Irrigation, Agronomy and Environment


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Description

The group is interested in the scientific study of the interaction between crops, water, soil and the environment in one of the more arid regions of Europe: the middle valley of the Ebro river. Agriculture faces challenges such as globalization of markets, competition for the use of the resources water and soil, European regulations, increasing social demand for sustainability, and a growing demand of agricultural products. The scientific challenge is to produce scientific and technological information that will help to irrigated agricultural systems to be more competitive, more efficient and more sustainable.

For that purpose it is necessary to:

  1. Establish innovative technologies for the diagnosis and management.
  2. Increase the efficiency of resources use.
  3. Increase the stability of yield.
  4. Preserve the agricultural resources and the environment.

Objective

The research activities of the "Irrigation, Agronomy and the Environment" Group focus on three priority research actions:

  1. Sustainable agricultural use of water and soil resources;
  2. Environmental impact of agricultural activities; and
  3. Crop agronomy.

Both the general objective and the priority research actions are in agreement with the objectives of the National Research Plan (Plan Nacional de I+D+I 2008-2011), Framework Program 7 of the European Union (2007-2013) and the RTD Plan of the Government of Aragón, Spain (PAID 2005-2008, Gobierno de Aragón).

This research Group is fully coordinated with the Soils and Irrigation Unit of the Agri-food Research and Technology Centre of the Government of Aragón (Unidad de Suelos y Riegos, Gobierno de Aragón). Coordination is implemented through the Associated Unit to CSIC formed by researchers of both Groups. Additionally, the Government of Aragón recognizes the Associated Group as a "Group of Excellence". The Associated Group is the environment where strategic planning and research implementation are performed.

Specific objectives

Modeling sprinkler and surface irrigation systems: on farm irrigation and distritution networks

Coordinator: Javier Burguete

Contact: jburguete@eead.csic.es

Models permit to obtain fast predictions of the performance of future scenarios in irrigation. Optimizing irrigation performance by experimentation is a complex, time-consuming and expensive process. If numerical models are available, irrigation optimization can be analyzed in a simple, fast and inexpensive way.

Modeling consists on the transformation of physical reality into mathematics. First, a set of variables closely characterizing the problem (in this case the application and distribution of water and fertilizers in irrigation systems) must be defined. In a second step, the equations governing the problem must be formulated using physics. Finally, it is necessary to solve these equations using accurate and/or fast mathematical methods. Finally, user-friendly software needs to be designed for widespread application.

Modeling surface irrigation requires the solution of the shallow water equations (including infiltration) and often the calibration of empirical coefficients for roughness and infiltration using experimental measurements. The theoretical characterization of the friction force in highly rough surfaces and the process of infiltration in furrows, borders and basins constitute active research lines of this group. Effort is being devoted to introduce the innovations developed by Pilar García-Navarro's group at the University of Zaragoza in surface irrigation models and branching canal models. An intense collaboration was established in the mid 1990s with this group specializing on the development of high-order accurate numerical methods for unsteady water flow and conservative methods adapted to channel and furrow junctions.

In sprinkler irrigation, experimental measurements of water application and drop size do not provide the information required to validate ballistic models: measurements of drop velocity are necessary. A method based on the analysis of the jet trajectory, statistical methods applied to the analyses provided by optical disdrometers and photographical methods have been proposed by our group to estimate the drop velocity. These new techniques have shown that the grouped movement of sprinkler drops during the initial phase of their trajectory causes a noticeable effect on the drag forces. This effect is neglected in the current ballistic models. An important research objective is the development of a new model incorporating this effect and its validation using the proposed techniques for drop velocity characterization. The current computation speed of computers, and the optimization of the numerical methods permit to simulate all the drops emitted by all sprinklers in a solid-set (or by a center pivot), thus enabling the analysis of border effects on irrigation performance. These studies will be complemented with the analysis of water transport in pressurized networks such as solid-sets, center pivots or distribution networks.

Optimizing water use and N fertilization in irrigated agricultural systems
Coordinator: José Cavero
Contact: jcavero@eead.csic.es

 

Irrigation water

Around 90% of the area involved in irrigation modernization projects in the Ebro valley will use sprinkler irrigation. During sprinkler irrigation some water is lost in its way from the sprinklers to the soil, the losses being higher when windy and dry climatic conditions prevail in the area. These losses strongly modify the microclimatic conditions where plants are growing, resulting in relevant plant physiological changes. The work done in the last years on this topic focus on estimating the impact of these losses on the yield of the most relevant irrigated crops in the Ebro valley (maize and alfalfa).

 

Harvesting an experiment on
day-time and night-time irrigation in maize.
 

 

Research has been performed to characterize the magnitude and duration of microclimatic (temperature and vapour pressure deficit) and physiological (evapotranspiration, canopy temperature and photosynthesis) changes in maize and alfalfa. Changes have been assessed 1-2 h before, during and 3-4 h after sprinkler irrigation events (solid-sets and centre-pivots) in day-time and night-time periods. Factors favouring or moderating these changes have been studied. We have used sap flow and chambers implementing infrared gas analysers to continuously determine evapotranspiration and photosynthesis during irrigation events. During daytime irrigation events maize and alfalfa transpiration decrease. Evapotranspiration reduction in maize amounts to about 2-3% of the applied water. We have shown that daytime irrigation of maize results in a 10% yield reduction. Causes for this yield reduction are being analysed. In the coming years alfalfa will be targeted to further characterize its response to day-time / night-time irrigation and to irrigation depth

 

Chambers used to study the impact of sprinkler Irrigation on maize photosynthesis.

 

N fertilization

Nitrogen is the most difficult nutrient to manage in irrigated agricultural systems. Several studies performed by the research group have shown that nitrogen management should be improved to minimize off-site pollution and to decrease crop production costs. In the last years, research has been done on catch crops during the winter time in maize monoculture, on the optimization of nitrogen fertilization in maize after alfalfa, and on the use of crop simulation models to determine the impact of crop management on nitrate losses in irrigation return flows.

The use of barley as a catch crop in maize monoculture permits to limit nitrogen losses, but reduces maize yield by 15%. When maize follows an alfalfa crop, nitrogen fertilization can be reduced down to 150 kg N/ha. In the Violada watershed (Almudévar, Huesca, Spain), the application of the APEX model led to the conclusion that the best option to reduce nitrogen losses is the change of the irrigation system from surface to sprinkler.

 

Soils and habitats of interest related with agricultural activities

Coordinator: Juan Herrero and Carmen Castañeda

Contact: jhi@eead.csic.es and ccastaneda@eead.csic.es

Soil is envisaged as a key constituent of the environment, subject of transformations related with land use changes. We have focused on the environmental impact of agriculture in the arid conditions of the central Ebro Valley. These conditions pose ill-known problems, often without parallel in the other Western European countries. We study soil salt-affection in both irrigated and non-irrigated lands. These studies are applied to the agricultural production and to the conservation of habitats protected or having environmental interest, most of them saline wetlands. The soils of the wetlands and surrounding agricultural lands are studied at several observation scales with adapted methods ranging from satellite imagery to the microscope. Integrating the study of soil features with different disciplines broadens the scope of agricultural and environmental applications. In the field, this approach will allow the monitoring of soils considered hot spots in terms of land use changes.

Foreseen actions are:

1. Study of the soils in the field. We start with landscape observation with the classical techniques of field reconnaissance and photointerpretation. The habitats of interest are identified and delineated base on vegetation study. After this survey we search the soil features associated with past or present singular conditions, like salinity or hydromorphism. For this purpose, soils are sampled by augering or by pits. The pits allow the description and sampling of pedons including the extraction of undisturbed soil blocks when needed. We also use physical, chemical or mineralogical analyses to detect features of interest. Our aim is an integrated knowledge of the soil throughout a continuum of observation scales using techniques from microscopy to remote sensing described in the following sections.

 

A pit enables to distinguish the soil horizons (1) and to separately sample these horizons (2 and 3).
If needed, undisturbed blocks of soils can be taken (4) for their study under the microscope or by non-destructive techniques.

 

2. The investigation on undisturbed soil samples by a) establishing a laboratory of micromorphology for the preparation of thin section of soils and other unconsolidated materials containing soluble minerals, and b) the application of the techniques of microscopy. It will be a seminal infrastructure for the study of soils morphology, mapping, and evaluation. These will be tools for implementing and monitoring soil conservation measures in the scenario of the new irrigation schemes or other changes in land use

 

The undisturbed blocks of soils are impregnated with plastic to produce consolidated blocks and tablets (1).
By lapping the tablets we obtain soil sections 25 micrometers thick for the study under polarizing
microscope. At the thin section (2) the typical peloidal morphology of uncertain origin and lenticular
gypsum indicate lacustrine environment. In (3) Fe-Mn oxide coatings in aggregate faces along voids
evidence oxidation and reduction conditions, and in (4) calcium carbonate forms coatings visible in the field.

 

3. Remote sensing based on optical and radar imagery support the study of habitats threatened by agricultural intensification. The methodology developed in our playa-lakes will be extended to other wetlands on arid environments. The applications are delineation, inventory and characterization of soils and vegetation at the interface of agricultural lands with wild or protected habitats. This action includes specific radar applications for studying the deformation of the terrain, particularly the subsidence caused by evaporites dissolution.

 

Saline wetlands (La Playa, Pueyo, and Pito) in Monegros, Spain, are blue in a Quickbird image (RGB 432
composition) (1). Optical sensors show the irrigated lands in red tones in a false color composition (2),
while in radar images, the irrigated lands stand out by the high intensity of the signal (3). Radar can also
measure ground deformations, in (4) different colors have been applied to the deformation fringes
associated to a mine nearby Zaragoza, Spain

 

Collective irrigation management: diagnosis and technological support

Coordinator: Enrique Playán
Contact: enrique.playan@eead.csic.es

This is a traditional research action in the group, which has focused on the diagnosis of collective irrigation performance and on the support to water management at the irrigation district level using the Ador software. Progress in this line is being fostered by current developments in the lines devoted to on-farm irrigation sytem and crop modelling, by the availability of crop water requirements data and by the generalization of telemetry/remote control systems at the irrigation district level.


Foreseen actions include:


1. Diagnosis of collective irrigation in water users associations will continue. We will focus on recently modernized irrigated areas using telemetry / remote control systems. The goal will be analysing their operation and facilitate integration of new technologies in water and energy (pumping) management .


2. Progress in the development and validation of models including the crop, the soil, the irrigation system, the land tenure structure and the collective conveyance system. Such models will be developed for surface irrigation – open channel collective networks – canals and particularly for sprinkler/drip irrigation – pressurized collective networks – canals. These models of pressurized systems will lead to the development of collective irrigation schedulers, devoted to schedule and implement irrigation in real-time applications using telemetry/remote control systems. The scheduler is designed to reduce farmers' input in irrigation control to a supervisory role, reduce water and energy input and sustain crop yield. District irrigation evaluation will be required to deepen in the understanding of farmers' scheduling rules. Field experimentation at the research facilities and selected irrigation districts will support software calibration and system validation.


3. Continued development of the Ador software for the management of irrigation districts. Version 2.0 has been released, introducing crop water requirements and performance indicators. Ador is a pillar of the subline extension strategy, and will therefore implement developments resulting from other research actions.

 

International consulting is one of the tasks associated
to this research line. In the picture, opportunistic irrigated
agriculture by the Nile River near Khartoum, Sudan.

 

 

On-farm irrigation systems: evaluation, design and management improvements.
Coordinator: Nery Zapata and Raquel Salvador
Contact: vzapata@eead.csic.es and rsalvador@eead.csic.es

 

This activity has a long tradition in our research group. The evaluation of an irrigation system is the study that provides the information necessary to make a diagnosis of the system operation, determining the weak points of the system. The irrigation system performance depends on technical, meteorological and agronomical factors. The weight of each one of those factors is different if it is a surface, sprinkler or dripped irrigation system. One of the objectives is to develop, calibrate and validate simulation models for agricultural and urban irrigation systems. The on farm irrigation models are coupled with crop models to simulate spatial variability of water distribution and crop yield. The progress of this line has resulted in the development of an automatic programmer for on farm solid set sprinkler irrigation. The automatic programmer prototype generates the irrigation schedules of the different hydraulic sectors of a farm and executes the irrigation orders. The device has be successfully proven on filed, it has reduced the labour time that the farmer dedicates to the irrigation activity and it has also reduced the applied amount of water without affecting crop yield.

 

Experimental results of irrigation depth (ID, m3ha-1) and corn yield (Kgha-1) for the two experimental
seasons and for the three treatments analysed: the farmer schedule and two automatic schedules
performed by the automatic programmer device, a simplified one and an advanced one.

 

Foreseen actions include:


1.  Progress in the development and validation of the new generation of on farm automatic programmers for sprinkler irrigation. The prototype for solid set has been proved successfully and the new step is to develop a tool for sprinkler irrigation machines as pivot or frontal move systems. This work has two parts that evolve parallel, one part is the development of the simulation tool and the second part is the field experiments designed to calibrate and validate the simulation tool. In this line, water distribution for the most common emitter (fixed plate and rotator plates) used in sprinkler irrigation machines and working under different technical and meteorological conditions have been characterized on field. Also the dynamic of the sprinkler machine has been experimentally studied and its correspondent simulation tool is under development. Finally, this line will be completed coupling the different simulation tools as the dynamic of the machine, the hydraulic model, the emitter water distribution models and the crop simulation model. Field tests will be performed to calibrate and validate the tool.
2. The irrigation simulation tool has been also developed for drip irrigation systems, especially for advanced irrigation strategies as regulated deficit irrigation in stone fruit orchards. The tool called RIDECO can be freely download at the website: http://digital.csic.es/handle/10261/45608
3. Progress in the evaluation of the irrigation performance in private and public urban landscapes. Characterizing the crop water requirements for the different species and the adequacy to the water applied along the irrigation season.