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Awan U.K.,University of Bonn | Ibrakhimov M.,Urgench State University | Tischbein B.,University of Bonn | Kamalov P.,Urgench State University | And 3 more authors.
Irrigation and Drainage | Year: 2011

Irrigated agriculture is widespread in the Central Asian drylands and important for food security of the region. However irrigation practices based on rules made for cotton production on large units do not provide adequate guidance for the now widespread small farms that produce cotton wheat and rice. Excessive unsustainable water use is the consequence. Land and water resource management practices were analysed in 2006 for the irrigated area (approx. 1885ha) of a water users' association (WUA) as a case study. The Shomakhulum WUA is situated in the Khorezm region Uzbekistan in the Aral Sea Basin. The designed water allowance of 0.40 l s -1 ha -1 was 46% higher than the 0.21 l s -1 ha -1 required in 2006. A ponding experiment conducted at two locations under typically shallow groundwater conditions showed that actual seepage losses in the major distributing canal (Pakhtakiyar) in the WUA were about 2% at one site and negative at the other. This does not support the present blanket recommendation of an additional 29% of water to compensate for anticipated seepage losses. Considering the effects of shallow groundwater the seasonal leaching requirements were estimated at 200mm versus the 400mm based on the blanket local recommendations for a 14ha cotton field. However the actually applied water amounted to 670mm which exceeds the calculated requirements by 235% and the local recommendation by 68%. The findings showed (i) excessive irrigation water supply and in turn high wastage owing to an underestimation of the potential shallow groundwater contribution (ii) overestimation of conveyance losses and (iii) excessive leaching due to outdated knowledge on leaching requirements when compared to standards. We suggest that the outdated water allowance the inaccurate estimation of the conveyance efficiency and excessive water applications during leaching cause a waste of precious fresh water and a rise in the shallow groundwater levels which consequently increases secondary soil salinity. The revision of irrigation and leaching norms combined with an improved knowledge on seepage dynamics under shallow groundwater levels is needed before any further recommendations can be made to the farmers in order to reach the objective of sustainable agriculture in the area. © 2011 John Wiley & Sons Ltd.


Buenemann M.,New Mexico State University | Martius C.,International Center for Agricultural Research in the Dry Areas | Martius C.,Inter American Institute for Global Change Research IAI | Jones J.W.,University of Florida | And 8 more authors.
Land Degradation and Development | Year: 2011

Sustainable dryland management seeks to improve the conditions of people and ecosystems affected by degradation, but it is often unclear which land management strategies work, which ones do not and why. Monitoring and assessment (M&A) can support decision-making by providing this information. As implied by the 10-year Strategy of the United Nations Convention to Combat Desertification (UNCCD), however, M&A efforts have thus far been insufficient or inadequate. We argue that integrative geospatial approaches should be implemented to enhance dryland management decision-making. By assimilating and linking human and environmental data, qualitative and quantitative data, as well as field and remotely sensed data in a spatially explicit framework, such approaches facilitate assessments of both the complexities and place-specificities inherent to sustainability. In addition, they help represent different stakeholder perspectives, promote communication among scientists from diverse backgrounds as well as between scientific and local experts, facilitate inter-institutional knowledge sharing, and create synergy between the UNCCD and other Conventions. Due to these benefits as well as the rapid evolution and increasing availability and affordability of geospatial data and technologies in all countries, it is appropriate to begin capitalizing more fully on them now for the M&A of land management sustainability. In order for integrative geospatial approaches to become more central to M&A efforts, however, capacities and infrastructure must be improved and standards and protocols developed for the collection, analysis, and modeling of data, for the evaluation of outputs, and for the reporting of results. Copyright © 2010 John Wiley & Sons, Ltd.


Awan U.K.,University of Bonn | Tischbein B.,University of Bonn | Conrad C.,University of Würzburg | Martius C.,University of Bonn | And 2 more authors.
Water Resources Management | Year: 2011

Irrigation water management in Central Asia is notorious for its inefficiency. We assessed the operational performance of the irrigation scheme in one Water Users Association (WUA), Shomakhulum, in Khorezm district, Uzbekistan, in 2007 to provide recommendations for strategic water management planning. Relative evapotranspiration (RET), delivery performance ratio (DPR), drainage ratio (DR), depleted fraction (DF), overall consumed ratio (OCR), field application ratio (FAR) and conveyance ratio (CR) were used as performance indicators. The components of the water balance were obtained through remote sensing techniques and hydrological field measurements. The surface energy balance algorithm for land (SEBAL) was applied to MODIS satellite data to derive actual and potential evapotranspiration. Inflows and outflows were quantified with field measurements in the irrigation and drainage network using discharge rating curves. Ponding experiments allowed determining canal seepage losses. Water balances at field level were established for application efficiency estimations. The indicator values were then compared to efficiency target values taken from the literature in order to assess the operational capabilities of the irrigation scheme. The general performance of the irrigation scheme is very poor. DPRs exceeding 1.0 indicate that more water is delivered to the system than is demanded. The seasonal DF of 0.4 is lower than the target value of 0.6. Losses during the field application averaged at 57%, which is 24% above target values. Seasonal DR, OCR, CR and RET are 0.55, 0.51, 0.76 and 0.82 against the target values of 0.1, 0.54, 0.84 and 0.75, respectively. We conclude that the distribution mechanism can be considerably improved. Besides improving water distribution (timing and equity) in the network, another recommended intervention would be to increase the DF, particularly by interventions at field level that raise the FAR, which in turn will improve DR and OCR. This can be achieved by introducing modern water management approaches such as laser leveling, double-sided irrigation, and control of inflow through flow-measuring devices installed at farm gates, and adequate water pricing. © 2011 Springer Science+Business Media B.V.


Lamers J.P.A.,University of Bonn | Martius C.,Inter American Institute for Global Change Research IAI | Khamzina A.,University of Bonn | Matkarimova M.,Urgench State University | And 2 more authors.
Nutrient Cycling in Agroecosystems | Year: 2010

Afforestation is a prospective strategy to improve soil fertility of salt-affected, irrigated croplands in Central Asia. The effect of macro- and mesofauna and microflora on the decomposition of tree leaves, collected ca. 2 weeks before natural fall, was monitored during 367 days. The three-year-old tree plantations consisted of Elaeagnus angustifolia L., Ulmus pumila L., and Populus euphratica Oliv. The leaf decay rate was determined in 25 × 25 cm sized polyester litterbags with mesh sizes of 10,000 μm (coarse), 250 μm (medium), and 20 μm (fine). Decomposition in the coarse litterbags, allowing access by the entire decomposer community, was highest in P. euphratica at 61% weight loss after 367 days. In the same period, the weight loss in E. angustifolia was 51% and in U. pumila 52%. Combined correlation and multiple regression analyses revealed that decomposability was determined by mesh size, initial C/N ratio, crude fiber-to-N (CF/N) ratio, leaf area, and specific leaf area. A high correlation existed between traits impacting decomposition by the entire decomposer population and the digestibility of leaves by animals as measured in the laboratory (the in vitro digestibility). Initial leaf N (34 g N kg-1 DM) content was highest in E. angustifolia, followed by 23 g N kg-1 DM in U. pumila and 22 g N kg-1 DM in P. euphratica. The C/N ratio followed the order of P. euphratica (21.8) > U. pumila (19.4) > E. angustifolia (13.1). The CF/N ratio followed the order P. euphratica (5.2) > E. angustifolia (3.9) > U. pumila (2.9). Despite a lower decay rate and a higher N content remaining in leaves after 367 days in comparison to both other species, E. angustifolia had the highest potential for soil bio-amelioration. This was due to its foliage production (6 t ha-1 on average), which was about 2.5 times higher than that of the other species, giving a total leaf N loss of about 97 kg N ha-1 in coarse mesh bags. The N loss from U. pumila and P. euphratica leaves amounted to 33 and 23 kg N ha-1, respectively. The potential of leaf decomposition for supplementing soil N in the region depends on the decay rate, the initial leaf N content, the annual leaf biomass production, and differences between N contents over the course of the decomposition period. These can be additional criteria for selecting tree species suitable for afforestation of the degraded, irrigated croplands in Central Asia. © 2009 Springer Science+Business Media B.V.


Kihara J.,Tropical Soil Biology And Fertility Institute of CIAT | Kihara J.,University of Bonn | Bationo A.,Tropical Soil Biology And Fertility Institute of CIAT | Bationo A.,The Green Office | And 4 more authors.
Nutrient Cycling in Agroecosystems | Year: 2011

Smallholder land productivity in drylands can be increased by optimizing locally available resources, through nutrient enhancement and water conservation. In this study, we investigated the effect of tillage system, organic resource and chemical nitrogen fertilizer application on maize productivity in a sandy soil in eastern Kenya over four seasons. The objectives were to (1) determine effects of different tillage-organic resource combinations on soil structure and crop yield, (2) determine optimum organic-inorganic nutrient combinations for arid and semi-arid environments in Kenya and, (3) assess partial nutrient budgets of different soil, water and nutrient management practices using nutrient inflows and outflows. This experiment, initiated in the short rainy season of 2005, was a split plot design with 7 treatments involving combinations of tillage (tied-ridges, conventional tillage and no-till) and organic resource (1 t ha-1 manure + 1 t ha-1 crop residue and; 2 t ha-1 of manure (no crop residue) in the main plots. Chemical nitrogen fertilizer at 0 and 60 kg N ha-1 was used in sub-plots. Although average yield in no-till was by 30-65% lower than in conventional and tied-ridges during the initial two seasons, it achieved 7-40% higher yields than these tillage systems by season four. Combined application of 1 t ha-1 of crop residue and 1 t ha-1 of manure increased maize yield over sole application of manure at 2 t ha-1 by between 17 and 51% depending on the tillage system, for treatments without inorganic N fertilizer. Cumulative nutrients in harvested maize in the four seasons ranged from 77 to 196 kg N ha-1, 12 to 27 kg P ha-1 and 102 to 191 kg K ha-1, representing 23 and 62% of applied N in treatments with and without mineral fertilizer N respectively, 10% of applied P and 35% of applied K. Chemical nitrogen fertilizer application increased maize yields by 17-94%; the increases were significant in the first 3 seasons (P < 0.05). Tillage had significant effect on soil macro- (>2 mm) and micro-aggregates fractions (<250 μm >53 μm: P < 0.05), with aggregation indices following the order no-till > tied-ridges > conventional tillage. Also, combining crop residue and manure increased large macro-aggregates by 1.4-4.0 g 100 g-1 soil above manure only treatments. We conclude that even with modest organic resource application, and depending on the number of seasons of use, conservation tillage systems such as tied-ridges and no-till can be effective in improving crop yield, nutrient uptake and soil structure and that farmers are better off applying 1 t ha-1 each of crop residue and manure rather than sole manure. © 2011 Springer Science+Business Media B.V.


Kihara J.,Tropical Soil Biology And Fertility Institute of CIAT | Martius C.,Zentrum fur Entwicklungsforschung ZEF | Martius C.,Inter American Institute for Global Change Research IAI | Bationo A.,The Green Office | And 5 more authors.
Applied Soil Ecology | Year: 2012

Stable soil aggregates and high microbial diversity are essential for efficient nutrient recycling in soil. This study evaluated effects of different arable land-use systems on soil aggregation and associated composition and total diversity of bacteria and fungi. For this purpose, 5- and 3-year-old field trials were selected, two in sub-humid (orthic Acrisols and oxidic Ferralsols) and one in semi-arid (chromic Cambisol) region in Kenya. The treatments included combinations of tillage (conventional tillage [CT] and reduced tillage [RT]), crop residue management (0 and 2tha -1 maize stover) and cropping systems (continuous maize, maize-soybean intercropping and rotation) in the sub-humid sites, and of different tillage (CT, no-till and tied-ridging) and organic fertilization management (manure and crop residue) in semi-arid Kenya. The innovativeness of this study is the research in tropical soils where the concept of aggregate hierarchy is not generally accepted yet. The results showed that aggregate mean weight diameter (MWD) at 0-15cm depths had increased from 19 to 34% under RT relative to CT management (P<0.05). Crop residue additions also significantly increased MWD by 22% at the top 5cm (P<0.01) compared to treatments without residue in oxidic Ferralsols. At all the three sites, tillage resulted in greatest shifts of bacterial and fungal community composition, while cropping system had largest positive effect on the total microbial diversity indices. Total microbial diversity indices as well as MWD were higher in soybean-maize intercropping systems than under rotation or continuous maize cropping. Changes in total bacterial diversity related inversely to changes in the amount of free silt+clay, while fungal diversity related inversely to the contents of soil macro-aggregates >2mm (P<0.05). We conclude that RT plus supply of organic resources and intercropping are best strategies to increase total diversity of soil bacteria and fungi and improve soil structure in these tropical soils. © 2012 Elsevier B.V.


Murgida A.M.,University of Buenos Aires | Gonzalez M.H.,CONICET | Gonzalez M.H.,University of Buenos Aires | Tiessen H.,Inter American Institute for Global Change Research IAI
Regional Environmental Change | Year: 2014

Regional change under agricultural expansion in the Chaco of Argentina is determined by interactions of rainfall change, infrastructure development, socio-economic actions and values, and the social perceptions of change. Our study focused on adaptation in the socio-environmental system which is the key to understanding opportunities, uncertainties and risk in the context of historical change. Change in land use from extensive grazing through mixed farming and on to industrial-scale soybean production was made possible by a trend of increasing rainfall that reduced the risk of crop failure from drought since the 1970s. Rainfall change coincided with a period in which the Chaco forest was suffering extensive degradation from long-term extractive use. The degradation aided agricultural expansion since the degraded state of the ecosystem justified public policies of deforestation. In parallel to these resource-based processes, public policy changed in the late 70s and 80s toward favoring privatization of state land and exclusion of small producers. This permitted the land concentration needed for industrial-scale production. Technological innovation in both water and land resource management reinforced the process of concentration because small producers rarely have the financial or educational capital to develop or implement emerging technologies. One of the results of the intensification and expansion of agriculture is that soil surface sealing, waterlogging and flood risk are now effective at a landscape scale. To address these risks, private enterprise and government efforts must now come together toward innovative policies in integrated landscape management. © 2014 Springer-Verlag Berlin Heidelberg.


Djumaeva D.,Center for Development Research | Lamers J.P.A.,Center for Development Research | Martius C.,Inter American Institute for Global Change Research IAI | Vlek P.L.G.,Center for Development Research
Journal of Arid Environments | Year: 2012

Leaf chlorophyll meters can be used to support easy and efficient crop nitrogen (N) management. They can be used on tree species native to Central Asia that have been suggested for afforesting salt-affected croplands, but its use demands a priori calibration as the relationship between chlorophyll meter measurements and leaf N contents is crop/species specific. Data collected with a SPAD-502 leaf chlorophyll meter during 2006-2008 was used to generate a calibration dataset for the leaf N status of three tree species. The second-degree polynomial relationships between the SPAD-502 readings and total leaf chlorophyll and N content had higher predictive power than linear relationships for all species, although with differences among them. The validation was completed with the same species grown at a different location (difference in space) and with older trees (difference in age). The comparison between predicted and spectrophotometrically determined leaf N content showed a root mean square error (RMSE) of 25 mg g -1 DM, which corresponds to a relative RMSE of 10% for Elaeagnus angustifolia. For Gleditsia triacanthos and Robinia pseudoacacia they were 11 mg g -1 DM and 16%, 14 mg g -1 DM and 10%, respectively. The findings demonstrate that the SPAD-502 can with confidence be used for non-destructive assessment of tree foliar N status of these three species, although only within the range of the SPAD-502 values used for the calibration. Options for the use of the SPAD-502 for forest management in agroforestry-based land use systems in Central Asia are addressed. © 2012 Elsevier Ltd.


Kihara J.,Tropical Soil Biology And Fertility Institute of CIAT | Bationo A.,Tropical Soil Biology And Fertility Institute of CIAT | Waswa B.,Center for Development Research | Kimetu J.M.,Tropical Soil Biology And Fertility Institute of CIAT | And 5 more authors.
Experimental Agriculture | Year: 2012

Reduced tillage is said to be one of the potential ways to reverse land degradation and ultimately increase the productivity of degrading soils of Africa. We hypothesised that crop yield following a modest application of 2 t ha -1 of crop residue in a reduced tillage system is similar to the yield obtained from a conventional tillage system, and that incorporation of legumes in a cropping system leads to greater economic benefits as opposed to a cropping system involving continuous maize. Three cropping systems (continuous maize monocropping, legume/maize intercropping and rotation) under different tillage and residue management systems were tested in sub-humid western Kenya over 10 seasons. While soybean performed equally well in both tillage systems throughout, maize yield was lower in reduced than conventional tillage during the first five seasons but no significant differences were observed after season 6. Likewise, with crop residue application, yields in conventional and reduced tillage systems are comparable after season 6. Nitrogen and phosphorus increased yield by up to 100% compared with control. Gross margins were not significantly different among the cropping systems being only 6 to 39% more in the legume-cereal systems relative to similar treatments in continuous cereal monocropping system. After 10 seasons of reduced tillage production, the economic benefits for our cropping systems are still not attractive for a switch from the conventional to reduced tillage. © 2011 Cambridge University Press.


Hurlbert M.A.,University of Regina | Hurlbert M.A.,University of Amsterdam | Montana E.,Inter American Institute for Global Change Research IAI
Journal of Sustainable Development | Year: 2015

Climate change in many local and regional scales is expected to include climate hazards and extreme conditions including hailstorms, droughts, floods, hurricanes, hail, tornadoes and storms. Droughts are serious climate hazards threatening water supply for human consumption and also agricultural production and are anticipated to increase in intensity and duration in both Mendoza, Argentina and southern Alberta, Canada. Both Mendoza and Alberta have irrigated agriculture and their rivers are fed primarily by snowmelt and rainfall runoff from mountainous headwaters. Many similarities exist between water law and governance in the Mendoza river basin, Argentina and the Oldman river basin in southern Alberta, Canada. However, many differences also exist. Can these governance systems ensure the continuation of agricultural production in the area into the future given increased development and climate change? Utilizing the institutional design principles of adaptive capacity and water governance, this paper will compare and contrast the water governance institutional structures in the two study areas. Data was obtained from two multi-disciplinary studies of institutional adaptation to climate change studying vulnerability of local agricultural producers and communities to climate change, and the interplay of water governance structures, and adaptive capacities. The water governance systems of both countries show concerns relating to gaps in information and equitable outcomes; in addition there are concerns of a lack of capacity to enable reflexivity. Both systems have been responsive (although there is room for improvement). Through strengthening these identified weaknesses these systems can continue to be resilient into the future. © 2015 by the authors.

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