• Authors:
    • Qin, Y.
    • Li Fengmin
    • Li, Y.
    • Xiang, S.
    • Cao, X.
    • Wu, T.
  • Source: Dryland crop production: technology breakthroughs and study cases
  • Year: 2007
  • Summary: Fertilization according to soil hydraulic conditions, fertilization in balance of nutrition and fertilization with nutrient use efficiency and sustainability are reestablished as the principles of fertility management in dryland area on the Loess Plateau according to the natural conditions and soil properties. Corresponding techniques to the principles are reviewed and represented in the paper.
  • Authors:
    • Castillo Gonzalez, F.
    • Perez Olvera, M. A.
    • Navarro Garza, H.
  • Source: Revista Fitotecnia Mexicana
  • Volume: 30
  • Issue: 2
  • Year: 2007
  • Summary: In this study we compared the plant coverage ability and main agronomic characteristics of five plant species in Nonoalco (2250 masl) and Ixayoc (2500 masl) in north eastern State of Mexico. The populations were: Scarlet runner bean ( Phaseolus coccineus), two faba bean varieties ( Vicia faba, var 'Purepecha' and 'V-35'), common vetch ( Vicia sativa), and oat ( Avena sativa var 'Saia'), in an experimental design in random blocks with three replications, in 6*4 m experimental plots. The scarlet runner and faba beans were planted in rows, while the vetch and oat were thrown sowed. The main variables evaluated were: percentage of area coverage and plant height, on four dates; biomass production at 70 d and at harvest, and grain yield. The results showed differences among populations in ground coverage and agronomic characteristics. Oat and vetch had the best ground cover in both sites. Oat showed the highest growth in both sites, and vetch had the second best behavior. The 'Purepecha' faba bean showed the lowest growth in both sites. The highest production of biomass for all populations in both periods, were obtained in Nonoalco because of its physical-chemical soil characteristics.
  • Authors:
    • Marais, G. F.
    • Pakendorf, K. W.
    • Pretorius, Z. A.
    • Prins, R.
    • Komen, J. S.
  • Source: Australian Journal of Agricultural Research
  • Volume: 58
  • Issue: 6
  • Year: 2007
  • Summary: The cultivation of small grain cereals was introduced to South Africa by Dutch settlers in the 17th Century. According to historical records the first documented epidemic of wheat stem rust occurred in the south-western parts of the current Western Cape in 1726. Recurring stem and leaf rust epidemics were associated with expanding wheat production and became particularly severe in the winter-rainfall regions of the Western and Eastern Cape, as well as in the summer-rainfall regions of the Free State. The wheat stripe rust pathogen was first detected in South Africa in 1996. Due to susceptibility of cultivars at the time of this exotic introduction, stripe rust has caused significant losses in commercial wheat production over the past 10 years. Pathotype surveys of Puccinia graminis and P. triticina were initiated in the 1920s, but were discontinued until research on wheat stem rust was resumed in the 1960s. Recent evidence has shown that P. graminis f. sp. tritici continues to evolve. In addition, the annual number of wheat stem rust collections is increasing, emphasising the sustained threat of this damaging pathogen. A stem rust pathotype first detected in 2000, with newly acquired virulence for Sr8b and Sr38, currently constitutes more than 80% of all collections. Leaf and stem rust diseases also occur on barley, oat, triticale, and rye and are important production constraints in several regions. Some studies have described variability in these pathogens but long-term records of pathogenicity changes in barley and oat rust are not available. Cereal rust diseases have clearly played an important role in South African agriculture and many production regions remain favourable for rust development. Current expertise in cereal rusts covers most technologies necessary to study the respective host-pathogen systems. However, a general lack of capacity and fragmentation of research groups prevent a unified approach and remain a challenge for sustainable cereal rust control in South Africa. A national strategy for cereal rust control, with particular emphasis on pathogen and host resources, and breeding for resistance, is urgently needed.
  • Authors:
    • Chauhan, S. K.
    • Baljit, S.
    • Saralch, H. S.
  • Source: Agroforestry: systems and practices
  • Year: 2007
  • Summary: Punjab is the richest state in the country in term of per capita income and has earned the name as food bowl of the country by putting 84-85 per cent of its geographical area under highly intensive, technical and mechanical agriculture with cropping intensity as high as 185 per cent and contributing more than one third of rice and half of its wheat production to the central pool of food reserve. The food grain production in the state has increased approximately twelve times in a span of about 50 years after independence from 20 lac tones in 1950-51 to 234.89 lakh tonnes in 2002-2003. Achieving this high productivity without caring for natural resources has resulted in a considerable loss in the inherent production potential and deterioration of soil health. As a result, man is getting serious warning signals in the form of lowering of water table, drought, high rate of environmental pollution, extremes of climatic parameters, etc. Agriculture in the state has become too intensive, wasteful and reckless and the radical changes are required to maintain the balance. Therefore, there is a strong thinking to diversify farming in the state to maintain the sustainability of the whole system. The state government is stressing hard to save the natural resources through the diversification in traditional crop rotation and adopt resource-conserving measures. With the introduction of fast growing multipurpose tree species in Punjab during sixties, agroforestry has been recognized as a sustainable system of high potential to boost the state's meager forest resources and to check the further degradation of natural resources. Highly productive block planting of poplar intercropped with wheat, sugarcane, turmeric, oats, berseem, mustard, medicinal plants, seasonal flowers, vegetables, etc. has become popular in irrigated tracts of the state. Boundary planting of eucalypts in the wheat- paddy cropping system and scattered trees of kikar, khair, shisham, dek, etc. on cultivated lands under rainfed conditions, especially in the sub-montane foot hill zone, play an important role in soil conservation and boosting the socio-economic status of the farmers. These tree species have inherent potential of increasing the productivity of problematic lands of the state. Therefore, the diversion of farmlands towards agroforestry will not only increase tree cover but also achieve the desired objective of National Forest Policy-1988 and conserve the precious natural resources like ground water, soil, biodiversity, etc. and prove to be a viable alternative sustainable land use system, which is renewable and eco-friendly as compared to sole agricultural crops in the years to come. The profitability of tree plantations on farmers' fields will further improve with the implementation of trading of carbon credits under Kyoto Protocol.
  • Authors:
    • Lares, M. T.
    • Liebig, M. A.
    • Merrill, S. D.
    • Tanaka, D. L.
    • Krupinsky, J. M.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Crop sequence is an important management practice that may lower the risk for leaf spot diseases of spring wheat ( Triticum aestivum L.). Field research was conducted near Mandan, ND, to determine the impact of crop sequences on leaf spot diseases of hard red spring wheat early in the growing season. Spring wheat was evaluated for disease severity following crop sequence combinations of 10 crops [buckwheat ( Fagopyrum esculentum Moench)], canola ( Brassica napus L.), chickpea ( Cicer arietinum L.), corn ( Zea mays L.), dry pea ( Pisum sativum L.), grain sorghum [ Sorghum bicolor (L.) Moench], lentil ( Lens culinaris Medik.), oil seed sunflower ( Helianthus annuus L.), proso millet ( Panicum miliaceum L.), and hard red spring wheat. Spring wheat leaves with distinct lesions were collected for determination of lesion number and percentage necrosis data, which were used to estimate leaf spot disease severity. Pyrenophora tritici-repentis (Died.) Drechs., the cause of tan spot, and Phaeosphaeria nodorum (E. Muller) Hedjaroude, the cause of Stagonospora nodorum blotch, were the major leaf spot diseases and consistently present throughout the growing season. The frequency of isolation following alternative crops was generally lower compared with spring wheat following wheat. Leaf spot diseases on spring wheat were impacted by crop sequencing. Spring wheat following crop sequences with alternative crops for 1 or 2 yr had lower levels of disease severity compared with a continuous spring wheat treatment early in the growing season. Disease severity was apparently not related to the percentage of crop residue coverage on the soil surface associated with various crop sequence combinations. New alternative crops preceding spring wheat reduce levels of leaf spot diseases.
  • Authors:
    • Ascough, J. C.,II
    • McMaster, G. S.
    • Andales, A. A.
    • Hansen, N. C.
    • Sherrod, L. A.
  • Source: Transactions of the ASABE
  • Volume: 50
  • Issue: 5
  • Year: 2007
  • Summary: Alternative agricultural management systems in the semi-arid Great Plains are receiving increasing attention. GPFARM is a farm/ranch decision support system (DSS) designed to assist in strategic management planning for land units from the field to the whole-farm level. This study evaluated the regional applicability and efficacy of GPFARM based on simulation model performance for dry mass grain yield, total soil profile water content, crop residue, and total soil profile residual NO 3-N across a range of dryland no-till experimental sites in eastern Colorado, USA. Field data were collected from 1987 through 1999 from an on-going, long-term experiment at three locations in eastern Colorado along a gradient of low (Sterling), medium (Stratton), and high (Walsh) potential evapotranspiration. Simulated crop alternatives were winter wheat ( Triticum aestivum), maize ( Zea mays), sorghum ( Sorghum bicolor), proso millet ( Panicum miliaceum), and fallow. Relative error (RE) of simulated mean, root mean square error (RMSE), and index of agreement (d) model evaluation statistics were calculated to compare modelled results to measured data. A one-way, fixed-effect ANOVA was also performed to determine differences among experimental locations. GPFARM simulated versus observed REs ranged from -3 to 35% for crop yield, 6 to 8% for total soil profile water content, -4 to 32% for crop residue, and -7 to -25% for total soil profile residual NO 3-N. For trend analysis (magnitudes and location differences), GPFARM simulations generally agreed with observed trends and showed that the model was able to simulate location differences for the majority of model output responses. GPFARM appears to be adequate for use in strategic planning of alternative cropping systems across eastern Colorado dryland locations; however, further improvements in the crop growth and environmental components of the simulation model (including improved parameterization) would improve its applicability for short-term tactical planning scenarios.
  • Authors:
    • Han, X.
    • Liu, P.
    • Li, L.
    • Huang, J.
    • Sun, O.
    • Zhou, Z.
  • Source: Biogeochemistry
  • Volume: 82
  • Issue: 2
  • Year: 2007
  • Summary: Equilibrium carbon stock is the result of a balance between inputs and outflows to the pool. Changes in land-use are likely to alter such balance, resulting in different carbon stores under different land-use types in addition to the impacts of global climate change. In an agro-pastoral ecotone of Inner Mongolia, northern China, we investigated productivity and belowground carbon and nitrogen stores under six different types of land-uses, namely free grazing (FG), grazing exclusion (GE), mowing (MW), corn plantation (CP), fallow (FL), and alfalfa pasture (AP), and their impacts on litter and fine roots in semiarid grassland ecosystems. We found that there were great variations in aboveground net primary production (ANPP) across the six land-use types, with CP having markedly high ANPP; the FG had significantly reduced soil organic carbon (SOC) and nitrogen stores (SON) to 100 cm depth compared with all other types of land uses, while very little litter accumulation was found on sites of the FG and CP. The top 20 cm of soils accounted for about 80% of the root carbon and nitrogen, with very little roots being found below 50 cm. About 60% of SOC and SON were stored in the top 30 cm layer. Land-use change altered the inputs of organic matters, thus affecting SOC and SON stores accordingly; the MW and GE sites had 59 and 56% more SOC and 61% more SON than the FG. Our estimation suggested that restoring severely degraded and overgrazed grasslands could potentially increase SOC and SON stores by more than 55%; conversion from the native grasses to alfalfa could potentially double the aboveground biomass production, and further increase SOC and SON stores by more than 20%. Our study demonstrated significant carbon and nitrogen storage potential of the agro-pastoral ecotone of northern China through land-use changes and improved management in the context of mitigating global climate change.
  • Authors:
    • Grace,P.
  • Source: Healthy Soils Symposium
  • Year: 2007
  • Authors:
    • Grace, P.
    • Rochester, I.
    • Crothers, B.
    • Chen, D.
    • Weier, K.
    • Rowlings, D.
    • Kiese, R.
    • Butterbach-Bahl, K.
    • Li, Y.
  • Source: Non-CO2 Greenhouse Gas Fluxes in Australian-New Zealand Landscapes
  • Year: 2007
  • Authors:
    • Grace, P.
    • Rowlings, D.
    • Peterson, N.
    • Weier, K.
    • Kiese, R.
    • Butterbach-Bahl, K.
  • Source: Non-CO2 Greenhouse Gas Fluxes in Australian-New Zealand Landscapes
  • Year: 2007