• Authors:
    • HongYeng, L.
    • Agamuthu, P.
  • Source: Article
  • Volume: 103
  • Issue: 2
  • Year: 2015
  • Summary: High levels of nitrogen (N) are typically used in leafy vegetable farms to maximize production. However, such practice often leads to nutrient pollution. Hence, N balance in intensive leafy vegetable farm production must be explored to improve current farm management practices and to avoid environmental pollution. This study aimed to generate partial N balance in two organic (OF1 and OF2) and two conventional (CF1 and CF2) vegetable farms by employing material flow analysis/substance flow analysis in the STAN modeling software. Results showed that 31,556, 32,798, 19,498, and 19,337 t ha(-1) y(-1) of materials entered CF1, CF2, OF1, and OF2, respectively, and contributed to the nitrogen surplus levels of 1577, 1667, 2953, and 961 kg N ha(-1) y(-1), respectively. The STAN model revealed the presence of N surplus in the organic and conventional systems used in the study.
  • Authors:
    • Nuesslein, K.
    • Cerri, C.
    • Feigl, B.
    • Lammel, D.
  • Source: Frontiers in Microbiology
  • Volume: 6
  • Year: 2015
  • Summary: Ecological processes regulating soil carbon (C) and nitrogen (N) cycles are still poorly understood, especially in the world's largest agricultural frontier in Southern Amazonia. We analyzed soil parameters in samples from pristine rainforest and after land use change to pasture and crop fields, and correlated them with abundance of functional and phylogenetic marker genes (amoA, nirK, nirS, norB, nosZ, nifH, mcrA, pmoA, and 16S/18S rRNA). Additionally, we integrated these parameters using path analysis and multiple regressions. Following forest removal, concentrations of soil C and N declined, and pH and nutrient levels increased, which influenced microbial abundances and biogeochemical processes. A seasonal trend was observed, suggesting that abundances of microbial groups were restored to near native levels after the dry winter fallow. Integration of the marker gene abundances with soil parameters using path analysis and multiple regressions provided good predictions of biogeochemical processes, such as the fluxes of NO3, N20, CO2, and CH4. In the wet season, agricultural soil showed the highest abundance of nitrifiers (amoA) and Archaea, however, forest soils showed the highest abundances of denitrifiers (nirK, nosZ) and high N, which correlated with increased N20 emissions. Methanogens (mcrA) and methanotrophs (pmoA) were more abundant in forest soil, but methane flux was highest in pasture sites, which was related to soil compaction. Rather than analyzing direct correlations, the data integration using multivariate tools provided a better overview of biogeochemical processes. Overall, in the wet season, land use change from forest to agriculture reduced the abundance of different functional microbial groups related to the soil C and N cycles; integrating the gene abundance data and soil parameters provided a comprehensive overview of these interactions. Path analysis and multiple regressions addressed the need for more comprehensive approaches to improve our mechanistic understanding of biogeochemical cycles.
  • Authors:
    • Tzanopoulos, J.
    • Bravo-Monroy, L.
    • Potts, S. G.
  • Source: Article
  • Volume: 211
  • Year: 2015
  • Summary: Bees and other insects provide pollination services that are key to determining the fruit set on coffee plantations. These pollination services are influenced by local ecology as well as human factors, both social and economic. To better understand these different factors, we assessed their effect on pollinators and coffee pollination services in Santander, Colombia. We quantified the effect of key ecological drivers on pollinator community composition, such as the method of farm management (either conventional or organic) and the surrounding landscape composition, specifically the proximity to forest. We found that ambient levels of pollination services provided by the local pollinator fauna (open pollination) accounted for a 10.52.0% increase in final coffee fruit set, and that the various pollinators are affected differently by the differing factors. For example, our findings indicate that conventional farm management, using synthetic inputs, can promote pollinators, especially if they are in close proximity to natural forest fragments. This is particularly true for stingless bees. Honeybee visitation to coffee is also positively influenced by the conventional management of farms. Factors associated with greater numbers of stingless bees on farms include greater shade cover, lower tree densities, smaller numbers and types of trees in bloom, and younger coffee plantations. A forested landscape close to farms appears to enhance these factors, giving increased stability and resilience to the pollinating bees and insects. However we found that organic farms also support diverse pollinator communities, even if distant from forest fragments. The contribution of honeybees to pollination value (US$129.6/ha of coffee) is greater than that of stingless bees (US$16.5/ha of coffee). Since the method of farm management has a major impact on the numbers and types of pollinators attracted to farms, we have analysed the statistically significant social factors that influence farmers' decisions on whether to adopt organic or conventional practices. These include the availability of technology, the type of landowner (whether married couples or individual owners), the number of years of farmers' formal education, the role of institutions, membership of community organizations, farm size, coffee productivity and the number of coffee plots per farm. It is hoped that the use of our holistic approach, which combines investigation of the social as well as the ecological drivers of pollination, will help provide evidence to underpin the development of best practices for integrating the management of pollination into sustainable agricultural practices.
  • Authors:
    • Perluss, P.
    • Drouvot, H.
    • Drouvot, C.
  • Source: International Journal of Sustainable Development
  • Volume: 17
  • Issue: 1
  • Year: 2014
  • Summary: With the objective to offer contributions to resolve ecological, social and economic problems in Amazonia, Brazil's sustainable production of palm oil legislation has the specific goal of mobilising public administrations, private business, social aid agencies and family farmers with the following overall objectives: create employment and increase income by means of palm cultivation; reforest degraded lands in the Amazon (Margulis, 2004); contribute to carbon storage with the goal of reducing greenhouse gases; and induce family farmers to participate in the programme and thus favour their social inclusion. The study is based on information from documentary research undertaken to identify and a series of regionally-based interviews. Our research reveals that the national programme has mobilised a range of stakeholders (governments, firms, universities and NGOs) and small farmers' associations.
  • Authors:
    • Noor, N.
    • Chowhdhury, M. S.
    • Mahmud, K.
    • Huq, S. M. I.
  • Source: Canadian Journal of Pure and Applied Sciences
  • Volume: 8
  • Issue: 2
  • Year: 2014
  • Summary: Addition of biochar to soils has the potentials to reduce the emission of greenhouse gases from soil. The primary objectives of this study were to see the impacts of biochar and the corresponding biomass application on the emission of carbon dioxide (CO 2), carbon monoxide (CO), phosphine (PH 3) and volatile organic compounds (VOCs) from soil investigated in a closed container experiment. Three replications of seven different treatments were applied: (i) soil only (control), soil incorporated with - (ii) rice husk, (iii) biochar produced from rice husk, (iv) straw, (v) biochar from straw, (vi) saw dust and (vii) biochar produced from saw dust. The study reveals that addition of biochar had significant effects (P<0.05) on reducing CO 2 and PH 3 emission while no statistically significant effects on VOCs emanation was evident. Application of biochar could not suppress the CO emissions. Our study indicates that, different types of biochars have different effects on the emission of different gases.
  • Authors:
    • Sanabria, C.
    • Rodriguez, E.
    • Xiomara Pullido, S.
    • Loaiza, S.
    • del Pilar Hurtado, M.
    • Gutierrez, A.
    • Gomez, Y.
    • Chaparro, P.
    • Botero, C.
    • Bernal, J.
    • Arguello, O.
    • Rodriguez, N.
    • Lavelle, P.
    • Velasquez, E.
    • Fonte, S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 185
  • Year: 2014
  • Summary: In the Orinoco River Basin of eastern Colombia large scale and rapid conversion of natural savannas into commercial agriculture exists as a critical threat for the ecological integrity of this fragile region. The highly acidic and compacted soils inherent to this region require thorough physical and chemical conditioning in order for intensive cropping systems to be established. Assessing the impact of this dramatic soil perturbation on biodiversity, ecosystem services and other elements of the natural capital is an urgent task for designing sustainable management options in the region. To address this need, we evaluated soil macro invertebrate communities and soil-based ecosystem services (climate regulation, hydrologic functions, soil stability provided by macro aggregation and nutrient provision potential) in four major production systems: improved pastures, annual crops (rice, corn and soy bean), oil palm and rubber plantations, and compared them to the original savanna. Fifteen plots of each system were sampled along a 200 km natural gradient of soil and climatic conditions. In each plot, we assessed climate regulation by measuring green house gas emissions (N2O, CH4 and CO2) and C storage in aboveground plant biomass and soil (0-20 cm). Soil biodiversity (macro invertebrate communities) and three other soil-based ecosystem services, were assessed using sets of 12-20 relevant variables associated with each service and synthesized via multivariate analyses into a single indicator for each ecosystem function, adjusted in a range of 0.1-1.0. Savannas yielded intermediate values for most indicators, while each production system appeared to improve at least one ecosystem service. For example, nutrient provision (chemical fertility) was highest in annual cropping systems (0.78 +/- 0.03) due to relatively high concentrations of Ca, Mg, N, K, and available P and low Al saturation. Hydrological functions and climate regulation (C storage and GHG emissions) were generally improved by perennial crops (oil palm and rubber), while indicators for macro invertebrate biodiversity and activity (0.73 +/- 0.05) and soil macro aggregation (0.76 +/- 0.02) were highest within improved pastures. High variability within each system indicates the potential to make improvements in fields with lowest indicator values, while differences among systems suggest the potential to mitigate negative impacts by combining plots with contrasted functions in a strategically designed landscape mosaic. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • El-Sharkawy, M.
  • Source: Photosynthetica
  • Volume: 52
  • Issue: 2
  • Year: 2014
  • Summary: Earth's climate has experienced notable changes during the past 50-70 years when global surface temperature has risen by 0.8°C during the 20th century. This was a consequence of the rise in the concentration of biogenic gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and ozone) in the atmosphere that contribute, along with water vapor, to the so-called 'greenhouse effect'. Most of the emissions of greenhouse gases have been, and still are, the product of human activities, namely, the excessive use of fossil energy, deforestations in the humid tropics with associated poor land use-management, and wide-scale degradation of soils under crop cultivation and animal/pasture ecosystems. General Circulation Models predict that atmospheric CO 2 concentration will probably reach 700 mol(CO 2) mol -1. This can result in rise of Earth's temperature from 1.5 to over 5°C by the end of this century. This may instigate 0.60-1.0 m rise in sea level, with impacts on coastal lowlands across continents. Crop modeling predicts significant changes in agricultural ecosystems. The mid- and high-latitude regions might reap the benefits of warming and CO 2 fertilization effects via increasing total production and yield of C 3 plants coupled with greater water-use efficiencies. The tropical/subtropical regions will probably suffer the worst impacts of global climate changes. These impacts include wide-scale socioeconomic changes, such as degradation and losses of natural resources, low agricultural production, and lower crop yields, increased risks of hunger, and above all waves of human migration and dislocation. Due to inherent cassava tolerance to heat, water stress, and poor soils, this crop is highly adaptable to warming climate. Such a trait should enhance its role in food security in the tropics and subtropics.
  • Authors:
    • Takahashi, H.
    • Limin, S. H.
    • Darung, U.
    • Hadi, A.
    • Arai, H.
    • Hatano, R.
    • Inubushi, K.
  • Source: SOIL SCIENCE AND PLANT NUTRITION
  • Volume: 60
  • Issue: 3
  • Year: 2014
  • Summary: Land use change in tropical peat soil is thought to cause intense greenhouse gas emissions by enhancing organic matter decomposition. Although microbes in peat soil play key roles in the emission of greenhouse gases, their characteristics remain unknown. This study was conducted to clarify the effect of land use change (drainage, forest fire and agricultural land use) on the control of gas emission factors with respect to the characteristics of microbes in tropical peat soils. Field observations were carried out in Central Kalimantan, Indonesia, from July 2009 to March 2011. Carbon dioxide (CO 2) and nitrous oxide (N 2O) fluxes in tropical peat soils were measured in an undrained natural forest, a drained forest, two burned forests and four croplands. A fumigation-extraction method was used to measure the soil microbial biomass to evaluate the relationships among the soluble organic carbon (SOC), microbial biomass carbon (MBC) and nitrogen (MBN) and the CO 2 and N 2O fluxes in peat soils. Regarding the relationships between weekly precipitation and N 2O emission, positive relationships were found in both the forest and cropland soils. However, the slope of the regression line was much higher in the croplands than in the forest soils. The CO 2 fluxes in the croplands but not in the forest soils were significantly correlated with both precipitation and N 2O fluxes. In contrast, the CO 2 fluxes in the forest but not in the croplands were significantly correlated with the MBC and the MBC/SOC ratio. The SOC did not show any relationship with the CO 2 fluxes but showed a positive relationship with the MBN and a negative linear relationship with the nitrate (NO 3-) concentration. In addition, the MBN showed a negative relationship with most of the probable numbers of ammonium oxidizers. These results indicate that the agricultural land use of tropical peat soils varied the factors controlling greenhouse gas emissions through microbial activities. Therefore, the microbial biomass may be a key factor in controlling CO 2 fluxes in forest soils but not in agricultural peat soils. However, precipitation may be a key factor in agricultural peat soils but not in forest soils.
  • Authors:
    • Smith, P.
    • Matthews, R.
    • Farmer, J.
    • Smith, J. U.
  • Source: Migration and Adaption Strategies for Global Change
  • Volume: 19
  • Issue: 6
  • Year: 2014
  • Summary: Land use change on Indonesian peatlands contributes to global anthropogenic greenhouse gas (GHG) emissions. Accessible predictive tools are required to estimate likely soil carbon (C) losses and carbon dioxide (CO 2) emissions from peat soils under this land use change. Research and modelling efforts in tropical peatlands are limited, restricting the availability of data for complex soil model parameterisation and evaluation. The Tropical Peatland Plantation-Carbon Assessment Tool (TROPP-CAT) was developed to provide a user friendly tool to evaluate and predict soil C losses and CO 2 emissions from tropical peat soils. The tool requires simple input values to determine the rate of subsidence, of which the oxidising proportion results in CO 2 emissions. This paper describes the model structure and equations, and presents a number of evaluation and application runs. TROPP-CAT has been applied for both site specific and national level simulations, on existing oil palm and Acacia plantations, as well as on peat swamp forest sites to predict likely emissions from future land use change. Through an uncertainty and sensitivity analysis, literature reviews and comparison with other methods of estimating soil C losses, the paper identifies opportunities for future model development, bridging between different approaches to predicting CO 2 emissions from tropical peatlands under land use change. TROPP-CAT can be accessed online from www.redd-alert.eu in both English and Bahasa Indonesia.
  • Authors:
    • Osaki, M.
    • Limin, S.
    • Kusin, K.
    • Hirano, T.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 2
  • Year: 2014
  • Summary: In Southeast Asia, a huge amount of peat has accumulated under swamp forests over millennia. Fires have been widely used for land clearing after timber extraction, thus land conversion and land management with logging and drainage are strongly associated with fire activity. During recent El Nino years, tropical peatlands have been severely fire-affected and peatland fires enlarged. To investigate the impact of peat fires on the regional and global carbon balances, it is crucial to assess not only direct carbon emissions through peat combustion but also oxidative peat decomposition after fires. However, there is little information on the carbon dynamics of tropical peat damaged by fires. Therefore, we continuously measured soil CO 2 efflux [peat respiration (RP)] through oxidative peat decomposition using six automated chambers on a burnt peat area, from which about 0.7 m of the upper peat had been lost during two fires, in Central Kalimantan, Indonesia. The RP showed a clear seasonal variation with higher values in the dry season. The RP increased logarithmically as groundwater level (GWL) lowered. Temperature sensitivity or Q10 of RP decreased as GWL lowered, mainly because the vertical distribution of RP would shift downward with the expansion of an unsaturated soil zone. Although soil temperature at the burnt open area was higher than that in a near peat swamp forest, model simulation suggests that the effect of temperature rise on RP is small. Annual gap-filled RP was 38282 (the mean1 SD of six chambers) and 36274 gC m -2 yr -1 during 2004-2005 and during 2005-2006 years, respectively. Simulated RP showed a significant negative relationship with GWL on an annual basis, which suggests that every GWL lowering by 0.1 m causes additional RP of 89 gC m -2 yr -1. The RP accounted for 21-24% of ecosystem respiration on an annual basis.