Wind blown sediment mass budget of Sahelian village land units in Niger

2001 ◽  
Vol 172 (5) ◽  
pp. 523-531 ◽  
Author(s):  
Jean-Louis Rajot

Abstract To assess the mass budget of aeolian sediments transported by wind (erosion vs. deposition) at the scale of village land units (25 kmX25 km), measurements were carried out during 3 years (from 1996 to 1998) in a cultivated field and in a fallow area simultaneously. These were located in the Sahelian zone of Niger with an average annual rainfall of 560 mm. The vertical upward fluxes of particles <20 mu m exported from the study area were estimated from the horizontal sediment fluxes measured using BSNE sand catchers. This mass of exported dust was compared with the vertical downward fluxes of particles of the same size range (<20 mu m) measured using passive CAPYR collectors. Values of deposition recorded in the field and in the fallow were similar. In the field, wind erosion reached its maximum in May and June when the vegetation cover was minimal. In the fallow area, wind erosion was always very low in comparison with the field. It occurred during the strongest storms when the grass cover was minimal. Nevertheless, the net balance between deposition and erosion was highly positive in the fallow areas. These results have been extrapolated at the scale of the village land units based on the current land use. At this scale, the balance was positive for the arable land, indicating a net deposition of aeolian sediments of +0.36 t ha (super -1) yr (super -1) . However, the complete disappearance of fallow land would result in a balanced budget for the arable land.

Author(s):  
B.K. Cameron

THE PROPERTY to be discussed is a mixed sheep and cropping unit, situated ei ht a miles east of Ashburton and midway between the Ra aia and the Ashburton rivers. Average annual rainfall is 27 in., evenly spread, but there is very high summer evaporation and therefore frequent droughts. On average, the soil is below wilting point for 40 to 50 days each summer. Winters are cold with the soil temperature being below 48°F for about four months each year. The soil is a Lismore stony silt loam averaging 9 in. in depth over gravel.


2021 ◽  
Vol 16 (10) ◽  
pp. 102-110
Author(s):  
Vivek Chauhan ◽  
Sunita Devi ◽  
Sonaxi Sharma ◽  
Shamsher S. Kanwar

Carum carvi (Caraway) is a member of Apiaceae family which originated in Asia. Due to its economic importance, it is widely cultivated. Caraway is the only annual species, commonly present in arable land, moist meadows and on low lands to mountains. Caraway has different applications in pharmaceutical and food industries. Phytochemical screening of different medicinal plants is helpful in identifying new sources of industrially and therapeutically important compounds. In this study, Caraway obtained from forest surrounding the village Goherman, Lahaul and Spiti, Himachal Pradesh (India) was used. Seed extract of caraway extracted in methanol (MSE) and distilled water (WSE) was used for phytochemical analysis to determine the constituents of caraway seeds. Further, caraway seeds extract was checked for antibacterial activity [Staphylococcus aureus (ATCC 6538), Salmonella typhimurium (NCTC 74), Escherichia coli (ATCC 25922) and Staphylococcus epidermidis (ATCC 12228)], antioxidant activity and acid neutralizing activity. After analysing the results, it can be said that caraway seeds possess many medicinal properties and it can be used in enhancing human health.


2017 ◽  
Vol 68 (8) ◽  
pp. 781
Author(s):  
R. A. Culvenor ◽  
M. R. Norton ◽  
J. De Faveri

Perennial grasses have production and environmental benefits in areas of southern Australia typified by the mixed farming zone of southern New South Wales (NSW). The perennial grass phalaris (Phalaris aquatica L.) is widely used in southern Australia; however, it would find more use in the mixed farming zone if its persistence in marginal rainfall areas (450–500 mm average annual rainfall) were improved. We evaluated a range of germplasm (n = 29) including wild accessions, lines bred from these, and existing cultivars for persistence and production at three sites in a summer-dry area of southern NSW with 430–460-mm average annual rainfall. Two sites were used over 4 years and the third site over 5 years. Summer dormancy, maturity time and seedling growth were also assessed. Analysis of genotype × environment interaction employing factor analytic models and accounting for spatial and temporal correlations indicated that changes in persistence occurred mainly over time rather than between sites. Ranking changes occurred in the dry establishment phase of the experiment and during a severe final summer drought, with few changes occurring in the intervening high-rainfall years. Lines that survived the establishment phase best had vigorous seedlings and earlier maturity, whereas those surviving the final summer best were earlier maturing and higher in summer dormancy with high winter-growth activity. Some later maturing lines within the higher summer dormancy group were less persistent. Some accessions from North Africa were the most persistent; also, populations bred from these and other more persistent accessions generally persisted and produced better than cultivars used presently. However, present cultivars were capable of high yield in the higher rainfall years. We suggest that persistence of higher summer dormancy cultivars over very dry years could be improved by selecting for earlier maturity time.


Author(s):  
Abdul Wali Ahmed Al-Khulaidi ◽  
Abdul Habib Al-Qadasi ◽  
Othman Saad Saeed Al-Hawshabi

The study area is located on the South western mountains of Republic of Yemen, It is characterized by arid and semi-arid climate with high temperatures and low average annual rainfall. The aims of this study are to explore the natural plant species of one of the Important Plant areas of Arabian Peninsula and to evaluate the chance to be a protected area. 61 sample sites covering the whole ecological zones haven been conducted. 135 plant species are found, in which 3 plant species were endemic, 7 near endemic, 29 regional endemic. The study revealed also three vegetation communities with 7 vegetation associations (vegetation types). Vegetation dominated by Ficus cordata, F. sycomorus, Salvadora persica Tamarix aphylla and Ziziphus spina-christi were found on main wadis. Vegetation communities dominated by Acacia asak, Anisotes trisulcus, Jatropha variegate and Zygocarpum yemenense were found on rocky slopes and stony plateau.


2016 ◽  
Vol 24 (2) ◽  
pp. 1-6 ◽  
Author(s):  
Peter Ivan ◽  
Tatiana Chebeňová

Abstract Globally, the human population is growing, which causes increasing demands on landscapes. Human activity significantly influences the ecological balance, especially in the negative. Ecological stability is the basis for assessments of all environmental conditions and for assessments according to new land uses. The area of interest is evaluated according to both positive and negative factors. There are many methodologies for calculating ecological stability, e.g., Muchová et al. (2009); Řeháčková - Pauditšová (2007); Kupková (2002); Streďanský et al. (1995) and Löw et al. (1984). The aim of this paper is to compare the works of the mentioned authors concerning the ecological stability of the district of Levice (Slovakia), specifically in the municipal cadastre region of Bielovce. The land uses of this territory have changed during some periods. We compared the state of the land uses in the years 1950, 2012 and 2014. During this period, the proportion of arable land increased, and the proportion of forest decreased. In the area of interest, the ecological stability increased, but not as significantly as we expected. The processed data were prepared in GIS.


2013 ◽  
pp. 01
Author(s):  
João Batista Pereira Cabral ◽  
Valter Antonio Becegato ◽  
Francismário Ferreira dos Santos

The erosivity index (EI30) and its spatialization were determined for the contribution basins of the Cachoeira Dourada hydroelectric system reservoir, located between the states of Goiás and Minas Gerais and limited by coordinates 640000-760000 m W and 7910000-7975000 m N. Average monthly and annual rainfall data corresponding to eight localities and to a 30-year period were treated. It was observed that in this period the average annual rainfall was 1441 mm, the highest and lowest indexes having occurred respectively in January and July (7.5 mm). EI30 varied from 7100 to 8500 MJ mm (ha h)-1. The most representative period was October to March, corresponding to 7880.3 MJ mm (ha h)-1and 94% of the average annual EI30. The average rainfall variation coefficient for all stations was 82.73%. There is an irregular rainfall distribution in the region and consequently a non-uniform spatialization of the erosivity indexes within the influence area of the reservoir. The highest rainfall values coincide with the period of soil preparation and development of annual-cycle plants, mainly soybean and corn.


2015 ◽  
Vol 16 (1-2) ◽  
pp. 102-106
Author(s):  
A. P. Travleyev ◽  
V. A. Gorban

At the present time the great part of soils is exposed to various negative processes. One of the basic processes that lead to the degradation of soils in Ukraine is the erosion. According to the recent data, water and wind erosion covers 13.9 million hectares; it is about 33 % of the total arable land in the country. On this basis, the greater relevance belongs to the scientific studies displaying the features of negative phenomena of our soil, and, most importantly, the ways of solving of these urgent problems on the soil cover of Ukraine. The monograph «Soil erosion in Ukraine: the evolution of theory and practice» of such famous scientists in the field of Soil Erosion Science as Voloshchuk M. D., Petrenko N. I. and Yatsenko S. V. is one of such fundamental works. In the present monograph, considerable attention is paid to the periodization of the formation and development of the doctrine of soil erosion in Ukraine. The authors identify six basic stages of formation of the national Soil Erosion Science. The paper discusses the characteristic features of isolation of Soil Erosion Science as an independent scientific direction and a self-discipline, which are based on the works of such renowned scientists as P. S. Tregubov, M. N. Zaslavsky and G. I. Shvebs. A significant place in the monograph is devoted to the characteristics of the scientific centers of Ukraine, in which the Soil Erosion Science has been developed. These centers are distinguished by leading scientists, under the leadership of whom, the erosion processes have been studied. The authors of the monograph provides four main scientific centers of the country in the field of Soil Erosion Science development: National Scientific Centre «Institute of Agriculture of the National Academy of Agricultural Sciences» (central region), National Scientific Center «Institute for Soil Science and Agrochemistry Research named after O. N. Sokolovsky», Scientific-Technical Center «Fertility» (Kharkiv region), Odessa I. I. Mechnikov National University (south region), Lviv National Agrarian University, Institute of Ecology of the Carpathians of National Academy of Sciences of Ukraine, Ivan Franko National University of Lviv and others (west region). In addition to considering the features of the listed centers, in the work there is a presentation of a brief description of the project, research institutes, agricultural and agroforestry research stations that are active in a scientific work in relation to soil erosion processes. In the work, there are also the historical aspects and mechanisms for the further development of wind erosion researches. Considerable attention the authors of the monograph pay to the analysis of the current state, challenges and prospects of solving the problem on protecting the soil from erosion. The main problem of the country's soil, which is the cause of widespread erosion, is a very high agricultural development of the territory, more than half of which falls onto an arable land. At the end of the monograph, there are a large number of photos, provided by Professor M. D. Voloshchuk, which recorded various aspects of soil erosion manifestations, as well as the ways of its overcoming in the conditions of forest-steppe and steppe zones in Ukraine and on the territory of Moldova. The reviewed monograph is certainly a very relevant and timely generalizing scientific research that will be useful in the theoretical and practical use of students, academic staff of the natural and agricultural higher education institutions, research organizations.


2021 ◽  
pp. 232102222110514
Author(s):  
Kolawole Ogundari ◽  
Adebola Abimbola Ademuwagun ◽  
Ogechukwu Appah

The climatic change crisis has led to a renewed interest in understanding the dynamic of climatic variability over time. This is because rainfall variability in response to climate change poses a severe threat to global food security and agricultural production in general. As a result of this, the study investigates the convergence of rainfall variability in Nigeria. We use historical climate data on annual rainfall collected from meteorological stations across 12 states and covering 1992–2013. This gives rise to a balanced panel data of 12 states and 20 periods, which yields 240 observations. The study used a sigma convergence hypothesis test estimated using ordinary least square, fixed-effect and feasible generalized least square models. The coefficient of variation is taken as a measure of rainfall variability in the study. The results showed a negative (declining) linear correlation between rainfall’s coefficient of variation and data year. This means that rainfall variability decreased over time. This indicates evidence of convergence of rainfall, which means states with lower average annual rainfall are catching up on states with higher average annual rainfall over time. And, from the agricultural production standpoint, this result shows that the potential threat of rainfall variability to food security is not severe. In addition, it indicates a decrease in risk and uncertainty in food crop production associated with rainfall variability. JEL Classifications: O13, O55, Q10, Q54


2021 ◽  
Author(s):  
Thomas Weninger ◽  
Simon Scheper ◽  
Nathan King ◽  
Karl Gartner ◽  
Barbara Kitzler ◽  
...  

<p>Wind erosion of arable soil is considered a risk factor for Austrian fields, but direct measurements of soil loss are not available until now. Despite this uncertainty, vegetated windbreaks have been established to minimize adverse wind impacts on arable land. The study addresses these questions: i) How relevant is wind erosion as a factor of soil degradation? ii) How important is the protective effect of vegetated windbreaks? iii) Are systematic patterns of spatial and temporal variability of wind erosion rates detectable in response to weather conditions? </p><p>Two experimental fields adjacent to windbreaks were equipped with sediment traps, soil moisture sensors, and meteorological measurement equipment for microclimatic patterns. Sediment traps were arranged in high spatial resolution from next to the windbreak to a distance of ten times the windbreak height. Beginning in January 2020, the amount of trapped sediment was analyzed every three weeks. The highest wind erosion rates on bare soil were observed in June and July. For unprotected fields with bare soil, upscaled annual erosion rates were as high as 0.8 tons per hectare, and sediment trapped increased in a linear fashion with distance from the windbreak. Soil water content near the surface (5 cm depth) was three percent higher at a distance of two times the height of the windbreak than at a distance of six times the height. For the same respective distances from the windbreak, we observed 29 days of soil water contents below the wilting point compared with 60 days.</p><p>The preliminary outcomes confirmed the expected effects of windbreaks on soil erosion and microclimate in agricultural fields. Prospective results from multiple vegetation periods will be used in an upscaling approach to gain informations for the whole basin. That is meant to be done by a combination with a soil wind erosion model which was so far used for regional modelling of wind erosion susceptibility.</p>


Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 584 ◽  
Author(s):  
Graciela Ponce-Antón ◽  
Anna Arizzi ◽  
Maria Zuluaga ◽  
Giuseppe Cultrone ◽  
Luis Ortega ◽  
...  

Archaeological lime mortars from the Tower Keep and West perimeter wall of Irulegi Castle (Navarre, Spain) were analysed to determine susceptibility to deterioration. Chemical, mineralogical, textural and physical characterisation was performed by different tests and multianalysis techniques in order to determine the intrinsic features of the original historical mortars at the castle. Samples from the Tower Keep are more prone to deteriorate compared with the West perimeter wall due to high water absorption capacity and high porosity. A high degree of pore interconnection, high desorption index and the presence of high pore volume in the 0.01 to 1 µm size range affect the mortar durability since pores retain water longer inside the mortar. Local environment conditions with persistent annual rainfall, high humidity and temperature variations contribute to the decay process of the original mortar. Characterisation of historical mortars not only allows better understanding of susceptibility to deterioration but also helps the design of compatible and durable repair mortar for future interventions on historical heritage. Compatibility of new materials with the historical mortar will be ensured by studying mortar characteristics and properties.


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