• Authors:
    • Enders, A.
    • Thies, J. E.
    • Lehmann, J.
    • Guerena, D. T.
    • Karanja, N.
    • Neufeldt, H.
  • Source: Biology and Fertility of Soils
  • Volume: 51
  • Issue: 4
  • Year: 2015
  • Summary: Studies document increases in biological nitrogen fixation (BNF) following applications of biochar. However, the underlying mechanisms for this response remain elusive. Greenhouse experiments were conducted to test the effects of biochar mineral nutrients, pH, and volatile matter (VM) on BNF in common beans ( Phaseolus vulgaris L.). Biochars were produced from seven feedstocks pyrolyzed at either 350 or 550°C. Biochars were treated with acid to reduce mineral nutrient contents, with acetone to remove acetone-soluble VM, with steam to reduce both the mineral and VM contents, or left untreated. The biochar additions at a rate of 15 t ha -1 resulted in an average 262% increase in shoot biomass, 164% increase in root biomass, 3575% increase in nodule biomass, and a 2126% increase in N derived from atmosphere (Ndfa) over the control. Simple mineral nutrients and soil acidity amelioration from the biochar were only to a minimal extent responsible for these increases ( r2=0.03; P=0.0298, n=201). Plant growth and Ndfa were significantly correlated with plant P uptake ( r2=0.22; P0.05). Improved P nutrition resulted from 360% greater mycorrhizal colonization with biochar additions. Removal of acetone-soluble VM increased plant growth and Ndfa, and VM extracted from the biochar produced at 350°C reduced the growth of rhizobia in yeast extract mannitol agar (YMA) medium. In contrast, acetone-soluble VM extracted from seven biochars produced at 550°C increased the growth of rhizobium in the YMA compared to an acetone-residue control, suggesting differential effects of VM forms on rhizobia.
  • Authors:
    • McNamara, N.
    • Dondini, M.
    • Smith, P.
    • Davies, C.
    • Robertson, A.
  • Source: Journal
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: The lignocellulosic perennial grass Miscanthus has received considerable attention as a potential bioenergy crop over the last 25years, but few commercial plantations exist globally. This is partly due to the uncertainty associated with claims that land-use change (LUC) to Miscanthus will result in both commercially viable yields and net increases in carbon (C) storage. To simulate what the effects may be after LUC to Miscanthus, six process-based models have been parameterized for Miscanthus and here we review how these models operate. This review provides an overview of the key Miscanthus soil organic matter models and then highlights what measurers can do to accelerate model development. Each model (WIMOVAC, BioCro, Agro-IBIS, DAYCENT, DNDC and ECOSSE) is capable of simulating biomass production and soil C dynamics based on specific site characteristics. Understanding the design of these models is important in model selection as well as being important for field researchers to collect the most relevant data to improve model performance. The rapid increase in models parameterized for Miscanthus is promising, but refinements and improvements are still required to ensure that model predictions are reliable and can be applied to spatial scales relevant for policy. Specific improvements, needed to ensure the models are applicable for a range of environmental conditions, come under two categories: (i) increased data generation and (ii) development of frameworks and databases to allow simulations of ranging scales. Research into nonfood bioenergy crops such as Miscanthus is relatively recent and this review highlights that there are still a number of knowledge gaps regarding Miscanthus specifically. For example, the low input requirements of Miscanthus make it particularly attractive as a bioenergy crop, but it is essential that we increase our understanding of the crop's nutrient remobilization and ability to host N-fixing organisms to derive the most accurate simulations.
  • Authors:
    • Normand,F.
    • Lauri,P. E.
    • Legave,J. M.
  • Source: Acta Horticulturae
  • Volume: 1075
  • Year: 2015
  • Summary: Climate change is becoming an observed reality, very likely due to the increase of anthropogenic greenhouse gas concentration. Since a few decades, several research teams around the world carry out a huge work to model the future climatic change during the 21st century, based on several scenarios of greenhouse gas emission. We have to expect rise in average temperatures, in atmospheric CO 2 concentration, in soil salinity in some areas, and lower and more irregular rainfall. The climate variability and the frequency of extreme events (scorching heat, heavy rainfall, drought, hurricane) are also expected to rise. Climate change is therefore a great concern for agriculture. Mango is one of the most widely cultivated and popular fruits in these regions for its economic and nutritional values. It is the fifth most cultivated fruit in the world. It is consequently justified to wonder about the impact of climate change on the mango tree and about the consequences on mango production and cultivation. The lack of crop model for mango prevents the prediction of the effects of climate change on mango tree development and production. They are then assessed on the basis of our current knowledge on the influence of climatic variables on mango tree development and production. We describe the influence of climatic variables on processes of agronomical importance for the mango tree: photosynthesis, vegetative and reproductive development, fruit quality. We then review the climate changes predicted for two areas of mango production and draw the possible consequences for mango cultivation. Finally, we propose some research ways to adapt mango cultivation to climate change in the coming decades, such as cultivar and rootstock selection, and improvement of cultural practices. The interest of developing a mango crop model is discussed.
  • Authors:
    • Reichert,J. M.
    • Rodrigues,M. F.
    • Bervald,C. M. P.
    • Brunetto,G.
    • Kato,O. R.
    • Schumacher,M. V.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 204
  • Year: 2015
  • Summary: No-tillage planting in mechanically-chopped secondary-forest seeks to replace slash-and-burning agriculture. We evaluated the effect of horizontal (HC) and vertical (VC) chopping-and-mulching mechanisms on vegetation fragmentation and decomposition rate and nutrient release from chopped residue, and on cassava production in eastern Amazon. Chopped-and-mulched residue was classified into four residue-size (Fs 1=1-7, Fs 2=7-25, Fs 3=25-35, and Fs 4=>35 mm) and six residue-type (with husk/bark - WB, partially chopped - PC, compact - C, partially shredded into fibers - PS, completely shredded into fibers - CS, and formless residue - F) classes. In litter-bags, residual dry matter (DM) was determined at five different days after chopping-and-mulching and residue distribution on soil surface (DAD), whereas release of N, P, K, Ca, and Mg was evaluated at four days. Residues-size and -type classes showed similar decomposition behavior, with a reduction of approximately 60% of initial DM at 90 DAD. Nevertheless, reduction in DM was slow, where 52 days are necessary for half of labile residue to be decomposed, with part of labile and recalcitrant residue remaining on soil surface. DM and nutrients in residue reduced over time. DM was 25% for residues-size classes for HC, 20% for VC, and 26% for residue-type classes, on average, at 300 DAD. Nutrients remaining in residues at 300 DAD were 26% and 27% of N, 26% and 22% of P, 29% and 22% of K, 16% and 15% of Ca, and 17% and 23% of Mg, respectively for HC and VC. Release of nutrients was, generally, greater for smaller residue-size classes, similar between chopping-and-mulching mechanisms, and did not affect cassava yield.
  • Authors:
    • Kibue,Grace Wanjiru
    • Pan,Genxing
    • Zheng,Jufeng
    • Li Zhengdong
    • Mao,Li
  • Source: Environment, Development and Sustainability
  • Volume: 17
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural production is a complex interaction between human and natural environment, making agriculture both significantly responsible and vulnerable to climate change. China, whose socioeconomy is fundamentally dependent on agriculture, is already experiencing climate-change-related issues that threaten food security and sustainable development. Climate change mitigation and adaptation are of great concern to ensure food security for the growing population and improve the livelihoods of poor smallholder producers. A questionnaire survey was conducted in Henan Province, China to assess agronomic practices of smallholder farmers, adaptation strategies and how climate change awareness and perceptions influence the farmers' choice of agronomic practices. The results showed that the vast majority of farmers owned < 10 Chinese Mu (0.7 ha) and nearly all farmers' relied on intensive use of chemical fertilizers and pesticides to increase yield at the detriment of environment. However, farmers who were aware of climate change had adopted agronomic practices that reduce impacts of climate change. Information about climate change, lack of incentives, lack of credit facilities and small farm sizes were major hindrance to adaptation and adoption of farming practices that can reduce impacts of climate change. This study recommends that research findings should be disseminated to farmers in timely and appropriate ways. The central government should formulate policies to include subsidies and incentives for farmers to motivate adoption of eco-friendly agronomic practices.
  • Authors:
    • Zhang,K.
    • Castanho,A. D. de A.
    • Galbraith,D. R.
    • Moghim,S.
    • Levine,N. M.
    • Bras,R. L.
    • Coe,M. T.
    • Costa,M. H.
    • Malhi,Y.
    • Longo,M.
    • Knox,R. G.
    • McKnight,S.
    • Wang,J. F.
    • Moorcroft,P. R.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: There is considerable interest in understanding the fate of the Amazon over the coming century in the face of climate change, rising atmospheric CO 2 levels, ongoing land transformation, and changing fire regimes within the region. In this analysis, we explore the fate of Amazonian ecosystems under the combined impact of these four environmental forcings using three terrestrial biosphere models (ED2, IBIS, and JULES) forced by three bias-corrected IPCC AR4 climate projections (PCM1, CCSM3, and HadCM3) under two land-use change scenarios. We assess the relative roles of climate change, CO 2 fertilization, land-use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change are primarily determined by the direction and severity of projected changes in regional precipitation: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%. However, the models predict that CO 2 fertilization will enhance vegetation productivity and alleviate climate-induced increases in plant water stress, and, as a result, sustain high biomass forests, even under the driest climate scenario. Land-use change and climate-driven changes in fire frequency are predicted to cause additional aboveground biomass loss and reductions in forest extent. The relative impact of land use and fire dynamics compared to climate and CO 2 impacts varies considerably, depending on both the climate and land-use scenario, and on the terrestrial biosphere model used, highlighting the importance of improved quantitative understanding of all four factors - climate change, CO 2 fertilization effects, fire, and land use - to the fate of the Amazon over the coming century.
  • Authors:
    • Brunetto, G.
    • Tassinari, A.
    • Vidal, R. F.
    • Lourenzi, C. R.
    • Lorensini, F.
    • Ferreira, P. A.
    • Ceretta, C. A.
    • Conti, L.
  • Source: Brazilian Journal of Soil Science
  • Volume: 39
  • Issue: 3
  • Year: 2015
  • Summary: The application of pig slurry rates and plant cultivation can modify the soil phosphorus (P) content and distribution of chemical species in solution. The purpose of this study was to evaluate the total P, available P and P in solution, and the distribution of chemical P species in solution, in a soil under longstanding pig slurry applications and crop cultivation. The study was carried out in soil columns with undisturbed structure, collected in an experiment conducted for eight years in the experimental unit of the Universidade Federal de Santa Maria (UFSM), Santa Maria (RS). The soil was an Argissolo Vermelho distrofico arenico (Typic Hapludalf), subjected to applications of 0, 20, 40, and 80 m(3) ha(-1) pig slurry. Soil samples were collected from the layers 0-5, 5-10, 10-20, 20-30, 30-40, and 40-60 cm, before and after black oat and maize grown in a greenhouse, for the determination of available P, total P and P in the soil solution. In the solution, the concentration of the major cations, anions, dissolved organic carbon (DOC), and pH were determined. The distribution of chemical P species was determined by software Visual Minteq. The 21 pig slurry applications increased the total P content in the soil to a depth of 40 cm, and the P extracted by Mehlich-1 and from the solution to a depth of 30 cm. Successive applications of pig slurry changed the balance between the solid and liquid phases in the surface soil layers, increasing the proportion of the total amount of P present in the soil solution, aside from changing the chemical species in the solution, reducing the percentage complexed with Al and increasing the one complexed with Ca and Mg in the layers 0-5 and 5-10 cm. Black oat and maize cultivation increased pH in the solution, thereby increasing the proportion of HPO42- and reducing H2PO4- species.
  • Authors:
    • Schneider, L. C.
    • Burbano, D. V.
    • Lerner, A. M.
    • McGroddy, M. E.
    • Rudel, T. K.
  • Source: Science Journal
  • Volume: 47
  • Issue: 4
  • Year: 2015
  • Summary: Agriculture, particularly pasture, is the second largest source of greenhouse gas emissions from tropical regions. Silvopastoral systems may increase carbon pools in pastures while maintaining productivity. Adding trees to pasture provides carbon sinks in woody biomass, and may improve degraded soils and increase the stability of soil carbon pools. In this study we quantified the biomass carbon stored in spontaneous silvopastoral systems in southeastern Ecuador. We compared the stem density, basal area, aboveground biomass, and organic carbon in the top 20 cm of soil in 100 pastures, ranging from 3 to 250 hectares, in four different communities. Aboveground live woody biomass, calculated using allometric equations and two different wood densities, varied from 10.99 to 66.1 Mg per hectare. Soil organic carbon pools ranged from 85.0 to 97.6 Mg per hectare. Stem density, basal area, and aboveground live biomass all positively correlated with pasture age. We found no relationship between pasture age or stem density and soil organic carbon pools. We measured live woody biomass carbon pools of 34-1070 Mg of carbon per farm in these silvopastoral systems. We found no effects on productivity of the herbaceous layer, suggesting that having a low density of trees in pastures could substantially increase the number of trees and the associated carbon sequestration without affecting cattle production.
  • Authors:
    • Sharma,R.
    • Chauhan,S. K.
    • Tripathi,A. M.
  • Source: Agroforestry Systems
  • Volume: 90
  • Issue: 4
  • Year: 2015
  • Summary: India is a large developing country with more than seventy per cent population earning their livelihood from diverse land use activities. Changing climate is a worry for the nation but the country cannot afford to slow down the developing/developmental activities. Landuse activities in irrigated agro-ecosystems have started shifting from traditional agriculture to smart agriculture to meet the country’s food requirements and secure livelihood security. But this shift has been achieved at the cost of natural resources and degradation of environment. Realizing the benefits of climate smart agriculture in the changing scenario, farmers are adapting slowly to it but appropriate details of climate vulnerability and package of climate smart agriculture including tree-crop interaction are very limited for adoption. It is important to assess the strengths and weaknesses of carbon sequestration (CS) projects with respect to their practical potential rather than biophysical potential for registration under clean development mechanism for additional income. There is a need to address the technical, economic, legal and social issues of the adopters because they have to lock their land for long time for CS projects, therefore confidence building measures are essentially required to make them aware/motivate for adoption of trees on their farms for mitigation of greenhouse gases (GHGs) and adaptation against changing climate. However, the potential of agroforestry (AF) systems has not been reflected in registration of CS projects due to lack of best practices in AF, procedures and methodologies for carbon accounting, etc., which requires thorough review to develop appropriate models for payments of environmental benefits. Poplar based AF has been considered here as an example to understand the process of accounting CS and its practical applicability for environmental payments. © 2015 Springer Science+Business Media Dordrecht
  • Authors:
    • Rathmann, R.
    • Soria, R.
    • Portugal-Pereira, J.
    • Schaeffer, R.
    • Szklo, A.
  • Source: Article
  • Volume: 81
  • Year: 2015
  • Summary: This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO 2e and could reach 64 million tonne CO 2e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers.