Analysis of Soil Nitrate Ion Selective Electrode (ISE) Sensor using Arduino UNO

The ecological concern over soil and groundwater pollution caused by agricultural activities has led to the growing interest in precision agriculture. One of the most common types of fertilizer is the nitrogen fertilizer which needed in major amount for plant growth. Over fertilization will contaminate soil and groundwater which can have adverse effect on environment and human health. The main purpose of this research is to measure soil nitrate concentration using nitrate ion-selective electrode (ISE) sensor and Arduino programmable microcontroller. The optimum soil-to-water ratio and the effect of soil solution clarity will be investigated. Standard sampling procedures was conducted at oil palm plantation area, Felda Bukit Goh, Pahang, Malaysia. Validation of the results were carried out in the laboratory. The recorded data indicated accurate readings for Nitrate ISE Arduino was R² = 0.84. The soil-to-water ratio of 1:2.5 was observed as an optimal proportion ISE analysis. A clear soil solution was crucial for maintaining the accuracy of ISE sensor, to avoid declining of 46.2% accuracy. These results could assist researchers and farmers to accurately monitor the concentrations of soil nitrate on the field effectively as well as an insight to ISE sensor with Arduino technologies

Continuous measurement of nitrate concentration in a highly event-responsive agricultural catchment in south-west of France: is the gain of information useful?

A nitrate sensor has been set up to measure every 10 min the nitrate signal in a stream draining a small agricultural catchment dominated by fertilized crops during a 2-year study period (2006–2008) in the south-west of France. An in situ sampling protocol using automatic sampler to monitor flood events have been used to assume a point-to-point calibration of the sensor values. The nitrate concentration exhibits nonsystematic concentration and dilution effects during flood events. We demonstrate that the calibrated nitrate sensor signal gathered from the outlet is considered to be a continuous signal using the Nyquist–Shannon sampling theorem. The objectives of this study are to quantify the errors generated by a typical infrequent sampling protocol and to design appropriate sampling strategy according to the sampling objectives. Nitrate concentration signal and flow data are numerically sampled to simulate common sampling frequencies. The total fluxes calculated from the simulated samples are compared with the reference value computed on the continuous signal. Uncertainties are increasing as sampling intervals increase; the method that is not using continuous discharge to compute nitrate fluxes bring larger uncertainty. The dispersion and bias computed for each sampling interval are used to evaluate the uncertainty during each hydrological period. High underestimation is made during flood periods when high-concentration period is overlooked. On the contrary, high sampling frequencies (from 3 h to 1 day) lead to a systematic overestimation (bias around 3%): highest concentrations are overweighted by the interpolation of the concentration in such case. The in situ sampling protocol generates less than 1% of load estimation error and sample highest concentration peaks. We consider useful such newly emerging field technologies to assess short-term variations of water quality parameters, to minimize the number of samples to be analysed and to assess the quality state of the stream at any time

Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Simultaneous detection of ammonium and nitrate in environmental samples using on ion-selective electrode and comparison with portable colorimetric assays

Simple, robust, and low-cost nitrate-and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10−6 and 2.5 × 10−3 M with a detection limit of 5.5 × 10−7 M. On the other hand, MMA-DMA—based membranes showed suitability for both ammonium-and nitrate-selective electrodes, and were successfully applied to detect NO3− and NH4+ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO3− and NH4+ with the linear range concentration between 5.0 × 10−5 and 5.0 × 10−2 M (LOD = 11.3 µM) and 5.0 × 10−6 and 1.0 × 10−3 M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO3− and NH4+ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted

Nitrogen retention in mature constructed wetlands

Master's thesis in Environmental engineeringConstructed wetlands are created for the purpose of treating anthropogenic discharges, such as agricultural and urban runoff to reduce the potential of undesirable effects in receiving waters. Leikvollbekken is a mature constructed wetland located in north-west of Store Stokkavatnet in Stavanger Municipality. The wetland is a two-pond free water surface system constructed with the aim to reduce excessive nitrogen and phosphorus in the pelvis before reaching Store Stokkavatnet. The main focus of this thesis was to monitor the constructed wetland with respect to nitrogen. Nitrogen removal in the wetland was believed to occur through biological assimilation and dissimilation. The hypothesis was that the degree of retention would depend on flow, resulting in a positive retention over time. With some exceptions, weekly water samples were collected in the period October 2018 to May 2019 in inlet, mid-pond and outlet of the wetland. Flow in and out of the wetland was measured with an interval of 15 minutes during the thesis period by an integrated flow meter at site. Grab samples from Store Stokkavatn and Madlabekken were included in a period to compare concentrations with water in Leikvollbekken. In addition, a storm event was included to investigate the effect of high hydraulic loadings on influent concentrations and concentrations in the wetland. Water samples were analyzed for total nitrogen, nitrate and ammonium. Total and fixed suspended solids, pH, conductivity, alkalinity and color were included to investigate if any significant correlations existed with nitrogen concentrations in the samples taken. The overall results showed higher concentrations in Leikvollbekken compared to Store Stokkavatn and Madlabekken. A positive retention of 9.4 % TN (68.6 kg), 6.1 % NO3- (33.8 kg) and 87.1% NH4+ (7.2 kg) was observed during the period studied. Highest concentrations were observed during the storm event. An interesting observation was the increasing concentrations of TN, NO3- and NH4+ in mid-pond and outlet samples in April and during the storm event, indicating contribution from additional sources than the inlet water. No significant correlation between average flow per sampling and total nitrogen was found. Moreover, no connection was found between nitrogen compounds and the additional parameters except conductivity and color.submittedVersio

Simultaneous detection of ammonium and nitrate in environmental samples using on ion-selective electrode and comparison with portable colorimetric assays

Simple, robust, and low-cost nitrate-and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10−6 and 2.5 × 10−3 M with a detection limit of 5.5 × 10−7 M. On the other hand, MMA-DMA—based membranes showed suitability for both ammonium-and nitrate-selective electrodes, and were successfully applied to detect NO3− and NH4+ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO3− and NH4+ with the linear range concentration between 5.0 × 10−5 and 5.0 × 10−2 M (LOD = 11.3 µM) and 5.0 × 10−6 and 1.0 × 10−3 M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO3− and NH4+ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted

DEVELOPMENT OF NOVEL SENSORS FOR ANIONS OF ENVIRONMENTAL INTEREST

A range of ion-selective electrodes (ISEs) for the determination of nitrate has been produced based upon rubbery membranes having covalently bound betaine salt sensor molecules. The best performing electrode contained N,N,N-triallyl leucine betaine (6.5 % m/m) covalently bound to polystyrene-block-polybutadiene-block-polystyrene (SBS) (43.5% m/m), with 2-nitrophenyIoctyl ether (2-NPOE) as solvent mediator (40 % m/m) and dicumyl peroxide (DCP) as free radical initiator (10% m/m). The Nemstian slope was -59.1 mV per decade over a linear range of 1 x 10'^-5 x 10"^ mol dm'^ nitrate, a limit of detection of 0.34 pmol dm'^ nitrate and a selectivity coefiBcient for nitrate against chloride ( ^ ° N 0 3 . , CI-) of 3.4 X IQ"^. The speed of response was less than 1 minute over the linear Nerastian range. The lifetime in the laboratory exceeded 5 months with no potentiometric drift over the linear Nemstian range. Temperafure dependency (0-25°C), pH range (2-12) and a selection of interfering anions (F', CI", B r , T, SCN, CIO4", HCO3", NO2", S04^ phthalate) were studied. A field evaluation by continuous immersion in both agricultural drainage weirs and a river were undertaken. The nitrate results obtained with the ISEs compared very favourably (R^=0.99) with those obtained with a segmented-flow instmment in a concentration range 0.47-16 ppm nitrate-N. The electrodes perfonned continuously for over 5 months in mnoff water from a field and over 2 months in river water. The ISEs did not require recalibration and no deterioration in performance or fouling of the membrane surface was observed. A preliminary investigation of a phosphate ionophore based upon a heterocyclic macrocycle was also undertaken. This work, based on previous literature, resulted in a dibasic phosphate electrode having a linear Nemstian range from 3 x lO"'' to 1 x 10"^ mol dm'^, a slope of -27 mV per activity decade and a Umit of detection of 1 x 10"^ mol dm"^ HP04^".Institute of Grassland and Environmental Research, North Wyke, Okehampto

Towards In-situ Based Printed Sensor Systems for Real-Time Soil-Root Nutrient Monitoring and Prediction with Polynomial Regression

This dissertation explores how to increase sensor density in the agricultural framework using low-cost sensors, while also managing major bottlenecks preventing their full commercial adoption for agriculture, accuracy and drift. It also investigated whether low-cost biodegradable printed sensor sheets can result in improved stability, accuracy or drift for use in precision agriculture. In this dissertation, multiple electrode systems were investigated with much of the work focused on printed carbon graphene electrodes (with and without nanoparticles). The sensors were used in two configurations: 1) in varying soil to understand sensor degradation and the effect of environment on sensors, and 2) in plant pod systems to understand growth. It was established that 3) the sensor drift can be controlled and predicted 2) the fabricated low-cost sensors work as well as commercial sensors, and 3) these sensors were then successfully validated in the pod platform. A standardized testing system was developed to investigate soil physicochemical effects on the modified nutrient sensors through a series of controlled experiments. The construct was theoretically modeled and the sensor data was matched to the models. Supervised machine learning algorithms were used to predict sensor responses. Further models produced actionable insight which allowed us to identify a) the minimal amounts of irrigation required and b) optimal time after applying irrigation or rainfall event before achieving accurate sensor readings, both with respect to sensor depth placement within the soil matrix. The pore-scale behavior of solute transport through different depths within the sandy soil matrix was further simulated using COMSOL Multi-physics. This work leads to promising disposable printed systems for precision agriculture