• Authors:
    • Huber-Sannwald, E.
    • Anaya, C. A.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 147
  • Year: 2015
  • Summary: Conversion of tropical forests to croplands greatly reduces stock size of soil organic resources. Low-impact agriculture may curtail this loss in soil fertility, and favor long-term agroecosystem functioning. In east tropical Mexico, indigenous smallholders have been managing sugarcane plots without burning, fertilizing, tillaging, and removal of crop residues for the last 70 years. This study examined the long-term effects of such low-input sugarcane agriculture on soil aggregate structure and soil organic carbon (SOC) and soil nitrogen (N) stocks along a 50-year chronosequence of cultivation including differently aged sugarcane plots and tropical forests as a reference site. Soils were physically fractioned in four aggregate size classes and in four soil organic matter (SOM) fractions and changes in C concentrations and C/N ratios of these fractions were assessed. Long-term cultivation did not alter soil aggregate structure, or litter C content; however it reduced significantly litter N content in sugarcane compared to forest plots. After 20 years of cultivation, SOC and soil N stocks dropped by 25% at 0-10. cm soil depth compared to current C stocks in forest soils. After 50 years of cultivation, pooled over 0-20. cm, SOC stocks were similar in sugarcane and forest plots, while soil N stocks remained 12-19% lower in sugarcane than in forest plots. The mineral-associated organic C fraction remained unaffected by land use change. Forest conversion to sugarcane, depleted the free light particulate organic matter (POM) C fraction at 0-10. cm depth. Forest intra-aggregate POM C concentration declined after 20 years of cultivation and then recovered after 50 years of cultivation at 0-10. cm depth. This study demonstrates that traditional sugarcane cropping may be a long-term sustainable alternative to sequester SOC, while maintaining moderate soil N fertility levels without trading off on sugarcane production.
  • 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:
    • Cisz, M.
    • Galdos, M.
    • Hilbert, J.
    • Rod, K.
    • Ferreira, A.
    • Leite, L.
    • Kaczmarek, D.
    • Chimner, R.
    • Resh, S.
    • Asbjornsen, H.
    • Scott, D.
    • Titus, B.
    • Gollany, H.
  • Source: Environmental Management
  • Volume: 56
  • Issue: 6
  • Year: 2015
  • Summary: Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems incrementally remove greater quantities of organic matter, which in turn affects soil organic matter and associated carbon and nutrient storage (and hence long-term soil productivity) and off-site impacts. While these consequences have been extensively studied for some crops and sites, the ongoing and impending impacts of biomass removal require management strategies for ensuring that soil properties and functions are sustained for all combinations of crops, soils, sites, climates, and management systems, and that impacts of biomass management (including off-site impacts) are environmentally acceptable. In a changing global environment, knowledge of cumulative impacts will also become increasingly important. Long-term experiments are essential for key crops, soils, and management systems because short-term results do not necessarily reflect long-term impacts, although improved modeling capability may help to predict these impacts. Identification and validation of soil sustainability indicators for both site prescriptions and spatial applications would better inform commercial and policy decisions. In an increasingly inter-related but constrained global context, researchers should engage across inter-disciplinary, inter-agency, and international lines to better ensure the long-term soil productivity across a range of scales, from site to landscape.
  • Authors:
    • Olalde-Portugal, V.
    • Luna-Guido, M.
    • Hernandez-Valdez, E.
    • Manuel Ruiz-Valdiviezo, V.
    • del Rosario Cardenas-Aquino, M.
    • Aguilar-Chavez, A.
    • Diaz-Rojas, M.
    • Dendooven, L.
  • Source: Applied Soil Ecology
  • Volume: 73
  • Year: 2014
  • Summary: Agriculture is an important source of greenhouse gases (GHG), mostly carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Application of charcoal to agricultural soils is known to reduce GHG emissions while application of fertilizer or wastewater sludge increases them. Therefore, the objective of this work was to study the effect of charcoal application on GHG emissions from soil planted with wheat (Triticum aestivum L.) and amended with wastewater sludge or urea, or left unamended. Wheat fertilized with urea or wastewater sludge, at a rate of 150 kg N ha(-1), was cultivated in soil amended with or without 2% (w/w) charcoal, a biochar used mostly for heating, in a greenhouse. Emission of CO2, CH4 and N2O, soil characteristics and plant development were monitored. Charcoal had no significant effect on the emission of CO2, CH4 and N2O in wastewater sludge or urea-amended soil. The wheat development and yields, and soil pH and electrolytic conductivity were also not affected by charcoal application. It was found that charcoal did not affect the emissions of the monitored GHG, wheat or soil characteristics. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Gavito, M. E.
    • Garciarreal, A.
    • Villamil-Echeverri, L.
    • Merlin-Uribe, Y.
    • Astier, M.
    • Masera, O. R.
  • Source: Ecological Indicators
  • Volume: 43
  • Issue: August
  • Year: 2014
  • Summary: There is a worldwide growing awareness of the negative impacts of the increasing fossil fuel reliance and greenhouse gas (GHG) emissions from agriculture, in particular for intensive crop systems. We analyze the energy balances and greenhouse gas emissions from export-oriented avocado orchards in Mexico. Avocado is a very important export crop and one of the main drivers of land-use change in the country. We compared 12 avocado orchards under organic and conventional management during two production cycles (2010 and 2011) in a representative region of Central Mexico. Our analysis shows no significant differences in energy consumption and GHG emissions between organic and conventional systems with 55 and 56 GJ ha(-1), and 3.30 t CO2 equiv. ha(-1) and 3.57 t CO2 equiv. ha(-1), respectively. Organic systems show three times more use of renewable energy than their conventional counterparts. However both systems depend heavily on fossil fuel inputs, machinery and N-fertilizers (synthetic or organic). Also, there is a high heterogeneity in management practices and input application within both systems, which is reflected in a large variation of their energy-related parameters. Given that avocado production is rapidly expanding in Mexico, a move toward organic production without systematically changing toward less fossil fuel dependent agricultural practices would not be sufficient to ensure a sustainable production. (c) 2014 Elsevier Ltd. All rights reserved.
  • Authors:
    • Garcia-Gaytan, A.
    • Boden, K.
    • Verhulst, N.
    • Patino-Zuniga, L.
    • Dendooven, L.
    • Luna-Guido, M.
    • Govaerts, B.
  • Source: Journal of Crop Improvement
  • Volume: 28
  • Issue: 4
  • Year: 2014
  • Summary: Organic matter content increases in soil with no-tilled permanent raised beds (PBs) compared with soil with conventionally tilled beds (CBs), and this might affect greenhouse gas (GHG) emissions. Greenhouse gas (CO 2, N 2O, and CH 4) emissions were measured from PBs, from which crop residue was either removed or retained and from CBs where crop residue was retained. The CO 2 emission was not affected by tillage, but CH 4 and N 2O emissions were lower in PBs when residue was retained than in CBs. Removing crop residue from PBs reduced CO 2 emissions compared with when it was retained, but it had no effect on N 2O and CH 4 emissions. The global warming potential (GWP) of GHG emissions was higher in CBs (801 kg CO 2/ha/year) than in PBs (517 kg CO 2/ha/year) with crop-residue retention, but more C was sequestered in the 0-60 cm soil layer in PBs (83.4 Mg C/ha) than in CBs (79.2 Mg C/ha). Crop-residue removal in PBs had little effect on the GWP of GHG compared with PBs with crop residue retained, but less C was sequestered in the latter (63.1 Mg C/ha). Net GWP (considering soil C sequestration, GHG emissions, fuel used, glyphosate application, fertilizer and seed production) was lower in CBs with crop-residue retention (1062 kg CO 2/ha/year) than in PBs with crop-residue removal (6,120 kg CO 2/ha/year), but it was larger than in PBs with crop-residue retention (-681 kg CO 2/ha/year). We found that reduced tillage when beds were made permanent and crop-residue retention greatly reduced net GWP compared with when beds were tilled and remade each year. We found that retention of crop residue in PBs increased the emission of CO 2 compared with where it was removed, but tillage did not affect fluxes of CO 2. Emission of CH 4 and N 2O was larger from CBs than from PBs, but crop-residue management in PBs had no significant effect on fluxes of CH 4 and N 2O. Concentrations of mineral N were larger in CBs than in PBs, whereas the removal of crop residue from PBs increased mineral N concentration. Soil temperature was higher in CBs than in PBs and in PBs with crop residue retained compared with where it was removed. Soil water was better preserved in PBs than in CBs and in PBs where residue was retained than where it was removed. The higher water content in the PB compared with the CB will favor plant growth during dry spells. However, retaining crop residues in PBs will require sufficient application of inorganic N, as mineral N in soil is lower in PBs than in CBs or PBs with crop residue removed. Limited N availability in PBs with crop residue retained might reduce yields as poor farmers in the central highlands of Mexico apply little or no N fertilizer. Reduced tillage on PBs and crop-residue retention strongly reduced the net GWP of the system compared with the case when beds were remade each year. PBs with residue retention reduced net GWP by 50% compared with CBs with residue retention, but the removal of residues from the PBs more than doubled it.
  • Authors:
    • Rappaport, A. G.
    • Mitra, S.
    • Francis, B.
    • Harris, R.
    • Thomson, A. M.
    • Reeves, J. B.
    • Ebinger, M. H.
    • Wielopolski, L.
    • Rice, C. W.
    • Izaurralde, R. C.
    • Etchevers, J. D.
    • Sayre, K. D.
    • Govaerts, B.
    • McCarty, G. W.
  • Source: PLOS ONE
  • Volume: 8
  • Issue: 1
  • Year: 2013
  • Summary: Three advanced technologies to measure soil carbon (C) density (g C m -2) are deployed in the field and the results compared against those obtained by the dry combustion (DC) method. The advanced methods are: (a) Laser Induced Breakdown Spectroscopy (LIBS), (b) Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), and (c) Inelastic Neutron Scattering (INS). The measurements and soil samples were acquired at Beltsville, MD, USA and at Centro International para el Mejoramiento del Maiz y el Trigo (CIMMYT) at El Batan, Mexico. At Beltsville, soil samples were extracted at three depth intervals (0-5, 5-15, and 15-30 cm) and processed for analysis in the field with the LIBS and DRIFTS instruments. The INS instrument determined soil C density to a depth of 30 cm via scanning and stationary measurements. Subsequently, soil core samples were analyzed in the laboratory for soil bulk density (kg m -3), C concentration (g kg -1) by DC, and results reported as soil C density (kg m -2). Results from each technique were derived independently and contributed to a blind test against results from the reference (DC) method. A similar procedure was employed at CIMMYT in Mexico employing but only with the LIBS and DRIFTS instruments. Following conversion to common units, we found that the LIBS, DRIFTS, and INS results can be compared directly with those obtained by the DC method. The first two methods and the standard DC require soil sampling and need soil bulk density information to convert soil C concentrations to soil C densities while the INS method does not require soil sampling. We conclude that, in comparison with the DC method, the three instruments (a) showed acceptable performances although further work is needed to improve calibration techniques and (b) demonstrated their portability and their capacity to perform under field conditions.
  • Authors:
    • Rodriguez-Delfin, A.
  • Source: Acta Horticulturae
  • Issue: 947
  • Year: 2012
  • Summary: Hydroponics has been used during years for research in the field of plant mineral nutrition and related topics. Today the soilless culture method is the most intensive horticulture production and is being applied with success in developed countries for commercial purposes. The growing and future of hydroponics in Latin America will much depend of the developing and adaptation of less sophisticated commercial systems. These have to be cost competitive with respect to the high sophisticated technology generated and used in developed countries, using natural and local substrates, developing native or endemic crops of the Region with economical potential for its high feed or medicinal value, among others. Meanwhile, as there is a considerable decreasing of agricultural soils in the world, soilless culture would be an important production alternative in urban and peri-urban areas, mainly in undeveloped countries. Inside the context of urban agriculture, hydroponics could be applied in the cities with more simple and low cost of technologies, mainly in extreme poverty areas, as a way to spread vegetables for self-consumption and to support the family or community income. Also to create micro-companies that will generate employments. There are no official statistics on the evolution of the state of the hydroponic cultures in Latin America. The main hydroponic systems used are the drip irrigation and NFT system. According with their profits, the main hydroponic crops are lettuce, tomato, pepper and strawberry. In Andean countries like Peru, Bolivia, Colombia and Ecuador, aeroponics is being developing to obtain basic potato tuber seed, free of virus. In relation to the media used in soilless culture, there is no ideal or optimum substrate, because a great diversity in media could be used, as pure or as mix form. Among the inorganic substrates it is possible to use quarry, river and quartz sand, gravel, pumice and tezontle. Husk rice, coco fiber, peat moss and sawdust are used as organic media. The use of rock wool is not generalized in the Region, but in countries like Mexico and Chile it is mainly used in tomato crop with drip irrigation system. Brazil and Mexico are the more representative hydroponic countries in Latin America. The area of soilless culture is increasing in the Region and every day there is much interest to learn and to dominate this technique of plants production without using soil. A great number of international courses, seminaries, congresses and symposia organized in countries like Peru, Mexico, Brazil, Costa Rica and Chile demonstrate this affirmation. Finally, it is necessary to obtain a hydroponic certification, as well as the organic products, to support the hydroponic growers in our countries.
  • Authors:
    • Conde, C.
    • Martinez-Lopez, B.
    • Estrada, F.
    • Gay-Garcia, C.
  • Source: CLIMATIC CHANGE
  • Volume: 110
  • Issue: 3-4
  • Year: 2012
  • Summary: This paper presents a review of the methodology applied for generating the regional climate change scenarios utilized in important National Documents of Mexico, such as the Fourth National Communication to the United Nations Framework Convention on Climate Change, the Fourth National Report to the Convention on Biological Diversity and The Economics of Climate Change in Mexico. It is shown that these regional climate change scenarios, which are one of the main inputs to support the assessments presented in these documents, are an example of the erroneous use of statistical downscaling techniques. The arguments presented here imply that the work based on such scenarios should be revised and therefore, these documents are inadequate for supporting national decision- making.
  • Authors:
    • Sauer, T.
    • Soolaneyakanahally, R.
    • de Gooijer, H.
    • Bentrup, G.
    • Schoeneberger, M.
    • Brendle, J.
    • Zhou, X.
    • Current, D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 67
  • Issue: 5
  • Year: 2012