• Authors:
    • Smith, H. J.
    • Trytsman, G.
    • Bloem, J. F.
  • Source: Biological Nitrogen Fixation: Towards Poverty Alleviation through Sustainable Agriculture
  • Volume: 48
  • Issue: 1-3
  • Year: 2009
  • Summary: Farm lands of resource-poor communities in South Africa are depleted of nutrients due to continuous mono-cropping, limited use of fertilisers, and sometimes leaching caused by high rainfall. Despite the well-known advantages of biological nitrogen fixation (BNF) in cropping systems, less than 10% of the grain crops planted annually in these areas are legumes. Using a participatory research and development approach, resource-poor farmers were introduced to conservation agriculture (CA) practices, including BNF, that promoted zero (or reduced) tillage, increased retention of soil cover, as well as crop diversification. Because crop rotation and intercropping of legumes with cereals are known to contribute to soil fertility while enhancing food security, resource-poor fanners from various Provinces in South Africa were trained on the benefits of legume culture for eight years. As a result, these resource-poor farmers did not only get training in inoculation techniques, but were also supplied with inoculants for use on their farms. Data collected from Farmers Demonstration Trials at Belvedere, Dumbarton and Lusikisiki, showed that the grain and fodder yield of maize planted after legumes, and maize intercropped with legumes, were comparable to those of maize receiving high N fertilizer dose (i.e. 54 kg N at planting and 54 kg N as top-dressing). The same data further showed that Rhizobium inoculation, when combined with application of low levels of P and K. significantly increased crop yields within farmers' trial plots. BNF therefore offers a great opportunity for resource-poor farmers in South Africa to increase their crop yields and thus improve the quality of their livelihoods through the adoption of affordable and sustainable biological technologies that enhance soil fertility.
  • Authors:
    • Gathala, M. K.
    • Singh, K. K.
    • Sharma, S. K.
    • Saharawat, Y. S.
    • Tetarwal, J. P.
    • Ladha ,J. K.
    • Gupta, R. K.
    • Jat, M. L.
    • Singh, S.
  • Source: ACIAR PROCEEDINGS
  • Issue: 127
  • Year: 2008
  • Summary: Resource-conserving technologies with double no-till practices represent a major shift in production techniques for attaining optimal productivity, profitability and water use in rice-wheat (RW) systems in the Indo-Gangetic Plain. Permanent raised beds (PRB) and double no-till with flat layouts are under evaluation for RW systems for a range of soils, climate, cultivars and seeding/crop establishment techniques (dry seeding, transplanting). To date, results have been inconsistent and systematic information on trials with PRB is lacking. Four researcher- and farmer-managed experiments were conducted with various tillage and crop establishment techniques for RW on PRB and flat layouts. The yield of rice on PRB was significantly lower than that on double no-till flat layouts, whereas wheat yield was highest on PRB. The total RW system yield with PRB was similar to that of other tillage and crop establishment techniques. However, irrigation and input (irrigation plus rain) water productivity (kg grain/m 3 of water) of both rice and wheat was much higher on PRB. In farmer-managed trials of transplanted basmati rice on PRB, profitability was highest on PRB (US$684/ha) and lowest with traditional practices (US$531/ha). In a researcher-managed long-term experiment, the soil physical properties (bulk density, mean weight diameter of aggregates, cone index and infiltration rate) improved significantly on PRB compared with the conventional puddled transplanted rice-tilled wheat system.
  • Authors:
    • Reddy, K. C.
    • Reddy, S. S.
    • Nyakatawa, E. Z.
    • Raper, R. L.
    • Reeves, D. W.
    • Lemunyon, J.
    • Roberson, T.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 2
  • Year: 2008
  • Summary: Increased CO2 release from soils resulting from agricultural practices such as tillage has generated concerns about contributions to global warming, Maintaining current levels of soil C and/or sequestering additional C in soils are important mechanisms to reduce CO2 in the atmosphere through production agriculture. We conducted a study in northern Alabama from 2003 to 2006 to measure CO2 efflux and C storage in long-term tilled and non-tilled cotton (Gossypium hirsutum L.) plots receiving poultry litter or ammonium nitrate (AN). Treatments were established in 1996 on a Decatur silt loam (clayey, kaolinitic thermic, Typic Paleudults) and consisted of conventional-tillage (CT), mulch-tillage (MT), and no-tillage (NT) systems with winter rye [Secale cereale (L.)] cover cropping and AN and poultry litter (PL) as nitrogen sources. Cotton was planted in 2003, 2004, and 2006. Corti was planted in 2005 as a rotation crop using a no-till planter in all plots, and no fertilizer was applied. Poultry litter application resulted in higher CO2 emission from soil compared with AN application regardless of tillage system. In 2003 and 2006, CT (4.39 and 3.40 mu mol m(-2) s(-1), respectively) and MT (4.17 and 3.39 mu mol m(-2) s(-1), respectively) with, PL at 100 kg N ha(-1) (100 PLN) recorded significantly higher CO2 efflux compared with NT with 100 PLN (2.84 and 2.47 mu mol m(-2) s(-1), respectively). Total soil C at 0- to 15-cm depth was not affected by tillage but significantly increased with PL application and winter rye cover cropping. In general, cotton, produced with NT conservation tillage in conjunction with PL and winter rye cover cropping reduced CO2 emissions and sequestered more soil C compared with control treatments.
  • Authors:
    • Dhuyvetter, K. C.
    • Staggenborg, S. A.
    • Gordon, W. B.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 6
  • Year: 2008
  • Summary: Grain sorghum [ Sorghum bicolor (L.) Moench] is often grown where water stress is expected. But, improved drought tolerance in corn ( Zea mays L.) hybrids has resulted in increased dryland corn production in preference to grain sorghum. However, grain sorghum may still have a yield advantage over corn in drought prone environments. This study was conducted to determine if grain sorghum has either a yield or economic advantage over corn when drought or temperature stress occurs. Yield and weather data from crop performance testing programs in Kansas and Nebraska (1992-2005) were analyzed. Grain sorghum produced higher yields than corn in environments where corn yields were <6.4 Mg ha -1. When net returns ($ ha -1) were considered for grain sorghum prices that were set at 70, 87, 100, and 117% of corn prices, grain sorghum net returns were higher than corn net returns when corn yields were ≤4.4, 6.6, 8.8, and 13.6 Mg ha -1, respectively. Both corn and grain sorghum yields were positively correlated to June through August precipitation and negatively correlated to June through August maximum temperatures. The yield difference (grain sorghum minus corn) increased as July and August maximum temperatures increased. Monthly minimum temperatures affected corn yield less than grain sorghum yield. Producers in this region likely can minimize production risks by considering this historical yield information. At locations in this region where corn yields are consistently <6.4 Mg ha -1, producers should consider producing grain sorghum.
  • Authors:
    • Egbert, S. L.
    • Wardlow, B. D.
  • Source: Remote Sensing of Environment
  • Volume: 112
  • Issue: 3
  • Year: 2008
  • Summary: Improved and up-to-date land use/land cover (LULC) data sets that classify specific crop types and associated land use practices are needed over intensively cropped regions such as the U.S. Central Great Plains, to support science and policy applications focused on understanding the role and response of the agricultural sector to environmental change issues. The Moderate Resolution Imaging Spectroradiometer (MODIS) holds considerable promise for detailed, large-area crop-related LULC mapping in this region given its global coverage, unique combination of spatial, spectral, and temporal resolutions, and the cost-free status of its data. The objective of this research was to evaluate the applicability of time-series MODIS 250 m normalized difference vegetation index (NDVI) data for large-area crop-related LULC mapping over the U.S. Central Great Plains. A hierarchical crop mapping protocol, which applied a decision tree classifier to multi-temporal NDVI data collected over the growing season, was tested for the state of Kansas. The hierarchical classification approach produced a series of four crop-related LULC maps that progressively classified: (1) crop/non-crop, (2) general crop types (alfalfa, summer crops, winter wheat, and fallow), (3) specific summer crop types (corn, sorghum, and soybeans), and (4) irrigated/non-irrigated crops. A series of quantitative and qualitative assessments were made at the state and sub-state levels to evaluate the overall map quality and highlight areas of misclassification for each map. The series of MODIS NDVI-derived crop maps generally had classification accuracies greater than 80%. Overall accuracies ranged from 94% for the general crop map to 84% for the summer crop map. The state-level crop patterns classified in the maps were consistent with the general cropping patterns across Kansas. The classified crop areas were usually within 1-5% of the USDA reported crop area for most classes. Sub-state comparisons found the areal discrepancies for most classes to be relatively minor throughout the state. In eastern Kansas, some small cropland areas could not be resolved at MODIS' 250 m resolution and led to an underclassification of cropland in the crop/non-crop map, which was propagated to the subsequent crop classifications. Notable regional areal differences in crop area were also found for a few selected crop classes and locations that were related to climate factors (i.e., omission of marginal, dryland cropped areas and the underclassification of irrigated crops in western Kansas), localized precipitation patterns (overclassification of irrigated crops in northeast Kansas), and specific cropping practices (double cropping in southeast Kansas).
  • Authors:
    • Scudamore, K.
  • Source: World Mycotoxin Journal
  • Volume: 1
  • Issue: 3
  • Year: 2008
  • Summary: The cereal food chain covers events from the sowing of the seed until the point of ingestion of a food by the consumer. Mycotoxins may develop prior to harvest or through inadequate storage. Most mycotoxins are inherently stable natural chemicals but cleaning, milling and different methods of processing can change their concentrations. Legislation is necessary to protect the consumer so it is important to consider, among other things, the relationship between concentrations of mycotoxins in the raw grains and those in the product purchased by the consumer, especially where different limits are specified at successive stages in manufacture. Recent studies of the fate of fusarium mycotoxins in the cereal food chain carried out alongside industry in the UK have examined changes in the concentrations of deoxynivalenol, nivalenol, T-2 toxin, HT-2 toxin and zearalenone in wheat, maize and oats and the fumonisin mycotoxins in maize at key stages in the cereal chain. For example, fumonisin concentrations in maize grits after milling were reduced by about 75% compared with the raw maize, but remained similar to the maize in the flour and were increased (*3 to *5) in the bran and meal. Maize flour and grits were then processed into a range of food products such as breakfast cereals, cornflakes, extruded snack products and tortillas and the changes in concentrations were established. Simple extrusion of flour or grits reduced fumonisins by a further 30-70% depending on the process. Deoxynivalenol and zearalenone were found to be more stable than fumonisins during most processes.
  • Authors:
    • Carter,D.
    • L.,Barton
    • Biswas,W. K.
  • Source: Water and Environment Journal
  • Volume: 22
  • Issue: 3
  • Year: 2008
  • Authors:
    • Naylor,T.
    • Macdonald,B. C. T.
    • Denmead,O. T.
    • Wilson,S.
    • White,I.
    • Moody,P.
    • Griffith,D. W. T.
    • Salter,B.
    • Wang, T.
  • Source: Proceedings of the 2008 Conference of the Australian Society of Sugar Cane Technologists
  • Volume: 30
  • Year: 2008
  • Authors:
    • Baigent, R.
    • Kelly, K. B.
    • Phillips, F. A.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 48
  • Year: 2008
  • Authors:
    • Barton, L.
    • Kiese, R.
    • Gatter, D.
    • Butterbach-Bahl, K.
    • Buck, R.
    • Hinz, C.
    • Murphy, D. V.
  • Source: Global Change Biology
  • Volume: 14
  • Issue: 1
  • Year: 2008
  • Summary: Understanding nitrous oxide (N2O) emissions from agricultural soils in semi-arid regions is required to better understand global terrestrial N2O losses. Nitrous oxide emissions were measured from a rain-fed, cropped soil in a semi-arid region of south-western Australia for one year on a sub-daily basis. The site included N-fertilized (100 kg N ha−1 yr−1) and nonfertilized plots. Emissions were measured using soil chambers connected to a fully automated system that measured N2O using gas chromatography. Daily N2O emissions were low (−1.8 to 7.3 g N2O-N ha−1 day−1) and culminated in an annual loss of 0.11 kg N2O-N ha−1 from N-fertilized soil and 0.09 kg N2O-N ha−1 from nonfertilized soil. Over half (55%) the annual N2O emission occurred from both N treatments when the soil was fallow, following a series of summer rainfall events. At this time of the year, conditions were conducive for soil microbial N2O production: elevated soil water content, available N, soil temperatures generally >25 °C and no active plant growth. The proportion of N fertilizer emitted as N2O in 1 year, after correction for the ‘background’ emission (no N fertilizer applied), was 0.02%. The emission factor reported in this study was 60 times lower than the IPCC default value for the application of synthetic fertilizers to land (1.25%), suggesting that the default may not be suitable for cropped soils in semi-arid regions. Applying N fertilizer did not significantly increase the annual N2O emission, demonstrating that a proportion of N2O emitted from agricultural soils may not be directly derived from the application of N fertilizer. ‘Background’ emissions, resulting from other agricultural practices, need to be accounted for if we are to fully assess the impact of agriculture in semi-arid regions on global terrestrial N2O emissions.