• Authors:
    • Riseman, A.
    • Chapagain, T.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 1
  • Year: 2015
  • Summary: Enhancing soil organic carbon (SOC), nitrogen (N) and water use efficiency (WUE) are significant challenges in intensive wheat production. An intercropping system combining wheat and grain legumes may help maintain SOC, soil mineral N and WUE while also providing an opportunity to sequester carbon (C) in low input organic systems. We grew wheat (Triticum aestivum cv. 'Scarlet') as a monoculture and intercropped with either common bean (Phaseolus vulgaris cv. 'Red Kidney', or cv. 'Black Turtle'), or fava bean (Vicia faba cv. 'Bell') in rows of 1:1, 2 wheat: 1 bean or broadcast arrangement without fertilizers for 2 years to assess the effects of genotype and spatial arrangement on biological nitrogen fixation and seasonal transfer, WUE, gross ecosystem photosynthesis (GEP), and net ecosystem productivity (NEP). Stable isotope methods (C-13 and N-15 natural abundance) were used to quantify C and N within the plant and soil system. Field CO2 exchange measurements used a dynamic closed transparent chamber connected to a portable CO2 analyzer. Intercropped plots had higher percent N derived from symbiotic N-2 fixation, and increased C and N accumulation compared to monocultured wheat. The fava bean cv. Bell intercrops showed increased nodulation (60-80 % more nodules) and percent N derived from symbiotic N-2 fixation (10-12 % higher) compared to common beans resulting in the fixation of 74 kg N ha(-1) biologically from the 1:1 arrangement. The highest rate of N-transfer (13 %) was observed in the wheat-fava bean cv. Bell combination when planted in the 1:1 arrangement. All intercrops accumulated more N in shoot biomass compared to monoculture wheat with wheat-fava bean cv. Bell (1:1 arrangement) accumulating the highest N (34 kg N ha(-1), i.e., 176 % higher) and C (214 g C m(-2) year(-1), i.e., 26 % higher). All plots fixed the most CO2 (i.e., greatest GEP) during mid-growth stage (50 days after seeding i.e., prior to flowering) however, wheat-fava bean cv. Bell in the 1:1 arrangement displayed the greatest NEP sequestering C at the seasonal daytime average rate of 208 mg C m(-2) h(-1) (i.e., 7 % higher than wheat monoculture plots). Intrinsic WUE of wheat, as indicated by delta C-13, was also improved when grown with fava bean cv. Bell or common bean cv. Red Kidney. This study demonstrated that intercropping wheat and fava bean is an effective strategy to achieve greater nitrogen fixation and transfer to the wheat counterparts, higher WUE, and ecosystem productivity than wheat monocultures in areas with low soil N and C. Furthermore, the wheat-fava bean cv. Bell (1:1 arrangement) was more productive than either the 2:1 or mixed planting arrangements.
  • Authors:
    • Running, S. W.
    • Bagne, K. E.
    • Moreno, A. L.
    • Reeves, M. C.
  • Source: CLIMATIC CHANGE
  • Volume: 126
  • Issue: 3-4
  • Year: 2014
  • Summary: The potential effects of climate change on net primary productivity (NPP) of U.S. rangelands were evaluated using estimated climate regimes from the A1B, A2 and B2 global change scenarios imposed on the biogeochemical cycling model, Biome-BGC from 2001 to 2100. Temperature, precipitation, vapor pressure deficit, day length, solar radiation, CO2 enrichment and nitrogen deposition were evaluated as drivers of NPP. Across all three scenarios, rangeland NPP increased by 0.26 % year(-1) (7 kg C ha(-1) year(-1)) but increases were not apparent until after 2030 and significant regional variation in NPP was revealed. The Desert Southwest and Southwest assessment regions exhibited declines in NPP of about 7 % by 2100, while the Northern and Southern Great Plains, Interior West and Eastern Prairies all experienced increases over 25 %. Grasslands dominated by warm season (C4 photosynthetic pathway) species showed the greatest response to temperature while cool season (C3 photosynthetic pathway) dominated regions responded most strongly to CO2 enrichment. Modeled NPP responses compared favorably with experimental results from CO2 manipulation experiments and to NPP estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS). Collectively, these results indicate significant and asymmetric changes in NPP for U.S. rangelands may be expected.
  • Authors:
    • Mendoza, T.
  • Source: International Journal of Agricultural Technology
  • Volume: 10
  • Issue: 1
  • Year: 2014
  • Summary: This study involved estimating the carbon foot print (CF) of sugar production in Eastern Batangas, Philippines whose aims were to identify the "hot spots" of sugar production, to suggest practical options to "cool" these identified hot spots, and to recommend policy options to address the social cost of carbon (SCC). The sources of CF included the detailed operations involved in sugarcane production (plant cane and ratoon) up to milling to produce raw sugar, and the associated CF in cane burning (expressed in CO 2 equivalence). The carbon foot print (CF) of sugarcane production (farm level) was estimated at 5.56 CO 2 t/ha, 16% of total (or 0.067 tCO 2/ton cane) while processing the canes in the mill contributed 47% (16.5 tCO 2), (200 tCO 2/ton cane, 1.98 kg CO 2/kg sugar). The conventional practice of burning canes contributed 37% greenhouse gases at 12.9 tCO 2/ha which led to a considerable increase in CF from 22.03 tCO 2/ha to 34.9 tCO 2/ha or 2.64 to 4.2 kg CO 2/kg sugar. Deducting the equivalent CO 2 sequestered in the soil due to the unburned trash, roots, and stumps retained in the soil as humus - C (at 2.06 t CO 2/ha) decreased the carbon foot print of sugar slightly from 4.2 to 3.98 kg CO 2 per kg sugar. At P13.51/tCO 2, the estimated social cost of carbon (SCC) as year 2011 was PhP 2.34/kg. The SSC of sugar is instructive to (1) the environmental cost of sugar and (2) the needed adjustments in production practices to reduce the sugar carbon foot print in order to ecologically sustain sugarcane production. There is a need to increase the soil organic matter to improve fertilizer use efficiency, soil water-holding capacity, and ultimately increase the energy efficiency of sugar production. N-fertilizer input and cane burning were the two identified major sources of GHG emission. Shifting the conventional production systems to an alternative cane production system where there would be no cane burning and only 50% N-fertilizer would be applied would lead to 40% reduction in CF, from 3.98 to 2.32 kg CO 2 per kg sugar. Accordingly, SCC would decrease from PhP 2.34 to PhP 1.38 per kg sugar. Issuance of a sugar order is necessary to provide the legal basis of charging SCC to the industry key players to fund the programmatic shift of the conventional sugarcane production to an alternative systems to reduce the CF of sugar and to improve the economic viability and the long term sustainability of sugarcane production.
  • Authors:
    • Pangga, I. B.
    • Chakraborty, S.
    • Roper, M. M.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 7
  • Year: 2012
  • Summary: Soil multitrophic interactions transfer energy from plants as the predominant primary producer to communities of organisms that occupy different positions in the food chain and are linked by multiple ecological networks, which is the soil food web. Soil food web sequesters carbon, cycles nutrients, maintains soil health to suppress pathogens, helps plants tolerate abiotic and biotic stress, and maintains ecosystem resilience and sustainability. Understanding the influence of climate change on soil multitrophic interactions is necessary to maintain these essential ecosystem services. But summarising this influence is a daunting task due to a paucity of knowledge and a lack of clarity on the ecological networks that constitute these interactions. The scant literature is fragmented along disciplinary lines, often reporting inconsistent findings that are context and scale-dependent. We argue for the differentiation of soil multitrophic interactions along functional and spatial domains to capture cross-disciplinary knowledge and mechanistically link all ecological networks to reproduce full functionalities of the soil food web. Distinct from litter mediated interactions in detritosphere or elsewhere in the soil, the proposed 'pathogen suppression' and 'stress tolerance' interactions operate in the rhizosphere. A review of the literature suggests that climate change will influence the relative importance, frequency and composition of functional groups, their trophic interactions and processes controlling these interactions. Specific climate change factors generally have a beneficial influence on pathogen suppression and stress tolerance, but findings on the overall soil food web are inconsistent due to a high level of uncertainty. In addition to an overall improvement in the understanding of soil multitrophic interactions using empirical and modelling approaches, we recommend linking biodiversity to function, understanding influence of combinations of climatic factors on multitrophic interactions and the evolutionary ecology of multitrophic interactions in a changing climate as areas that deserve most attention.
  • Authors:
    • Elazegui, D. D.
    • Chupungco, A. R.
    • Nguyen, M. R.
  • Source: Philippine Journal of Crop Science
  • Volume: 36
  • Issue: 2
  • Year: 2011
  • Summary: This study discusses the seed system, production and marketing of eggplant, Solanum melongena L., considered as one of the most important vegetable crops in the Philippines. Data analyzed were obtained from focus group discussions in major eggplant producing provinces of Pangasinan, Batangas and Quezon; key informant interviews with representatives of government agencies and seed companies, and traders; and secondary sources such as government reports and other publications. The eggplant seed system is generally organized, involving public and private sectors. There are different varieties available in the market but seed developers do not opt for seed registration nor plant variety protection because of the rigorous process involved. Instead, seed companies adopt well-established seed production and quality control strategies and vigorous marketing and promotion to improve sales. Commercial growers of eggplant adopt hybrid seeds, while open-pollinated varieties (OPVs) are mainly used for small-scale production. Between 2000 and 2009, eggplant production increased by 21% despite a relatively lower increase (6%) in area planted. Average yield ranged 8-10 mt ha -1. Eggplant production is profitable, but major problems include fruit and shoot borer (FSB) infestation, bacterial wilt, irrigation supply and climate-related problems. Production involves intensive use of pesticides, bearing some implications on human health and environment. This should call the attention of Local Government Units which are in the forefront of providing extension services. Moreover, research and development should continuously receive adequate support to address these concerns. Research and development thrusts could include varietal improvement of eggplant and alternative pest control strategies such as integrated pest management (IPM) technology and intercropping. The current effort on R & D of Bt eggplant addresses the problem of FSB and heavy dependence of farmers on pesticides. With the stringent regulatory system of the Philippines on the commercial propagation of GM crops, adverse impact on human health and environment will be curtailed.
  • Authors:
    • Barfoot, P.
    • Brookes, G.
  • Year: 2008
  • Authors:
    • Dale, B. E.
    • Kim, S.
  • Source: Biomass and Bioenergy
  • Volume: 26
  • Issue: 4
  • Year: 2004
  • Summary: The global annual potential bioethanol production from the major crops, corn, barley, oat, rice, wheat, sorghum, and sugar cane, is estimated. To avoid conflicts between human food use and industrial use of crops, only the wasted crop, which is defined as crop lost in distribution, is considered as feedstock. Lignocellulosic biomass such as crop residues and sugar cane bagasse are included in feedstock for producing bioethanol as well. There are about 73:9 Tg of dry wasted crops in the world that could potentially produce 49:1 GL year-1 of bioethanol. About 1:5 Pg year-1 of dry lignocellulosic biomass from these seven crops is also available for conversion to bioethanol. Lignocellulosic biomass could produce up to 442 GL year-1 of bioethanol. Thus, the total potential bioethanol production from crop residues and wasted crops is 491 GL year-1, about 16 times higher than the current world ethanol production. The potential bioethanol production could replace 353 GL of gasoline (32% of the global gasoline consumption) when bioethanol is used in E85 fuel for a midsize passenger vehicle. Furthermore, lignin-rich fermentation residue, which is the coproduct of bioethanol made from crop residues and sugar cane bagasse, can potentially generate both 458 TWh of electricity (about 3.6% of world electricity production) and 2:6EJ of steam. Asia is the largest potential producer of bioethanol from crop residues and wasted crops, and could produce up to 291 GL year -1 of bioethanol. Rice straw, wheat straw, and corn stover are the most favorable bioethanol feedstocks in Asia. The next highest potential region is Europe (69:2 GL ofbioethanol), in which most bioethanol comes from wheat straw. Corn stover is the main feedstock in North America, from which about 38:4 GL year -1 of bioethanol can potentially be produced. Globally rice straw can produce 205 GL of bioethanol, which is the largest amount from single biomass feedstock. The next highest potential feedstock is wheat straw, which can produce 104 GL of bioethanol. This paper is intended to give some perspective on the size ofthe bioethanol feedstock resource, globally and by region, and to summarize relevant data that we believe others will 0nd useful, for example, those who are interested in producing biobased products such as lactic acid, rather than ethanol, from crops and wastes. The paper does not attempt to indicate how much, if any, of this waste material could actually be converted to bioethanol.
  • Authors:
    • Sathaye, J. A.
    • Makundi, W. R.
  • Source: Environment, Development and Sustainability
  • Volume: 6
  • Issue: 1-2
  • Year: 2004
  • Summary: This paper summarizes studies of carbon mitigation potential (MP) and costs of forestry options in seven developing countries with a focus on the role of agroforestry. A common methodological approach known as comprehensive mitigation assessment process (COMAP) was used in each study to estimate the potential and costs between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios derived from the demand for forest products and forestland for other uses such as agriculture and pasture. By using data on estimated carbon sequestration, emission avoidance, costs and benefits, the model enables one to estimate cost effectiveness indicators based on monetary benefit per tC, as well as estimates of total mitigation costs and potential when the activities are implemented at equilibrium level. The results show that about half the MP of 6.9 GtC (an average of 223 MtC per year) between 2000 and 2030 in the seven countries could be achieved at a negative cost, and the other half at costs not exceeding $100 per tC. Negative cost indicates that non-carbon revenue is sufficient to offset direct costs of about half of the options. The agroforestry options analyzed bear a significant proportion of the potential at medium to low cost per tC when compared to other options. The role of agroforestry in these countries varied between 6% and 21% of the MP, though the options are much more cost effective than most due to the low wage or opportunity cost of rural labor. Agroforestry options are attractive due to the large number of people and potential area currently engaged in agriculture, but they pose unique challenges for carbon and cost accounting due to the dispersed nature of agricultural activities in the tropics, as well as specific difficulties arising from requirements for monitoring, verification, leakage assessment and the establishment of credible baselines.
  • Authors:
    • Shively, G. E.
    • Zelek, C. A.
  • Source: Land Economics
  • Volume: 79
  • Issue: 3
  • Year: 2003
  • Summary: We present a method for measuring the opportunity cost of sequestering carbon on tropical farms. We derive the rates of carbon sequestration for timber and agroforestry systems and compute incentive compatible compensating payment schedules for farmers who sequester carbon. The method is applied to data for an agricultural watershed in the Philippines. Area- and land quality-adjusted total costs are estimated. The present value of the opportunity cost of carbon storage via land modification falls between $3.30 and $62.50 per ton. Carbon storage through agroforestry is found to be less costly than via a pure tree-based system.
  • Authors:
    • Ball, A.
    • Pretty, J.
  • Year: 2001