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    Towards an early warning system for wheat blast: epidemiological basis and model development
    (2021-07-26) Fernandes, J.M.; E.M. del Ponte; J.P. Ascari; T.J. Krupnik; Willingthon Pavan; F. Vargas; T. Berton
    Wheat blast is caused by the fungus Pyricularia oryzae Triticum pathotype (PoT). Significantly damaging wheat blast epidemics are sporadic and limited to tropical wheat growing areas in South America. Unexpectedly, wheat blast was reported in Bangladesh and Zambia in 2016 and 2020, respectively. The urgent need to deal with a poorly studied disease has mobilized the scientific community. Original research and reviews have been published in various venues. Nevertheless, disease control is still a difficult task. Much less research has, however, focused on crucially important and complex ecological interactions at the field, landscape, or regional levels. This chapter reviews aspects of the epidemiology of wheat blast, mainly those related to inoculum and its role for the epidemics. It then describes the models that have been developed by the authors as well as the decision support system. Examples of the implementation of a warning system in Bangladesh and Brazil are also illustrated.
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    Floodwater ammonium, nitrogen use efficiency and rice yields with fertilizer deep placement and alternate wetting and drying under triple rice cropping systems
    (2016-01-08) Azmul Huda; Yam Kanta Gaihre; Md. Rafiqul Islam ; Upendra Singh; M. R. Islam; Joaquin Sanabria; M. Abdus Satter; Hasina Afroz; Alee Halder; M. Jahiruddin
    Fertilizer management should consider optimum time, rates and methods of application to increase use efficiency and crop yield. We conducted field experiments at Bangladesh Agricultural University, Bangladesh, to investigate the effects of deep placement of urea briquettes (UB) and NPK briquettes (NPK) compared to broadcast prilled urea (PU) at different N rates on dynamics of floodwater NH4 ?-N, ammonia (NH3) volatilization, rice yield and nitrogen use efficiency (NUE) during four consecutive rice-growing seasons in 2012–2013. The floodwater NH4 ?-N and NH3 volatilization in broadcast PU increased with N rates, while in deep-placed treatments irrespective of N rates it was similar to the control. Across seasons and water regime, UB or NPK significantly (P\0.05) increased grain yield and nitrogen recovery compared to broadcast PU. During the Boro season (across water regime), UB78 and NPK78 increased grain yield by 40 and 29 %, respectively, compared to broadcast PU78, while N recovery increased from 35 % of PU to 63–67 % in deep placement. Deep placement of UB52 or NPK52 during Aus–Aman and UB78 or NPK78 during Boro can be one of the best N management options for increasing NUE and crop yield. Alternate wetting and drying irrigation, though, had no significant effect on grain yield or on NUE. Its adoption could save irrigation water without any yield reduction during the Boro season. However, more studies across different soils, climate and management practices are needed for further understanding the interactive effects of fertilizer and water management on yield, NUE and soil fertility.
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    Measuring Agricultural and Structural Transformation
    (2017) Anwar Naseem; James F Oehmke; Jock R. Anderson; Samba Mbaye; Carl E. Pray; Latha Nagarajan; Charles B Moss; Lori A Post
    Over the past three decades, substantial progress has been made in reducing poverty and hunger globally, primarily through structural transformations of economies transitioning from subsistence agriculture to wage employment in manufacturing and services. However, this transformation has been uneven, with Africa facing challenges in achieving similar outcomes. This paper explores the dynamics of contemporary structural transformation, focusing on various attributes that shape the process, such as economic, demographic, agricultural, social, political, ecological, and temporal factors. It highlights the need for a more nuanced understanding of structural transformation in today's context and presents empirical analyses, including cross-country assessments and sub-national case studies, to shed light on the evolving nature of this transformation. The paper also discusses the changing employment patterns and sectoral shifts, emphasizing the growing importance of rural nonfarm employment and the role of agriculture in inclusive growth. Ultimately, it provides a comprehensive perspective on the complexities of contemporary structural transformation and its implications for policy analysis and development strategies.
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    Nitrogen use efficiency, crop productivity and environmental impacts of urea deep placement in lowland rice fields
    (2016-12) Yam Kanta Gaihre; Upendra Singh; Azmul Huda; S. M. Mofijul Islam ; M. Rafiqul Islam; Jatish Chandra Biswas; Josh DeWald
    Nitrogen (N) fertilization is critical for cereal production; however, its low use efficiency poses both economic and environmental concerns. Urea deep placement (UDP) in lowland rice fields is one of the best currently applicable management techniques to increase N use efficiency (NUE) and crop productivity. Multi-location experiments conducted in Bangladesh in 2014-2015 have demonstrated several benefits of UDP use including reduced N losses through ammonia volatilization and greenhouse gas nitrous oxide (N2O) and nitric oxide (NO) emissions. Nitrogen loss as N2O and NO emissions were measured continuously throughout rice-growing and fallow seasons using an automated gas sampling and analysis system. Across the years and sites, UDP increased yield on average by 21% as compared to broadcast urea while using at least 25% less fertilizer. UDP reduced floodwater ammonium and ammonia volatilization similar to the control (N0) treatment, while both were significantly higher in broadcast urea treatments. UDP reduced N2O emissions by up to 80% as compared to broadcast urea under continuous flooded (CF) conditions. The effects of UDP on N2O emissions under alternate wetting and drying (AWD) irrigation practices were site specific: depending on the duration and intensity of soil drying, emissions were reduced under mild soil drying but increased with more intense soil drying. These results confirm that UDP not only increases NUE and grain yields but also reduces negative environmental impacts including N2O emissions.
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    Changes of Soil Microbial Population and Structure Under Short-term Application of an Organically Enhanced Nitrogen Fertilizer
    (2016) Winings John H.; Yin Xinhua; Sampson Agyin-Birikorang; Upendra Singh ; Joaquin Sanabria ; Savoy Hubert J.; Allen Fred L.; Saxton Arnold M.; DeForest Jared L
    Interest in the use of alternate fertilizers has increased during recent years to improve soil productivity. An organically enhanced N fertilizer, containing 14.9% N, 4.3% P2O5, 18.1% S, 0.6% Fe, and 8% organic C, and is produced from a sterilized organic additive extracted from municipal wastewater biosolids and chemical fertilizers was evaluated for its effects on soil microbial populations and abundances in 0- to 15-cm depth of of two silt loam soils located at Jackson and Grand Junction, Tennessee. This treatment was compared to conventional N fertilizers and zero N control under nonirrigated corn (Zea mays L.) from 2011 to 2013. Three N-applied treatments (organically enhanced N fertilizer, ammonium sulfate, urea/NPKZn briquette) at 128/170 kg ha −1 and the zero N control were imposed at each location. The organically enhanced N fertilizer decreased the relative abundance of arbuscular mycorrhizal fungi but increased that of general microbes relative to the zero N control and increased that of general microbes compared with NPKZn briquette 4 to 7 months after their applications at an N rate of 128 kg ha −1 for corn within 2 years of experimentation on a relatively infertile soil with low organic matter. Soil general microbes and arbuscular mycorrhizal fungi were the two sensitive indicators of soil microbial structure response to fertilization. However, effects of the organically enhanced N fertilizer on soil microbial populations were not noticeable after corn harvest. In conclusion, application of the organically enhanced N fertilizer has noticeable influence on soil microbial structure/abundance but not on populations on relatively infertile soils with low organic matter from a short-term perspective.