Turnover of soil organic matter under pasture as determined by 13C natural abundance

Soil Research ◽  
1990 ◽  
Vol 28 (2) ◽  
pp. 267 ◽  
Author(s):  
JO Skjemstad ◽  
RP Lefeuvre ◽  
RE Prebble
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Type ◽  
Vegetation Cover ◽  
Natural Abundance ◽  
The Other ◽  
Photosynthetic Pathway ◽  
Paspalum Dilatatum ◽  
13C Natural Abundance ◽  
Pennisetum Clandestinum

The change in vegetation cover from rainforest with a C3 photosynthetic pathway to grasses with C4 pathways was used to follow input rates and turnover of organic matter in a krasnozem over an 83 year period. The measurement of 613c values on soils from three depths (0.0-7.5, 7.5-15.0, 60.0-80.0 cm) indicated that charcoal was a serious contaminant in the light fractions (<1.6 Mg mW3) of all samples and should be removed. Of the two grasses studied (Paspalum dilatatum and Pennisetum clandestinum), the latter gave more input of organic matter into the 7.5-15.0 cm horizon. In the other horizons, both grasses performed equally. Organic matter within microaggregates (<0.2 mm) proved to contain up to 32% more old carbon than the remaining soil after 83 years. Turnover times for organic matter in the >1.6 Mg m-3 fraction from the three depths were calculated as 60, 75 and 276 years respectively, compared with 75, 108 and 348 years for the organic matter within microaggregates from the same horizons. It is concluded that the presence of microaggregates is an important factor in stabilizing organic matter in this soil type. Some difficulties with the technique are also discussed.

Structural and dynamic properties of soil organic-matter as reflected by 13C natural-abundance, pyrolysis mass-spectrometry and solid-state 13C NMR-spectroscopy in density fractions of an oxisol under forest and pasture

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 59 ◽  
Author(s):  
A Golchin ◽  
JM Oades ◽  
JO Skjemstad ◽  
P Clarke
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Isotopic Composition ◽  
Particulate Organic Matter ◽  
Organic Materials ◽  
Natural Abundance ◽  
13C Natural Abundance ◽  
Clay Particles ◽  
Density Fractions ◽  
Soil Organic Matter Turnover

Changes in the content and isotopic composition of organic carbon as a consequence of deforestation and pasture establishment were studied in three neighbouring areas on an Oxisol from Australia and used to measure the turnover of forest-derived carbon (C3) under pasture (C4) over 35 and 83 year time scales. The results indicated that the quantity of forest-derived carbon declined rapidly during the first 35 years under pasture but the content remained nearly stable thereafter, suggesting the presence of two pools of carbon with different turnover times. The calculated values for turnover time of labile and resistant fractions of forest-derived carbon were 35 and 144 years respectively. The soil samples were separated into five fractions with densities <1.6 (free and occluded), 1.6-1.8, 1.8-2.0 and >2.0 Mg m-3. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter contained in different density fractions was classified as free particulate organic matter (1.6 free), occluded particulate organic matter (<1.6 occluded, 1.6-1.8 and 1.8-2.0) and clay associated organic matter (>2.0 Mg m-3). The 13C natural abundance showed that the free particulate organic matter formed a significant pool for soil organic matter turnover when the forest was replaced by pasture. Compared with free particulate organic matter, the organic materials occluded within aggregates had slower turnover times. The occluded organic materials were in different stages of decomposition and had different chemical stabilities. Comparison of the chemistry and isotopic composition of occluded organic materials indicated that the O-alkyl C content of the occluded organic materials was inversely related to their stabilities whereas their aromatic C content was directly related to their stabilities. In soils under pasture, a considerable amount of forest-derived carbon was associated with clay particles in the fractions .2.0 Mg m-3. The rate of accumulation of pasture-derived carbon was also rapid in this fraction, indicating the presence of two different pools of carbon (C3 and C4) associated with clay particles. The forest-derived carbon had the highest stability in the fractions >2.0 Mg m-3, probably due to strong interaction with active aluminium or iron and aluminium oxides associated with clay surfaces.

Partial cut harvesting and ectomycorrhizae: early effects in Douglas-fir-larch forests of western Montana

1980 ◽  
Vol 10 (3) ◽  
pp. 436-440 ◽  
Author(s):  
A. E. Harvey ◽  
M. J. Larsen ◽  
M. F. Jurgensen
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Douglas Fir ◽  
The Other ◽  
Western Montana ◽  
Root Tips ◽  
Residue Removal ◽  
Larch Forests ◽  
Early Effects

Numbers of ectomycorrhizae were assessed 3 years after harvesting approximately 50% of the overstory in two Douglas-fir-larch stands in western Montana, one was subjected to intensive residue removal, the other broadcast burned 1 year after harvest. Numbers of active ectomycorrhizal root tips were significantly reduced in the broadcast burned stand compared to either the intensively utilized stand or to an adjacent, undisturbed stand. This indicates that on difficult-to-regenerate sites, particularly where soil organic matter is low, it may be advantageous to dispose of slash created in partial cuts by means other than burning.

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 Differences in soil organic matter and humus of sandy soil after application of biochar substrates and combination of biochar substrates with mineral fertilizers

2020 ◽  
Vol 23 (3) ◽  
pp. 117-124
Author(s):  
Dušan Šrank ◽  
Vladimír Šimanský
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Carbon Content ◽  
Humic Substances ◽  
Sandy Soil ◽  
The Other ◽  
Mineral Fertilizers ◽  
Other Hand ◽  
Sheep Manure ◽  
The Impact

The effort to achieve the sustainable farming system in arable soil led to the intensive search for a new solution but an inspiration can also be found in the application of traditional methods of soil fertility improvement as it is shown in numerous examples in history. Recently many scientific teams have focused their attention on the evaluation of biochar effects on soil properties and crop yields. Since there are a lot of knowledge gaps, especially in explanations how biochar can affect soil organic matter (SOM) and humus substances, we aimed this study at the solution of these questions. Therefore, the objective of the experiment was to evaluate the impact of two biochar substrates (B1 – biochar blended with sheep manure, and B2 – biochar blended with sheep manure and the residue from the biogas station) at two rates (10 and 20 t ha-1) applied alone or in combination with mineral fertilizers (Urea was applied in 2018, at rate 100 kg ha-1, and Urea at rate 100 kg ha-1 + AMOFOS NP 12-52 at 100 kg ha-1 were applied in 2019) on the quantity and quality of SOM and humus of sandy soil (Arenosol, Dolná Streda, Slovakia). The results showed that application of the biochar substrates together with mineral fertilizers (MF) had more pronounced effect on the organic matter mineralization in the sandy soil which resulted in low accumulation of soil organic carbon (Corg) and labile carbon compared to biochar substrates treatments without MF. The share of humic substances in Corg significantly decreased by 16, 50, 16 and 24% in B1 at 10 t ha-1, B1 at 20 t ha-1, B2 at 10 t ha-1 and B2 at 20 t ha-1 treatments, respectively, compared to the control. A similar tendency was observed for biochar substrates treatments + MF, compared to MF control. The carbon content of humic substances (CHS) was equal to 4.40 – 5.80 g kg-1 and the biochar substrates had statistically significant influence on CHS content. On average, there was a smaller decrease of CHS in B1 at rate 10 t ha-1 than at rate 20 t ha-1 and no effect of B2 compared to control. The carbon content of fulvic acid (CFA) was 9% higher in B1 at 10 t ha-1, and 20 t ha-1, 47% higher in B2 at 10 t ha-1 and 17% higher in B2 at 20 t ha-1 compared to control. As a result of biochar substrates + MF application, the reduction in CFA was observed. The results showed a decrease of CHA : CFA ratio with association to biochar substrates alone application compared to control on one hand, and a wider of CHA : CFA ratio in biochar substrates + MF treatments in comparison to MF control on the other hand. Humus stability was increased in biochar substrates alone treatments compared to control, on the other hand, compared to MF control, the application of biochar substrates + MF resulted in a lower humus stability.

Soybean Tolerance to Metribuzin

Weed Science ◽  
1973 ◽  
Vol 21 (4) ◽  
pp. 308-309 ◽  
Author(s):  
H. D. Coble ◽  
J. W. Schrader
Keyword(s):  
Organic Matter ◽  
Glycine Max ◽  
Soil Organic Matter ◽  
The Other ◽  
Severe Injury ◽  
Simulated Rainfall ◽  
Planting Depth ◽  
Treatment Tolerance

Tolerance of greenhouse-grown soybean (Glycine max (L.) Merr.) to preemergence applications of 4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)one (metribuzin) was greatly influenced by herbicide rate, soil organic matter, and simulated rainfall after treatment. Planting depth affected tolerance in cases where effects of the other variables were marginal. Severe injury was observed with 1.1% soil organic matter except at the 0.56 kg/ha herbicide rate with no rainfall for 10 days after treatment. Tolerance increased with increasing soil organic matter to the point where no injury occurred at 16.8 or 40.0% organic matter, even at herbicide rates up to 1.68 kg/ha with 1.25 cm simulated rainfall immediately after treatment.

Adsorption and Diffusion of Dinitroaniline Herbicides in Soils

Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 450-455 ◽  
Author(s):  
G. L. Jacques ◽  
R. G. Harvey
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
The Other ◽  
Silt Loam ◽  
Relative Mobility ◽  
Water Saturated ◽  
And Diffusion ◽  
Dinitroaniline Herbicides

Adsorption of benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine), dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), profluralin [N-(cyclopropylmethyl)-α,α,α-tri-fluoro-2,6-dinitro-N-propyl-p-toluidine], and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was studied in 10 Wisconsin soils. Ratios of the quantity of each herbicide adsorbed and quantities remaining in the soil solution at equilibrium (Kd value) on a Piano silt loam (Typic Argiudoll fine-silty, mixed, mesic) remained relatively constant over a range of concentrations. Herbicide adsorption by the soils was related more closely to soil organic matter than to the other soil chemical and physical properties. Diffusion of the herbicides in Piano silt loam was affected by soil water. Diffusion of trifluralin, profluralin and benefin decreased as soil water increased. Diffusion of dinitramine and fluchloralin did not change significantly with change in water content. Diffusion of oryzalin increased at the highest soil water content. None of the herbicides moved more than 10 mm in the soil during a 17-day period. In unsaturated Piano silt loam, relative mobility of the herbicides was trifluralin ≥benefin>profluralin>fluchloralin>dinitramine≥oryzalin. Oryzalin reached highest mobility in water-saturated soil.

Particulate organic matter in soil under different management systems in the Brazilian Cerrado

Soil Research ◽  
2012 ◽  
Vol 50 (8) ◽  
pp. 685 ◽  
Author(s):  
Arcângelo Loss ◽  
Marcos Gervasio Pereira ◽  
Adriano Perin ◽  
Fernando Silva Coutinho ◽  
Lúcia Helena Cunha dos Anjos
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
The Other ◽  
Management Systems ◽  
Soil Conditions ◽  
Brazilian Cerrado ◽  
Cerrado Vegetation ◽  
No Till ◽  
Planting System

The combination of the no-till planting system (NTS) and pasture (e.g. brachiaria grass, Urochloa sp.) for livestock production constitutes a crop–livestock integration (CLI) system. CLI systems significantly increase the total organic carbon (TOC) content of soil and the particulate organic carbon (POC) of soil organic matter (SOM). The present study evaluated TOC and the granulometric fractions of SOM under different management systems in a Cerrado area in the state of Goiás. Two areas applying crop rotation were evaluated, one using CLI (corn/brachiaria grass/bean/cotton/soybean planted sequentially) and the other NTS (sunflower/pearl millet/soybean/corn planted sequentially). A third area covered with natural Cerrado vegetation (Cerradão) served as a reference to determine original soil conditions. Soil was randomly sampled at 0–5, 5–10, 10–20, and 20–40 cm. The TOC, POC, and mineral-associated organic carbon (MOC) were assessed, and POC and MOC stocks calculated. The CLI system resulted in greater TOC levels than NTS (0–5, 5–10, and 10–20 cm). Compared with the Cerradão, CLI areas exhibited higher stocks of TOC (at 5–10 and 10–20 cm) and POC (at 0–40 cm). Results obtained for TOC and POC fractions show that land management with CLI was more efficient in increasing SOM than NTS. Moreover, when compared with NTS, the CLI system provided better POC stratification.

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