Leys and soil organic matter

1964 ◽  
Vol 63 (3) ◽  
pp. 377-383 ◽  
Author(s):  
C. R. Clement ◽  
T. E. Williams
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Seed Production ◽  
Arable Land ◽  
Row Crops

1. The increase in soil carbon has been assessed in arable land sown to different leys variously managed.2. Under swards cut for herbage conservation, carbon in the top 15 cm. of soil increased by about 0-05 % each year. Although an increase of 0-3 % was found immediately under drills of cocksfoot grown for seed production, there was no increase midway between the drills and, for a given area of land, the carbon increment under such row-crops is probably similar to that under cut swards.

scholarly journals The Role of Trees and Pastures in Organic Agriculture

2015 ◽  
Vol 4 (3) ◽  
pp. 51 ◽  
Author(s):  
Joseph R. Heckman
Keyword(s):  
Soil Erosion ◽  
Soil Carbon ◽  
Organic Farming ◽  
Arable Land ◽  
Organic Matter Content ◽  
United States Department ◽  
Omega 3 ◽  
Row Crops ◽  
Tree Crops ◽  
Organic Farm

<p>Environmental concerns associated with annual row crop grain production – including soil erosion, soil carbon loss, intensive use of chemicals and petroleum, limited arable land, among others – could be addressed by converting conventional livestock production to an organic pasture based system. The inclusion of tree crops would further enhance the opportunity for feeding pasture- raised livestock by providing shelter and alternative feed sources. Biodiversity is an essential aspect of an organic farm plan. The idea of including tree crops and other perennials into the vision of an organic farm as a “living system” is very much compatible with the goals and philosophy of organic farming. Before modern no-till farming systems were developed, tree crops and pasture systems were found to provide similar benefits for controlling soil erosion and conserving soil carbon. For example, J. Russell Smith’s <em>Tree Crops: A Permanent Agriculture</em> (Smith, 1950) and pioneered tree crop agriculture as the alternative to annual row crops for protecting soils from erosion while producing livestock feed such as acorns, nuts, and fodder. A survey of Mid-Atlantic USA soils under pasture found 60% higher soil organic matter content than cultivated fields. Because United States Department of Agriculture’s National Organic Program (USDA-NOP) standards require dairy cattle consume pasture forage and limited grain (7 C.F.R. pt. 206), organic milk contains higher concentrations of omega-3 and fewer omega-6 fatty acids than conventional milk. Organic standards also state “the producer must not use lumber treated with arsenate or other prohibited materials for new [fence posts] installations or replacement purposes in contact with soil or livestock.” Black locust (<em>Robinia pseudoacacia</em>) is a fast growing renewable alternative to treated lumber with many attributes compatible with organic farming. This versatile tree fixes nitrogen (N), provides flowers for honey bees and other pollinators, and produces a highly durable dense wood ideal for fence posts useable for up to 50 year.</p>

scholarly journals Towards a representation of priming on soil carbon decomposition in the global land biosphere model ORCHIDEE (version 1.9.5.2)

2016 ◽  
Vol 9 (2) ◽  
pp. 841-855 ◽  
Author(s):  
Bertrand Guenet ◽  
Fernando Esteban Moyano ◽  
Philippe Peylin ◽  
Philippe Ciais ◽  
Ivan A Janssens
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Global Scale ◽  
Soil Incubation ◽  
First Order ◽  
Carbon Decomposition ◽  
Litter Manipulation ◽  
Global Land ◽  
Biosphere Model

Abstract. Priming of soil carbon decomposition encompasses different processes through which the decomposition of native (already present) soil organic matter is amplified through the addition of new organic matter, with new inputs typically being more labile than the native soil organic matter. Evidence for priming comes from laboratory and field experiments, but to date there is no estimate of its impact at global scale and under the current anthropogenic perturbation of the carbon cycle. Current soil carbon decomposition models do not include priming mechanisms, thereby introducing uncertainty when extrapolating short-term local observations to ecosystem and regional to global scale. In this study we present a simple conceptual model of decomposition priming, called PRIM, able to reproduce laboratory (incubation) and field (litter manipulation) priming experiments. Parameters for this model were first optimized against data from 20 soil incubation experiments using a Bayesian framework. The optimized parameter values were evaluated against another set of soil incubation data independent from the ones used for calibration and the PRIM model reproduced the soil incubations data better than the original, CENTURY-type soil decomposition model, whose decomposition equations are based only on first-order kinetics. We then compared the PRIM model and the standard first-order decay model incorporated into the global land biosphere model ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems). A test of both models was performed at ecosystem scale using litter manipulation experiments from five sites. Although both versions were equally able to reproduce observed decay rates of litter, only ORCHIDEE–PRIM could simulate the observed priming (R2  =  0.54) in cases where litter was added or removed. This result suggests that a conceptually simple and numerically tractable representation of priming adapted to global models is able to capture the sign and magnitude of the priming of litter and soil organic matter.

scholarly journals Predicting decadal trends and transient responses of radiocarbon storage and fluxes in a temperate forest soil

2012 ◽  
Vol 9 (8) ◽  
pp. 3013-3028 ◽  
Author(s):  
C. A. Sierra ◽  
S. E. Trumbore ◽  
E. A. Davidson ◽  
S. D. Frey ◽  
K. E. Savage ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Empirical Model ◽  
Temperate Forest ◽  
Global Environmental Change ◽  
Carbon Dynamics ◽  
Co2 Efflux ◽  
Soil C ◽  
Soil Carbon Dynamics

Abstract. Representing the response of soil carbon dynamics to global environmental change requires the incorporation of multiple tools in the development of predictive models. An important tool to construct and test models is the incorporation of bomb radiocarbon in soil organic matter during the past decades. In this manuscript, we combined radiocarbon data and a previously developed empirical model to explore decade-scale soil carbon dynamics in a temperate forest ecosystem at the Harvard Forest, Massachusetts, USA. We evaluated the contribution of different soil C fractions to both total soil CO2 efflux and microbially respired C. We tested the performance of the model based on measurable soil organic matter fractions against a decade of radiocarbon measurements. The model was then challenged with radiocarbon measurements from a warming and N addition experiment to test multiple hypotheses about the different response of soil C fractions to the experimental manipulations. Our results showed that the empirical model satisfactorily predicts the trends of radiocarbon in litter, density fractions, and respired CO2 observed over a decade in the soils not subjected to manipulation. However, the model, modified with prescribed relationships for temperature and decomposition rates, predicted most but not all the observations from the field experiment where soil temperatures and nitrogen levels were increased, suggesting that a larger degree of complexity and mechanistic relations need to be added to the model to predict short-term responses and transient dynamics.

Changes in soil carbon under long-term maize in monoculture and legume-based rotation

2001 ◽  
Vol 81 (1) ◽  
pp. 21-31 ◽  
Author(s):  
E G Gregorich ◽  
C F Drury ◽  
J A Baldock
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Magnetic Resonance ◽  
Soil Carbon ◽  
Crop Residues ◽  
Cropping Systems ◽  
Natural Abundance ◽  
Organic C ◽  
Soil C

Legume-based cropping systems could help to increase crop productivity and soil organic matter levels, thereby enhancing soil quality, as well as having the additional benefit of sequestering atmospheric C. To evaluate the effects of 35 yr of maize monoculture and legume-based cropping on soil C levels and residue retention, we measured organic C and 13C natural abundance in soils under: fertilized and unfertilized maize (Zea mays L.), both in monoculture and legume-based [maize-oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-alfalfa] rotations; fertilized and unfertilized systems of continuous grass (Poa pratensis L.); and under forest. Solid state 13C nuclear magnetic resonance (NMR) was used to chemically characterize the organic matter in plant residues and soils. Soils (70-cm depth) under maize cropping had about 30-40% less C, and those under continuous grass had about 16% less C, than those under adjacent forest. Qualitative differences in crop residues were important in these systems, because quantitative differences in net primary productivity and C inputs in the different agroecosystems did not account for observed differences in total soil C. Cropping sequence (i.e., rotation or monoculture) had a greater effect on soil C levels than application of fertilizer. The difference in soil C levels between rotation and monoculture maize systems was about 20 Mg C ha-1. The effects of fertilization on soil C were small (~6 Mg C ha-1), and differences were observed only in the monoculture system. The NMR results suggest that the chemical composition of organic matter was little affected by the nature of crop residues returned to the soil. The total quantity of maize-derived soil C was different in each system, because the quantity of maize residue returned to the soil was different; hence the maize-derived soil C ranged from 23 Mg ha-1 in the fertilized and 14 Mg ha-1 in the unfertilized monoculture soils (i.e., after 35 maize crops) to 6-7 Mg ha-1 in both the fertilized and unfertilized legume-based rotation soils (i.e., after eight maize crops). The proportion of maize residue C returned to the soil and retained as soil organic C (i.e., Mg maize-derived soil C/Mg maize residue) was about 14% for all maize cropping systems. The quantity of C3-C below the plow layer in legume-based rotation was 40% greater than that in monoculture and about the same as that under either continuous grass or forest. The soil organic matter below the plow layer in soil under the legume-based rotation appeared to be in a more biologically resistant form (i.e., higher aromatic C content) compared with that under monoculture. The retention of maize residue C as soil organic matter was four to five times greater below the plow layer than that within the plow layer. We conclude that residue quality plays a key role in increasing the retention of soil C in agroecosystems and that soils under legume-based rotation tend to be more “preservative” of residue C inputs, particularly from root inputs, than soils under monoculture. Key words: Soil carbon, 13C natural abundance, 13C nuclear magnetic resonance, maize cropping, legumes, root carbon

scholarly journals Effects of changing land use in the Netherlands on net carbon fixation.

1991 ◽  
Vol 39 (4) ◽  
pp. 237-246 ◽  
Author(s):  
J. Wolf ◽  
L.H.J.M. Janssen
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
The Netherlands ◽  
Input Data ◽  
Carbon Fixation ◽  
Arable Land ◽  
Rate Of Change ◽  
Pool Size ◽  
Average Amount

The changed crop rotation on arable land, the decreasing grassland area and the increase in forest area in the Netherlands resulted in a decrease in C pool size. For the calculation of this C pool a method requiring only three input data (average amount of crop or tree residue rate, soil organic matter decomposition and the humification coefficient) has been applied. However the method can only be applied to situations in equilibrium where all three input data are equal. For a changing land use a new state of equilibrium and rate of change in C pool size can be calculated. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Leys and soil organic matter:III. The accumulation of macro-organic matter in the soil under different swards

1972 ◽  
Vol 78 (2) ◽  
pp. 333-341 ◽  
Author(s):  
E. A. Garwood ◽  
C. R. Clement ◽  
T. E. Williams
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Arable Land ◽  
N Fertilizer ◽  
Plant Debris ◽  
Total Soil ◽  
Grazed Swards ◽  
Mesh Sieve

SUMMARYMacro-organic matter (roots and partially decomposed plant debris retained on a 0·25 mm mesh sieve) was measured in soils under various swards. Under a grazed perennial ryegrass/white clover sward, sown on arable land, macro-organic matter in the top 15 cm of soil rose steadily in the first 8 years to 15·8 t/ha, but subsequently declined. Under arable cropping there was great variation with crop and season. Under grass, most of the macro-organic matter accumulated in the top 2 cm of soil, particularly during the first 3 or 4 years. More macro-organic matter was found under perennial ryegrass/white clover than under cocksfoot/white clover swards.After 3 years under grass macro-organic matter accounted for 10% of the total soil carbon, and represented about half the increase in soil carbon.Half, or less, of the nitrogen which accumulated in soil under grass was in the macroorganic matter fraction. The differences between swards which received no N fertilizer and those which received 940 kg/ha over 3 years was small, 16–40 kg N/ha respectively for cut and frequently grazed swards. The ratio of C:N in macro-organic matter under different swards averaged 22:1.

scholarly journals CO2-C losses and carbon quality of selected Maritime Antarctic soils

2012 ◽  
Vol 25 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Juliana Vanir De Souza Carvalho ◽  
Eduardo De Sá Mendonça ◽  
Newton La Scala ◽  
César Reis ◽  
Efrain Lázaro Reis ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Temperature ◽  
Soil Carbon ◽  
Humic Substances ◽  
Microbial Activity ◽  
Chemical Characteristics ◽  
Maritime Antarctic ◽  
Antarctic Soils ◽  
Humification Degree

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.

scholarly journals Soil Organic 14C Dynamics: Effects of Pasture Installation on Arable Land

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 1023-1031 ◽  
Author(s):  
Paul F. A. M. Römkens ◽  
Jan Hassink ◽  
Johannes Van der Plicht
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Arable Land ◽  
Isotope Ratios ◽  
Vertical Displacement ◽  
Heavy Fraction ◽  
Physical Fractionation ◽  
Fractionation Method ◽  
Heavy Fractions ◽  
Fraction Density

In a study addressing composition and recovery of soil carbon following pasture installation on arable land, radiocarbon isotope ratios were measured in size- and density-separated soil organic matter (SOM) fractions in a pasture and maize plot. The average soil carbon age increased with depth from 444 yr in the 0–30-cm layer to 2456 yr in the 60–80-cm layer in the pasture soils, and from 42 to 1625 yr in the maize-cultivated soil. Weight fractionation of the macro-organic matter (size >150 μm) in a light (density <1.17 g cm-3) intermediate (1.17 g cm-3 < density < 1.37 g cm-3), and heavy fraction (density >1.37 g cm-3) resulted in markedly different ages for different fractions with ages increasing from 2 yr in the light fraction to >3000 yr in the heavy fractions. 13C and 14C (accelerator mass spectrometry (AMS)) isotope ratios in the <20 μm fraction in the 60–80-cm layer indicated that vertical displacement of colloidal organic material occurred during maize cropping. The physical fractionation method, in combination with natural level 13C and 14C analysis, resulted in a better insight in carbon dynamics that occur after the conversion of arable land to pasture.

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