• Authors:
    • Murari, L.
  • Source: Regional Environmental Change
  • Volume: 11
  • Issue: Supplement 1
  • Year: 2011
  • Summary: One of the targets of the United Nations 'Millennium Development Goals' adopted in 2000 is to cut in half the number of people who are suffering from hunger between 1990 and 2015. However, crop yield growth has slowed down in much of the world because of declining investments in agricultural research, irrigation, and rural infrastructure and increasing water scarcity. New challenges to food security are posed by accelerated climatic change. Considerable uncertainties remain as to when, where and how climate change will affect agricultural production. Even less is known about how climate change might influence other aspects that determine food security, such as accessibility of food for various societal groups and the stability of food supply. This paper presents the likely impacts of thermal and hydrological stresses as a consequence of projected climate change in the future potential agriculture productivity in South Asia based on the crop simulation studies with a view to identify critical climate thresholds for sustained food productivity in the region. The study suggests that, on an aggregate level, there might not be a significant impact of global warming on food production of South Asia in the short term (
  • Authors:
    • Grace, P.
    • Barton, L.
    • Chen, D.
    • Eckard, R.
    • Kelly, K.
    • Officer, S.
    • Scheer, C.
    • Schwenke, G.
    • Wang, W.
  • Source: Soil Solutions for a Changing World
  • Year: 2011
  • Authors:
    • Shelton, H. M.
    • Radrizzani, A.
    • Kirchhof, G.
    • Dalzell, S. A.
  • Source: Crop and Pasture Science
  • Volume: 62
  • Issue: 4
  • Year: 2011
  • Summary: Soil organic carbon (OC) and total nitrogen (TN) accumulation in the top 0–0.15 m of leucaena–grass pastures were compared with native pastures and with continuously cropped land. OC and TN levels were highest under long-term leucaena–grass pasture (P < 0.05). For leucaena–grass pastures that had been established for 20, 31, and 38 years, OC accumulated at rates that exceeded those of the adjacent native grass pasture by 267, 140, and 79 kg/ha.year, respectively, while TN accumulated at rates that exceeded those of the native grass pastures by 16.7, 10.8, and 14.0 kg/ha.year, respectively. At a site where 14-year-old leucaena–grass pasture was adjacent to continuously cropped land, there were benefits in OC accumulation of 762 kg/ha.year and in TN accumulation of 61.9 kg/ha.year associated with the establishment of leucaena–grass pastures. Similar C : N ratios (range 12.7–14.5) of soil OC in leucaena and grass-only pastures indicated that plant-available N limited soil OC accumulation in pure grass swards. Higher OC accumulation occurred near leucaena hedgerows than in the middle of the inter-row in most leucaena–grass pastures. Rates of C sequestration were compared with simple models of greenhouse gas (GHG) emissions from the grazed pastures. The amount of carbon dioxide equivalent (CO2-e) accumulated in additional topsoil OC of leucaena–grass pastures ≤20 years old offset estimates of the amount of CO2-e emitted in methane and nitrous oxide from beef cattle grazing these pastures, thus giving positive GHG balances. Less productive, aging leucaena pastures >20 years old had negative GHG balances; lower additional topsoil OC accumulation rates compared with native grass pastures failed to offset animal emissions
  • Authors:
    • Richards, A. E.
    • Cook, G. D.
    • Lynch, B. T.
  • Source: Ecosystems
  • Volume: 14
  • Issue: 3
  • Year: 2011
  • Authors:
    • Basso, F. C.
    • Andreotti, M.
    • P. e Carvalho, M. de
    • Lodo, B. N.
    • Montanari, R.
  • Source: Revista Brasileira de Ciências Agrárias
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: With the use of no-till farming, the soil physical and chemical properties are constantly changed, directly reflecting on plant yield and composition. In 2006, in the municipality of Selviria, Mato Grosso do Sul, Brazil, the linear and spatial correlations between the plant attributes and the attributes of a Rhodic Hapludox were analyzed. The objective of this work was to select among the analyzed soil attributes the one that best explained the variability of agricultural yield. For this, the geostatistical grid was installed for the soil and plant collection in 124 sampling points in a 4,000 m2 area. In the soil samples, collected at three depths (0-0.10 m, 0.20-0.30 m and 0.10-0.20 m), the microporosity, macroporosity, total porosity, bulk density and organic matter content were determined. In the plant, the yield (fresh and dry matter) and the crude protein content were determined. From the spatial viewpoint, there was a direct correlation between the dry matter yield and the soil organic matter content, as well as an inverse correlation between the crude protein content and the macroporosity and total porosity of soil. Therefore, the surface organic matter content behaved as a soil chemical quality indicator to estimate the dry matter yield of Cajanus cajan L. under the conditions of this research.
  • Authors:
    • Brar, A. S.
    • Mahal, S. S.
    • Buttar, G. S.
    • Deol, J. S.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 4
  • Year: 2011
  • Summary: A field experiment was conducted to work out the water productivity, economics and energetics of basmati rice ( Oryza sativa L.)-wheat [ Triticum aestivum (L.) emend. Fiori & Paol] sequence under different methods of crop establishment during 2005-06 and 2006-07. The treatments included combinations of two crop establishment methods of basmati rice (direct seeded and transplanted) and three seeding techniques of succeeding wheat (conventional, bed planting and zero tillage). Productivity of basmati rice-wheat sequence was significantly higher with transplanted basmati rice (TPBR) than direct seeded basmati rice (DSBR) irrespective of seeding technique of succeeding wheat. However, crop establishment methods of wheat did not show any significant impact on total productivity of basmati rice-wheat sequence during both the years. Total water use was 9.5 and 8.2 per cent higher in TPBR-wheat sequence than DSBR-wheat sequence during 2005-06 and 2006-07, respectively. In this sequence the highest net return was obtained from TPBR-zero till sown wheat sequence, which was closely followed by TPBR-conventionally sown wheat sequence but both gave more net returns than DSBR-zero till sown wheat sequence. The highest energy output was recorded in TPBR-conventionally sown wheat, while energy use efficiency was maximum in TPBR-zero till sown wheat, during both the years because of lowest energy input in zero till sown wheat than conventional and bed planting.
  • Authors:
    • Campos, L. P.
    • Leite, L. F. C.
    • Maciel, G. A.
    • Iwata, B. de F.
    • Nobrega, J. C. A.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 12
  • Year: 2011
  • Summary: The objective of this work was to evaluate the chemical attributes in a Xanthic Ferralsol under different tillage systems in the cerrado of Piaui State, Brazil. Four tillage systems were evaluated: three-year-old conventional tillage; no-tillage with three (NT3) and five years old (NT5), using millet as cover crop; and no-tillage with nine years old (NT9), of which seven years used millet as cover crop and two used forage. A native cerrado area was taken as reference. Soil samples were collected in wet and dry seasons at soil depths, 0.00-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m, and analyzed for pH, Al 3+, H+Al, Ca 2+, Mg 2+, K +, sum of bases (SB), effective (t) and potential (T) cation exchangeable capacity, base (BS) and Al 3+ saturation (m%), available P and total organic carbon (TOC). The system NT9 showed the highest values of pH and lowest of Al 3+, H+Al, and m%. The highest values for Ca 2+, K, SB, t, T, V% and P, were observed under NT5 and NT9, until 0.20 m depth. The highest TOC contents were verified also under NT5 and NT9, except for 0.00-0.05 m soil depth. Organic matter accumulation associated with pasture under no-till increases TOC content at deeper soil layers in the dry period.
  • Authors:
    • Campos-Magana, S. G.
    • Cadena-Zapata, M.
  • Source: Campos-Magana, SG
  • Volume: 42
  • Issue: 4
  • Year: 2011
  • Summary: A five year field experiment was conducted to assess the interaction between soil tillage levels, maize-sorghum-legume rotation and two levels of chemical fertilization at the rain feed tropical region of southeast Mexico. The purpose of this research work was to asses this interaction over the variation of some soil quality indices and the effect on the productivity of the soil-grain yield. The treatments for soil tillage were zero till and the intensive traditional soil tillage of the region. Crop rotations employed were five years maize (mmmmm), five years sorghum (sssss), two rotations; (smsms) and (msmsm) and two intercropping of legumes (f)-cereals, (fsfsf) and (fmsmf). Ninety two and 136 units of nitrogen were the two levels of fertilization and were applied only to the cereals. The evaluated soil index in the first and fifth year were organic matter (mo), water infiltration rate (ir), aggregate stability (as), ph, biomass microbiana (mb), nitrogen soluble nitrogen, soil density (sd), soil depth (sd), electrical conductivity (ec) and availability of nutrients. In general terms, the best grain yield for both sorghum and maize were obtained with the no till treatment although no big differences were observed between them. The five year sorghum mean yield under no till with fertilization levels 1 and 2 were 3.6 and 4.5 Mg/ha, whereas, with conventional tillage these were just 3.1 and 4.1 Mg/ha, respectively. The grain yield of maize with level 2 of nitrogen, with zero and traditional till were 5.1 and 4.6 Mg/ha; however, with nitrogen level 1 there were no apparent advantages of the first treatment (3.8 Mg/ha in both cases). The type of crop rotation and soil tillage level mainly affected the chemical soil index at 0 to 5 cm depth. However, no effect occurred with the way of handling crop residues and with the levels of chemical fertilization. The main values of electrical conductivity were attributed to an increase in the solubility of some elements. It was also observed that, under no till, there was an increase of the levels of soluble carbon.
  • Authors:
    • Bustamante, M. M. da C.
    • Cruvinel, E. B. F.
    • Kozovits, A. R.
    • Zepp, R. G.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: In the last 40 years, a large area of savanna vegetation in Central Brazil (Cerrado) has been converted to agriculture, with intensive use of fertilizers, irrigation and management practices. Currently, the Cerrado is the main region for beef and grain production in Brazil. However, the consequences of these agricultural practices on NO, N 2O and CO 2 emissions from soil to atmosphere are still poorly investigated. The objectives of this study were to quantify soil emissions of NO-N, N 2O-N and CO 2-C in different no-till cultivation systems in comparison with native savanna vegetation. The agricultural areas included: (a) the maize and Brachiaria ruzizienses intercropping system followed by irrigated bean in rotation; (b) soybean followed by natural fallow; and (c) cotton planting over B. ruzizienses straw. The study was performed from August 2003 to October 2005 and fluxes were measured before and after planting, after fertilizations, during the growing season, before and after harvesting. NO-N fluxes in the soybean field were similar to those measured in the native vegetation. In the cornfield, higher NO-N fluxes were measured before planting than after planting and pulses were observed after broadcast fertilizations. During Brachiaria cultivation NO-N fluxes were lower than in native vegetation. In the irrigated area (bean cultivation), NO-N fluxes were also significantly higher after broadcast fertilizations. Most of the soil N 2O-N fluxes measured under cultivated and native vegetation were very low (<0.6 ng N 2O-N cm -2 h -1) except during bean cultivation when N 2O-N fluxes increased after the first and second broadcast fertilization with irrigation and during nodule senescence in the soybean field. Soil respiration values from the soybean field were similar to those in native vegetation. The CO 2-C fluxes during cultivation of maize and irrigated bean were twice as high as in the native vegetation. During bean cultivation with irrigation, an increase in CO 2-C fluxes was observed after broadcast fertilization followed by a decrease after the harvest. Significantly lower soil C stocks (0-30 cm depth) were determined under no-tillage agricultural systems in comparison with the stocks under savanna vegetation. Fertilizer-induced emission factors of N oxides calculated from the data were lower than those indicated by the IPCC as default.
  • Authors:
    • Duboc, O.
    • Zehetner, F.
    • Gerzabek, M. H.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: The increase in crop production brought by the green revolution in India is now shadowed by new challenges related to soil degradation (e.g., erosion, decline of soil organic matter content, salinization) and scarcity of water resources. The present work particularly discusses the contribution of no-till and organic farming, which are increasingly being adopted in India, to meet the increasing food demand in a sustainable way. Under no-till, erosion is reduced to rates close to those found in natural ecosystems, provided enough mulch is retained at the surface which is usually not the case in India, because of competing uses, for example, fodder, fuel, construction material, and also crop residue burning for land preparation. No-till should therefore not be considered separately from complementary measures, aiming at retaining mulch on the soil surface. Efficient recycling of organic material needs to be implemented concomitantly with diversifying fodder and fuel sources which requires enhancing the multifunctionality of farming systems. These prerequisites make it difficult for farmers to adopt no-till, particularly the poorer ones for whom experimentation with new techniques often involve unbearable financial risks. Organic farming apprehends the farm as an organism, and is thus a good option to improve sustainability as introduced above, by e.g., closing nutrient cycling. However, organic farming typically implies tillage for weed control (no chemical herbicides). "Natural farming," as promoted by Fukuoka (197834. Fukuoka, M. 1978. The one-straw revolution: an introduction to natural farming, Rodale Press. View all references) combines no-till with organic farming. An overview of available literature on Indian experiences with "natural farming," most of it originating from unconventional sources (i.e., reports available on Internet, but no peer reviewed literature) indicates that crop yields can compare well with the highest yields in a particular region. Increased productivity and environmental benefits are also often mentioned. The limited accuracy of these sources makes it necessary to pursue further investigations, and we conclude with propositions for future work in this context. This should start with a rigorous assessment of existing " natural farming" systems regarding their productivity and environmental benefits, in order to demonstrate its potential before starting projects that promote the system for broader adoption.