• Authors:
    • Hao, M.
    • Fan, J.
    • Malhi, S.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 3
  • Year: 2010
  • Summary: Nitrate (NO 3-) leaching and water contamination have become a worldwide concern. In this review, some examples are presented to show the extent and magnitude of NO 3- accumulation in the soil profiles and its potential effects on contamination of ground water and surface water under dryland farming in northern China. Climatic and management factors affecting NO 3- leaching are also discussed. In northern China, rainfall is relatively sparse, but the high intensity of precipitation and porous soils play an important role in the accumulation of NO 3N in soil and its subsequent leaching in the soil profile. There is a risk of nitrate accumulation and leaching when high rates of fertilizer N are applied to improve crop yields, and it becomes even worse when conventional land use is changed from cereal crops to vegetable crops and fruit orchards. Under such conditions, shallow ground water might be polluted by NO 3-. This suggests that more attention should be paid to prevent this problem by using best management practices, especially by controlling the amount of N fertilizer input, balanced fertilization, split N application, inclusion of crops with deep taproots in the rotation and minimizing summer fallow (especially tilled) frequency.
  • Authors:
    • Abbaspour, K.
    • Schulin, R.
    • Yang, H.
    • Faramarzi, M.
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 11
  • Year: 2010
  • Summary: In most parts of Iran, water scarcity has been intensifying and posing a threat to the sustainability of agricultural production. Wheat is the dominant crop and the largest irrigation water user in Iran; hence, understanding of the crop yield-water relations in wheat across the country is essential for a sustainable production. Based on a previously calibrated hydrologic model, we modeled irrigated and rainfed wheat yield ( Y) and consumptive water use ( ET) with uncertainty analysis at a subbasin level in Iran. Simulated Y and ET were used to calculate crop water productivity ( CWP). The model was then used to analyze the impact of several stated policies to improve the agricultural system in Iran. These included: increasing the quantity of cereal production through more efficient use of land and water resources, improving activities related to soil moisture conservation and retention, and optimizing fertilizer application. Our analysis of the ratio of water use to internal renewable water resources revealed that 23 out of 30 provinces were using more than 40% of their water resources for agriculture. Twelve provinces reached a ratio of 100% and even greater, indicating severe water scarcity and groundwater resource depletion. An analysis of Y-CWP relationship showed that one unit increase in rainfed wheat yield resulted in a lesser additional water requirement than irrigated wheat, leading to a larger improvement in CWP. The inference is that a better water management in rainfed wheat, where yield is currently small, will lead to a larger marginal return in the consumed water. An assessment of improvement in soil available water capacity ( AWC) showed that 18 out of 30 provinces are more certain to save water while increasing AWC through proper soil management practices. As wheat self-sufficiency is a desired national objective, we estimated the water requirement of the year 2020 (keeping all factors except population constant) to fulfill the wheat demand. The results showed that 88% of the additional wheat production would need to be produced in the water scarce provinces. Therefore, a strategic planning in the national agricultural production and food trade to ensure sustainable water use is needed. This study lays the basis for a systematic analysis of the potentials for improving regional and national water use efficiency. The methodology used in this research, could be applied to other water scarce countries for policy impact analysis and the adoption of a sustainable agricultural strategy.
  • Authors:
    • Rasul, G.
  • Source: International Journal of Rural Management
  • Volume: 6
  • Issue: 1
  • Year: 2010
  • Summary: Although South Asian countries made impressive progress in food production during 1960s, 1970s and 1980s, the dynamism in the agricultural sector has, however, lost recently. Productivity of major food grains has slowed down and even declined, for some crops and food production is failing to keep pace with population growth. Therefore, food security has remained a major concern in South Asian countries. The linkage between food production and the Himalayan mountains is poorly understood though the Himalayan mountains are the major source of dry season water in Pakistan, Nepal, Bangladesh and Bhutan for irrigated rice and wheat, which are the staple food in South Asia. In view of that this article briefly examines the role of the Himalayan mountain systems in food production and agricultural sustainability in South Asian countries looking at the emerging challenges posed by the increasing water stress and climate change. The analysis suggests that a common challenge is being faced by all South Asian countries - for increased food production to meet the demand of burgeoning population, the growing stress of water as rice and wheat, the staple food in South Asia, require huge amounts of water. Moreover, the increased food production in South Asia has to come from the same amount of land, by increasing productivity through bringing additional land under irrigation, as the frontier for expansion of agricultural land has almost been exhausted. The availability of irrigation water is, therefore, critical for increased food production and agricultural sustainability in entire South Asia. Climate change introduces a new challenge to agriculture and food security in South Asia. Recent studies suggest that the impact of climate change on cereal production in South Asia could be negative and that may be as high as 18.2-22.1 per cent. Our analysis reveals that the Hindu Kush-Himalayan mountain systems play a significant role in agriculture and food security in South Asia through water supply, climate and wind regulation, groundwater recharge and in sustaining wetland ecosystems. It is the major source of dry season water for several large river systems, such as the Indus, the Ganges and the Brahmaputra from the snow and glacier melt of the Himalayas, which provide the main basis for surface and groundwater irrigation. These three rivers form the largest river basins (Indo-Ganga-Brahmaputra) which are the major source of rice and wheat in South Asia. Besides surface water, the contribution of mountain discharge to groundwater is also significant, which makes it an important resource for agriculture and food security in South Asia. In addition to providing surface and groundwater, the Himalayan mountain system provides huge inputs to agriculture through regulating micro-climates as well as wind and monsoon circulation, and by supporting river and wetland ecosystems in South Asia. It is estimated that the Ganges river ecosystem alone supports 25,000 or more species, ranging from micro-organisms to mammals, which support agricultural sustainability and provide livelihoods for millions of people. This article concludes that the long-term agricultural sustainability and food security of South Asia is heavily dependent on the water and other ecosystem services it receives from the Himalayan ecosystems. Attention therefore must be paid to conserve the Himalayan ecosystems in order to ensure sustained flow of ecosystem services required for agriculture, food production and overall well-being of Himalayan and downstream population. Options and opportunities for enhancing the agricultural sustainability and food security by sustainable utilization of Himalayan resources and ecosystem services are briefly analyzed and suggestions have been made.
  • Authors:
    • Iqbal, N.
    • Goher, M.
    • Hameed, A.
  • Source: Cereal Research Communications
  • Volume: 38
  • Issue: 2
  • Year: 2010
  • Summary: Detection of genotypic variation in response to water stress at seedling stage could help in escalating selection intensity in breeding drought tolerant varities. Nine genotypes were tested for seedling survivability under drought stress. Four genotypes, i.e. 'Sarsabz', 'Sitta', 'Fareed' and 'FD-83', showed complete survival on resumption of irrigation after drought stress. These genotypes were late dying as they withered slowly under drought. Percent wilting and percent survival on resumption of irrigation were negatively correlated. Six genotypes were selected on the basis of seedling survivability (late and early dying) and evaluated for seedling growth response under drought. Root length and dry weight increased significantly under stress in 'Sitta', 'FD-83' and 'Fareed'. Drought stress also increased the root-to-shoot length ratio in 'FD-83' and 'Fareed'. However, seedling fresh and dry weight significantly reduced in 'Nesser' and 'Inqalab-91' under stress. In 'FD-83', seedling fresh and dry weight increased over control under stress. Results indicated that seedling survivability, root-to-shoot length ratio, root length and dry weight were most important traits for screening drought tolerance at seedling stage. On the basis of these indices, 'Sitta', 'Fareed' and 'FD-83' were classified as drought tolerant, 'Sarsabz' and 'Nesser' as moderately tolerant and 'Inqalab-91' as sensitive genotypes. Collectively, results suggested that selection by combining seedling survivability, growth response, RWC and leaf water potential can be efficiently used for rapid evaluation of drought tolerance in wheat breeding.
  • Authors:
    • Kephart, K. D.
    • Klouser, L.
    • Johnston, J. A.
    • Johnston, R. H.
    • Hogg, A. C.
    • Dyer, A. T.
  • Source: Phytopathology
  • Volume: 100
  • Issue: 1
  • Year: 2010
  • Summary: Caused by a complex of Fusarium species including F. culmorum, F. graminearum, and F. pseudograminearum, Fusarium crown rot (FCR) is an important cereal disease worldwide. For this study, Fusarium population dynamics were examined in spring wheat residues sampled from dryland field locations near Bozeman and Huntley, MT, using a quantitative real-time polymerase chain reaction (qPCR) Taqman assay that detects F. culmorum, F. graminearum, and F. pseudograminearum. Between August 2005 and June 2007, Fusarium populations and residue decomposition were measured eight times for standing stubble (0 to 20 cm above the soil surface), lower stem (20 to 38 cm), middle stem (38 to 66 cm), and chaff residues. Large Fusarium populations were found in stubble collected in August 2005 from F. pseudograminearum-inoculated plots. These populations declined rapidly over the next 8 months. Remnant Fusarium populations in inoculated stubble were stable relative to residue biomass from April 2006 until June 2007. These two phases of population dynamics were observed at both locations. Relative to inoculated stubble populations, Fusarium populations in other residue fractions and from noninoculated plots were small. In no case were FCR species observed aggressively colonizing noninfested residues based on qPCR data. These results suggest that Fusarium populations are unstable in the first few months after harvest and do not expand into noninfested wheat residues. Fusarium populations remaining after 8 months were stable for at least another 14 months in standing stubble providing significant inoculums for newly sown crops.
  • Authors:
    • Kumar, S. N.
    • Byjesh, K.
    • Aggarwal, P. K.
  • Source: Mitigation and Adaptation Strategies for Global Change
  • Volume: 15
  • Issue: 5
  • Year: 2010
  • Summary: Climate change associated global warming, rise in carbon dioxide concentration and uncertainties in precipitation has profound implications on Indian agriculture. Maize ( Zea mays L.), the third most important cereal crop in India, has a major role to play in country's food security. Thus, it is important to analyze the consequence of climate change on maize productivity in major maize producing regions in India and elucidate potential adaptive strategy to minimize the adverse effects. Calibrated and validated InfoCrop-MAIZE model was used for analyzing the impacts of increase in temperature, carbon dioxide (CO 2) and change in rainfall apart from HadCM3 A2a scenario for 2020, 2050 and 2080. The main insights from the analysis are threefold. First, maize yields in monsoon are projected to be adversely affected due to rise in atmospheric temperature; but increased rainfall can partly offset those loses. During winter, maize grain yield is projected to reduced with increase in temperature in two of the regions (Mid Indo-Gangetic Plains or MIGP, and Southern Plateau or SP), but in the Upper Indo-Gangetic Plain (UIGP), where relatively low temperatures prevail during winter, yield increased up to a 2.7°C rise in temperature. Variation in rainfall may not have a major impact on winter yields, as the crop is already well irrigated. Secondly, the spatio-temporal variations in projected changes in temperature and rainfall are likely to lead to differential impacts in the different regions. In particular, monsoon yield is reduced most in SP (up to 35%), winter yield is reduced most in MIGP (up to 55%), while UIGP yields are relatively unaffected. Third, developing new cultivars with growth pattern in changed climate scenarios similar to that of current varieties in present conditions could be an advantageous adaptation strategy for minimizing the vulnerability of maize production in India.
  • Authors:
    • Kalungu, J. W.
    • Monteiro, R. O. C.
    • Coelho, R. D.
  • Source: Ciência Rural
  • Volume: 40
  • Issue: 10
  • Year: 2010
  • Summary: This paper reviews various irrigation technologies in both South Africa and Kenya that enable improvements in their socio-economic conditions. The two countries are located in semi-arid areas that experience extreme fluctuations in the availability of rain water for plant growth. Population growth exceeds the ability to produce food in numerous countries around the world and the two countries are not an exception. This experiment examined the constraints that farmers face and the role of government and nongovernmental organization in the uptake of modern technologies for irrigation. Detailed mechanisms and options to secure sustainable irrigation which are economically viable are considered. Despite the higher production of cereals and grains, fruits, and flowers also thrive in the two countries. Total irrigated area, crops grown and irrigation systems used in the two countries are discussed.
  • Authors:
    • Starkey, S.
    • Reese, J.
    • Viswanathan, P.
    • Orozco, G. V.
    • Cardona, P. S.
    • Khan, S. A.
    • Murugan, M.
    • Smith, C. M.
  • Source: Journal of Economic Entomology
  • Volume: 103
  • Issue: 3
  • Year: 2010
  • Summary: The Russian wheat aphid, Diruaphis noxia (Kurdjumov) (Hemiptera: Aphididae), is globally one of the most devastating pests of bread wheat, Tritium aestivum L.; durum wheat, Triticum turgidum L.; and barley, Hordeum vulgare L. Host plant resistance is the foundation for cereal insect pest management programs, and several sources of D. noxia resistance have been incorporated in cultivars to manage D. noxia damage. The emergence of D. noxia North American biotype 2 (RWA2) in Colorado has made all known Dn genes vulnerable except the Dn7 gene from rye, Secale cereale, and has warranted exploration for sources of resistance to both RWA1 and RWA2. The category of resistance in resistant donor plants may exert selection pressure over the aphid population to form a new virulent population. In the current study, we report tolerance and antibiosis resistance to RWA1 and RWA2 in the barley genotype 'Stoneham'. The rate and degree of expression of resistance in Stoneham against RWA1 and RWA2, although not similar, are greater than the partial resistance in 'Sidney'. Antixenosis resistance to RWA1 or RWA2 was not observed in Sidney or Stoneham. The tolerance identified in Stoneham is encouraging because it may delay D. noxia biotype selection and fits well in a dryland barley cropping system.
  • Authors:
    • WCI
  • Volume: 2010
  • Year: 2010
  • Summary: Welcome to the Western Climate Initiative (WCI). The WCI is a collaboration of independent jurisdictions working together to identify, evaluate, and implement emissions trading policies to tackle climate change at a regional level. This is a comprehensive effort to reduce greenhouse gas pollution, spur investment in clean-energy technologies that create green jobs and reduce dependence on imported oil.
  • Authors:
    • Post, W. M.
    • Ugarte, D. J. D. L. T.
    • Nelson, R. G.
    • Marland, G.
    • Wilson, B. S.
    • Yang, B.
    • Bandaru, V.
    • Bernacchi, C. J.
    • Mueller, R.
    • Hellwinckel, C. M.
    • Baskaran, L. M.
    • Brandt, C. C.
    • West, T. O.
  • Source: Ecological Applications
  • Volume: 20
  • Issue: 4
  • Year: 2010
  • Summary: Net annual soil carbon change, fossil fuel emissions from cropland production, and cropland net primary production were estimated and spatially distributed using land cover defined by NASA's moderate resolution imaging spectroradiometer (MODIS) and by the USDA National Agricultural Statistics Service (NASS) cropland data layer (CDL). Spatially resolved estimates of net ecosystem exchange (NEE) and net ecosystem carbon balance (NECB) were developed. The purpose of generating spatial estimates of carbon fluxes, and the primary objective of this research, was to develop a method of carbon accounting that is consistent from field to national scales. NEE represents net on-site vertical fluxes of carbon. NECB represents all on-site and off-site carbon fluxes associated with crop production. Estimates of cropland NEE using moderate resolution (1 km2) land cover data were generated for the conterminous United States and compared with higher resolution (30-m) estimates of NEE and with direct measurements of CO2 flux from croplands in Illinois and Nebraska, USA. Estimates of NEE using the CDL (30-m resolution) had a higher correlation with eddy covariance flux tower estimates compared with estimates of NEE using MODIS. Estimates of NECB are primarily driven by net soil carbon change, fossil fuel emissions associated with crop production, and CO2 emissions from the application of agricultural lime. NEE and NECB for U.S. croplands were -274 and 7 Tg C/yr for 2004, respectively. Use of moderate- to high-resolution satellite-based land cover data enables improved estimates of cropland carbon dynamics.