CIAT Soils

Permanent URI for this collectionhttps://hdl.handle.net/10568/56650

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Impact of arbuscular mycorrhizal fungi and earthworms on soil aggregate stability, glomalin, and performance of pigeonpea, Cajanus cajan
(Journal Article, 2019) Muchane, Mary N.; Pulleman, Mirjam Margreet; Vanlauwe, Bernard; Jefwa, Joyce; Kuyper, Thomas W.
Earthworms and arbuscular mycorrhizal fungi (AMF) modify soil physical and chemical properties. However, little is known about how their interactions affect water-stable aggregation, glomalin and crop performance. A greenhouse experiment was run for 9 months to test the effects of earthworms (endogeic, Pontoscolex corethrurus; and epigeic, Dichogaster bolaui) and AMF (none, Glomus etunicatum and Scutellospora verrucosa) on water-stable aggregation, glomalin levels in aggregate size classes and crop performance. The test crop was pigeonpea (Cajanus cajan (L.) Millsp.). The soil material used for the experiment was a humic nitisol from central Kenya mixed with sand (ratio 1:1). Grass residue (equivalent to 20tha–1) was placed on top. The AMF root colonisation and external hyphal length, water-stable macroaggregates and microaggregates, total and easily-extractable glomalin in aggregate size classes, plant biomass and plant N and P uptake were measured. Earthworms were a major source of variation for soil aggregation, glomalin content and crop performance. The epigeic earthworms (D. bolaui) increased the amount of water-stable macroaggregates (by 10%) and glomalin in microaggregates and improved crop (growth and biomass) performance. The endogeic earthworms (P. corethrurus) reduced external hyphal length, root colonisation and crop performance but had no effect on water-stable aggregates and glomalin levels in in aggregate size classes. A significant AMF×earthworm interaction was observed for plant biomass and concentrations of nitrogen (N) and phosphorus (P). The AMF species together with epigeic earthworms increased plant biomass and N and P concentrations. Our results contribute to the understanding of interactions between AMF and earthworms in relation to soil aggregation, plant productivity and nutrient uptake.
Farmland could be used to sustainably offset America’s entire carbon footprint—if the will exists
(News Item, 2018-01-24) Verchot, Louis V.
Forest restoration: Getting serious about the ‘plus’ in REDD+
(Book Chapter, 2018) Verchot, Louis V.; Sy, Veronique de; Romijn, Erika; Herold, Martin; Coppus, Ruben
Rehabilitation of Degraded Lands in Semiarid and Subhumid Ecologies in India
(Book Chapter, 2018) Singh, Virendra Pal; Verchot, Louis V.; Martius, C.; Nayak, D.; Rizvi, J.
Land degradation is a complex phenomenon caused by natural and anthropogenic factors. These factors create and accelerate soil erosion and contribute to the loss of biodiversity and degradation of soil quality and hydrological features. Adoption of a gamut of appropriate soil and water conservation measures, protection of vegetation from overgrazing, assisted regeneration of vegetation, etc. maybe one of the viable options to protect, rehabilitate, and rejuvenate the degraded lands. This paper presents the results achieved 10 years after the application of these measures in the semiarid (Rajasthan) and subhumid (Odisha) ecologies in India. There were considerable changes and improvements in ecological features in both the ecologies. Reduced level of soil erosion, some increase in soil depth, enhanced vegetation cover, improved vegetation composition and intraspecies density, and hydrological conditions were positively altered. The hydrological changes were visible not only at the study site but also in the villages inhabited in downstream of the study sites, where inhabiting communities claim increased and for longer duration water level in their wells. Due to increased water availability, these communities have successfully ventured in growing more crops, indicating increased cropping intensity on their land. The changes have also been noticed on the improvement in the composition of floating avian and wild animal population at the rehabilitated sites, which have attracted their in-migration, and appear capable of harboring them. The impact of rehabilitation efforts on soil chemical properties in both ecologies has been negligible during a decade or more of the rehabilitation efforts in this study. Therefore, any significant improvement in soil quality improvement in short term seems an unrealistic and fallacious expectation. The rehabilitation of degraded lands through social and biological measures, e.g., respectively, protection from grazing and assisted regeneration of vegetation, seems to have better impact than the physical/mechanical means. The details of the findings from the two cases – one from each ecology – are presented in this paper.
Linking soil respiration and water table depth in tropical peatlands with remotely sensed changes in water storage from the gravity recovery and climate experiment
(Journal Article, 2019-04-15) Swails, Erin; Yang, X.; Asefi, S.; Hergoualc'h, Kristell; Verchot, Louis V.; McRoberts, R.E.; Lawrence, D.
The response of soil respiration to climatic drivers in undrained forest and drained oil palm plantations in an Indonesian peatland
(Journal Article, 2019-01-15) Swails, E.; Hertanti, D.; Hergoualc'h, Kristell; Verchot, Louis V.; Lawrence, D.
Earthworms regulate plant productivity and the efficacy of soil fertility amendments in acid soils of the Colombian Llanos
(Journal Article, 2019-02) Fonte, Steven J.; Botero, César; Quintero, Carolina; Lavelle, Patrick M.; Kessel, Chris van
The Llanos region of Colombia represents one of the last large agricultural frontiers and is undergoing a rapid conversion from naturalized savanna to intensive agriculture with high agrochemical inputs and tillage. This massive land-use conversion has considerable impact on ecosystem services and biodiversity, particularly soil macrofauna, yet the full implications of this land-use shift for long-term agroecosystem productivity are poorly understood. To better elucidate potential land-use change impacts on agricultural production we used experimental microcosms in the greenhouse to evaluate how the common earthworm, Pontoscolex corethrurus, influences plant growth, nutrient uptake, and key soil properties relative to the application of lime and P fertilizer, both common soil fertility amendments in the region. Additionally, we aimed to explore the potential for interactions between earthworms and these amendments across distinct plant types, the grass Brachiaria decumbens and the legume Phaseolus vulgaris, which display different rooting patterns and nutrient acquisition strategies. Earthworms increased the biomass production of B. decumbens by 180% and N uptake by more than 240%, while P fertilizers and lime additions increased total biomass by less than 30% each for B. decumbens. Effects on P. vulgaris were similar, but less pronounced with earthworms increasing total biomass production by 35% and total plant N content by 70%, while neither lime nor P alone significantly influenced total biomass or N uptake. However, a significant interaction between earthworms and lime enhanced total biomass N content of P. vulgaris by more than 150% relative to microcosms without P. corethrurus, suggesting that earthworms can greatly enhance the efficacy of lime in soils. Additionally, we found that earthworms greatly improved soil aggregation, but only in the presence of plants, and that this effect was most prominent in microcosms with P. vulgaris. When testing treatment effects on soil P availability, only fertilizer P additions significantly influenced resin P, but not microbial biomass P. Our findings suggests the importance of developing management strategies that promote the activity and diversity of earthworms and other soil biota as a means to enhance crop productivity, resource use efficiency and a range of soil-based ecosystem services in the Llanos region and beyond.
Improving the utility of erosion pins: absolute value of pin height change as an indicator of relative erosion
(Journal Article, 2018-04) Kearney, Sean P.; Fonte, Steven J.; García, Edwin; Smukler, Sean M.
Participatory evaluation of improved grasses and forage legumes for smallholder livestock production in Central America
(Journal Article, 2019-10) García, Edwin; Siles, Pablo; Eash, Lisa; Hoek, Rein van der; Kearney, Sean P.; Smukler, Sean M.; Fonte, Steven J.
Smallholder livestock systems in Central America are typically based on pastures with traditional grasses and associated management practices, such as pasture burning and extensive grazing. With the rise of the global population and a corresponding increase in demand for meat and milk production, research efforts have focused on the development of improved grasses and the incorporation of legume species that can increase productivity and sustainability of Central American livestock systems. However, farmer adoption remains very limited, in part due to the lack of site-specific evaluation and recommendations by local institutions. Using a multi-site participatory approach, this study examined the potential of five improved grasses and five species of forage legumes as alternatives to the broadly disseminated grass Hyparrhenia rufa (cv. Jaragua) in pasture-based cattle systems in western Honduras and northern El Salvador. Improved grasses (four Brachiaria sp. and Megathyrsus maximus) produced significantly more biomass than H. rufa; also four of the five legume varieties evaluated (Canavalia ensiformis, Canavalia brasiliensis, Vigna unguiculata, and Vigna radiata) demonstrated high adaptability to diverse environmental conditions across sites. Farmer participatory evaluation offers a valuable means to assess performance of forages and will likely contribute to their improved utilization. Future research is needed on more refined management recommendations, pasture system design, costs and environmental benefits associated with the adoption of these forages in local livestock production systems.
Effects of tillage and crop residue management on runoff, soil loss and crop yield in the Humid Highlands of Ethiopia
(Journal Article, 2019-01) Adimassu, Zenebe; Alemu, Getachew; Tamene, Lulseged D.
This study was conducted on Eutric Nitisols of Holeta Agricultural Research Center (HARC) in the humid highlands of Ethiopia. The main objective was to assess the effect of tillage and crop residue management on runoff, soil loss and wheat (Triticum aestivum L.) yield over three years (2009–2011). Nine treatments combining three tillage practices (zero, minimum and conventional tillage) and three rates of crop residue (0, 1 and 2 t ha−1 yr−1) were used. The experiment was laid out in a Randomized Complete Block Design with three replications. The result showed that average runoff was significantly higher (332 mm) in zero tillage without crop residue (T0C0) and lower (198 mm) in conventional tillage with 2 t ha−1 yr−1 crop residue (T2C2). The average soil loss was lower (16 t ha−1 yr−1) in zero tillage with 2 t ha−1 yr−1 crop residue (T0C2) and higher (30 t ha−1 yr−1) in conventional tillage without crop residue (T2C0). Although, zero and minimum tillage treatments reduced soil loss significantly as compared with conventional tillage practices, the annual soil loss (16 t ha−1 yr−1) is still much higher than the tolerable soil loss for the Ethiopian highlands (2–10 t ha−1 yr−1). This suggests the need to complement zero and minimum tillage practices with physical soil and water conservation practices. On average, highest grain (2 t ha−1) and biomass (6 t ha−1) yields of wheat were recorded in T2C2 while the lowest grain and biomass yields were recorded in T0C0. Based on the above observation, we argue that conventional tillage combined with sufficient crop residue is the most appropriate approach to reduce runoff and increase wheat yield in the short-term. However, zero tillage practices with crop residue are effective to reduce soil loss. As this study was based on results of three years data, long-term study is needed to figure out the long-term impacts of tillage and crop residue management in Ethiopia.
Native arbuscular mycorrhizal fungi increase the abundance of ammoniaoxidizing bacteria, but suppress nitrous oxide emissions shortly after urea application
(Journal Article, 2019-03) Teutscherova, Nikola; Vázquez, Eduardo; Arango, Jacobo; Arévalo, Ashly; Benito, Marta; Pulleman, Mirjam Margreet
Crop soil simulation modeling
(Poster, 2016) Sommer, Rolf; Kihara, Job Maguta; Gurmessa, Biyensa Dubiwak; Tamene, Lulseged D.
Competition for land resources: Driving forces and consequences in crop-livestock production systems of the Ethiopian highlands
(Journal Article, 2018-12) Mekuria, Wuletaw; Mekonnen, Kindu; Thorne, Peter J.; Bezabih, Melkamu; Tamene, Lulseged D.; Abera, Wuletawu
Introduction: Ethiopia has made efforts to tackle the challenges of low crop and livestock productivity and degradation of land resources through various rural development strategies. However, increasing demands for food, animal feed, fuel, and income-generating activities are putting pressure on the land. In this paper, we describe the production pressure and competition between crop and livestock production, quantify rates of land-use/cover (LULC) changes, and examine driving forces and consequences of land conversion. Methods: The study was conducted in Gudo Beret watershed, North Shewa Zone of Amhara region, Ethiopia. It used a combination of methods including remote sensing, household interviews, field observations, focus group discussions, and key informant interviews. Supervised and unsupervised image classification methods were employed to map LULC classes for 31 years (1984–2016). Results: The results of satellite remote sensing revealed that 51% of the land in the study area was subject to accelerated land conversions. The household survey results indicated that feed resources and grain production pressures were 1.43 and 1.34 t ha−1 respectively. The observed annual changes in plantation and settlement areas were 2.6% and 2.9%. This was mainly at the expense of bushland and grazing land systems. Cropland increased (0.4% year−1) while grazing land reduced (3.5% year−1) under contrasting dynamics and competitive changes. An increase in human and livestock populations and farm expansion were major drivers of land conversion that adversely affected household livelihoods and the natural ecosystem. The consequences of these pressures resulted in a lack of animal feed, low crop-livestock productivity, and a reduction in natural vegetation coverage. Conclusions: We suggest that sustainable land resource management, more integrated crop-livestock production, and the use of productivity-enhancing technologies could play a role in managing competition for land resources.
Protection, restoration and the sustainable use of landscapes — remedies to land degradation, and solutions to achieve the SDGs
(Book Chapter, 2018) Tamene, Lulseged D.; Abera, Wuletawu; Woldearegay, Kifle; Sommer, Rolf
Simultaneous adoption of integrated soil fertility management technologies in the Chinyanja Triangle, Southern Africa
(Journal Article, 2018-08) Mponela, Powell; Kassie, Girma T.; Tamene, Lulseged D.
Empirical scientific evidence indicates that there is still room for increasing food production by improving land productivity. This study aimed at identifying the key determinants that govern farmers’ decisions to adopt multiple components of integrated soil fertility management (ISFM) in a maize mixed cropping system of the Chinyanja Triangle, Southern Africa. Revealed preferences of ISFM components were collected from 320 randomly selected households and multivariate probit (MVP) model was used to analyse the simultaneous effects on adoption based on biophysical plot and household‐level socioeconomic attributes. The results show that farmers’ choices of a set of ISFM components are determined by a mix of factors that address the trade‐offs and synergies among them. Non‐farm income, moderate land quality perception, and education influence simultaneous technology adoption, while gender and crop loss increase the likelihood of farmers’ decisions to adopt independent options. Having other sources of income supports co‐adoption of inorganic fertilizer, residue incorporation, and crop rotation. Input/output market access, access to information, financial sources, and climate variability also play pivotal role in technology adoption. These results indicate that resource availability, learning costs, finances, and risk aversion need to be considered when designing and promoting ISFM technologies as a package.
Soil structure formation and organic matter distribution as affected by earthworm species interactions and crop residue placement
(Journal Article, 2019-03) Frazão, Joana; Goede, Ron G.M. de; Capowiez, Yvan; Pulleman, Mirjam Margreet
Aqueous peat extract exposes rhizobia to sub-lethal stress which may prime cells for improved desiccation tolerance
(Journal Article, 2018-09) Atieno, Mary Otieno; Wilson, Neil; Casteriano, Andrea; Crossett, Ben; Lesueur, Didier; Deaker, Rosalind
Contributions from carbon and nitrogen in roots to closing the yield gap between conventional and organic cropping systems
(Journal Article, 2018-09) Córdoba, Eva María; Chirinda, Ngonidzashe; Li, F.; Olesen, Jørgen E.
This study investigates the effect of different crop rotation systems on carbon (C) and nitrogen (N) in root biomass as well as on soil organic carbon (SOC). Soils under spring barley and spring barley/pea mixture were sampled both in organic and conventional crop rotations. The amounts of root biomass and SOC in fine (250–253 μm), medium (425–250 μm) and coarse (>425 μm) soil particulate organic matter (POM) were determined. Grain dry matter (DM) and the amount of N in harvested grain were also quantified. Organic systems with varying use of manure and catch crops had lower spring barley grain DM yield compared to those in conventional systems, whereas barley/pea showed no differences. The largest benefits were observed for grain N yields and grain DM yields for spring barley, where grain N yield was positively correlated with root N. The inclusion of catch crops in organic rotations resulted in higher root N and SOC (g C/m2) in fine POM in soils under barley/pea. Our results suggest that manure application and inclusion of catch crops improve crop N supply and reduce the yield gap between conventional and organic rotations. The observed positive correlation between root N and grain N imply that management practices aimed at increasing grain N could also increase root N and thus enhance N supply for subsequent crops.
Greenhouse gas emissions along a peat swamp forest degradation gradient in the Peruvian Amazon: soil moisture and palm roots effects
(Journal Article, 2019-04) Lent, Jeffrey van; Hergoualc'h, Kristell; Verchot, Louis V.; Oenema, Oene; Groenigen, Jan Willem van
Tropical peatlands in the Peruvian Amazon exhibit high densities of Mauritia flexuosa palms, which are often cut instead of being climbed for collecting their fruits. This is an important type of forest degradation in the region that could lead to changes in the structure and composition of the forest, quality and quantity of inputs to the peat, soil properties, and greenhouse gas (GHG) fluxes. We studied peat and litterfall characteristics along a forest degradation gradient that included an intact site, a moderately degraded site, and a heavily degraded site. To understand underlying factors driving GHG emissions, we examined the response of in vitro soil microbial GHG emissions to soil moisture variation, and we tested the potential of pneumatophores to conduct GHGs in situ. The soil phosphorus and carbon content and carbon-to-nitrogen ratio as well as the litterfall nitrogen content and carbon-to-nitrogen ratio were significantly affected by forest degradation. Soils from the degraded sites consistently produced more carbon dioxide (CO2) than soils from the intact site during in vitro incubations. The response of CO2 production to changes in water-filled pore space (WFPS) followed a cubic polynomial relationship with maxima at 60–70% at the three sites. Methane (CH4) was produced in limited amounts and exclusively under water-saturated conditions. There was no significant response of nitrous oxide (N2O) emissions to WFPS variation. Lastly, the density of pneumatophore decreased drastically as the result of forest degradation and was positively correlated to in situ CH4 emissions. We conclude that recurrent M. flexuosa harvesting could result in a significant increase of in situ CO2 fluxes and a simultaneous decrease in CH4 emissions via pneumatophores. These changes might alter long-term carbon and GHG balances of the peat, and the role of these ecosystems for climate change mitigation, which stresses the need for their protection.
Independent data for transparent monitoring of greenhouse gas emissions from the land use sector – What do stakeholders think and need?
(Journal Article, 2018-07) Romijn, Erika; Sy, Veronique de; Herold, Martin; Böttcher, Hannes; Román Cuesta, Rosa María; Fritz, Steffen; Schepaschenko, Dmitry; Avitabile, Valerio; Gaveau, David; Verchot, Louis V.; Martius, Christopher
The agriculture, forestry and other land use (AFOLU) sectors contribute substantially to the net global anthropogenic greenhouse gas (GHG) emissions. To reduce these emissions under the Paris Agreement, effective mitigation actions are needed that require engagement of multiple stakeholders. Emission reduction also requires that accurate, consistent and comparable datasets are available for transparent reference and progress monitoring. Availability of free and open datasets and portals (referred to as independent data) increases, offering opportunities for improving and reconciling estimates of GHG emissions and mitigation options. Through an online survey, we investigated stakeholders’ data needs for estimating forest area and change, forest biomass and emission factors, and AFOLU GHG emissions. The survey was completed by 359 respondents from governmental, intergovernmental and non-governmental organizations, research institutes and universities, and public and private companies. These can be grouped into data users and data providers. Our results show that current open and freely available datasets and portals are only able to fulfil stakeholder needs to a certain degree. Users require a) detailed documentation regarding the scope and usability of the data, b) comparability between alternative data sources, c) uncertainty estimates for evaluating mitigation options, d) more region-specific and detailed data with higher accuracy for sub-national application, e) regular updates and continuity for establishing consistent time series. These requirements are found to be key elements for increasing overall transparency of data sources, definitions, methodologies and assumptions, which is required under the Paris Agreement. Raising awareness and improving data availability through centralized platforms are important for increasing engagement of data users. In countries with low capacities, independent data can support countries’ mitigation planning and implementation, and related GHG reporting. However, there is a strong need for further guidance and capacity development (i.e. ‘readiness support’) on how to make proper use of independent datasets. Continued investments will be needed to sustain programmes and keep improving datasets to serve the objectives of the many stakeholders involved in climate change mitigation and should focus on increased accessibility and transparency of data to encourage stakeholder involvement.

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