Valley Irrigation Research Articles

Aerial Mapping of the Peruvian Chira Valley Banana Production System to Monitor the Expansion of Fusarium Wilt Caused by Tropical Race 4

The recent incursion of Fusarium wilt of banana (FWB) caused by TR4 threatens banana production in the Chira Valley of Peru. To develop a management strategy, we mapped the entire production area from the air. During 12 flights at an altitude of 610 m (2,000 ft), we gathered 133,700 images in a timeframe of 2 weeks and constructed an orthomosaic map of 73,000 ha. This unveiled the complex logistic network across the banana-producing region, comprising 150 km of primary roads, as well as numerous secondary and tertiary unpaved paths through and bordering banana plantations. Moreover, the Poechos reservoir—with a total length of 450 km—feeds the entire Chira Valley irrigation system, which could further exacerbate TR4 expansion. Using georeferenced landscape details (digital terrain model), we determined areas prone to flooding, which is also relevant for disseminating TR4. Analyses of the maps resulted in the identification of many suspect areas for direct sampling and subsequent analyses to study the expansion of TR4. At four locations, we confirmed two cases, and by June 8, 2023, a total of 207 cases were reported. We conclude that TR4 is a serious threat to the entire region, which exports approximately 25% of the global organic bananas. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Assessing the Impact of IrrigaSys Decision Support System on Farmers’ Irrigation Practices in Southern Portugal: A Post Evaluation Study

The IrrigaSys decision support system (DSS) has supported farmers’ decision-making regarding irrigation scheduling in the Sorraia Valley irrigation district in Southern Portugal over a span of six years (2017–2022). This study aims to conduct a postevaluation of farmers’ adherence to the DSS, employing a multicriteria analysis (MCA) approach with data from the 2019 (driest year) and 2020 (average year) growing seasons. Two distinct scenarios were taken into consideration: the first focused on water conservation, and the second centered on farmers’ economic returns. The outcomes of the first scenario revealed that farmers exhibited a reasonable level of expertise, particularly during the driest season. They achieved water-saving indicators comparable to those obtained when adhering to optimized irrigation schedules generated weekly by the DSS. In the wetter season, discrepancies emerged between farmers’ and model indicators, primarily attributed to challenges in integrating reliable information from precipitation forecasts into the decision-making process. In the second scenario, both farmers’ and model results exhibited close economic indicators throughout both seasons. While IrrigaSys requires further developments, these results show that the DSS has effectively contributed to supporting irrigation water management in the study region.

Groundwater-surface water interactions in a semi-arid irrigated agricultural valley: A hydrometric and tracer-aided approach

The purpose of this study was to assess hydrological controls (e.g., rainfall, irrigation practices, river discharge, dam operation, evaporation) on surface (SW)- ground water (GW) interactions in an irrigated valley within semi-arid Patagonia Argentina (−65.49 W, −43.29 S). We combined different sampling designs (watershed/sub-watershed scales, longitudinal and monthly samplings) from 2015 to 2019 to investigate the temporal and spatial variation of hydrometrics, electrical conductivity (EC) and stable isotope composition of surface and ground water. Results showed that plant transpiration in the upper basin, evaporation in the middle basin and the reservoir dynamics modified water salinity and left an imprint in stable isotopes. Water tables in the irrigated valley were high (0.5–2 m level from soil surface) and presented higher salinity than river water. Groundwater salinity, temporal variation of water table levels and stable isotopes suggested that groundwater is subjected to evaporation, is recharged from field seepage and, at a lesser extent, from local rainwater. River salinity increased downstream of the irrigated valley during the whole study period (3 years), showing the effects of agriculture and urbanization. EC also responded to the opening and closing of irrigation channels. EC and daily discharge statistical analysis revealed that groundwater recharge the stream below a threshold discharge of 26 m.s−1; with river salinity increasing linearly as daily discharge decrease. This study illustrates the deep modifications that agricultural systems, mainly surface irrigation, produce on semiarid watersheds. Given that SW and GW components are currently not isolated and flow regulation and irrigation practices are playing a critical role in soil quality and river chemistry at low flow conditions, a conjunctive water management strategy must be implemented in order to prevent further land and water quality degradation.

ECONOMIC EFFICIENCY OF SMALL-HOLDER WHEAT FARMERS AROUND HADEJIA VALLEY IRRIGATION SCHEME IN JIGAWA STATE, NIGERIA

The study analyzed economic efficiency of small-holder wheat farmers around Hadejia Valley Irrigation scheme in Jigawa, State Nigeria. Multi-stages sampling procedure was used to select 346 wheat farmers from the study area. Data were collected with the aid of questionnaire. Both descriptive and inferential statistics were used to analyzed the data. The stochastic frontier analysis results indicated that a unit increase in the use of land, fertilizer, labour and herbicide contributed to wheat output by 0.577, 0.341, 0.078 and 0.174 respectively. The predicted technical, allocative and economic efficiencies were 0.76, 0.32 and 0.24 respectively. This implies that wheat farmers were not fully efficient and output could have been increased by 24% and about 68% of cost would have been saved. Furthermore, tobit regression results revealed that age of the farmers positively affected technical (0.0012, p<0.10), allocative (0.0025, p<0.05) and economic (0.0023, p<0.01) efficiencies of wheat farmers’ production in the study area. The sex of the wheat farmers was significant (0.0472, p<0.05) and positively affecting wheat farmers technical efficiency. Education of the wheat farmers significantly (p<0.10) and negatively affected their technical (-0.0021) inefficiencies, access to extension service was influencing both technical (- 0.0223, p<0.10) and economic (- 0.0789, p<0.10) inefficiencies negatively. The study concluded that wheat farmers were not fully efficient and more output (24%) could be achieved with the same level of inputs as indicated by the increasing return to scale of 1.197. The study therefore, recommended that concerted efforts should be made towards training farmers on appropriate inputs combination by extension agents to improve and boost wheat production in the study area.

Trophic ecology of co-occurring fishes in the Sundays River Valley irrigation ponds, assessed using stable isotope and gut content analyses.

The analysis of food web structures has increased the understanding of the dynamics of organisms belonging to different trophic levels. In this study, the diet of two native species, Glossogobius callidus and Gilchristella aestuaria, was assessed in the presence of two non-native species, Oreochromis mossambicus and Gambusia affinis, in irrigation ponds, Eastern Cape Province, South Africa. The proportion of dietary items consumed and assimilated by the four fish species were inferred from gut contents and carbon and nitrogen stable isotope analysis. Stable isotope analysis revealed that both G. affinis and O. mossambicus had a larger isotopic niche size than G. callidus and G. aestuaria. Although G. callidus fed on benthic resources and G. aestuaria fed on phytoplankton, gut content analysis showed that G. callidus, O. mossambicus and G. affinis fed predominantly on benthic resources, whereas G. aestuaria fed mainly on plankton resources. Considerable niche overlap corroborates the view that resource competition is a major factor shaping the composition of the four fish species. This study highlighted the low diversity of the food web within the Sundays River Valley irrigation ponds, where food items are shared by all the small-bodied fishes.

Physical Controls on Irrigation Return Flow Contributions to Stream Flow in Irrigated Alluvial Valleys

Irrigation can be a significant source of groundwater recharge in many agricultural regions, particularly in arid and semi-arid climates. Once infiltrated, irrigation recharge can travel via subsurface flowpaths that return to the river system in a lagged manner, supplementing natural streamflow weeks, months, or even years from when the irrigation was applied. In regions that experience low flows during summer and early fall, return flows can be a significant source of supplementary streamflow. Many water planning and operations models either ignore return flows or roughly approximate them with analytical solutions. Thus, return flows represent an important but often overlooked component of the hydrological exchange and overall water balance in agricultural regions. This study uses groundwater models to explore a wide range of factors that control irrigation return flow timing in irrigated alluvial valleys. A sensitivity analysis approach is used to assess how factors such as the extent of irrigated land adjacent to a stream, irrigation recharge rate, aquifer hydraulic conductivity, aquifer thickness, water table configuration, and seasonal fluctuations in stream stage control the timing of subsurface return flows. Modeling is conducted using MODFLOW models representing an irrigated alluvial valley adjacent to a stream. While a simplification of the full complexity in real systems, the models are a significant advancement from the analytical solution and provide new insight into the timescales of return flows over a broad range of possible conditions. To contextualize our modeling results, they are compared to an analytical solution commonly used for approximating return flows to evaluate its performance. Our findings show what factors and conditions influence return flow timing and control whether they contribute to streamflow over short term (months) or longer term (seasonal) time scales.

Productivity and profitability of sweet potato (ipomoea batatas l.), dry bean (Phaseolus Vulgaris) and maize (Zea mays l.) as selected field crops in irrigated smallholder agricultural enterprises (ISAEs) in Vhembe District, Limpopo Province, South Africa

The study was conducted as part of assessing the productivity and profitability of irrigated smallholder agricultural enterprises in the Vhembe district. Agro-ecological conditions at Upper Mutale valley (sub-humid) and Madimbo Corridor smallholder irrigation schemes (semi-arid) are significantly different. This confirms that the variables of smallholder irrigation schemes are affected by diversity and similarities attributed to different livelihood needs. The purpose of the study was to assess the influence of productivity and profitability on irrigated smallholder agricultural enterprises in the Vhembe District. A representative sample was based on the number of irrigated smallholder irrigation entrepreneurs per irrigated smallholder irrigation production area within the two identified agro-ecological zones. Primary data were collected using a questionnaire and village walk (observation). At least 294 women and youth smallholder irrigation entrepreneurs were sampled for interviews and prompt responses on the influence of productivity and profitability of selected field crops (Dry bean, Sweet Potatoes and Maize) on irrigated Smallholder Agricultural Enterprise. The study applied both primary and secondary data collection instruments. An average selected mean output of irrigated smallholder agricultural product were determined. The results through comparison between informal and formal markets show that the ISAEs who rely on the informal market is making more profit than the formal market. In selling through the formal market, the market deducts 5% of commission while the market agent deducts 7.5% of sales on the gross value of the sold product. This doesn’t include the transportation charges to the market. The Farm Gate market opportunity seems to be the most predominant approach of marketing at ISAEs. These results re-affirms that ISAEs can also be alternative employment to Women and Youth who remain at home while their counterpart is looking for employment in cities. In the end, the study provides strong motivation on socio-economic impact assessment examines how an irrigated smallholder agricultural area has and will change the lives of current and future residents of a community and its local economy.

Proximity of Residence to Irrigation Determines Malaria Risk and Anopheles Abundance at an Irrigated Agroecosystem in Malawi.

ABSTRACT.As countries of sub-Saharan Africa expand irrigation to improve food security and foster economic growth, it is important to quantify the malaria risk associated with this process. Irrigated ecosystems can be associated with increased malaria risk, but this relationship is not fully understood. We studied this relationship at the Bwanje Valley Irrigation Scheme (800 hectares) in Malawi. Household prevalence of malaria and indoor Anopheles density were quantified in two cross-sectional studies in 2016 and 2017 (5,829 residents of 1,091 households). Multilevel logistic regression was used to estimate the association between distance to the irrigation scheme and malaria infection and mosquito density. The prevalence of malaria infection was 50.2% (2,765/5,511) by histidine-rich protein 2–based malaria rapid diagnostic tests and 30.1% (1,626/5,403) by microscopy. Individuals residing in households within 3 km of the scheme had significantly higher prevalence of infection (adjusted odds ratio [aOR] = 1.41; 95% confidence interval [CI] 1.18, 1.68); school-aged children had the highest prevalence among age groups (aOR = 1.34; 95% CI 1.11, 1.63). Individuals who reported bed net use, and households with higher socioeconomic status and higher level of education for household head or spouse, had lower odds of malaria infection. Female Anopheles mosquitoes (2,215 total; Anopheles arabiensis, 90.5%, Anopheles funestus, 9.5%) were significantly more abundant in houses located within 1.5 km of the scheme. Proximity of human dwellings to the irrigation scheme increased malaria risk, but higher household wealth index reduced risk. Therefore, multisectoral approaches that spur economic growth while mitigating increased malaria transmission are needed for people living close to irrigated sites.

Dynamic seasonal response of Ceratitis capitata (Diptera: Tephritidae) to fruit juice-based lures in fig orchards

Ceratitis capitata is the most serious agricultural pest in Argentinean fruit-growing regions. The use of baited traps for Medfly control is an expanding and increasingly successful integrated management strategy. The high cost of traps and attractants is one of the main limitations for use on either a massive scale or a small-scale control. This study aimed to evaluate the advantages or disadvantages of using natural fruit juice-based lures for Medfly adult monitoring at the orchard level in an irrigated valley. Medfly capture with a standard protein attractant was compared with peach, apple, sweet orange, fig, and grape juices. All attractants were evaluated in 1.5-liter disposable plastic bottles that served as traps. The most relevant finding was the interaction between attractant effectiveness and season. While the standard yeast was the most effective attractant during summer, the highest Medfly caught values recorded during both spring and autumn were achieved with traps baited with orange juice. The use of fruit juices as attractants and disposable bottles as traps can decrease the impact on non-target insects and reduce management costs.

Isolation and Identification of Naegleria Species in Irrigation Channels for Recreational Use in Mexicali Valley, Mexico.

Members of the genus Naegleria are free-living amoebae that are widely distributed in water and soil environments. Moreover, Naegleria fowleri is a pathogenic amoeba species that causes a fatal disease in the central nervous system known as primary amoebic meningoencephalitis (PAM) in humans. Since most reported infections due to N. fowleri are reported in recreational waters worldwide, this study was aimed to describe the presence of these amoebic genus in Mexicali Valley irrigation channels of recreational use. A total of nine water samples were collected and processed by triplicate, in nine different sites of the Valley. After filtering and culturing the samples, plates were examined, and the observed amoebae were morphologically identified at the genus level. In addition, the pathogenicity of these amoebic isolates was checked, and molecular characterization was performed by PCR/sequencing. The results revealed the presence of Naegleria spp. in all the channels sampled. Finally, molecular identification confirmed the presence of five different species of Naegleria: N. fowleri, N. australiensis, N. gruberi, N. clarki and N. pagei. The presence of these protists, particularly N. fowleri, should be considered as a potential human health risk in the region.

IrrigaSys: A web-based irrigation decision support system based on open source data and technology

IrrigaSys is a decision support system (DSS) for irrigation water management based on online, open source tools. The aim of this paper is to describe the structure of IrrigaSys and how it is implementation at the plot scale. The DSS includes remote access to local meteorological stations for weather conditions, a meteorological model for weather forecast, the MOHID-Land model for the computation of the soil water balance and irrigation scheduling, and a database for data repository. Despite its complexity, the data necessary to run IrrigaSys is minimal, and include as mandatory input information on the location of field plots, crop type, sowing and harvest dates, soil texture, irrigation method, and daily/weekly applied irrigation depths. Based on this information, the system automatically downloads the weather data from the meteorological station located closest to the agricultural plot, as well as the weather forecast for the seven incoming days. The soil water balance is then computed from sowing to the present date (updating always the system with newly acquired information) as well as the recommended irrigation schedule for the incoming week. Results are made available via a web interface, a mobile app, a SMS, and email. The IrrigaSys further provides the Normalized Difference Vegetation Index (NDVI) computed from the most recent Sentinel-2 imagery available with a resolution of 10 m. The IrrigaSys was developed in close cooperation with the Water Board from the Sorraia Valley irrigation district, southern Portugal, supporting 103 plots of 30 farmers over the last 5 years. This stakeholder has been fundamental for successfully running the system. This paper further discusses the main strengths and limitations of IrrigaSys, with the latter being naturally associated to difficulties in providing reliable estimates for all field plots based on limited data.

Assessment of Multi-Date Sentinel-1 Polarizations and GLCM Texture Features Capacity for Onion and Sunflower Classification in an Irrigated Valley: An Object Level Approach

The objective of this work is to evaluate the capacity of the C-band Synthetic Aperture Radar (SAR) time series imagery, acquired by the European satellite Sentinel-1 (S1), for the agriculture crop classification and its reliability to differentiate onion from sunflower, among others. The work then focused on classifying land cover in intensively cultivated agricultural regions. The study was developed in the Bonaerense Valley of the Colorado River (BVCR), Buenos Aires Province in Argentina, backed up by the field truth of 1634 field samples. In addition to the onion and sunflower crops, there are other crops present in the study area such as cereals, alfalfa, potatoes and maize, which are considered as the image background in the classification process. The field samples database was used for training and supporting a supervised classification with two machine learning algorithms—Random Forest (RF) and Support Vector Machine (SVM)—obtaining high levels of accuracy in each case. Different S1 SAR time-series features were used to assess the performance of S1 crop classification in terms of polarization VH+VV, Grey Level Co-occurrence Matrix (GLCM) image texture and a combination of both. The analysis of SAR data and their features was carried out at OBIA lot level (Object Based Image Analysis) showing an optimal strategy to counteract the effect of the residual and inherent speckle noise of the radar signal. In the process of differentiating onion and sunflower crops, the analysis of the VH+VV stack with the SVM algorithm delivered the best statistical classification results in terms of Overall Accuracy (OA) and Kappa Index, (Kp) when other crops (image background) were not considered (OA = 95.35%, Kp = 0.89). Certainly, the GLCM texture analysis derived from the S1 SAR images is a valuable source of information for obtaining very good classification results. When differentiating sunflower from onion considering also other crops present in the BVCR, the GLCM stack proved to be the most suitable dataset analyzed in this work (OA = 89.98%, Kp = 0.66 for SVM algorithm). This working methodology is applicable to other irrigated valleys in Argentina dedicated to intensive crops. There are also variables inherent to each lot, soil, crop and agricultural producer that differ according to the study area and that should be considered for each case in the future.

Estimating spatio-temporal distributions of mosquito breeding pools in irrigated agricultural schemes: a case study at the Bwanje Valley Irrigation Scheme

BackgroundThe association between irrigation and the proliferation of adult mosquitoes including malaria vectors is well known; however, irrigation schemes are treated as homogenous spatio-temporal units, with little consideration for how larval breeding varies across space and time. The objective of this study was to estimate the spatio-temporal distribution of pools of water facilitating breeding at the Bwanje Valley Irrigation Scheme (BVIS) in Malawi, Africa as a function of environmental and anthropogenic characteristics.MethodsIrrigation structure and land cover were quantified during the dry and rainy seasons of 2016 and 2017, respectively. These data were combined with soil type, irrigation scheduling, drainage, and maintenance to model suitability for mosquito breeding across the landscape under three scenarios: rainy season, dry season with limited water resources, and a dry season with abundant water resources.ResultsResults demonstrate seasonal, asymmetrical breeding potential and areas of maximum breeding potential as a function of environmental characteristics and anthropogenic influence in each scenario. The highest percentage of suitable area for breeding occurs during the rainy season; however, findings show that it is not merely the amount of water in an irrigated landscape, but the management of water resources that determines the aggregation of water bodies. In each scenario, timing and direction of irrigation along with inefficient drainage render the westernmost portion of BVIS the area of highest breeding opportunity, which expands and contracts seasonally in response to water resource availability and management decisions.ConclusionsChanges in the geography of breeding potential across irrigated spaces can have profound effects on the distribution of malaria risk for those living in close proximity to irrigated agricultural schemes. The methods presented are generalizable across geographies for estimating spatio-temporal distributions of breeding risk for mosquitoes in irrigated schemes, presenting an opportunity for greater geographically targeted strategies for management.

ANALYSIS OF FARM INCOME OF BENEFICIARIES AND NON-BENEFICIARIES OF HADEJIA VALLEY IRRIGATION PROJECT IN JIGAWA STATE, NIGERIA

The study examined the impact of Hadejia Valley irrigation project (HVIP) on farm income of beneficiaries in Jigawa State, Nigeria. From the list of 7036 respondents, 207 project beneficiaries and 146 non-beneficiaries were selected using a multi-stage random sampling making a total of 353 as the sample size of the study. Data were obtained using structured questionnaire and analyzed using descriptive statistics and F-test statistics. The results showed that beneficiaries and non-beneficiaries had a mean age of 47 and 45 years, a mean household size of 15 and 21 persons, educational levels of 8 and 7 years and mean off-farm income of N137,797.00 and N237,104 .00, respectively. The study also established 30 and 24 years of irrigation farming experience, farm sizes of 3.2 and 2.1 hectares, N33,641.00 and N55, 709.00 spent in hiring labour, farm distances of 3 and 0.9 kilometres, 5 and 3 extension visits per season, a mean of N52,771.00 and N50,205.00, N50,205.68 and N32,422.33 as credit and subsidy, respectively. Membership of cooperative associations indicated a mean of 0.8 and 0.5 for beneficiaries and non-beneficiaries, respectively. In the study area, the average total cost of production per hectare of beneficiaries and non-beneficiaries were N527,179.00 and N363, 191.00, and net farm income of N814,852.00 and N403,753.00 realized, respectively. The result of the F-test statistics on cost of production indicated F1,410 of 68.3> F at critical value of 3.86 at p = 5. 66E07 and farm income F1,410 of 726.3 >F at critical value of 3.86 at p = 8.56E-93 (P<0.05) level of significance. This suggested a significant impact of Hadejia valley irrigation project on farm income of the respondents. The study concludes that the project has had positive impact on the farm income of the project beneficiaries. It therefore, recommends that government should encourage income sources diversification; measures should be taken by the project authority to address inadequate access to extension. The project beneficiaries should form farmers’ co-operatives and measures should be taken by the project authorities to promote cost-saving technologies that encourage release of labour from irrigation to reduce the cost of production.

Quantifying irrigation recharge sources using groundwater modeling

Irrigated agriculture has created artificially high groundwater levels that are now considered the normal condition in some Montana (USA) valleys. Rural housing developments that use wells completed in these shallow aquifers depend upon the annual recharge from irrigation practices and infrastructure. However, water conservation efforts aiming to reduce the volume of irrigation water diverted from streams, by either converting fields from flood irrigation to sprinkler irrigation or lining irrigation canals, may reduce recharge to the underlying alluvial aquifers. For resource managers looking to both preserve the groundwater resource for domestic well use and reduce the volume of water diverted from rivers, knowing the primary source of groundwater recharge is key to choosing the most appropriate water-saving method.To address this question, a groundwater model of an irrigated valley was constructed to quantify the relative importance of groundwater recharge from infiltration of flood-applied irrigation water versus leakage from irrigation canals. In contrast to using assumed infiltration rates based upon irrigation method efficiency, applied irrigation recharge rates were approximated through the model by matching the magnitude and timing of measured hydrographs.Model results suggest that 1. canal leakage is the primary irrigation-related recharge source in this flood-irrigated valley, and 2. assumed applied-irrigation recharge rates based upon irrigation method can greatly overestimate recharge. Flood irrigation’s low efficiency (a high percentage of applied water is not evapotranspired) may result in groundwater recharge studies that find applied irrigation is the more important groundwater recharge pathway. Our work shows that water budgets and groundwater models that use inputs based upon irrigation method efficiency may overstate the importance of irrigation application to groundwater recharge.At this site, irrigation-water conservation efforts that also aim to maintain domestic groundwater supplies should focus on improving the efficiency of irrigation method rather than reducing leakage from the canals.

Geospatial Distribution of Some Phosphorus and Potassium Forms as Influenced by Period of Irrigation in the Kano River and the Hadejia Valley Irrigation Schemes, Nigeria.

This study was carried out at Kano River Irrigation Project (KRIP) (latitudes 11º 36ʹ 0.05ʺ N to 11º 49ʹ 57.97ʺ N and longitudes 8º 28ʹ 17.02ʺ E to 8º 29ʹ 41.82ʺ E) and Hadejia Valley Irrigation Project (HVIP) (latitudes 12º 17ʹ 48.75ʺ N to 12º 24ʹ 58.28ʺ N and longitudes 9º 51ʹ 31.29ʺ E to 10º 2ʹ17.42ʺ E). The soils are largely deep, well-drained Calcic Luvisols. The aim was to assess the geospatial distribution of some plant-nutrition related forms of P and K. A total of 37 and 19 irrigation sectors were identified in KRIP and HVIP respectively. Google earth was used to tag 109 and 41 sampling points randomly within both developed and undeveloped sectors of KRIP and HVIP respectively. With the aid of projects’ sitemaps, the sectors were demarcated into six periods of irrigation: 0 years (Non -irrigated), 1-10 years, 10-19 years, 20-29 years, 30-39 years and ≥ 40 years as applicable. GPS was used to track the tagged points at the time of sampling. Sur- face soil samples were collected by augering to 30 cm depth with fabricated steel augers. Samples were analyzed for physical and chemical properties. Available (AP) and total (TP) forms of P as well as water-soluble (WSK), exchangeable (Ex. K) and non-exchangeable (NEK) forms of K were analyzed. Basic soil prop- erties were compared by ANOVA using JMP version 12. Geostatistical analysis and Geospatial variability of various forms of P and K were performed with the GS+ software (version 10). Ordinary Kriging was used for the spatial interpola- tion. Texturally, the soils of the KRIP was sandy loam while that of the HIVP was predominantly sandy clayey loam. The pH (mean = 6.68) and EC (mean = 0.21 dsm-1) values across the sites indicated that despite the years of irrigation the areas are not under immediate salinization risk. There was no specific pattern of distribution of basic cations in both the two schemes. There is an observable tendency in the distribution of the forms of P and K evaluated of their being at higher concentrations in longer-periods irrigated lands in both the scheme. The nugget to sill ratio revealed a strong spatial dependence (< 25 %) for WSK. Moderately spatial dependence (25 to 75 %) was observed for available P, total P, noN-exchangeable K and exchangeable potassium. It was concluded that there may be a stronger influence of the irrigation method on the spatial distribution of the forms of the nutrients over other factors such as parent material and weathering.

Carbon and water footprints of Brazilian mango produced in the semiarid region

Awareness regarding carbon and water footprint has gained visibility, encouraging actions towards compliance with the main available standards by fruit producers. This study presents the carbon and water footprint of packed mango produced in Vale do Sao Francisco, the main irrigated valley in Brazil. It provides an approach to identify the critical processes and opportunities for improvements in the conventional crop system that may support producers in the task of developing future site-specific assessments. This assessment followed ISO 14046 and ISO 14067 for water and carbon footprints, respectively, as well as specific requirements of product category rule (PCR) 013 for fruits and nuts and Publicly Available Specification (PAS) 2051-1 for horticulture products. Primary data was collected for nursery (seedling), land use change, crop production, and packaging, considering five exported mango varieties: Palmer, Keitt, Kent, Haden, and Tommy Atkins. The carbon footprint assessment was based on the impact category climate change, while water footprint encompassed the following categories: water scarcity, marine and freshwater eutrophication, human toxicity (carcinogenic and non-carcinogenic), and freshwater ecotoxicity. The footprint analysis was performed for 1 kg of packed mango. The three main processes responsible for both footprints were related to crop production: fertilizer and electricity production as well as mango cropping. Moving from Caatinga vegetation to mango orchards increased carbon storage but was not enough to offset the impact on climate change. For water footprint, it was observed that the total volume of applied irrigation water was already below technical requirements and cannot be reduced, the same occurring for nitrogen fertilization. Scenario analysis showed that the use of alternative electricity sources and the reuse of wastewater brought no major improvement in results. Furthermore, the choice of local or country level characterization factors for water scarcity changed results significantly. Discussions are made regarding (i) the relevance of mango footprints when compared to other irrigated fruits, (ii) possibilities for improving mango footprint performance, (iii) the need for updating product category rules for fruits, and (iv) the quality of provided inventories and results. The comparison of mango footprints with previous studies of irrigated fruits showed that mango performance is similar or better than many irrigated fruits, cultivated all over the world. Moreover, footprints may be further reduced if mango orchards are established in previously deforested land or areas occupied with annual crops and if improvements are made in the irrigation and fertilization practices at each mango production stage.

Peopling the Cañete valley circa AD 600: A view from Cerro de Oro

Recent archaeological research in the lower Cañete valley shows that most of its current irrigation system may have been constructed circa AD 600, in relationship to the a series of small settlements along the valley and particularly, with a large urban settlement located at the far north end of the valley, 13 km from the Cañete River. Evidence from this settlement – Cerro de Oro – shows that a large population migrated to the site around AD 600 and started a large construction project that developed into a complex urban settlement in less than 50 years. This study follows several lines of evidence, mainly archaeological and ethnohistorical, in order to shed light on the construction of Cerro de Oro, its population and how they procured and processed their food, as well as its relationship to the development of the valley irrigation system. As a secondary objective, this study uses this information to explore whether climatological events such as floods may have played a role in the migration to the site.

A history of the 2014 Minute 319 environmental pulse flow as documented by field measurements and satellite imagery

As provided in Minute 319 of the U.S.-Mexico Water Treaty of 1944, a pulse flow of approximately 132 million cubic meters (mcm) was released to the riparian corridor of the Colorado River Delta over an eight-week period that began March 23, 2014 and ended May 18, 2014. Peak flows were released in the early part of the pulse to simulate a spring flood, with approximately 101.7mcm released at Morelos Dam on the U.S.-Mexico border. The remainder of the pulse flow water was released to the riparian corridor via Mexicali Valley irrigation spillway canals, with 20.9mcm released at Km 27 Spillway (41km below Morelos Dam) and 9.3mcm released at Km 18 Spillway (78km below Morelos Dam). We used sequential satellite images, overflights, ground observations, water discharge measurements, and automated temperature, river stage and water quality loggers to document and describe the progression of pulse flow water through the study area. The rate of advance of the wetted front was slowed by infiltration and high channel roughness as the pulse flow crossed more than 40km of dry channel which was disconnected from underlying groundwater and partially overgrown with salt cedar. High lag time and significant attenuation of flow resulted in a changing hydrograph as the pulse flow progressed to the downstream delivery points; two peak flows occurred in some lower reaches. The pulse flow advanced more than 120km downstream from Morelos Dam to reach the Colorado River estuary at the northern end of the Gulf of California.

Taking account of uncertainties in digital land suitability assessment.

Simulations are used to generate plausible realisations of soil and climatic variables for input into an enterprise land suitability assessment (LSA). Subsequently we present a case study demonstrating a LSA (for hazelnuts) which takes into account the quantified uncertainties of the biophysical model input variables. This study is carried out in the Meander Valley Irrigation District, Tasmania, Australia. It is found that when comparing to a LSA that assumes inputs to be error free, there is a significant difference in the assessment of suitability. Using an approach that assumes inputs to be error free, 56% of the study area was predicted to be suitable for hazelnuts. Using the simulation approach it is revealed that there is considerable uncertainty about the ‘error free’ assessment, where a prediction of ‘unsuitable’ was made 66% of the time (on average) at each grid cell of the study area. The cause of this difference is that digital soil mapping of both soil pH and conductivity have a high quantified uncertainty in this study area. Despite differences between the comparative methods, taking account of the prediction uncertainties provide a realistic appraisal of enterprise suitability. It is advantageous also because suitability assessments are provided as continuous variables as opposed to discrete classifications. We would recommend for other studies that consider similar FAO (Food and Agriculture Organisation of the United Nations) land evaluation framework type suitability assessments, that parameter membership functions (as opposed to discrete threshold cutoffs) together with the simulation approach are used in concert.