Critical review of the impacts of grazing intensity on soil organic carbon storage and other soil quality indicators in extensively managed grasslands

Abdalla, Mohamed; Hastings, Astley; Chadwick, David R.; Jones, Davey L.; Evans, C. D.; Jones, Michael B.; Rees, Robert M.; Smith, Pete

doi:10.1016/j.agee.2017.10.023

Cited by 369 publications

(239 citation statements)

References 139 publications

(202 reference statements)

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“…Similarly, Smiley et al (1986) found that treatments involving multiple clippings and removal of leaves and petioles from clover seedlings both increased root disease severity and decreased plant productivity. Such outcomes are not unexpected, as in grassland agroecosystems, livestock grazing intensity can have widespread impacts, including upon soil quality and organic carbon storage (Abdalla et al, 2018). In particular, heavy grazing is known to significantly reduce the total soil microbial, bacterial and fungal community size (Zhao et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Manipulating the ecosystem enables management of soilborne pathogen complexes in annual legume forage systems

You¹,

Barbetti²

2018

Plant Pathology

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Studies were undertaken to examine the potential for manipulating the ecosystem by altering forage species composition, intensity of grazing or by adding Rhizobium, to enhance productivity of subterranean clover (Trifolium subterraneum) forages affected by the soilborne pathogens Pythium irregulare and Rhizoctonia solani. Levels of tap and lateral root disease on clover and its productivity were differentially and significantly affected by the relative proportions of clover to annual ryegrass (Lolium rigidum). In the presence of P. irregulare, both tap and lateral root disease decreased as percentage clover composition increased (R2 = 0.58, 0.59, respectively); there was no such significant effect in the presence of R. solani (R2 = 0.08, 0.18, respectively). Increasing and maintaining high clover content in forage offers a means to both reduce root disease and increase productivity and forage legume stand persistence. With simulated grazing studies, continuous (i.e. intensive) grazing in the presence of P. irregulare resulted in the most severe tap and lateral root disease, poorest nodulation and smallest roots and shoots compared with intermittent grazing. Hence, reducing grazing intensity also offers potential for significantly increasing productivity of root‐rot‐affected clover forage. For Rhizobium studies, nodulation was reduced in the presence of P. irregulare or R. solani; the extent of this was dependent upon which pathogen and the clover variety. Overall, these different studies highlight significant potential for manipulating the ecosystem to better manage soilborne pathogen complexes and improve productivity and persistence in annual legume forage systems adversely affected by soilborne oomycete and fungal pathogens.

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Section: Discussionmentioning

confidence: 99%

Manipulating the ecosystem enables management of soilborne pathogen complexes in annual legume forage systems

You¹,

Barbetti²

2018

Plant Pathology

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“…It has previously been observed that when bush encroachment occurs, high-quality grass species often disappear, leaving behind hardy and less palatable grasses. Further, bush encroachment could occur due to the removal of keystone species and/or the removal of grasses that often help with maintaining the balance of tree-grass interactions [72,73].…”

Section: Tsetse Prevalence and Distribution Patternsmentioning

confidence: 99%

Tsetse Invasion as an Emerging Threat to Socioecological Resilience of Pastoral Communities in Karamoja, Uganda

et al. 2020

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Over 70% of Uganda is infested by the tsetse fly, which has negative effects on human and livestock health. From colonial to post-independent Uganda, the Government of Uganda has worked to eradicate the tsetse menace. Despite these efforts, recent veterinary reports from the Karamoja sub-region have indicated widespread tsetse invasion. This study investigated the potential impact of tsetse invasion on the socioecological resilience of pastoral communities in the Karamoja sub-region. Results indicated that tsetse invasion is spreading from north to south of Karamoja. The tsetse transmission route emerging from southern Karamoja is perceived to be a continuation of the tsetse belt from West Pokot, Kenya. Cases of livestock deaths, livestock abortions, decreased milk yields, restricted access to prime grazing lands, heightened human-wildlife conflicts and disruption on crop cultivation have been reported. A computed socioecological resilience index in the study area was positive but low. Owing to the transboundary characteristics of tsetse invasions and sources and the associated documented effects, an urgent, strategic and system-wide intervention should be undertaken to control the tsetse invasion in this sub-region. software, J.O. and J.P.M.; validation, A.E., J.O., J.P.M. and B.B.; formal analysis, A.E., J.O. and J.P.M.; investigation, A.E. and J.O.; resources, A.E.; data curation, J.O., J.P.M. and A.S.; writing-original draft preparation, A.E.; writing-review and editing, A.E., J.O., B.B., and A.S.; visualization, A.E., J.O., B.B. and A.S.; supervision, J.J.N.; project administration, A.E.; funding acquisition, A.E. and J.J.N. All authors have read and agreed to the published version of the manuscript.

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“…Conversion of savanna for small-and largescale livestock production, crop cultivation, and human settlement is common in Africa (Bombelli et al, 2009). As a consequence, vegetation cover, net primary productivity, and allocation of carbon and nutrients in plants and soil (Burke et al, 1998) as well as soil GHG emissions are affected (Abdalla et al, 2018;Carbone et al, 2008).…”

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confidence: 99%

Soil greenhouse gas emissions under different land-use types in savanna ecosystems of Kenya

et al. 2020

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Abstract. Field measurement data on greenhouse gas (GHG) emissions are still scarce for many land-use types in Africa, causing a high level of uncertainty in GHG budgets. To address this gap, we present in situ measurements of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) emissions from the lowlands of southern Kenya. We conducted eight chamber measurement campaigns on gas exchange from four dominant land-use types (LUTs) comprising (1) cropland, (2) bushland, (3) grazing land, and (4) conservation land between 29 November 2017 and 3 November 2018, accounting for regional seasonality (wet and dry seasons and transitions periods). Mean CO2 emissions for the whole observation period were the highest by a significant margin (p value < 0.05) in the conservation land (75±6 mg CO2-C m−2 h−1) compared to the three other sites, which ranged from 45±4 mg CO2-C m−2 h−1 (bushland) to 50±5 mg CO2-C m−2 h−1 (grazing land). Furthermore, CO2 emissions varied between seasons, with significantly higher emissions in the wet season than the dry season. Mean N2O emissions were highest in cropland (2.7±0.6 µg N2O-N m−2 h−1) and lowest in bushland (1.2±0.4 µg N2O-N m−2 h−1) but did not vary with season. In fact, N2O emissions were very low both in the wet and dry seasons, with slightly elevated values during the early days of the wet seasons in all LUTs. On the other hand, CH4 emissions did not show any significant differences across LUTs and seasons. Most CH4 fluxes were below the limit of detection (LOD, ±0.03 mg CH4-C m−2 h−1). We attributed the difference in soil CO2 emissions between the four sites to soil C content, which differed between the sites and was highest in the conservation land. In addition, CO2 and N2O emissions positively correlated with soil moisture, thus an increase in soil moisture led to an increase in emissions. Furthermore, vegetation cover explained the seasonal variation in soil CO2 emissions as depicted by a strong positive correlation between the normalized difference vegetation index (NDVI) and CO2 emissions, most likely because, with more green (active) vegetation cover, higher CO2 emissions occur due to enhanced root respiration compared to drier periods. Soil temperature did not show a clear correlation with either CO2 or N2O emissions, which is likely due to the low variability in soil temperature between seasons and sites. Based on our results, soil C, active vegetation cover, and soil moisture are key drivers of soil GHG emissions in all the tested LUTs in southern Kenya. Our results are within the range of previous GHG flux measurements from soils from various LUTs in other parts of Kenya and contribute to more accurate baseline GHG emission estimates from Africa, which are key to reducing uncertainties in global GHG budgets as well as for informing policymakers when discussing low-emission development strategies.

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Critical review of the impacts of grazing intensity on soil organic carbon storage and other soil quality indicators in extensively managed grasslands

Abstract: HighlightsThe impact of grazing on SOC is climate-dependent.Grazing increases SOC for C4 but decreases it for C3 and C3-C4 mixed grasslands.Grazing increases TN and BD but has no effect on soil pH.

Cited by 369 publications

References 139 publications

Manipulating the ecosystem enables management of soilborne pathogen complexes in annual legume forage systems

Manipulating the ecosystem enables management of soilborne pathogen complexes in annual legume forage systems

Tsetse Invasion as an Emerging Threat to Socioecological Resilience of Pastoral Communities in Karamoja, Uganda

Soil greenhouse gas emissions under different land-use types in savanna ecosystems of Kenya

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