• Authors:
    • Salgado-Garcia, S.
    • Aguirre-Rivera, J. R.
    • Ortiz-Ceballos, A. I.
    • Ortiz-Ceballos, G.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: In Central America, the traditional cropping system milpa de ano (summer season) and tornamilpa (winter season) were compared over 3 yr (2007-2009). Our experimental objectives were to measure the performance of a maize ( Zea mays L.)-velvet bean [ Mucuna pruriens (L.) DC. subsp. utilis (Wight) Burck] milpa system throughout the summer and winter cultivation, to detect any problems associated with velvet bean use, and to determine the contribution of this tropical legume to soil fertility and maize productivity. In each crop season (separated in space and time) we used a completely randomized design with a 2*2 factorial arrangement of treatments with five repetitions each: without velvet bean and without fertilizer (-V-F), with velvet bean and without fertilizer (+V-F), without velvet bean and with fertilizer (-V+F), and with velvet bean and with fertilizer (+V+F). Results showed that in the winter milpas the presence of velvet bean significantly increased the soil pH, organic matter content, total N, and decreased soil bulk density. In both cycles (winter and summer), treatment with velvet bean (+V) produced higher grain yield, while the treatment without velvet bean (-V) had a lower production. We concluded that the use of velvet bean in the winter milpa contributed to the restoration of soil fertility and increased yield maize in agricultural systems of the small-holder farmers based on low external input.
  • 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:
    • 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:
    • Austin,K. G.
    • Kasibhatla,P. S.
    • Urban,D. L.
    • Stolle,F.
    • Vincent,J.
  • Source: Web Of Knowledge
  • Volume: 10
  • Issue: 5
  • Year: 2015
  • Summary: Our society faces the pressing challenge of increasing agricultural production while minimizing negative consequences on ecosystems and the global climate. Indonesia, which has pledged to reduce greenhouse gas (GHG) emissions from deforestation while doubling production of several major agricultural commodities, exemplifies this challenge. Here we focus on palm oil, the world's most abundant vegetable oil and a commodity that has contributed significantly to Indonesia's economy. Most oil palm expansion in the country has occurred at the expense of forests, resulting in significant GHG emissions. We examine the extent to which land management policies can resolve the apparently conflicting goals of oil palm expansion and GHG mitigation in Kalimantan, a major oil palm growing region of Indonesia. Using a logistic regression model to predict the locations of new oil palm between 2010 and 2020 we evaluate the impacts of six alternative policy scenarios on future emissions. We estimate net emissions of 128.4-211.4 MtCO 2 yr -1 under business as usual expansion of oil palm plantations. The impact of diverting new plantations to low carbon stock land depends on the design of the policy. We estimate that emissions can be reduced by 9-10% by extending the current moratorium on new concessions in primary forests and peat lands, 35% by limiting expansion on all peat and forestlands, 46% by limiting expansion to areas with moderate carbon stocks, and 55-60% by limiting expansion to areas with low carbon stocks. Our results suggest that these policies would reduce oil palm profits only moderately but would vary greatly in terms of cost-effectiveness of emissions reductions. We conclude that a carefully designed and implemented oil palm expansion plan can contribute significantly towards Indonesia's national emissions mitigation goal, while allowing oil palm area to double.
  • 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:
    • Sales,M. V. S.
    • Gama-Rodrigues,A. C.
    • Comerford,N. B.
    • Cropper,W. P.
    • Gama-Rodrigues,E. F.
    • Oliveira,P. H. G.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Respecification of structural models allows evaluating new hypothesis and enhances understanding of how changes in one pool can affect the other pools in the model. The aim of this study was to evaluate the theoretical concept of P pools (unmeasurable variables-latent) using data from Hedley's sequential extraction method for a better understanding of the P cycle in tropical soils. The theoretical concept being tested is the degree to which available P is controlled by different soil P pools as measured by extraction techniques. The respecified models were adequate and able to represent a generalization of P cycling in soils. The best structural model including latent variables with multiple indicators was consistent with the theoretical concept that the indicators of soil P pools are P fractions determined by the sequential extraction method. In this model, not only is there a direct relationship between the organic, occluded and primary mineral pools and the available P pool, but the indirect relationships via the organic pool were theoretically and statistically adequate. Thus, the model showed the interrelationships of geochemical and biological processes on the available P and it corroborated the hypothesis of the dependence of the available P pool to the organic pool in unfertilized tropical soils.
  • Authors:
    • Guillaume,T.
    • Damris,M.
    • Kuzyakov,Y.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 9
  • Year: 2015
  • Summary: Indonesia lost more tropical forest than all of Brazil in 2012, mainly driven by the rubber, oil palm, and timber industries. Nonetheless, the effects of converting forest to oil palm and rubber plantations on soil organic carbon (SOC) stocks remain unclear. We analyzed SOC losses after lowland rainforest conversion to oil palm, intensive rubber, and extensive rubber plantations in Jambi Province on Sumatra Island. The focus was on two processes: (1) erosion and (2) decomposition of soil organic matter. Carbon contents in the Ah horizon under oil palm and rubber plantations were strongly reduced up to 70% and 62%, respectively. The decrease was lower under extensive rubber plantations (41%). On average, converting forest to plantations led to a loss of 10 Mg C ha -1 after about 15 years of conversion. The C content in the subsoil was similar under the forest and the plantations. We therefore assumed that a shift to higher delta 13C values in plantation subsoil corresponds to the losses from the upper soil layer by erosion. Erosion was estimated by comparing the delta 13C profiles in the soils under forest and under plantations. The estimated erosion was the strongest in oil palm (358 cm) and rubber (3310 cm) plantations. The 13C enrichment of SOC used as a proxy of its turnover indicates a decrease of SOC decomposition rate in the Ah horizon under oil palm plantations after forest conversion. Nonetheless, based on the lack of C input from litter, we expect further losses of SOC in oil palm plantations, which are a less sustainable land use compared to rubber plantations. We conclude that delta 13C depth profiles may be a powerful tool to disentangle soil erosion and SOC mineralization after the conversion of natural ecosystems conversion to intensive plantations when soils show gradual increase of delta 13C values with depth.
  • Authors:
    • Meriem, S.
    • Triadiati, T.
    • Leuschner, C.
    • Kotowska, M. M.
    • Hertel, D.
  • Source: Primary Research Article
  • Volume: 21
  • Issue: 10
  • Year: 2015
  • Summary: Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPP total) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPP total in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha -1) was more than two times higher than in jungle rubber stands (147 Mg ha -1) and > four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha -1). NPP total was higher in the natural forest (24 Mg ha -1 yr -1) than in the rubber systems (20 and 15 Mg ha -1 yr -1), but was highest in the oil palm system (33 Mg ha -1 yr -1) due to very high fruit production (15-20 Mg ha -1 yr -1). NPP total was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha -1) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations.