Center Pivot System Research Articles

Evaluation of Aquacrop model for a potato crop under different irrigation conditions

The processes of calibration and validation of the Aquacrop model for the simulation of the growth and development of a potato crop (Agria cultivar) that was irrigated with a center pivot system are described in this study. The field experiments were conducted during 2011 (calibration) and 2012 (validation) in a semiarid region in southeastern Spain. The potatoes were irrigated with four treatments (120%, 100%, 80%, and 60% of the water requirement). The Aquacrop model was suitable for the simulation of the growth and development of potatoes in the climatic conditions of the study area. The canopy cover, total dry matter, dry matter of tubers and evapotranspiration were the primary variables analyzed. An acceptable goodness of fit was found between observed and simulated values. So, statistical indicators such as the Willmott index of agreement (d) and the coefficient of determination (R2) showed good values (d and R2>0.90) for the primary variables analyzed. Both the model and the observed data found that 80% and 60% of the water requirements were the treatments that were most efficient in the use of water. A high temperature stress coefficient affecting the harvest index is recommended to be incorporated in the model for avoiding overestimations of yield.

Antagonistic rhizobacteria and jasmonic acid induce resistance against tomato bacterial spot

Tomato bacterial spot on tomato may be caused by four species of Xanthomonas and among them X. gardneri (Xg) is the most destructive one, especially in areas irrigated using a center pivot system in Minas Gerais state and the midwest region of Brazil. Due to the ineffectiveness of chemical control and the lack of cultivars with high levels of genetic resistance, this study investigated the potential of three antagonists (Streptomyces setonii (UFV618), Bacillus cereus (UFV592) and Serratia marcescens (UFV252)), and the hormone jasmonic acid (JA) as a positive control, to reduce bacterial spot symptoms and to potentiate defense enzymes in the leaves of tomato plants infected by Xg. Tomato seeds were microbiolized with each antagonist, and the soil was drenched with these bacteria. The plants were sprayed with JA 48 h before Xg inoculation. The final average severity on the tomato plants was reduced by 29.44, 59.26 and 61.33% in the UFV592, UFV618 and JA treatments, respectively. The UFV618 antagonist was as effective as JA in reducing bacterial spot symptoms on tomatoes, which can be explained by the greater activities of defense enzymes that are commonly involved in host resistance against bacterial diseases. These results suggest that JA and the UFV618 antagonist can be used in the integrated management of bacterial spot on tomatoes.

Impact of water deficit on light interception, radiation use efficiency and leaf area index in a potato crop (Solanum tuberosumL.)

SUMMARYThe aim of the current research was to analyse the effect of four water irrigation treatments (1·20, 1·00, 0·80 and 0·60 of the crop water requirement) on the relationships among leaf area index (LAI), radiation use efficiency (RUE) and green canopy cover in a potato crop (Solanum tuberosumL.) cv. Agria. The crop was established in a commercial plot irrigated with a centre pivot system in Southeast Spain during the 2011 and 2012 seasons. In both seasons, the highest light absorption efficiency values occurred at the LAI value of 3 that corresponded to maximum ground cover. With regard to the irrigation treatment, a significant linear response was indicated for RUE. The results indicate that the 1·00 irrigation treatment produced the best result, improving water resources management without reducing crop yield.

A non-destructive method for estimating onion leaf area

AbstractLeaf area is one of the most important parameters for characterizing crop growth and development, and its measurement is useful for examining the effects of agronomic management on crop production. It is related to interception of radiation, photosynthesis, biomass accumulation, transpiration and gas exchange in crop canopies. Several direct and indirect methods have been developed for determining leaf area. The aim of this study is to develop an indirect method, based on the use of a mathematical model, to compute leaf area in an onion crop using non-destructive measurements with the condition that the model must be practical and useful as a Decision Support System tool to improve crop management. A field experiment was conducted in a 4.75 ha commercial onion plot irrigated with a centre pivot system in Aguas Nuevas (Albacete, Spain), during the 2010 irrigation season. To determine onion crop leaf area in the laboratory, the crop was sampled on four occasions between 15 June and 15 September. At each sampling event, eight experimental plots of 1 m2were used and the leaf area for individual leaves was computed using two indirect methods, one based on the use of an automated infrared imaging system, LI-COR-3100C, and the other using a digital scanner EPSON GT-8000, obtaining several images that were processed using Image J v 1.43 software. A total of 1146 leaves were used. Before measuring the leaf area, 25 parameters related to leaf length and width were determined for each leaf. The combined application of principal components analysis and cluster analysis for grouping leaf parameters was used to reduce the number of variables from 25 to 12. The parameter derived from the product of the total leaf length (L) and the leaf diameter at a distance of 25% of the total leaf length (A25) gave the best results for estimating leaf area using a simple linear regression model. The model obtained was useful for computing leaf area using a non-destructive method.

Optimal reservoir capacity for centre pivot irrigation water supply: Maize cultivation in Spain

Centre pivots are one of the most widespread irrigation systems in the world. The aim was to develop a tool to optimise the design and management of the water distribution and centre pivot systems seeking to minimise water application cost per unit area (CT), including investment (Ca), operation (Ce), and maintenance costs. With this aim, two options were considered: to feed the centre pivot 1) directly from an aquifer or 2) using a regulation reservoir. A software tool DEPIRE (design of centre pivot with regulating reservoir), was developed and implemented in MATLAB 2012b (The MathWorks Inc., Natick, MA, USA). It determines optimal flows, pipe diameters, pumps power and the volume of the regulation reservoir for any crop water requirement, different electricity rates and water availability in the tube well. With this tool, the effect of the irrigated area (S), dynamic water level (DWL) in the aquifer and the pumping flow rate on the CT was evaluated for a maize crop in Spain. The study area representing the minor CT was 70 ha for direct pumping from the borehole and 100 ha when using an intermediate reservoir. Incorporating a regulation reservoir generates lower CT than direct feed from the borehole for S > 100 ha for any DWL. CT increased linearly with the DWL due to a significant increase in Ce which primarily affects the cost of water extraction from the aquifer, with a smaller effect on the application cost of the irrigation system.

Harvesting water in a center pivot irrigation system: Evaluation of distribution uniformity with varying operating parameters

The main objective of irrigation is to apply the optimum amount of water to the crop root zone that is needed for its growth. Also, when irrigation systems are used to apply fertilizers and pesticides, the irrigation process becomes even more critical in terms of uniformity. Consequently, it is important for center pivot owners and operators to periodically check the uniformity of their systems in order to adjust all the operating parameters involved. To assess the real distribution uniformity of irrigated water, a study was conducted in southern Libya; this paper reports the results of water irrigation in a center pivot system with respect to the effects that the operating pressure (P), the spacing between sprinklers (S), and the height of sprinkler above the ground surface (H) show on the distribution uniformity. Several factors define the uniformity of water distribution; in this work the coefficient of uniformity CU, the low quarter distribution uniformity DU lq , and the coefficient of variation CV are considered. The highest values reached by the uniformity parameters with varying the operating conditions define the best operating practices under which the whole system works efficiently. The final results are given in terms of operating conditions able to save total costs in the studied area and in places characterized by similar geo-hydrological conditions.

SITE-SPECIFIC PIVOT SPRINKLER ASSESSED FOR SAVING WATER IN AGRICULTURE

All center pivot systems currently available from the manufacturers can apply different rates of water during irrigation by varying speed. However, these systems generally cannot change the application rate along the length of the pivot boom. The whole system can speed up to apply less water or slow down to apply more. If a pivot is simultaneously crossing areas that are wet (drainage area) and dry (sandy), then a traditional system would have to address one problem of over- or under-irrigate one area or another. Conversely, a variable-rate pivot could apply less water to the wet area and more to the dry area at the same time. The system at the current study is a true variable rate center pivot. The system was developed and tested for two years where the water saving and sugar beet production were measured. Due to the dry weather in most of a season, the differences were clearer than the high rainy year during another season. The results indicated water saving in the second season (102 mm) while low change existed in water use in the first season (36 mm). Sugar beet and sugar production were similar under full irrigation (100% of water balance) and VRI (80% of water balance) for loamy soil (medium quality) for both two seasons, which means that we can obtain the same production with water saving.

Life Cycle Energy and Greenhouse Gas Emission Analysis of Groundwater‐Based Irrigation Systems

AbstractThe reliance on groundwater for irrigation is increasing in Australia and India, which is causing concerns to policy makers about energy consumption and greenhouse gas (GHG) emissions. Therefore, it is important to quantify the GHG emissions of all components of the groundwater‐based irrigation systems, over the entire life cycle to develop more environmentally friendly groundwater management strategies. This study identified and analysed energy use and GHG emissions associated with different components in the supply chain of groundwater‐based irrigation systems. An existing GHG emissions and energy‐accounting framework was adapted to enhance its capabilities by considering drilling techniques, water distribution and irrigation application methods. The results of this study highlighted that embodied and direct GHG emissions from drilling tube wells were higher in the Musi catchment, India, compared to South Australia. The study also highlighted that GHG emissions associated with water conveyance were higher for concrete and plastic‐lined channels than unlined channels. Drip irrigation systems in both countries were found to have more GHG emissions than gravity‐fed systems. Centre pivot systems were found to be emitting more than the drip systems in South Australia. We conclude that different components of the system have an impact on total GHG emissions and energy consumption for both countries. Any change in the most commonly used methods of drilling bore wells, water distribution in channels, and the irrigation methods, will have distinct impacts on energy consumption rates and GHG emissions. The developed conceptual framework provided a systematic complete analysis of the energy‐consuming and GHG‐emitting components associated with groundwater‐based irrigation systems. Policy makers and decision makers may use the developed framework to compare different system components to develop strategies that have minimal impact on the environment. Copyright © 2015 John Wiley & Sons, Ltd.

Uniformity Assessment of Irrigation with Centre Pivots in Uruguay

Irrigation with centre pivots has increased exponentially under the last decade in Uruguay; starting with a few sets, now there are more than 350 sets which cover 30.000 ha. To conduct performance evaluations of the centre pivots we selected a representative sample of the sets used in Uruguay: 20 sets in three different regions in the country, whose lateral longitude ranged from 398 to 802 m. Uniformity tests of the equipments were conducted according to the methodology proposed by the international standards: ANSI/ASAE S436.1 (JUN 1996). The uniformity coefficient of Hermann and Hein (CUh) of 16 sets reached acceptable values (80 to 87 %), while the rest obtained very low coefficient values (54 to 71%). Distribution Uniformity values (UD) followed the same tendency as CUh values. The 16 sets with high CUh, obtained high UD values (71 to 85%), whereas the rest got lower UD values (26 to 70%). Centre pivots may attain high application uniformity in Uruguayan agrosystems, given an adequate combination of system design and operation. An inaccurate management of centre pivots due to operation below required pressures and to poor maintenance of sprinklers will directly impact the sheets applied, and the application uniformity and efficiency of the centre pivot system.

A non-destructive method for estimating onion leaf area

AbstractLeaf area is one of the most important parameters for characterizing crop growth and development, and its measurement is useful for examining the effects of agronomic management on crop production. It is related to interception of radiation, photosynthesis, biomass accumulation, transpiration and gas exchange in crop canopies. Several direct and indirect methods have been developed for determining leaf area. The aim of this study is to develop an indirect method, based on the use of a mathematical model, to compute leaf area in an onion crop using non-destructive measurements with the condition that the model must be practical and useful as a Decision Support System tool to improve crop management. A field experiment was conducted in a 4.75 ha commercial onion plot irrigated with a centre pivot system in Aguas Nuevas (Albacete, Spain), during the 2010 irrigation season. To determine onion crop leaf area in the laboratory, the crop was sampled on four occasions between 15 June and 15 September. At each sampling event, eight experimental plots of 1 m

Friction Head Loss in Center-Pivot Laterals with Single Diameter and Multidiameter

In this paper, efficient closed form expressions to compute the friction head loss in center-pivot laterals using the method of the discrete outflow distribution are presented. The results are applicable to center-pivot systems with single diameter and multidiameter, with constant spacing between sprinklers along the lateral, with and without end gun sprinklers, and with and without closed outlets at the beginning of the lateral. The head loss between the last outlet and the end gun, usually neglected in the existing literature, is explicitly considered. The values of the friction head loss along the lateral obtained with the discrete outflow distribution are compared with those obtained with the continuous outflow distribution and with other expressions available in the literature. The proposed expressions provide a more general description of head loss and lead to more accurate results.

Does efficient irrigation technology lead to reduced groundwater extraction? Empirical evidence

Encouraging the use of more efficient irrigation technology is often viewed as an effective, politically feasible method to reduce the consumptive use of water for agricultural production. Despite its pervasive recommendation, it is not clear that increasing irrigation efficiency will lead to water conservation in practice. In this paper, we evaluate the effect of a widespread conversion from traditional center pivot irrigation systems to higher efficiency dropped-nozzle center pivot systems that has occurred in western Kansas. State and national cost-share programs subsidized the conversion. On an average, the intended reduction in groundwater use did not occur; the shift to more efficient irrigation technology has increased groundwater extraction, in part due to shifting crop patterns.

Modelling economic impacts of deficit irrigated maize in Brazil with consideration of different rainfall regimes

Deficit irrigation is often required to cope with droughts and limited water availability. However, to select an appropriate irrigation management, it is necessary to assess when economic impacts of deficit irrigation are acceptable. Thus, the main goal of this study was to evaluate economic water productivity for maize submitted to various levels of water deficits and different irrigation systems. The study was based on two different experiments conducted in Southern Brazil, one using sprinkler irrigation to supplement rainfall and the other using drip irrigation with precipitation excluded by a rainfall shelter to simulate cultivation under dry conditions. Water productivity indicators were calculated referring to: a) actual field collected data, including yields, commodity prices and production costs; and b) a sensitivity analysis to commodity prices and production costs. Alternative centre-pivot irrigation scenarios were also developed to assess their feasibility in terms of water use and productivity when irrigation is used to supplement rainfall or when rainfall is scarce. Results show that the feasibility of deficit irrigation is highly influenced by commodity prices and by the irrigation (and water) costs when the irrigation costs are a large part of the production costs. Results also show that deficit irrigation applied when rainfall is abundant is easier to implement than deficit irrigation where rainfall is very scarce, when only a mild stress is economically viable. For well-designed and managed centre-pivot systems, results confirm that adopting deficit irrigation when rainfall is scarce is less attractive than under conditions of irrigation to supplement rainfall. It could be concluded that farmers are unlikely to choose a deficit irrigation strategy unless they are facing reduced water availability for irrigation.

Crop coefficient, water requirements, yield and water use efficiency of sugarcane growth in Brazil

A correct evaluation of water losses as evapotranspiration (ET) by crops is important for allocating irrigation water and improving water use efficiency. Field experiments were conducted throughout 2009/2010 (second ratoon) and 2010/2011 (third ratoon) in a sugarcane field of a commercial distillery located on the coastal area of Paraiba state, Brazil. The main objective of this study was to determine crop coefficient, water requirements and water use efficiency (WUE) of sugarcane grown in a tropical climate. The experimental design was by randomized block design with four irrigation treatments and three replications using two center pivots. Crop evapotranspiration (ET) was determined by field soil water balance and reference evapotranspiration (ETo) was obtained based on Penman–Monteith method (FAO/56), using data of air temperature, relative humidity, wind speed and solar radiation from Data Collection Platform, located next to the experimental site. The experimental area was cultivated with irrigation applied weekly by a center pivot system in addition to rainfall. The irrigation scheduling was based on four irrigation levels (T1=25%, T2=50%, T3=75% and T4=100% of ETo). Results showed that ET and WUE are strongly influenced by soil water availability. When averaged across two years, productivity increased according to increases in water level. Sugarcane ET ranged from 2.7 (rain-fed condition) to 4.2mm day−1 (100% ETo irrigation treatment)

Estimation of leaf area index in onion (Allium cepa L.) using an unmanned aerial vehicle

Leaf area index ( LAI ) is one of the most common indices in agronomy , being a parameter associated with physiological processes. Canopy cover and structure are related to LAI and they have effects on the interaction between crops and the environment. The aim was to evaluate a non-destructive method to measure canopy cover in an onion crop using an unmanned aerial vehicle (UAV). A field experiment was conducted in a commercial onion plot irrigated with a centre pivot system during the 2010 irrigation season. Several data sampling events were carried out in order to determine leaf area in eight experimental plots. In each one of these plots, aerial photographs were taken using a vertical take-off and landing (VTOL) quadrotor aircraft. Canopy cover ( CC ) was obtained by means of software developed for this study. The maximum value of LAI represents a CC of 56%, which is high for the characteristics of this crop. Three models were used to analyse the relationship between leaf area index and canopy cover. According to the results, a more linear relationship was found between both parameters during early growth stages than during more advanced stages. For the linear model, which best fitted all growth stages; the slope that relates CC with LAI was 2.877 with a coefficient of determination of 0.837. ► A non-destructive method was evaluated to measure canopy cover in an onion crop. ► Aerial digital photography from unmanned aerial vehicles was used. ► A software tool was developed to determine canopy cover. ► Relationship between canopy cover and leaf area index found using an automatic IR imaging system.

Custos da irrigação e receita líquida do feijoeiro em um sistema pivô central sob variação do comprimento da tubulação de recalque e desnível topográfico

Neste trabalho, foi simulado o custo da irrigação de um sistema tipo pivô central com diferentes comprimentos da tubulação de recalque e desníveis topográficos na produção do feijoeiro comum, na região de Ilha Solteira -SP, bem como sua receita líquida. Considerou-se uma área irrigada pelo equipamento de 103,58 ha, sendo sua configuração a mais econômica possível para as variáveis consideradas. A participação da irrigação no custo de produção do feijoeiro variou de 14,8 a 21,5% entre as condições extremas, ou seja, do menor desnível topográfico (40 m) e comprimento da tubulação de recalque (2.000 m) ao maior desnível (80 m) e comprimento (3.000 m). Em todas as configurações do sistema de irrigação e com os preços praticados em agosto de 2008 ou com o preço histórico médio, seria viável a cultura do feijoeiro, proporcionando rendas líquidas de até R$ 3.959,64 ha-1 e até R$ 1.203,14 ha-1, respectivamente.

Real-Time Modelling and Optimisation for Water and Energy Efficient Surface Irrigation

The viability and sustainability of crop production is currently threatened by increasing water scarcity. Water scarcity problems can be addressed through improved water productivity and the options usually presumed in this context are efficient water use and conversion of surface irrigation to pressurised systems. By replacing furrow irrigation with drip or centre pivot systems, the water efficiency can be improved by up to 30% to 45%. However, the installation and application of pumps and pipes, and the associated fuels needed for these alternatives increase energy consumption. A balance between the improvement in water use and the potential increase in energy consumption is required. When surface water is used, pressurised irrigation systems increase energy consumption substantially, by between 65% to 75%, and produce greenhouse gas emissions around 1.75 times higher than that of gravity based irrigation systems so their use should be carefully planned keeping in view adverse impact of carbon emissions on the environment and threat of increasing energy prices. With gravity-fed surface irrigation methods, the energy consumption is assumed to be negligible. This study has shown that a novel real-time infiltration model REIP has enabled implementation of real-time optimisation and gravity fed surface irrigation with real-time optimisation has potential to bring significant improvements in irrigation performance along with substantial water savings of 2.92 ML/ha which is equivalent to that given by pressurised systems. The real-time optimisation and control thus offers a modern, environment friendly and water efficient system with close to zero increase in energy consumption and minimal greenhouse gas emissions.

Spatial variability for some properties of the wastewater irrigated soils

Composite surface soil samples (236 samples) were collected from three fodder farms irrigated for a long period with the treated sewage effluents or well water through a center pivot system. The soil of the 1st farm was loamy sand in texture while it was sandy loam for the other two farms, all were calcareous containing more than 10% of (CaCO3). The average values of EC for the 1st, 2nd and 3rd farms showed to be 3.48, 2.20 and 2.21dS m−1, respectively. The concentration of Zn was found to be 28.87mgkg−1 in the 1st farm, while it was 45.96 and 19.51mgkg−1 in the 2nd and 3rd farms, respectively. The Zn, Cu, Fe and Ni concentrations were higher in the farms irrigated with the treated sewage effluent than their concentrations in those irrigated with well water. The values were 28.87, 16.95, 4225, and 72.26mgkg−1 for Zn, Cu, Fe & Ni in 1st farm and 42.4, 60.5, 11215, and 180mgkg−1 for the 2nd farm. The Pb in the soil of the 1st, 2nd and 3rd farms reached 63.01, 37.10 and 27.69mgkg−1, respectively. It can be concluded that all soil properties except pH had high coefficients of variation, indicating strong variability over space. The data of geo-statistical analysis showed that only TDS and ESP in the 1st farm as well as OM in the 2nd farm had weak spatial dependency while other properties had moderate or strong spatial dependency. Moreover, the TDS and CaCO3 parameters of the 1st and 2nd farms had stronger nugget effects.

Use of digital photography from unmanned aerial vehicles for estimation of leaf area index in onion (Allium cepa L.)

Canopy cover and structure, which have considerable effects on the interaction between vegetation and the environment, especially in the case of crops, can be represented by a few parameters, which are based on the calculation of different vegetation indexes. One of the most common indexes in agronomy is the leaf area index, which is a parameter associated with agronomic, biologic, environmental, and physiologic processes. The aim of this study is to evaluate a non-destructive method to measure canopy cover in an onion crop by means of aerial digital photography from unmanned aerial vehicles, and to determine the relationship with leaf area index obtained by using an automated infrared imaging system. The field experiment was conducted in a 4.75ha commercial onion plot irrigated with a centre pivot system during the 2010 irrigation season. To determine the leaf area in the laboratory during crop development, data were sampled on three. At each sampling event, eight experimental plots of 1m2 were used. In each one of them, aerials photographies were taken by using a vertical take-off and landing quadracopter aircraft. Software for leaf area index calculation was developed to obtain canopy cover. Three models have been used to analyze the relationship between leaf area index and canopy cover. According to this, the model which best fits the relationship between leaf area index and canopy cover is the linear model. The relationship between both parameters was closer in the first stages than in more advanced stages.

Autonomous precision agriculture through integration of wireless underground sensor networks with center pivot irrigation systems

Precision agriculture (PA) refers to a series of practices and tools necessary to correctly evaluate farming needs. The accuracy and effectiveness of PA solutions are highly dependent on accurate and timely analysis of the soil conditions. In this paper, a proof-of-concept towards an autonomous precision irrigation system is provided through the integration of a center pivot (CP) irrigation system with wireless underground sensor networks (WUSNs). This Wireless Underground Sensor-Aided Center Pivot (WUSA-CP) system will provide autonomous irrigation management capabilities by monitoring the soil conditions in real time using wireless underground sensors. To this end, field experiments with a hydraulic drive and continuous-move center pivot irrigation system are conducted. The results are used to evaluate empirical channel models for soil-air communications. The experiment results show that the concept of WUSA-CP is feasible. Through the design of an underground antenna, communication ranges can be improved by up to 400% compared to conventional antenna designs. The results also highlight that the wireless communication channel between soil and air is significantly affected by many spatio-temporal aspects, such as the location and burial depth of the sensors, soil texture and physical properties, soil moisture, and the vegetation canopy height. To the best of our knowledge, this is the first work on the development of an autonomous precision irrigation system with WUSNs.