Operational water balance in irrigation districts

In pressure irrigation-water distribution networks, applied water volume is usually controlled opening a valve during a calculated time interval, and assuming constant flow rate. In general, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of pressure conditions.

Detailed study of water quality, bottom sediment, and biota associated with irrigation drainage in the Klamath basin, California and Oregon, 1990-92 /

Mode of access: Internet.

To allow producers to devote acreage conservation reserve acreage to water storage for irrigation [microform] : joint hearing before the Subcommittee on Cotton, Rice, and Sugar and the Subcommittee on Wheat, Soybeans, and Feed Grains of the Committee on Agriculture, House of Representatives, One Hundredth Congress, second session, on H.R. 5103, October 6, 1988.

"Serial no. 100-112."

Water-supply and irrigation papers of the United States Geological Survey.

Some nos. published in House Document series.

Irrigation development. History, customs, laws, and administrative systems relating to irrigations, water-courses, and waters in France, Italy, and Spain. The introductory part of the Report of the state engineer of California, on irrigation and the irrigation question.

"Authorities" at end of each chapter.

Annotated bibliography on the effects of irrigation practices on stream water quality with emphasis on salinity and pesticides /

Mode of access: Internet.

Papaya seedlings irrigation with saline water in soil with bovine biofertilizer

Water used for irrigation in semiarid regions of the world is not always of good quality, and may contain salts levels that inhibit plants growth. This study was conducted to evaluate the growth of papaya ( Carica papaya L.) ‘Golden’ seedlings irrigated with saline water in soil with and without bovine biofertilizer produced by anaerobic fermentation of a mixture of fresh bovine manure and water. The experiment was carried out in Areia County, Paraiba State, Brazil. Treatments were distributed in randomized blocks using a factorial design 5 × 2 relative to five salinity levels in irrigation water of 0.5, 1.0, 2.0, 3.0 and 4.0 dS m-1 in soil with and without bovine biofertilizer, corresponding to 10% of the substrate volume. At 90 d after emergence (DAE), both the electrical conductivity (EC) in soil saturation extract, biometric growth and DM production of papaya seedlings were evaluated. Increased salinity from 0.5 to 4.0 dS m-1 raised, within 90 DAE, soil EC of saturation extract (ECse) from 1.19 to 3.95 dS m-1 and from 1.23 to 3.63 dS m-1 in treatments with and without bovine biofertilizer, respectively. Also, the increase in water salinity from 0.5 dS m-1 to the estimated maximum values ranging from 1.46 to 2.13 dS m-1 stimulated seedling height to 11.42 and 18.72 cm in soil with and without bovine biofertilizer, respectively. Higher salinity levels in irrigation water increased soil salinity levels to values that inhibited both growth and quality of papaya seedlings, but with less severity when treated with bovine biofertilizer.

Evaluation of water use, yield and water productivity of a high-density orchard (cv. Cobrançosa) subjected to different irrigation regimes – An account of four years

The impact of different irrigation scheduling regimes on the water use, yield and water productivity from a high-density olive grove cv. Cobrançosa in southern Portugal was assessed during the irrigation seasons of 2011, 2012, 2013 and 2014. The experiments were conducted in a commercial olive orchard at the Herdade Álamo de Cima, near Évora (38o 29' 49.44'' N, 7o 45' 8.83'' W; alt. 75 m) in southern Alentejo, Portugal. The orchard was established with 10-year old Cobrançosa trees in grids of 8.0 x 4.2 m (300 trees ha-1) in the E-W direction, and experiments conducted on a shallow sandy loam Regosoil Haplic soil. From mid-May to the end of September the orchard was irrigated and three plots were subjected to one of two irrigation treatments: a control treatment A, irrigated to replace 100% ETc, a moderate deficit irrigation treatment B irrigated to 70% of ETc, and a more severe deficit irrigation treatment C that provided for approximately 50% of ETc. Daily tree transpiration rates were obtained by continuously monitoring of sap flow in representative trees per treatment. Among the irrigated treatments, water use efficiency (WUE, ratio of water used to irrigation- water applied) of treatment C was the highest, with a value of 0.89, being treatment B slightly lower, with a WUE of 0.76. Olive harvest for 2012 was an exceptional “on year”. Bearing yields showed contrasting differences within years where an “on year” was followed by an “off year”. In 2011 and 2012 treatment B yields were 41 and 50% higher than treatment C, respectively. In 2013 treatment B yield was 45% higher than yield of the fully irrigated treatment A, and treatment C showed practically the same yield than treatment A. In the “on year” of 2014 treatment B averaged 48% higher yield than treatment C. Treatment B farm irrigation water productivity (WPI-Farm, ratio of yield to water applied) was the highest among all treatments. Treatment A showed the lowest conversion efficiency of all treatments, indicating treatment B as the adequate deficit irrigation treatment for our Cobrançosa orchard

Adapting fruit production to climate change: how to increase intrinsic fruit quality and save water through deficit irrigation scheduling.

Fruit crops are an important resource for food security, since more than being nutrient they are also a source of natural antioxidant compounds, such as polyphenols and vitamins. However, fruit crops are also among the cultivations threatened by the harmful effects of climate change This study had the objective of investigating the physiological effects of deficit irrigation on apple (2020-2021), sour cherry (2020-2021-2022) and apricot (2021-2022) trees, with a special focus on fruit nutraceutical quality. On each trial, the main physiological parameters were monitored along the growing season: i) stem and leaf water potentials; ii) leaf gas exchanges; iii) fruit and shoot growth. At harvest, fruit quality was evaluated especially in terms of fruit size, flesh firmness and soluble solids content. Moreover, it was performed: i) total phenolic content determination; ii) anthocyanidin concentration evaluation; and iii) untargeted metabolomic study. Irrigation scheduling in apricot, apple and sour cherry is surely overestimated by the decision support system available in Emilia-Romagna region. The water stress imposed on different fruit crops, each during two years of study, showed as a general conclusion that the decrease in the irrigation water did not show a straightforward decrease in plant physiological performance. This can be due to the miscalculation of the real water needs of the considered fruit crops. For this reason, there is the need to improve this important tool for an appropriate water irrigation management. Furthermore, there is also the need to study the behaviour of fruit crops under more severe deficit irrigations. In fact, it is likely that the application of lower water amounts will enhance the synthesis of specialized metabolites, with positive repercussion on human health. These hypotheses must be verified.

Analysis of soil wetting and solute transport in subsurface trickle irrigation

The increased use of trickle or drip irrigation is seen as one way of helping to improve the sustainability of irrigation systems around the world. However, soil water and solute transport properties and soil profile characteristics are often not adequately incorporated in the design and management of trickle systems. In this paper, we describe results of a simulation study designed to highlight the impacts of soil properties on water and solute transport from buried trickle emitters. The analysis addresses the influence of soil hydraulic properties, soil layering, trickle discharge rate, irrigation frequency, and timing of nutrient application on wetting patterns and solute distribution. We show that (1) trickle irrigation can improve plant water availability in medium and low permeability fine-textured soils, providing that design and management are adapted to account for their soil hydraulic properties, (2) in highly permeable coarse-textured soils, water and nutrients move quickly downwards from the emitter, making it difficult to wet the near surface zone if emitters are buried too deep, and (3) changing the fertigation strategy for highly permeable coarse-textured soils to apply nutrients at the beginning of an irrigation cycle can maintain larger amounts of nutrient near to and above the emitter, thereby making them less susceptible to leaching losses. The results demonstrate the need to account for differences in soil hydraulic properties and solute transport when designing irrigation and fertigation management strategies. Failure to do this will result in inefficient systems and lost opportunities for reducing the negative environmental impacts of irrigation.

Modelling basin level allocation of water in the Murray-Darling Basin in a world of uncertainty, Murray-Darling Program Working Papers WPM05-1, Risk and Sustainable Management Group, 8 February 2005

Abstract: The Murray-Darling Basin comprises over 1 million km2; it lies within four states and one territory; and over 12, 800 GL of irrigation water is used to produce over 40% of the nation's gross value of agricultural production. This production is used by a diverse collection of some-times mutually exclusive commodities (e.g. pasture; stone fruit; grapes; cotton and field crops). The supply of water for irrigation is subject to climatic and policy uncertainty. Variable inflows mean that water property rights do not provide a guaranteed supply. With increasing public scrutiny and environmental issues facing irrigators, greater pressure is being placed on this finite resource. The uncertainty of the water supply, water quality (salinity), combined with where water is utilised, while attempting to maximising return for investment makes for an interesting research field. The utilisation and comparison of a GAMS and Excel based modelling approach has been used to ask: where should we allocate water?; amongst what commodities?; and how does this affect both the quantity of water and the quality of water along the Murray-Darling river system?

Attributes of irrigated rice and soil solution as affected by salinity levels of the water layer

In the State of Rio Grande do Sul, Brazil, flooded rice fields using Patos Lagoon as the source of water for irrigation are subject to be damaged by salinity, since this source is bound to the sea on its southern end. The sensitivity of rice is variable during plant development, being higher in the seedling and reproductive periods. However, there is not enough information about the behavior of plants under salt stress during the course of its development, especially in the vegetative stage. This study evaluated the effect of different levels of salinity of irrigation water on the salinity of soil solution over time and on some plant attributes, during the vegetative stage of rice. The study was conducted in a greenhouse, where seeds of the variety IRGA 424 were sown in pots and irrigated with water with electrical conductivity (ECi) levels of: 0.3, 0.75, 1.5, 3.0 and 4.5 dS m-1; from the tillering initiation (V4) until the panicle initiation (PI). The evaluations made were the electrical conductiviy of soil solution (ECe), the dry biomass of plants and stems, tillering, height and the transpiration of plants. The ECe increased with the ECi over time, and was determined by water transpiration flux in pots. The ECe values at the end of the experiment were high and, in most cases, higher than the critical values for flooded rice. The growth attributes of rice were negatively affected from ECi of 2.0 dS m-1 and ECe of 4.0 dS m-1.

Soil Water Potentials and Capsicum annuum L. under Salinity

ABSTRACT Investigations into water potentials in the soil-plant system are of great relevance in environments with abiotic stresses, such as salinity and drought. An experiment was developed using bell pepper in a Neossolo Flúvico (Fluvent) irrigated with water of six levels of electrical conductivity (0, 1, 3, 5, 7 and 9 dS m-1) by using exclusively NaCl and by simulating the actual condition (using a mixture of salts). The treatments were arranged in a randomized block design, in a 6 × 2 factorial arrangement, with four replicates. Soil matric (Ψm) and osmotic (Ψo) potentials were determined 70 days after transplanting (DAT). Soil total potential was considered as the sum of Ψm and Ψo. Leaf water (obtained with the Scholander Chamber) and osmotic potentials were determined before sunrise (predawn) and at noon at 42 and 70 DAT. There were no significant differences between the salt sources used in the irrigation water for soil and plant water potentials. The supply of salts to the soil through irrigation water was the main factor responsible for the decrease in Ψo in the soil and in bell pepper leaves. The total potential of bell pepper at predawn reached values of -1.30 and -1.33 MPa at 42 and 70 DAT, respectively, when water of 9 dS m-1 was used in the irrigation. The total potential at noon reached -2.19 MPa. The soil subjected to the most saline treatment reached a water potential of -1.20 MPa at 70 DAT. There was no predawn equilibrium between the total water potentials of the soil and the plant, indicating that soil potential cannot be considered similar to that of the plant. The determination of the osmotic potential in the soil solution should not be neglected in saline soils, since it has strong influence on the calculation of the total potential.

Water tanks as ecosystems. Local ecosystemic perception for integral management of water tanks in Tamil Nadu, South India

Water tanks offer from many centuries ago solutions in South India for several problems related with water scarcity. They are a traditional water harvesting system wide spread in this territory, allowing a potential decentralized and participatory management of the local population on their own resources. Although water tanks¿ main function is irrigation, they have many other uses, functions and natural resources associated, involving stakeholders in the villages apart from those farmers making use of the irrigation. Water tanks provide a variety of landscapes and biodiversity that creates a valuable heterogeneous territory. The complexity of such an ecosystem should be managed with an integral perspective, considering all the elements involved and their relations, and understanding that water tanks are not just water deposits. This multidisciplinary study tries to demonstrate the idea of water tanks as ecosystems, describing and analyzing deeply and in an unprecedentedly way the functions, uses, natural resources and stakeholders. The research also focuses in the assessment of the ecosystemic perception of the local population of some villages in Tamil Nadu, employing diverse anthropological methodology.

Guidelines for irrigation scheduling of banana crop in São Francisco Valley, Brazil. I - Root distribution and activity

In order to establish guidelines for irrigation water management of banana cv. Pacovan (AAB group, Prata sub-group) in Petrolina County, northeastern Brazil, the root distribution and activity were measured on an irrigated plantation, in a medium texture soil, with plants spaced in a 3 x 3 m grid. Root distribution was evaluated by the soil profile method aided by digital image analysis, while root activity was indirectly determined by the changing of soil water content and by the direction of soil water flux. Data were collected since planting in January 1999 to the 3rd harvest in September 2001. Effective rooting depth increased from 0.4 m at 91 days after planting (dap), to 0.6 m at 370, 510, and 903 dap, while water absorption by roots was predominantly in the top 0,6 m.