesting that much of the accumulated organic C occurred in an unprotected pool. The easily dispersed silt-sized fraction was the mineral-associated pool most responsive to changes in C inputs, whereas the microaggregate-derived silt-sized fraction best preserved C upon cultivation. These findings suggest that the silt-sized fraction is important for the long-term stabilization of organic matter through both physical occlusion in microaggregates and chemical protection by mineral association. Key words: Soil organic C, tillage, residue management, N fertilization, silt, clay


1993 ◽  
Vol 73 (1) ◽  
pp. 115-122 ◽  
Author(s):  
A. N'dayegamiye ◽  
D. A. Angers

The long-term effects of wood-residue applications on soil properties are not well documented. This study was undertaken to characterize the organic matter and aggregation of a sandy loam after 9 yr of biennial application of wood residues (tree clippings) at rates of 25, 50 and 100 Mg ha−1 with and without nitrogen fertilization. Carbon (C) and nitrogen (N) contents of the whole soil were determined as well as the C content of the density fractions and of the fractions soluble and insoluble to Na4P2O7. In comparison with the control, the whole-soil C content was 16–24% higher following application of wood residues alone and 16–37% higher for application of wood residues supplemented with nitrogen. The treatments had no effect on soil water-stable macroaggregation (> 250 μm). Wood-residue applications had no effect on the humic material (soluble in Na4P2O7) but favored the humin-C content (the fractions insoluble in Na4P2O7) by 25–60% relative to the control. The light-fraction organic matter was on average 68% larger, and the heavy fraction 17% larger, in the treated soils than in the control. On average, 80% of the differences in total organic C induced by residue application could be attributed to differences in the humin and heavy fractions. The long-term effect of wood-residue applications to the soil was, therefore, reflected in an accumulation of the more stable organic matter present as heavy and humin fractions. In addition, the differences in the light fractions suggested a short-term effect of wood-residue applications.Key words: Light and heavy fractions, wood residues, organic C, water-stable aggregates, humic acids, humins


Soil Research ◽  
2012 ◽  
Vol 50 (7) ◽  
pp. 527 ◽  
Author(s):  
Mark Conyers ◽  
Philip Newton ◽  
Jason Condon ◽  
Graeme Poile ◽  
Pauline Mele ◽  
...  

The aim of this study was to assess the long-term changes in some key soil chemical properties at the completion of three long-term trials in south-eastern Australia and the relationship between those soil properties. From a soil organic matter perspective, the build-up of carbon (%C) requires an accumulation of nitrogen (%N), and the build-up of %C and %N fertility comes at the cost of soil acidity. Rotation, tillage, and stubble practices combine to alter the quantity, quality (C : N), and the depth distribution of organic matter in a soil, but the three soil chemical properties reported here seem to also be in quasi-equilibrium at the three long-term sites. The consequence is that if the build-up of soil organic matter leads to soil acidification, then the maintenance of agricultural production will require liming. The emission of CO2 when limestone reacts with soil acids, plus the C cost of limestone application, will negate a proportion of the gains from C sequestration as organic matter in soil. Such cautionary information was doubtless unforeseen when these three long-term trials were initiated.


2010 ◽  
Vol 46 (5) ◽  
pp. 335-341 ◽  
Author(s):  
Eirini Katsalirou ◽  
Shiping Deng ◽  
David L. Nofziger ◽  
Argyrios Gerakis

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