Soil carbon fluxes and balances of crop rotations under long-term no-till

Abstract Background A field study with the same crop rotations was conducted to test the hypothesis that the soil Carbon fluxes and balances could vary according to the crop species and also mitigate carbon dioxide (CO2) emission. This study aimed to assess the CO2 emission from crop rotations according to C and N inputs from crop residue, the influences on soil organic carbon (SOC) and total soil nitrogen (TN) stocks, identifying the soybean production systems with positive C balance. Triticale (x Triticosecale) or sunflower (Helianthus annuus) are grown in the fall/winter; sunn hemp (Crotalaria juncea), forage sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), or fallow are the spring treatments, and soybean as a main crop in summer. Results We found that high C inputs from crop residues modify the C dynamics in crop rotations by reducing the C output (CO2) and increasing C sequestration in the soil. In general, the higher SOC, C stocks, and TN in soil surface were due to higher C and N inputs from sunn hemp or forage sorghum crop residues in spring. These crops also produced lower accumulated CO2 emissions and, when rotating with triticale in the fall-winter season resulted in a positive C balance, making these soybean crop rotations more efficient. Conclusion Our study suggests the ideal crop species choice in a rotation can mitigate the CO2 emissions by increasing C and N input from crop residues and consequently SOC and C stocks. In particular, crop rotation comprises an important tool to achieve a positive C balance, mitigate CO2 emissions and provide an additional ecosystem service to soybean cultivation option.

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Potential contribution by cotton roots to soil carbon stocks in irrigated Vertosols

Soil Research ◽

10.1071/sr08180 ◽

2009 ◽

Vol 47 (3) ◽

pp. 243 ◽

Cited By ~ 11

Author(s):

N. R. Hulugalle ◽

T. B. Weaver ◽

L. A. Finlay ◽

N. W. Luelf ◽

D. K. Y. Tan

Keyword(s):

Root Growth ◽

Soil Carbon ◽

Crop Residues ◽

Climatic Factors ◽

Carbon Stocks ◽

Potential Contribution ◽

Soil C ◽

C Stocks ◽

Root Death ◽

Soil Carbon Stocks

The well-documented decline in soil organic carbon (SOC) stocks in Australian cotton (Gossypium hirsutum L.) growing Vertosols has been primarily analysed in terms of inputs from above-ground crop residues, with addition to soil C by root materials being little studied. Potential contribution by cotton roots to soil carbon stocks was evaluated between 2002 and 2008 in 2 ongoing long-term experiments near Narrabri, north-western New South Wales. Experiment 1 consisted of cotton monoculture sown either after conventional tillage or on permanent beds, and a cotton–wheat (Triticum aestivum L.) rotation on permanent beds; Experiment 2 consisted of 4 cotton-based rotation systems sown on permanent beds: cotton monoculture, cotton–vetch (Vicia villosa Roth.), cotton–wheat, and cotton–wheat–vetch. Roundup-Ready™ (genetically modified) cotton varieties were sown until 2005, and Bollgard™ II-Roundup Ready™-Flex™ varieties thereafter. Root growth in the surface 0.10 m was measured with the core-break method using 0.10-m-diameter cores. A subsample of these cores was used to evaluate relative root length and root C concentrations. Root growth in the 0.10–1.0 m depth was measured at 0.10-m depth intervals with a ‘Bartz’ BTC-2 minirhizotron video microscope and I-CAP image capture system (‘minirhizotron’). The video camera was inserted into clear, plastic acrylic minirhizotron tubes (50-mm-diameter) installed within each plot, 30° from the vertical. Root images were captured 4–5 times each season in 2 orientations, left and right side of each tube, adjacent to a furrow, at each time of measurement and the images analysed to estimate selected root growth indices. The indices evaluated were the length and number of live roots at each time of measurement, number of roots which changed length, number and length of roots which died (i.e. disappeared between times of measurement), new roots initiated between times of measurement, and net change in root numbers and length. These measurements were used to derive root C turnover between times of measurements, root C added to soil through intra-seasonal root death, C in roots remaining at end of season, and the sum of the last 2 indices: root C potentially available for addition to soil C stocks. Total seasonal cotton root C potentially available for addition to soil C stocks ranged between ~50 and 400 g/m2 (0.5 and 4 t/ha), with intra-seasonal root death contributing 25–70%. These values are ~10–60% of that contributed by above-ground crop residues. As soil organic carbon in irrigated Vertosols can range between 40 and 60 t/ha, it is unlikely that cotton roots will contribute significantly to soil carbon stocks in irrigated cotton farming systems. Seasonal root C was reduced by cotton monoculture, stress caused by high insect numbers, and sowing Bollgard II varieties; and increased by sowing non-Bollgard II varieties and wheat rotation crops. Permanent beds increased root C but leguminous rotation crops did not. Climatic factors such as cumulative day-degrees and seasonal rainfall were positively related to seasonal root C. Root C turnover was, in general, highest during later vegetative/early reproductive growth. Large variations in root C turnover and seasonal C indices occurred due to a combination of environmental, management and climatic factors.

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C:N ratios and carbon distribution profile across rooting zones in oilseed and pulse crops

Crop and Pasture Science ◽

10.1071/cp10360 ◽

2011 ◽

Vol 62 (6) ◽

pp. 496 ◽

Cited By ~ 25

Author(s):

Y. T. Gan ◽

B. C. Liang ◽

L. P. Liu ◽

X. Y. Wang ◽

C. L. McDonald

Keyword(s):

Crop Residues ◽

Soil Depth ◽

High Water ◽

Triticum Aestivum L ◽

Rooting Depth ◽

Similar Response ◽

Distribution Profile ◽

Crop Species ◽

Pulse Crops ◽

C And N

Knowledge on the C : N ratio of crop residues is of great importance for modelling carbon (C) and nitrogen (N) dynamics of agricultural systems. This study determined (i) the C : N ratios in the seed, straw, and roots of selected broadleaf crops and (ii) the root C and N distribution in the 0–100 cm rooting zone. Three oilseed (Brassica napus canola, Brassica juncea mustard, Linum usitatissimum flax), three pulse crops (Cicer arietinum chickpea, Pisum sativum dry pea, Lens culinaris lentil), and spring wheat (Triticum aestivum L.) were grown under field conditions with low- (rainfall only) and high-water (rainfall plus irrigation) availability. Root C mass decreased substantially with rooting depth, with ~58% of root C mass in the top 20 cm of the soil, 78% in the top 40 cm, and 94% in the top 60 cm. Significant differences in root C mass between crop species occurred in the top 20 cm with canola, mustard, and wheat allocating 66% of their root C total, compared with 55% for dry pea, lentil, and flax, and 41% for chickpea. Root N mass followed a similar response to root C. Seed C : N ratios ranged between 6 and 17, whereas straw C : N ranged between 14 and 55, and root C : N between 17 and 75. Under low-water conditions, canola and mustard had a straw C : N of 33, lower than that of flax (38) and wheat (41). Under higher-water availability, however, mustard and wheat had straw C : N ratios at 55, greater than canola, mustard and flax (47). Three pulses had an average straw C : N ratio of 17, significantly lower than 41 for the oilseeds and 32 for wheat. On average, canola, mustard and wheat had greater root C : N ratios (44) than chickpea (33) and lentil (29), with dry pea having a smallest root C : N ratio (18). Root C : N ratios did not change with soil depth. These detailed measurements on the vertical distribution of root C and N as well as C : N ratios for various crops will assist in improving estimates of inputs for C and N cycling studies.

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Sustainable Management of Soil for Carbon Sequestration

Science & Technology Journal ◽

10.22232/stj.2017.05.02.10 ◽

2017 ◽

Vol 5 (2) ◽

pp. 132-140 ◽

Cited By ~ 1

Author(s):

Kewat Sanjay Kumar ◽

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Sustainable Management ◽

Management Practices ◽

Atmospheric Co2 ◽

Carbon Pools ◽

Carbon Stabilization ◽

Organic C ◽

Soil Ecosystems ◽

C Stocks

Mechanisms governing carbon stabilization in soils have received a great deal of attention in recent years due to their relevance in the global carbon cycle. Two thirds of the global terrestrial organic C stocks in ecosystems are stored in below ground components as terrestrial carbon pools in soils. Furthermore, mean residence time of soil organic carbon pools have slowest turnover rates in terrestrial ecosystems and thus there is vast potential to sequester atmospheric CO2 in soil ecosystems. Depending upon soil management practices it can be served as source or sink for atmospheric CO2. Sustainable management systems and practices such as conservation agriculture, agroforestry and application of biochar are emerging and promising tools for soil carbon sequestration. Increasing soil carbon storage in a system simultaneously improves the soil health by increase in infiltration rate, soil biota and fertility, nutrient cycling and decrease in soil erosion process, soil compaction and C emissions. Henceforth, it is vital to scientifically explore the mechanisms governing C flux in soils which is poorly understood in different ecosystems under anthropogenic interventions making soil as a potential sink for atmospheric CO2 to mitigate climate change. Henceforth, present paper aims to review basic mechanism governing carbon stabilization in soils and new practices and technological developments in agricultural and forest sciences for C sequestration in terrestrial soil ecosystems.

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Spatially Related Sampling Uncertainty in the Assessment of Labile Soil Carbon and Nitrogen in an Irish Forest Plantation

Applied Sciences ◽

10.3390/app11052139 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2139

Author(s):

Junliang Zou ◽

Bruce Osborne

Keyword(s):

Spatial Variability ◽

Soil Carbon ◽

Sampling Effort ◽

Limited Information ◽

Sampling Area ◽

Soil C ◽

Distribution Maps ◽

Soil C And N ◽

C And N ◽

Highly Correlated

The importance of labile soil carbon (C) and nitrogen (N) in soil biogeochemical processes is now well recognized. However, the quantification of labile soil C and N in soils and the assessment of their contribution to ecosystem C and N budgets is often constrained by limited information on spatial variability. To address this, we examined spatial variability in dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) in a Sitka spruce forest in central Ireland. The results showed moderate variations in the concentrations of DOC and DTN based on the mean, minimum, and maximum, as well as the coefficients of variation. Residual values of DOC and DTN were shown to have moderate spatial autocorrelations, and the nugget sill ratios were 0.09% and 0.10%, respectively. Distribution maps revealed that both DOC and DTN concentrations in the study area decreased from the southeast. The variability of both DOC and DTN increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. The cokriging technique performed better than the ordinary kriging for predictions of DOC and DTN, which are highly correlated. This study provides a statistically based assessment of spatial variations in DOC and DTN and identifies the sampling effort required for their accurate quantification, leading to improved assessments of forest ecosystem C and N budgets.

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Soil carbon fluxes and stocks in a Great Lakes forest chronosequence

Global Change Biology ◽

10.1111/j.1365-2486.2008.01741.x ◽

2009 ◽

Vol 15 (1) ◽

pp. 145-155 ◽

Cited By ~ 75

Author(s):

JIANWU TANG ◽

PAUL V. BOLSTAD ◽

JONATHAN G. MARTIN

Keyword(s):

Great Lakes ◽

Soil Carbon ◽

Carbon Fluxes

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

Canadian Journal of Soil Science ◽

10.4141/s00-041 ◽

2001 ◽

Vol 81 (1) ◽

pp. 21-31 ◽

Cited By ~ 142

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

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Agro-forestry Systems as a Means to Achieve Carbon Co-benefits in Nepal

Journal of Forest and Livelihood ◽

10.3126/jfl.v13i1.15366 ◽

2016 ◽

Vol 13 (1) ◽

pp. 59-68

Author(s):

Roshan M. Bajracharya ◽

Him Lal Shrestha ◽

Ramesh Shakya ◽

Bishal K. Sitaula

Keyword(s):

Organic Carbon ◽

Soil Properties ◽

Soil Carbon ◽

Bulk Density ◽

Agricultural Land ◽

Carbon Stocks ◽

Community Forests ◽

C Stocks ◽

Soil Carbon Stocks ◽

Agro Forestry

Land management regimes and forest types play an important role in the productivity and accumulation of terrestrial carbon pools. While it is commonly accepted that forests enhance carbon sequestration and conventional agriculture causes carbon depletion, the effects of agro-forestry are not well documented. This study investigated the carbon stocks in biomass and soil, along with the selected soil properties in agro-forestry plots compared to community forests (CF) and upland farms in Chitwan, Gorkha and Rasuwa districts of Central Nepal during the year 2012-2013. We determined the total above ground biomass carbon, soil organic carbon (SOC) stocks and soil properties (bulk density, organic carbon per cent, pH, total nitrogen (TN), available phosphorus (P), exchangeable potassium (K), and cation exchange capacity (CEC)) on samples taken from four replicates of 500 m2 plots each in community forests, agro-forestry systems and agricultural land. The soil was sampled in two increments at 0-15 cm and 15-30 cm depths and intact cores removed for bulk density and SOC determination, while loose samples were separately collected for the laboratory analysis of other soil properties. The mean SOC percent and corresponding soil carbon stocks to 30 cm depth were generally highest in CF (3.71 and 3.69 per cent, and 74.98 and 76.24 t ha-1, respectively), followed by leasehold forest (LHF) (2.26 and 1.13 per cent and 40.72 and 21.34 t ha-1, respectively) and least in the agricultural land (3.05 and 1.09 per cent, and 63.54 and 19.42 t ha-1, respectively). This trend was not, however, observed in Chitwan, where agriculture (AG) had the highest SOC content (1.98 per cent) and soil carbon stocks (42.5 t ha-1), followed by CF (1.8 per cent and 41.2 t ha-1) and leasehold forests (1.56 per cent and 35.3 t ha-1) although the differences were not statistically significant. Other soil properties were not significantly different among land use types with the exceptions of pH, total N, available P and CEC in the Chitwan plots. Typically, SOC and soil carbon stocks (to 30cm depth) were positively correlated with each other and with TN and CEC. The AGB-C was expectantly highest in Rasuwa district CF (ranging from 107.3 to 260.3 t ha-1) due to dense growth and cool climate, followed by Gorkha (3.1 to 118.4 t ha-1), and least in Chitwan (17.6 to 95.2 t ha-1). The highest C stocks for agro-forestry systems in both above ground and soil were observed in Rasuwa, followed by Chitwan district. Besides forests, agro-forestry systems also hold good potential to store and accumulate carbon, hence they have scope for contributing to climate change mitigation and adaptation with co-benefits.Journal of Forest and Livelihood 13(1) May, 2015, page: 56-68

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Examining soil carbon uncertainty in a global model: response of microbial decomposition to temperature, moisture and nutrient limitation

Biogeosciences Discussions ◽

10.5194/bgd-10-10229-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 10229-10269

Author(s):

J.-F. Exbrayat ◽

A. J. Pitman ◽

Q. Zhang ◽

G. Abramowitz ◽

Y.-P. Wang

Keyword(s):

Soil Carbon ◽

Nutrient Limitation ◽

Historical Change ◽

Cmip5 Models ◽

Earth System ◽

Microbial Decomposition ◽

Soil C ◽

System Models ◽

C And N ◽

Earth System Models

Abstract. Reliable projections of future climate require land–atmosphere carbon (C) fluxes to be represented realistically in Earth System Models. There are several sources of uncertainty in how carbon is parameterized in these models. First, while interactions between the C, nitrogen (N) and phosphorus (P) cycles have been implemented in some models, these lead to diverse changes in land–atmosphere fluxes. Second, while the parameterization of soil organic matter decomposition is similar between models, formulations of the control of the soil physical state on microbial activity vary widely. We address these sources uncertainty by implementing three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in an Earth System Model that can be run with three degrees of biogeochemical nutrient limitation (C-only, C and N, and C and N and P). All 27 possible combinations of a SMRF with a STRF and a biogeochemical mode are equilibrated before transient historical (1850–2005) simulations are performed. As expected, implementing N and P limitation reduces the land carbon sink, transforming some regions from net sinks to net sources over the historical period (1850–2005). Differences in the soil C balance implied by the various SMRFs and STRFs also change the sign of some regional sinks. Further, although the absolute uncertainty in global carbon uptake is reduced, the uncertainty due to the SMRFs and STRFs grows relative to the inter-annual variability in net uptake when N and P limitations are added. We also demonstrate that the equilibrated soil C also depend on the shape of the SMRF and STRF. Equilibration using different STRFs and SMRFs and nutrient limitation generates a six-fold range of global soil C that largely mirrors the range in available (17) CMIP5 models. Simulating the historical change in soil carbon therefore critically depends on the choice of STRF, SMRF and nutrient limitation, as it controls the equilibrated state to which transient conditions are applied. This direct effect of the representation of microbial decomposition in Earth System Models adds to recent concerns on the adequacy of these simple representations of very complex soil carbon processes.

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Simple additive simulation overestimates real influence: altered nitrogen and rainfall modulate the effect of warming on soil carbon fluxes

Global Change Biology ◽

10.1111/gcb.13588 ◽

2017 ◽

Vol 23 (8) ◽

pp. 3371-3381 ◽

Cited By ~ 5

Author(s):

Xiangyin Ni ◽

Wanqin Yang ◽

Zemin Qi ◽

Shu Liao ◽

Zhenfeng Xu ◽

...

Keyword(s):

Soil Carbon ◽

Carbon Fluxes

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Soil carbon sequestration through crops rotation in a Mediterranean Cambisols: measurement and modelling

10.5194/egusphere-egu21-6372 ◽

2021 ◽

Author(s):

Enrico Balugani ◽

Martina Maines ◽

Denis Zannoni ◽

Alessandro Buscaroli ◽

Diego Marazza

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Crop Rotation ◽

Soil Carbon Sequestration ◽

Crop Rotations ◽

Subtropical Climate ◽

Sequestration Potential ◽

Rothc Model ◽

Periodic Fluctuations

Soil carbon sequestration (SCS) has been identified by the IPCC as one of the most promising and cheap methodology to reduce atmospheric CO2. Moreover, an increase in soil organic carbon (SOC) levels improves soil quality by increasing soil structure (and, hence, resistance to erosion) and promoting soil ecosystems services like water retention, productivity, and biodiversity. Various agricultural techniques are available to increase SOC; among them, crop rotation can improve SOC through soil coverage, changes in water regimes, increase in both carbon inputs, and increase in soil aggregates formation.SOC dynamic models, such as RothC, have been suggested by the IPCC as a way to evaluate the SCS potentials of different soils. Such models could also be used to evaluate the sequestration potential of different agricultural practices. Moreover RothC allows to estimate the time within which the SOC variation, due to a certain agronomic management, can be considered significant as measurable above a threshold value.In this study, we evaluated the SOC changes for different crop rotations through direct measurements and RothC modelling, with the objective of: (a) estimating their SCS potential, and (b) propose a robust monitoring methodology for SCS practices. We performed the study in an agricultural field close to Ravenna (Italy) characterized by Cambisols and humid subtropical climate. Soil carbon content was assessed before the setup of the crop rotation, and after 3 years of rotation. A RothC model was calibrated with field data, and used to estimate SOC dynamics to 50 years, in order to assess long-term SCS. The model results were also used to assess the best methodology to estimate the SOC variation significance.The measured SOC was similar to the equilibrium SOC predicted by the RothC model, on average, for the crop rotations. The measurements showed that the SOC, already low at the beginning of the experiment, further decreased due to the crop rotation practice. Of those tested, the best for SCS involves the following crops: corn, soybeans, wheat on tilled soil, and soybeans; while the worst is with corn, wheat on tilled soil, and wheat on untilled soil. However, the SOC variations predicted by RothC for the various rotations were too small to be observable in the field during experimentation. This could be due both to the uncertainty associated with SOC sampling and analysis, and to the short duration of the experiment. The moving average computations on the simulation values allowed us to assess the time required to measure the long-term trend of SOC variation as significant with respect to the environmental background, instrumental error, and SOC periodic fluctuations. That time was estimated to range from 8 to 50 years, changing depending on the rotation type. Periodic fluctuations in SOC should be carefully considered in a monitoring protocol to assess SCS.

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