Center Pivot Research Articles

No increase of soil wind erosion with the establishment of center pivot irrigation system in Mu-Us sandy land

Center Pivot Irrigation system (CPIs) is widely used in newly exploited arable land in sandy lands. These sandy lands are currently stable because of climate change and ecological restoration efforts since the beginning of the 21st century in northern China. The exploitation of these fixed sandy lands to arable land with CPIs may affect the soil wind erosion, yet it remains unknown. The temporal changes of CPIs and its effect on wind erosion module were analyzed and modeled from 2000 to 2020 in Mu-Us sandy land using satellite images and Revised Wind Erosion Equation (RWEQ). The establishment of CPIs started from 2010, boomed in 2015 and peaked in 2020. They were mainly transformed from woodland, grassland, and barren land near rivers in east and southeast, and from cropland in inter-dunes in west and southwest of Mu-Us sandy land. The temporal and spatial pattern of CPIs well aligns with the land consolidation and requisition-compensation balance policies. In most of the Mu-Us sandy land, the annual erosion module is <25 t ha−1 a−1. Despite great variation, the annual, Winter and Spring erosion module of the Mu-Us sandy land or in Otog Qian and Yuyang, the CPIs concentrated counties, all decreased during 2000–2019. Although, wind erosion module in CPIs was lower than the surrounding area, it increased in 2019 given the same climate conditions as in 2010. Our results suggest 1) the establishment of CPIs in Mu-Us sandy land greatly depends on the local policy and natural endowment, and 2) although the set-up of CPIs showed no impact on the wind erosion with CPIs accounting for <1 % of Mu-Us sandy land, post-harvest of CPIs should be carefully concerned to prevent soil wind erosion.

Size and Dispatch Co-Optimisation of a Grid-Connected Agrivoltaic System

Agrivoltaic systems that leverage the opportunity of integrating solar photovoltaic (PV) systems into land used for agriculture, have been shown to provide an effective platform for a mutually beneficial cooperation between energy and food. However, the mainstream literature has failed to investigate the systematic design and dispatch considerations that must be made to ensure the robust and profit-maximising operation of a grid-connected agrivoltaic system from an energy perspective subject to meeting onsite load demands, such as irrigation pumps, centre pivot systems, and cow shed pumps. This necessitates formulating a coordinated, system-level strategic design and dispatch problem that considers the localised energy system and its individual components. Accordingly, this paper introduces a novel agrivoltaic system energy planning optimisation method with an integrated dispatch scheduling framework. The proposed method enables the consideration of augmenting value streams, such as temporal energy arbitrage with the grid, especially regarding the presence of behind-the-meter stationary battery storage devices and electric agricultural vehicles’ batteries. Furthermore, the proposed method has a general crop type-independent structure. This allows for greater adaptability of the method to different types of agrivoltaic systems. The effectiveness of the proposed method in improving the economic feasibility of grid-connected agrivoltaic systems is demonstrated based on simulation results obtained from its application to a conceptual agrivoltaic system backed by stationary and mobile battery storage systems, proposed for implementation in a rural location in Aotearoa New Zealand.

Balancing Anterior and Posterior Cruciate Ligaments in Adults.

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) represent the central pivot of the knee. The balance between these two ligaments impacts the tibiofemoral biomechanics. Each structure is the opposite of the other in terms of anteroposterior translation and rotation. The aimof this study was to find a correlation between the cross-sectional area of the ACL and PCL in adults. Magnetic resonance imaging (MRI) data analysis was conducted by a musculoskeletal radiologist using MRI planes tailored to the study's requirements. In all 62 studied patients, measurements were done according to the protocol. The study observed three types of intercondylar notches: Type U was identified in 35% (22) of patients, type W in 27% (17), and type A in 37% (23). The median difference between the ACL and PCL areas was found to be statistically significant (p = 0.02). A significant difference in the area of the ACL was detected between Type A and Type U notches (p = 0.02), while no significant differences were found between Type A-W and Type W-U after post hoc corrections (p > 0.05). Additionally, no significant difference was observed in the mean area of the PCL across all three notch types (p = 0.1). In 68% of the cases, the ACL is no less than 60% of the PCL in area, and no more than 120%. The size of ACL and PCL in healthy individuals also depends on other factors like synergistic and antagonistic muscle activities, occupation, and the hip-knee-ankle axis. For example, if the PCL area is 0.79 cm² and the measured structure is round (during a reconstruction a hamstring graft is round), the diameter is 10 mm. A native ACL is, in 68% of the cases, no less than 7.7 mm, and no more than 10.9 mm. The ACL-PCL size correlation helps in understanding the balance of the central pivot of the knee.

Integrating hydrologic modeling and satellite remote sensing to assess the performance of sprinkler irrigation

ABSTRACT Improving irrigation water management is a key concern for the agricultural sector, and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements. This study presents a novel methodology to explicitly estimate daily gross and net crop water requirements, actual crop water use, and irrigation efficiency of center pivot irrigation systems, by mainly utilizing the Sentinel-2 MultiSpectral Instrument (MSI) imagery at the farm scale. ETMonitor model is adapted to estimate actual water use (as the sum of canopy transpiration and evaporation of water intercepted by canopy and evaporation from soil) at daily/10-m resolution, benefiting from the high-resolution Sentinel-2 data and thus to assess the irrigation efficiency at the farm scale. The gross irrigation water requirement is estimated from the net crop water requirement and the water loss, including the water droplet evaporation directly into the air during application before droplets fall on the canopy and canopy interception loss. The method was applied to a pilot farmland with two major crops (wheat and potato) in the Inner Mongolia Autonomous Region of China, where modern equipment and appropriate irrigation methods are deployed for efficient water use. The estimated actual crop water use showed good agreement with the ground observations, e.g. the determination coefficients range from 0.67 to 0.81 and root mean square errors range from 0.56 mm/day to 1.24 mm/day for wheat and potato when comparing the estimated evapotranspiration with the measurement by the eddy covariance system. It also showed that the losses of total irrigated volume were 25.4% for wheat and 23.7% for potato, respectively, and found that the water allocation was insufficient to meet the water requirement in this irrigated area. This suggests that the amount of water applied was insufficient to meet the crop water requirement and the inherent water losses in the center pivot irrigation system, which imply the necessity to improve the irrigation practice to use the water more efficiently.

Physiology and Development of Soybean under Light Supplementation Treated with Herbicides in the Field

Soy is Brazil’s main commodity, and due to its importance, farmers have adopted several technological innovations, such as light supplementation, to increase grain productivity and quality. However, the use of artificial light can interfere with weed dynamics and herbicide efficiency. The objective of this work was to evaluate the effect of herbicides on weed control and qualitative and quantitative attributes of soybeans grown under light supplementation. A field experiment was set up in the city of Monte Carmelo, MG, Brazil. The treatments were distributed in plots mounted under a central pivot in two environments: with light supplementation (LED panels) and without light supplementation. The treatments were distributed across four blocks, and plots were subdivided in space. The herbicides used were glyphosate, diclosulam and glyphosate, s-metolachlor and glyphosate, fomesafen + clethodim, flumioxazin + clethodim. The variables analyzed were the number of weeds, biomass, and control; chlorophyll levels; initial fluorescence; ratio of variable fluorescence to maximum fluorescence; and soybean electron transport rate—indicators of soybean yield. Light supplementation increases the density and biomass of weeds and impairs the effectiveness of herbicides. However, light supplementation with LED panels installed on the central irrigation pivot promotes increased productivity and improvements in the quantitative and qualitative parameters of soybeans. Due to these benefits, light supplementation can be considered advantageous for irrigated soybean production.

Geotechnologies in Biophysical Analysis through the Applicability of the UAV and Sentinel-2A/MSI in Irrigated Area of Common Beans: Accuracy and Spatial Dynamics

The applicability of remote sensing enables the prediction of nutritional value, phytosanitary conditions, and productivity of crops in a non-destructive manner, with greater efficiency than conventional techniques. By identifying problems early and providing specific management recommendations in bean cultivation, farmers can reduce crop losses, provide more accurate and adequate diagnoses, and increase the efficiency of agricultural resources. The aim was to analyze the efficiency of vegetation indices using remote sensing techniques from UAV multispectral images and Sentinel-2A/MSI to evaluate the spectral response of common bean (Phaseolus vulgaris L.) cultivation in different phenological stages (V4 = 32 DAS; R5 = 47 DAS; R6 = 60 DAS; R8 = 74 DAS; and R9 = 89 DAS, in 99 days after sowing—DAS) with the application of doses of magnesium (0, 250, 500, and 1000 g ha−1). The field characteristics analyzed were mainly chlorophyll content, productivity, and plant height in an experimental area by central pivot in the midwest region of Brazil. Data from UAV vegetation indices served as variables for the treatments implemented in the field and were statistically correlated with the crop’s biophysical parameters. The spectral response of the bean crop was also detected through spectral indices (NDVI, NDMI_GAO, and NDWI_GAO) from Sentinel-2A/MSI, with spectral resolutions of 10 and 20 m. The quantitative values of NDVI from UAV and Sentinel-2A/MSI were evaluated by multivariate statistical analysis, such as principal components (PC), and cophenetic correlation coefficient (CCC), in the different phenological stages. The NDVI and MCARI vegetation indices stood out for productivity prediction, with r = 0.82 and RMSE of 330 and 329 kg ha−1, respectively. The TGI had the best performance in terms of plant height (r = 0.73 and RMSE = 7.4 cm). The best index for detecting the relative chlorophyll SPAD content was MCARI (r = 0.81; R2 = 0.66 and RMSE = 10.14 SPAD), followed by NDVI (r = 0.81; R2 = 0.65 and RMSE = 10.19 SPAD). The phenological stage with the highest accuracy in estimating productive variables was R9 (Physiological maturation). GNDVI in stages R6 and R9 and VARI in stage R9 were significant at 5% for magnesium doses, with quadratic regression adjustments and a maximum point at 500 g ha−1. Vegetation indices based on multispectral bands of Sentinel-2A/MSI exhibited a spectral dynamic capable of aiding in the management of bean crops throughout their cycle. PCA (PC1 = 48.83% and PC2 = 39.25%) of the satellite multiple regression model from UAV vs. Sentinel-2A/MSI presented a good coefficient of determination (R2 = 0.667) and low RMSE = 0.12. UAV data for the NDVI showed that the Sentinel-2A/MSI samples were more homogeneous, while the UAV samples detected a more heterogeneous quantitative pattern, depending on the development of the crop and the application of doses of magnesium. Results shown denote the potential of using geotechnologies, especially the spectral response of vegetation indices in monitoring common bean crops. Although UAV and Sentinel-2A/MSI technologies are effective in evaluating standards of the common bean crop cycle, more studies are needed to better understand the relationship between field variables and spectral responses.

Erratum for “Closure to ‘An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation’”

Erratum for “Closure to ‘An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation’”

Real-time mapping of crop canopy temperature using a wireless network of infrared thermometers on a central pivot

Efficient irrigation is essential for sustainable food production and regional water security. Temperature measurements provide information about crop water status, which allows the estimation of water needs and precise irrigation scheduling. This paper proposes a technology for agricultural irrigation management that combines cost-effective implementation with the ability to map crop canopy temperatures using a wireless network of infrared thermometers on a center pivot. The technology integrates Wireless Sensor Networks (WSN) with scalability options, IoT capabilities, and web data availability, enabling precise plant water stress quantification based on canopy temperature and soil water content. It facilitates real-time irrigation prescriptions while the center pivot is in motion, with canopy temperature sensors providing accurate readings of +/- 0.5 °C without additional calibration. Nonlinear Autoregressive Network with Exogenous Inputs (NARX) and Long Short-Term Memory (LSTM) neural network models were trained to predict irrigation prescriptions, achieving Root Mean Squared Error (RMSE < 4.18 mm) and correlation coefficient (r^2 > 0.82). This technology will allow the definition of real-time and site-specific prescriptions for variable-rate irrigation systems using infrared temperature sensors. Future work includes exploring LoRaWAN technologies, implementing a Differential Global Positioning System (DGPS), improving spatial resolution with data fusion algorithms, refining irrigation prescription models, reducing sensor costs and developing models considering soil and crop effects.

Response of wheat (Triticum aestivum L.) and cowpea (Vigna unguiculata L.) to foliar wetting with low pH mine waters containing acid-generating metal cations

Acid mine drainage (AMD) contains metals that have detrimental effects on crop growth if present in excess in plant-available form. The use of untreated AMD from coal mines for crop irrigation on strategically limed soils is considered a potential option for mine water management, especially in remote areas without access to water treatment infrastructure. However, leaf scorching and trace element enrichment of plant tissue are of potential concern, as these waters often contain high concentrations of potentially toxic, acid-generating metals (Al3+, Fe2+ and Mn2+) which may cause foliar damage and hyper-accumulate in plant tissue. The objectives of this trial were to quantify any foliar injury and metal accumulation in wheat (Triticum aestivum L.) and cowpea (Vigna unguiculata L.) vegetative material after foliar wetting with simulated AMD enriched with metal cations, and to ascertain if biomass production will be affected. In this trial, crop water requirements were not met through mine water irrigation, as this was only a foliar wetting investigation. Two pot experiments were set up, with wheat grown in the winter and cowpea in the summer season of 2021. Sulphuric acid was used to lower pH to 2, after the addition of low, intermediate and high concentrations of individual acid-generating metal cations, as well as a combination of all three cations. Areal foliar injury was greatest for cowpea (18.7%) with a combination of Al, Fe and Mn at the highest concentration. The crop was not able to recover at this injury level. No injury was recorded in wheat. Both crops accumulated only limited quantities of the metal cations. Calculated hazard quotient for cattle ranged from 0.022 to 0.53, indicating that such fodder would be safe to consume. It is concluded that there are large differences in crop specie susceptibility to leaf scorching after foliar wetting with acidic metal cation-rich mine waters. It is recommended, therefore, that because large volumes of mine water need to be managed, and centre pivot overhead irrigation is likely to be utilized to this end, that studies to screen more species to select crops tolerant to scorching through foliage wetting with mine water irrigation be conducted. Thereafter, studies to better understand root zone effects of irrigation with such waters need to be conducted on species that can tolerate foliar wetting with these waters.

Spatiotemporal Changes of Center Pivot Irrigation Farmland in the Mu Us Region and Its Impact on the Surrounding Vegetation Growth

Accurately understanding the distribution and changing trends of Center Pivot Irrigation (CPI) farmland in the Mu Us region and exploring the impact of CPI farmland construction on sandy land vegetation growth hold significant importance for local sustainable development. By using Landsat images to extract CPI farmland information and applying buffer zone analysis to explore the impact of CPI farmland construction on the surrounding vegetation growth, the results revealed the following key findings: (1) The number and area of CPI farmland units showed a continuous growth trend from 2008 to 2022. Spatially, Etoke Front Banner was the focal point of the CPI farmland unit construction, gradually expanding outward. In terms of scale, small-scale CPI farmland units (0–0.2 km2) dominated, while large-scale CPI farmland units (&gt;0.4 km2) were primarily distributed in Yulin City (Mu Us). (2) The growth rate of CPI farmland units in Yulin City gradually slowed down, while that in Ordos City (Mu Us) continued to exhibit a high growth trend. Affected by water-resource pressure and policies, CPI farmland units in Ordos City may continue to increase in the future, while they may stop growing or even show a downward trend in Yulin City. (3) CPI farmland mainly came from the conversion of cultivated land, but over time, more and more grassland was reclaimed as CPI farmland. The absence of cover planting after crop harvesting and the lack of shelterbelt construction may exacerbate land desertification in the region. (4) Within the typical region, CPI farmland unit construction promoted vegetation growth within the CPI units and the 500 m buffer zone but had an inhibitory effect on vegetation growth within the 500–3000 m buffer zone and no significant effect on vegetation growth within the 3000–5000 m buffer zone. (5) The decrease in groundwater reserves caused by CPI farmland unit construction was the primary reason for inhibiting the vegetation growth within the 500–3000 m buffer zone of CPI farmland units in the Mu Us region. This study can provide a scientific basis for the sustainable development of CPI farmland in semi-arid areas.

Developing a Hybrid Irrigation System for Smart Agriculture Using IoT Sensors and Machine Learning in Sri Ganganagar, Rajasthan

The agriculture sector is one of the largest consumers of fresh water. Different types of irrigation systems are available, including center pivot, drip and sprinkler systems, and linear motion systems. However, the complex structure of existing irrigation systems and their high maintenance costs encourage Indian farmers to continue using these methods. Due to its ease of use and low energy consumption, surface irrigation is one of the most popular irrigation techniques. Although the main reasons for poor irrigation application efficiency are uneven irrigation water distribution and deep absorption, using a variety of technologies, countries are trying to increase the sustainability of agriculture. Automated irrigation systems contribute significantly to water conservation. The combination of automation and Internet of Things (IoT) improves agricultural practices. These technologies help farmers understand their crops, minimize their impact on the environment, and preserve resources. They also enable efficient monitoring of the weather, water resources, and soil. This research proposes an intelligent, low-cost field irrigation system. The proposed prototype can measure soil moisture, rain status, wind speed, water level, temperature, and humidity using a hardware sensor and unit. To decide whether to turn on or off the motor, a variety of sensors are used to get a range of readings and conclusions. They enable automatic watering when soil moisture levels are below a certain threshold, and if soil moisture is equal to the required moisture, then the irrigation process stops. Every few minutes, the sensors measure the environmental factors. Data are collected and stored on a ThingSpeak cloud server for analysis. To evaluate the data we collected, we used a variety of models, such as K-nearest neighbors (KNN), Naïve Bayes, random forest, and logistic regression. Compared to other Naïve Bayes and random forest models, the accuracy rate was 98.8%, the mean square error was 0.16, and the results of logistic regression, KNN, and SVM were in order: (98.3%/1.66), (99.3%/0.66), and (99.5%/0.5), respectively. In the end, an automated irrigation system run on IoT applications gives farmers access to remote monitoring and control, as well as information about the specifics of the irrigation field.

Analysis of Lateral Forces for Assessment of Safety against Derailment of the Specialized Train Composition for the Transportation of Long Rails

This study proposes a theoretical method for evaluating the “safety against derailment” indicator of a specialized train composition for the transportation of very long rails. A composition of nine wagons, suitable for the transportation of rails with a length of 120 m in three layers, is considered. For the remaining recommended rail lengths, the number of wagons is reduced or increased, with the calculation model being modified depending on the required configuration. When the composition is in a curve with the minimum radius (R = 150 m), the rails bend, and some of them come into contact with the vertical stanchions of the wagon and cause additional lateral forces. These forces are then transferred through the wagon body, central pivot, bogie frame, and wheels and act on the wheel–rail contact points. They could potentially lead to derailment of the train composition. The goal of this study is to determine the additional lateral forces that arise because of the bent rails. For the purposes of this study, the finite element method was used. Based on the displacements of the support points of the rails (caused by the geometry of the curve), the bending line of the elastic load is determined and the forces in the supports are calculated. The resulting forces are considered when determining the derailment safety criterion. The analysis of the results shows that the wagon with fixing blocks is the most at risk of derailment. The front and intermediate wagons have criterion values very close to that of the empty wagon. This shows that the emerging horizontal elastic forces do not significantly influence the derailment process. The obtained results show that the transportation of long rails with specialized train composition can be realized on four layers. This will significantly increase the efficiency of delivering new long rails.

Reduction of energy consumption using remote Variable Frequency Drive (VFD)

The use of technology in irrigation is a parameter to be considered when there is a need for energy savings and greater process control. In several situations, it is necessary to adjust the characteristics of the hydraulic system during operation of the motor shaft in the irrigation system. The use of a Variable Frequency Driver (VFD) changes the frequency of the motor pump to allow the rotation of the motor shaft to suit the needs of the hydraulic system. With a change in the amount of water in the catchment tank, it becomes necessary to adjust the rotation of the motor shaft to a new head. The objective of this study was to develop a system capable of allowing remote control of a Variable Frequency Drive that controls a motor pump that feeds the central pivot. The system was developed from a microcomputer board Raspberry model and an Arduino microcontroller board controlling a potentiometer of 200k and it was observed that three motor-pump-inverter assemblies presented differences in the significance level between the data of the system and the obtained data. The data showed a strong positive correlation. This system can be an alternative when it is not possible to change the inverter parameters in the field.

Evaluating Intra-Field Spatial Variability for Nutrient Management Zone Delineation through Geospatial Techniques and Multivariate Analysis

This research study underscores the importance of effectively managing soil nutrients in a site-specific manner to enhance crop productivity while considering the spatial variability of the soil. The objective is to identify subfields with similar soil characteristics, referred to as management zones (MZs), to promote sustainable land utilization. This study was conducted in two central pivot fields located in Southern Idaho, USA, where barley and sugar beets were grown. Soil samples were collected from each field in a grid pattern and analyzed for various chemical properties. These properties included soil pH, organic matter, cation exchange capacity, excess lime, electrical conductivity, total inorganic nitrogen, phosphorus, potassium, calcium, magnesium, zinc, iron, manganese, copper, and boron. Descriptive statistics and normality assessments were performed, and the coefficient of variation was calculated to assess the heterogeneity of soil properties, revealing significant variability. To determine the spatial variability of soil properties, ordinary kriging was used revealing diverse spatial patterns for each location and soil variable examined with moderate to strong spatial dependence. To develop the MZs, a combination of principal component analysis and fuzzy k-means clustering was utilized, and specific parameters that represented the overall variability of soil properties in each field were identified. Based on the identified parameters, two clusters were created in each field. The first management zone (MZ1) exhibited lower values of soil pH, excess lime content, and electrical conductivity compared to the MZ2. Consequently, higher crop productivity was observed in MZ1 in both fields. The biomass yields of barley and sugar beets in MZ1 surpassed those in MZ2. This study highlights the effectiveness of the methodology employed to delineate MZs, which can be instrumental in precise soil nutrient management and maximizing crop productivity.

Vibration analysis of metallic structure of an innovative dam gate

An analysis of the vibrations that may occur at the gate of a dam is proposed. Thus, the determination of an optimal constructive solution is sought from the point of view of vibration behavior. The dam gate is part of a constructive solution of an oscillating center pivot dam, which closes the gates if the downstream water level rises above a certain limit. This constructive solution is new. The gates are controlled by the water level. Such a system is easy to implement practically and the construction and maintenance costs are lower than in the case of classic dams. The problem that arises is that of the behavior of such a structure to vibrations. The eigenvalues of the gate structure are determined for a constructive solution proposed by the designers and the behavior of the forced vibrations that can stress the gate is studied. The analysis is performed for the case where the dam gates are closed. The work continues previous research on the structure's resistance to static loads and justifies the use of this solution in design. The method used to carry out the study is the finite element method. The advantages of the studied structure consist of lower costs for the proposed relatively simple constructive solution.

Mapping and Characterization of Center Pivot and Lateral Move Irrigation Systems in South Carolina Using Quantum Geographic Information System

In recent decades, the adoption of overhead irrigation systems, especially center pivots, to irrigate row crops has been steadily increasing in South Carolina. The adoption of irrigation in the state has been enhanced by the predominance of coarse-textured soils with low water-holding capacities, which increases the likelihood of obtaining a significant and profitable crop yield response to irrigation. As the number of overhead irrigation systems in the state increases, it is vital to understand their number, location, and characteristics for better planning and managing available water resources. The objective of this project was to map and characterize the overhead irrigation systems (center pivots and lateral moves) available in each county in South Carolina. The Quantum Geographic Information System (QGIS) was used to manually locate and measure each overhead irrigation system in the state using a 2022 Google satellite image. Basic measurements included the length, number of spans, and wetted radius. In addition, the rotation angle of center pivots and the field length of lateral move systems were measured. This study found that with a few exceptions, the overwhelming majority of the overhead irrigation systems in the state were located in the central part of the Coastal Plain region, between the Fall Line and the coast, where groundwater resources are more abundant. Also, this study found a total of 2,980 center pivots and 15 lateral move irrigation systems in South Carolina. A total of 64,694 hectares were irrigated by center pivots, while lateral moves irrigated only 80 hecatares. Out of the 46 counties in the state, those with the highest number of center pivots were Orangeburg (633 pivots), Calhoun (361), Lee (296), Clarendon (249), Sumter (248), Lexington (197), Bamberg (130), Darlington (121), Hampton (117), and Barnwell (114). All the lateral move systems were located in the counties of Barnwell (11) and Darlington (4). Water stakeholders and agencies in South Carolina could use this information for long-term water resources planning at various levels. This research is also useful nationally to inform the understanding of irrigation practices in the southeastern United States.

Alfalfa (Medicago sativa L.) Nitrogen Utilization, Yield and Quality Respond to Nitrogen Application Level with Center Pivot Fertigation System

Nitrogen (N) application with a center-pivot fertigation system is commonly used for alfalfa production in the North China Plain, with its barren soil, but improper N application has resulted in lower N use efficiency and even negative effects on yield and quality. The effects of N application levels on soil NO3−-N content, nitrogen utilization, yield and quality of alfalfa at various cuttings and established years were evaluated under sprinkler fertigation to optimize the N application schedule. Four N application levels of 0, 12.5, 25 and 37.5 kg N ha−1 (N0, N1, N2 and N3) for each cutting were applied to alfalfa at the early vegetative stage from the first to third year after establishment. The results showed that the variation in soil NO3−-N content was mainly concentrated in the topsoil (0–40 cm) after N application via sprinkler fertigation. N uptake amount was dramatically improved through the N application for one-year-old alfalfa. Compared to the yield under the N0 treatment, the N application significantly improved the yield of alfalfa at the first two cuttings in the first year. The N use efficiency generally reached a high value with a low N application level. N application had an insignificant effect on the alfalfa quality classification during the three years. For obtaining high yield, quality and N use efficiency of alfalfa planted in the North China Plain, the N application level is recommended as 12.5 kg N ha−1 at the first cutting and 37.5 kg N ha−1 at the second cutting for one-year-old alfalfa.

Evaluation of Irrigation Uniformity and Equity Under Center Pivot Using Remote Sensing

Evaluation of Irrigation Uniformity and Equity Under Center Pivot Using Remote Sensing

Spatial and Temporal Variability of Water Application via a Center Pivot

Spatial and Temporal Variability of Water Application via a Center Pivot

A wideband low frequency 3D printed electromagnetic energy harvester based on orthoplanar springs

Electromagnetic energy harvesters are commonly known for their high performances in terms of power output conversion, and they are suitable for low frequency environmental vibrations.This work reports the study, design, development and experimental validation of a new extremely compact, low frequency, electromagnetic energy harvester based on two stacked ortho-planar springs, which exploits a promising magnets disposition.The device is composed by two stacked ortho-planar springs connected externally by a rigid frame. The two internal moving parts are connected to each other by a central pivot where an array of magnets is fixed on in a peculiar disposition: a half has a magnetic field directed upward, while the other half directed downward. A copper coil is wound into a housing fixed on the external frame. It comes a central massive cursor that axially moves, exploiting the springs compliance, relatively to the external frame.The prototype was almost completely realized by using Filament Fused Fabrication (FFF) additive manufacturing process in Onyx material, carbon fibre reinforced nylon.In the experimental assessment an oscillating excitation was applied on the external frame in multiple linear sweep frequency tests with different amplitude signals. The experimental validation shows a large bandwidth, from 10 to 30 Hz, and consistent output voltage and power signals.