57 research outputs found
Adopting yield-improving practices to meet maize demand in Sub-Saharan Africa without cropland expansion
No full textMaize demand in Sub-Saharan Africa is expected to increase 2.3 times during the next 30 years driven by demographic and dietary changes. Over the past two decades, the area cropped with maize has expanded by 17 million hectares in the region, with limited yield increase. Following this trend could potentially result in further maize cropland expansion and the need for imports to satisfy domestic demand. Here, we use data collected from 14,773 smallholder fields in the region to identify agronomic practices that can improve farm yield gains. We find that agronomic practices related to cultivar selection, and nutrient, pest, and crop management can double on-farm yields and provide an additional 82 million tons of maize within current cropped area. Research and development investments should be oriented towards agricultural practices with proven capacity to raise maize yields in the region.EEA BalcarceFil: Aramburu Merlos, Fernando. University of Nebraska-Lincoln. Department of Agronomy and Horticulture; Estados UnidosFil: Aramburu Merlos, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Tenorio, Fátima. University of Nebraska-Lincoln. Department of Agronomy and Horticulture; Estados UnidosFil: Mashingaidze, Nester. One Acre Fund; KeniaFil: Sananka, Alex. One Acre Fund; KeniaFil: Aston, Stephen. One Acre Fund; KeniaFil: Ojeda, Jonathan. Regrow Ag; AustraliaFil: Grassini, Patricio. University of Nebraska-Lincoln. Department of Agronomy and Horticulture; Estados Unido
Weed growth and crop yield responses to tillage and mulching under different crop rotation sequences in semi-arid conditions
No full textConservation agriculture (CA) is thought to reduce weed pressure from the third year of adoption, when recommended practices are followed. Weed growth and crop yield were assessed during the third and fourth year of maize–cowpea–sorghum rotation, second and third year of maize–cowpea rotation and first and second year of maize monocropping on a clay loam soil at Matopos Research Station (annual rainfall, 573 mm) following recommended CA management practices. Each experiment had a split-plot randomized complete block design with mouldboard plough (CONV), minimum tillage (MT) with ripper tine and planting basins as main-plot factor and maize residue mulch rate (0, 2 and 4 t/ha) as a subplot factor, with threefold replication. All subplots were surface mulched and weeded by hoe at the same time. We hypothesized that under MT weed growth would be considerable with maize monocropping but from year 3 of CA, weed growth would decrease and crop yield increase relative to values from unmulched CONV. Minimum tillage increased weed growth in 2nd year of maize monocropping. Under the maize–cowpea rotation, the considerable weed growth in planting basins was likely due to the large intrarow spacing and poor light competiveness of the cowpea variety. Mulch contributed to weed growth being suppressed by up to 36% under CA in the maize–cowpea–sorghum rotation relative to unmulched CONV. When planted on the same date, crop yield did not differ between CA and unmulched CONV. Maize–cowpea–sorghum rotation grain yield (3143 kg/ha) was double that under monocropping, probably due to improvements in soil physical and chemical conditions
Weed dynamics in low-input dryland smallholder conservation agriculture systems in semi-arid Zimbabwe
No full textThesis (PhD)--University of Pretoria, 2013.The reported requirement for a higher weeding effort due to increased weed infestations under conservation agriculture (CA) relative to conventional mouldboard plough tillage is perceived by both smallholder farmers and extension workers as the main limiting factor to the widespread adoption of CA by smallholder farmers in southern Africa. However, proponents of CA argue that weeds are only a problem under CA in the initial two years and decline afterwards resulting in reduced labour requirements for weeding under CA. They further posit that weeds are only major problem where minimum tillage (MT) is adopted without crop residue mulching and diverse crop rotations. This thesis explores the effect of time under CA on weed population dynamics and crop growth under the recommended CA practices and actual smallholder farmer practice in semi-arid Zimbabwe. Assessment of weed and crop growth on a long-term CA experiment at Matopos Research Station revealed that the MT systems of planting basins and ripper tine were associated with higher early season weed density and biomass than conventional early summer mouldboard tillage (CONV) in both the fifth (cowpea phase) and sixth (sorghum phase) years of CA. This increased weed infestation within the first four weeks after planting in CA necessitated early weeding to provide a clean seedbed and avert significant crop yield loss. Maize mulching only suppressed early season weed growth in sorghum mostly at a mulch rate of 8 t ha-1 which is not a mulching rate that is attainable on most smallholder farms. However, the lower maize residue mulch rate of 4 t ha-1 was consistently associated with increased weed emergence and growth as from the middle of the cropping season in both crop species. The increased weed infestations under the mulch were probably due to the creation of ‘safe sites’ with moist conditions and moderate temperatures. The high weed growth under the mulch contributed to the low sorghum grain yield obtained under mulched plots. In addition, maize mulching was also associated with a less diverse weed community that was dominated by the competitive Setaria spp. and difficult to hoe weed Eleusine indica (L.) Gaertn. However, the weed community under CA was similar to that under CONV tillage with no evidence of a shift to the more difficult to control weed species. The increased early season weed growth and high weed pressure under CA meant that it was still necessary to hoe weed four times within the cropping season to reduce weed infestations and improve crop growth even after four years of recommended CA practices. Early and frequent weeding was effective in reducing weed growth of most species including Setaria spp. and E. indica demonstrating that on smallholder farms where labour is available hoe weeding can provide adequate weed control. The wider spacing recommended for use in CA contributed to the low cowpea and sorghum grain yields obtained under CA compared to CONV tillage. On smallholder farms in Masvingo District, the MT system of planting basin (PB) was the only conservation farming (CF) component adopted by farmers. There was no difference in the total seedling density of the soil weed seed bank and density of emerged weeds in the field in PB and conventional mouldboard ploughing done at first effective rains (CONV tillage). However, the first weeding in PB was done at least 15 days earlier (P < 0.05) than in CONV tillage suggesting high early season weed growth in PB relative to CONV tillage. As weed density did not decline with time in PB, weed management did not differ with increase in years under PB. Shortage of inputs such as seed and fertiliser was identified by smallholder farmers as the most limiting factor in PB crop production with the area under PB was equivalent to the seed and fertiliser provided by CARE International for most farmers. On this small area, weeds could be managed by available family labour. Double the maize grain yield was obtained in PB (mean: 2856 kg ha-1) due to improved weed management and soil fertility. However, the use of poorly stored composts was found to introduce weeds into some PB fields. The findings of this study demonstrated that weed pressure was still high and weed management were still a challenge under the practice recommended to smallholder farmers in Zimbabwe even in the sixth year of practice. There is, therefore, a need for research on the economic feasibility of using herbicides, intercropping and optimal crop density to ameliorate the high weed pressure under CA.Plant Production and Soil Scienceunrestricte
Keywords, Trademarks, and the Gray Market: Why the Use is Not Fair
No full textThis Comment analyzes the escalating effects of Internet banner ads and gray marketers on trademark owners\u27 ability to control the use and sale of their marks as keywords and metatags. To unify these concepts, Ms. Nester utilizes the facts behind a suit filed by Estee Lauder, Inc. against an Internet fragrance retailer and an Internet search engine. The suit alleged trademark infringement and unfair competition, among other things, for the Internet entities\u27 unauthorized uses of Estee Lauder\u27s registered trademarks in fragrances. The author explores the facilitating and enabling effect of the Internet on gray market, or parallel importation, activity, such as the Internet retailer\u27s avoidance of substantial costs of operation and advertisement. In sum, Nester argues that the use and sale of keywords that trigger banner ads on the Internet enable gray marketers to unfairly profit off the good will of trademark owners and that such acts should be exempt from fair use and constitute trademark infringement. Moreover, these unauthorized activities are likely to cause consumer confusion, which in turn could lead to damage of marks\u27 good will
Origin of mantle eclogites from the Catoca pipe (Kasai Craton, Western Africa): three eclogite lithologies from two layers of oceanic crust
No full textResearch Data associated with the article "Origin of mantle eclogites from the Catoca pipe (Kasai Craton, Western Africa): three eclogite lithologies from two layers of oceanic crust" by Korolev N., Nikitina L.P., Goncharov A., Dubinina E.O., Melnik A., Müller D., Chen Y.X., Zinchenko V.N. (2019). The article submitted to Geochimica et Cosmochimica Acta (August 2019).
* Corresponding author N. Korolev
[email protected]
Response of weed flora to conservation agriculture systems and weeding intensity in semi-arid Zimbabwe
No full textA field study was conducted in the fifth (cowpea crop) and sixth (sorghum crop) seasons of a long-term conservation agriculture trial at Matopos Research Station to determine the effect of tillage, maize mulch rates and intensity of hoe weeding on weed density and community diversity. The experiment was a split-plot randomized complete block design with three replications. Tillage was the main plot factor; conventional tillage versus the minimum tillage (MT) systems of ripper tine and planting basins. Maize mulch rate (0, 4 and 8 t ha-1) was the sub-plot factor to which was super-imposed the intensity of hoe weeding treatment (low and high) as from the fifth season. Tillage system had no significant (P<0.05) effect on weed density and diversity. Whereas the maize mulch rate of 4 t ha-1 increased weed density in both crops, the mulch rate of 8 t ha-1 decreased the density of Portulaca oleracea and Corchorus tridens in sorghum. Weed density was lower and community diversity higher in the high than the low weeding intensity treatment in sorghum. Although, frequent hoe weeding can be used to control weeds in MT systems, labour shortages may ultimately limit the area under MT in smallholder agriculture.The Department for International Development of the United Kingdom (DFID-UK), the International Foundation for Science (IFS) and National Research Foundation (NRF, South Africa).http://www.academicjournals.org/AJA
Growth and Tolerance of Sesame (Sesamum indicum L.) Varieties to Pre and Postemergence Graminicides
No full textThe use of herbicides for weed control in arable crop production is known to be fast and effective. However, there is paucity of information on the safety of commonly used grass herbicides on emergence, growth, and productivity of sesame (Sesamum indicum L.) genotypes currently being grown in Zimbabwe. A study was carried out in Zimbabwe during the 2017/18 cropping season in Gokwe South to evaluate the effect of alachlor, metolachlor, propaquizafop, and fluazifop-p-butyl on seed germination, growth, and yield of three sesame genotypes, namely, IETC, Lind 02, and Ziada 94. A laboratory experiment was laid in a completely randomised design with genotype and herbicide type as the factors. Seed germination, radicle, and plumule length were recorded at the end of the experiment. In the pot studies, two separate experiments were carried out to evaluate the effect of pre and postemergence herbicides on 50% emergence, plant height, number of branches, 50% flowering, number of pods, and yield of three sesame genotypes. The laboratory experiment results revealed significant (p<0.05) interactions among varieties and preemergence graminicides for germination percentage, radicle length, plumule length, and germination vigor index. Alachlor and metolachlor differentially reduced all germination parameters in the sesame genotypes used in the study. In the preemergence pot studies, there were significant (p<0.05) interactions on 50% emergence, plant height, and number of branches but not on number of pods and yield. Metolachlor significantly reduced all the measured parameters in IETC and Ziada 94. In the postemergence pot study, propaquizafop significantly (p<0.05) reduced plant height, number of pods, and yield of sesame more than fluazifop-p-butyl and hand pulling. It can be concluded that metolachlor and propaquizafop are not safe for use in these sesame genotypes at dosage rates that were used in this study. There is need for further screening of more sesame genotypes for tolerance to these and other commonly used genotypes to avoid unintentional phytotoxic damage on sesame
Potential role of Conservation Agriculture in South Africa for carbon sequestration for climate mitigation : A provisional research agenda
No full textDuring a workshop and field visit in December 2019 in South Africa we discussed the Role soil C of Conservation Agriculture and carbon sequestration for climate mitigation. The insights of the workshop comprised of: (i) Integrating livestock into crop systems to achieve circularity, (ii) Economic and environmental sustainability is possible without subsidy, (iii) The transition towards sustainable farming can also be slow: Every step into the direction of sustainability if a good one, (iv) Vision and love for the land: a good farmer is a steward of the land; and (v) Ways to find hands-on local, but holistic solutions for every farm
The overview of online courses of russian as a foreign language
No full textIn this article the author describes in detail the online courses of Russian as a foreign language offered by leading Russian universities. The structure of the courses and the use of the English language as an interlanguage are analysed too. Referring to the researchers, the author draws conclusions about the effectiveness, importance and feasibility of using Internet technologies in teaching foreign languages
An applied statistician's creed
No full textHypothesis testing, as performed in the applied sciences, is criticized. Then assumptions that the author believes should be axiomatic in all statistical analyses are listed. These assumptions render many hypothesis tests superfluous. The author argues that the image of statisticians will not improve until the nexus between hypothesis testing and statistics is broken
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