1,721,175 research outputs found
Yield and water-production functions of two durum wheat cultivars grown under different irrigation and nitrogen regimes
No full textPerformance and Adaptation of the Vallerani Mechanized Water Harvesting System in Degraded Badia Rangelands
No full textRainwater harvesting in micro-catchments such as contour ridges and semicircular bunds is an option for utilizing the limited rainfall, improving productivity and combating land degradation in dry rangeland areas (Badia). However, implementation of this practice using manual labor or traditional machinery is slow, tedious and costly, and often impractical on a large scale. These limitations can be overcome using the ‘Vallerani’ plow for quickly constructing continuous and intermittent ridges. The plow (model Delfino (50 MI/CM), manufactured by Nardi, Italy) was tested and adapted to dry steppe (Badia) conditions in Jordan. The performance of the machine, its weaknesses and potential improvements were assessed in the 2006/07 season at three sites on 165 hectares of various terrain, slope and soil conditions. The performance parameters included effective field capacity (EFC), machine efficiency (ME) and fuel consumption (FC). Field tests were carried out at different tractor (134 HP) traveling speeds, pit sizes and contour spacings. Overall mean performance indicators gave an EFC of 1.2 ha/h, 51% ME and an average FC of 5.15 liter/ha. Increasing ridge spacing had a small effect on ME where, increasing traveling speed had a greater effect. A guide table was developed, relating performance parameters with ridge spacing, speed, and bund size setting. This could be a useful reference for the implementation and management of mechanized microcatchment construction in the Badia. The system performed well in the construction of continuous ridges. However, it was unable to construct intermittent ridges at speeds over 4 km/h; problems were encountered in properly staggering the bunds at successive contours
The role of supplemental irrigation and nitrogen in producing bread wheat in the highlands of Iran
No full textThe West Asia and North Africa (WANA) region, with a Mediterranean climate type, has an increasing deficit in cereal production, especially bread wheat. Rainfed cropping in the highlands of this region coincides with the severely cold winter with mostly, snow from November to April. Cereal yields, are low and variable mainly as a result of inadequate and erratic seasonal rainfall and associated management factors, such as late sowing (or late crop emergence). In an area where water is limited, small amounts of supplemental irrigation (SI) water can make up for the deficits in seasonal rain and produce satisfactory and sustainable yields. This field study (1999–2002) on a deep clay silty soil in north west of Iran was conducted with four SI levels (rainfed, 1/3, 2/3 and full irrigation requirements) combined with different N rates (0, 30, 60, 90 and 120 kg ha−1) with one wheat variety (Sabalan). Yields of rainfed wheat varied with seasonal rainfall and its distribution. A delay in the crop emergence from October (SI treatment) to November (rainfed) consistently reduced yields. With irrigation, crop responses to nitrogen were generally significant up to 60 kg N ha−1. An addition of only limited irrigation (1/3 of full irrigation) significantly increased yields and maximized water use efficiency (WUE). Use efficiency for water and N was greatly increased by SI. Under deficit irrigation, maximum WUE would be achieved when 60 kg N ha−1 is combined with 1/3 of full SI. Early crop germination is essential to ensure adequate crop stand before the winter frost and to achieve high yield. Early emergence can be achieved by applying a small amount (40–50 mm) of SI after sowing. Thus, when limited SI is combined with appropriate management, wheat production can be substantially and consistently increased in this highland semi-arid zone
Water Benchmarks of CWANA project - Characteristics of Benchmark Research Agroecosystems in WANA: Rainfed, Irrigated, and Marginal Drylands
No full textThis report was written in close cooperation with national agricultural research systems (NARS) at the benchmark sites. The six background papers provide valuable information on socioeconomics, natural resources and national development strategies in each benchmark country, and identify gaps that need to be addressed in the future. The synthesis paper will help understand the intricacies of the water benchmarks of CWANA, selecting and characterizing benchmark sites, and establishing baseline databases
Assessment of the severity and impact of drought spells on rainfed cereals in Morocco
No full textDrought is a major factor affecting cereal production in most the rainfed areas of West
Asia and North Africa. Recent increases in drought frequency in Morocco have resulted in
the yields of field crops being extremely variable and generally low. The objective of this
study is to assess drought severity in the main cereal production areas of Morocco and to
evaluate its effects on grain yield. Also the study seeks to evaluate if the standardized
precipitation index (SPI) may be used as a tool to predict drought and crop yield early in
the season. Data analysis showed that for the period 1988 to 2008, yields fluctuated from
150 to 3000 kg/ha with a coefficient of variation of between 30 and 50% in the north and
60 and 70% in the south. Based on the SPI, the regions studied experienced, on average,
a drought once every 2.6 years. However, very severe droughts were observed only once in 7 years. The SPIs computed for the periods October to June and January to March were
highly correlated. Moreover, there was a high positive correlation between the yield and
the SPI calculated for the period January to March. The coefficients of determination
varied between around 0.20 and 0.62 for bread and durum wheats, and between 0.28 and
0.69 for barley. It is concluded that soil moisture levels during the tillering and stem
elongation periods of the cereals are the most important determinants of yield. Hence an
SPI computed for the period January to March can be used to predict drought severity and
yields early in the seaso
Conjunctive use of green and blue water resources in agriculture: Methodology and application for supplemental irrigation
No full textSupplemental irrigation (SI) ensures an efficient conjunctive use of green and blue water resources in dryland cropping by alleviating the negative impacts of precipitation shortages and drought spells on plant growth and production. The management of SI at the field level is well documented but little is known about planning at basin scale. This work uses a geographic information system-based modelling approach together with suitability criteria to identify potential areas for expanding SI at scale. A spatial water allocation algorithm is developed to model SI water allocation using data layers consisting of climate surfaces, classified land-use maps, and a digital elevation model. Areas are prioritized stepwise, according to land suitability, until the available water is fully utilized.
The analysis was applied in a watershed in western Iran. The analysis revealed that, with SI, available water resources in the winter season can supplementally irrigate a new land area of about 2,900 ha, about twice the area conventionally irrigated in the dry season. However, adopting a deficit SI strategy allows irrigation of additional 3,220 ha, more than double of the current water allocation efficiency. The approach can be applied in any rainfed area with available water without major modifications, but further analysis is needed to evaluate its economics at scale
Managing Scarce Water Resources in Agriculture; Towards a paradigm change
No full textWater scarcity intensifying as many countries with chronic water scarcity, in addition the water for agriculture in dry areas is declining and Climate change adds to the problem
Water Harvesting and Supplemental Irrigation for Improved Water Productivity of Dry Farming Systems in West Asia and North Africa
No full textIn the dry areas, water, not land, is the most limiting resource for improved agricultural production. Maximizing water productivity, and not yield per unit of land, is therefore a better strategy for dry farming systems. Under such conditions, more efficient water management techniques must be adopted. Supplemental irrigation (SI) is a highly efficient practice with great potential for increasing agricultural production and improving livelihoods in the dry rainfed areas. In the drier environments, most of the rainwater is lost by evaporation; therefore the rainwater
productivity is extremely low. Water harvesting can improve agriculture by directing and concentrating rainwater through runoff to the plants and other beneficial uses. It was found that over 50% of lost water can be recovered at a very little cost. However, socioeconomic and environmental benefits of this practice are far more important than increasing agricultural water productivity. This paper highlights the major research findings regarding improving water productivity in the dry rainfed region of West Asia and North Africa. It shows that substantial and sustainable improvements in water productivity can only be achieved through integrated farm resources management. On-farm water productive techniques if coupled with improved irrigation management options, better crop selection and
appropriate cultural practices, improved genetic make-up, and timely socioeconomic interventions will help to achieve this objective. Conventional water management guidelines should be revised to ensure maximum water productivity instead of land productivity
Mechanization of transplanting shrubs seedlings and contours laser guiding for Vallerani system
No full textIn relevance to the project objectives and expected outputs, the reported research aimed at introducing a mechanized transplanting technique to the WH system to reduce costs and time of establishment of fodder shrubs, thus improving overall system capacity and making large-scale implementation more feasible. Therefore, the expected output is to improve WH and re-vegetation techniques with less cost and time of establishment for fodder shrubs
Water-yield relations and optimal irrigation scheduling of wheat in the Mediterranean region
No full textCrop yield is primarily water-limited in areas of West Asia and North Africa with a Mediterranean climate. Ten years of supplemental irrigation (SI) experiments in northern Syria were conducted to evaluate water-yield relations for bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L.), and optimal irrigation scheduling was proposed for various rainfall conditions. The sensitive growth stages of wheat to water stress were from stem elongation to booting, followed by anthesis, and grain-filling. Water stress to which crop subjected depends on rainfall and its distribution during the growing season; the stress started from early March (stem-elongation stage) or even in seedling stage in a dry year, and from mid-April (anthesis) in an average or wet year. Crop yield linearly increased with increase in evapotranspiration (ET), with an increase of 160 kg for bread wheat and of 116 kg for durum wheat per 10 mm increase of ET above the threshold of 200 mm. Water-use efficiency (WUE) with a yield greater than or equal to 3 t ha(-1) was ca. 60% higher than that with yield <3 t ha(-1); this emphasises the importance of that to achieve effective use of water, optimal water supply and relatively high yields need to be ensured. Quadratic crop production functions with the total applied water were developed and used to estimate the levels of irrigation water for maximizing yield, net profit and levels to which the crops could be under-irrigated without reducing income below that which would be earned for full SI under limited water resources. The analysis suggested that irrigation scenarios for maximizing crop yield and/or the net profit under limited land resource conditions should not be recommended. The SI scenarios for maximizing the profit under limited water resource conditions or for a targeted yield of 4-5 t ha(-1) were recommended for sustainable utilization of water resources and higher WUE. The time of irrigation was also suggested on the basis of crop sensitivity index to water stress taking rainfall probability and available soil water into account. (C) 1999 Elsevier Science B.V. All rights reserved
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