ICT for Leaching Monitoring

Created by: Chiling Chen

In order to study on the groundwater subsidy from different cropping systems, leaching monitoring started in 2008 and implemented in Taiwan agricultural long term ecological research (LTER) stations. In the beginning, leaching data were received by lysimeters, and then collected by labors manually in the field twice per month. The cost of data collection and transmission is expensive, real-time monitoring is incapable, and maintenance of instruments is in-efficiency. In this study, the goal is to develop a data transmission path. ICT (Information and Communication Technology) with different data transmission schemes was applied to improve the efficiency and immediacy on data transition from the field to the database in labs. Between 2010 and 2017, four generations of ICT have been developed and applied in LTER stations. WiFi, 2.5G (GPRS)、3G/4G network transmission, and Arduino cores are applied in different ICT generations. The first generation of data transmission used data loggers, developed by the original factory, with lower cost on renovation of instruments. However, complicated transmission paths, diverse instruments, poor weather resistance, and incapable on wireless function are the limitations of the first generation. Those limitations had been overcome by the second and third generations by using 2.5G (GPRS) and 3G/4G network transmission, respectively. Nevertheless, these generations are limited to the processes of data compression and encryption transmission which were developed by the system vendors. In addition, data can only be collected through the webpage provided by the vendors, instead of receiving data directly from the database using SQL (Structured Query Language). This is inappropriate for the advanced data treatment, organization, and analysis.  Finally, the four generation of data transmission have been developed using Arduino. It allows to redesigning the data logger and transmission instrument with more feasibility and flexibility. Radio Frequency (RF) has been imported into the transmission path to receive data from diverse instruments with fewer data loggers. In conclusion, according to the ICT technological advancement with the advantages of reasonable cost and high flexibility and feasibility, Arduino and other Open Source operation systems can be used to develop the data logger and related instruments to meet the users’ needs. Therefore, ICT is the most appropriate strategy to develop the long-term monitoring system in the fields and to apply to other environment monitoring systems.

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Information and Communication Technology (ICT) is the technology for data collection and digitization through instruments and sensors transferring to data storage devices. Digital information is transmitted through variety of communication technologies, including wired and wireless, to the endpoint. The world is moving towards micro and Nano-scale devices, and Wireless communication technologies are replacing its wired counterparts [1]. Wireless communications, such as Wi-Fi, Bluetooth, and 4G communication, is currently as the mainstream to reduce the consumptions of long-term maintenance. In addition, endpoints, such as data logger, database, and cloud, are used to receive information from sensors and store them for a long time. Subsequently, long-term analysis and big data utilization can be carried on. ICT, such as automation, robots, telemedicine, and mobile devices, are being widely applied. The development of advanced internet and convenience of interactive among devices are key components of the internet of thing (IOT). IOT is expected to offer advanced connectivity of devices, systems, and services that goes beyond machine-to-machine communications (M2M) and covers a variety of protocols, domains, and applications[2]. Our environment and surrounding objects become communicating. New applications thus arise in domains, i.e., logistic, health, rescue, environment preservation, etc. [3]

Nowadays, within an ICT data transmission system, data can be exchange between the equipment and facilities in a wireless regional network. Thus data logger can received data from the equipment within wireless regional network and then send to the terminal storage database through 4G network. There are many different schemes of ICT data transmission on the market. WiFi is the most popular wireless network transmission technology with transmission speed as fast as 54 Mbps; however, its transmission range is short about 45m and the power consumption is large, so it only capable as home network [4]. Bluetooth wireless technology applied for exchanging data over short distances, about 10m, from fixed and mobile devices. It is reliable point-to-multipoint data transfer. However, it is not appropriate for wireless network transmission system with limited number of access nodes (max. 7 nodes at once.) [5]. RF (radio frequency) communication is well-known for the low-power consumption with battery support system for moderate-range transmission (as far as 2km). RF can be used to develop a wireless network transmission system with more than 1000 nodes without the complicated communication protocol and multiple facilities [6]. LoRa (Long-Range) is a low power wide area network developed by IBM in 2015. It is specified on low-power consumption, long-range transmission (as far as 8km), and low-data-rate communications infrastructure that needs fewer base stations to serve more simple devices like online smoke detectors, temperature sensors or smart electrical heating controllers [7]. In Table 1, the advantages, limitations, and applications of different schemes, i.e., WiFi, Bluetooth, RF, and LoRa, are listed.

Table 1. Comparisons of different transportation

 Transmission Scheme Advantages Limitations Applications WiFi -Fast transmitted speed (54Mbps) -Good penetration -Short transmission distance (50m) -High power consumption -Complex communication protocal -WAP required -Transmission with grate amount of images -Indoor or circumstances with barriers -Availble with telephone Bluetooth -Low power consumption -Low transmited speed(1Mbps) -Short transmission distance (10m) -point-to-point transimission -Few ports (max. 7) - Short distance -Available with power supply RF(2.4GHz) -Low power consumption -Moderate transmission distance (2km) -Feasible self-assembly for internet -Low transmited speed (2Mbps) -Poor penetration -Spacious outdoor -Available with power supply -Internet composed by mulitple sensors LoRa -Low power consumption -Good transmission distance (8km) -Low transmited speed (50Kbps) -Spacious outdoor -Long distance -Small data size

Taiwan agricultural long term ecological research (LTER) stations where built on 2006 were set to investigate the effects of different manage and cultivated systems to biodiversity, productivity, and environment. Lysimeters were set on 2008 and continually increased around 2010-2016. In the beginning, data transmission mainly relied on cable transmission, sensor transmit digital information via RS-232 or RS-485 directly to computer by transmission line. This method needed to set computer in the experimental site long-termly and connect to the sensor. However, the equipment cost high, and expense of maintenance was costly. Subsequently, sensor manufacturer designs the data logger, and it can replace the computer. The volume of data logger decreases drastically, and it not only reduces the cost but also becomes more adapted to the climate. Nevertheless, research staffs still have to bring laptop and transmission line to experimental site to download data from data logger to computer periodically.

Sensor, communication, and the Internet are formed as a network system, which can transmit and analyze data to work as a sensor network. The data collection system is different from traditional ones. It provides brand new application especially in ecological research and resource management monitoring [8]. Wireless sensor networks (WSN) are well suitable for long-term environmental data acquisition and representation via IOT [9]. IOT is also used in detailed ﬁelds of environmental monitoring and management, including underwater resources management [10].

The strengths of the ICT system are real-time and remote monitoring, and it can lower the cost of labor. Also, maintenance personnel only need to check information delivered from remote device for a period of time, and then the condition of equipment operation can be under controlled. In advanced, wireless technology can facilitate the field investigation to not only monitoring in real-time, but also observing under severe weather condition, which were unable to be accomplished by traditional field works. For instance, United States Virginia Coast Reserves (VCR) includes three kinds of ecosystems: mainland, lagoons, and barrier islands. The long-term ecological research team, University of Virginia, investigates the local biosphere, climate, marine sphere, coastal environment, and soil hydrology, and the whole research takes advantage of wireless network technology to make the work more time-saving and labor-saving, then data collection becomes more completed [11].

IOT and cloud computing technology used to monitor the reservoir and the establishment of mine early warning system [12]. Agricultural IOT equipment is often used in greenhouse monitoring. The collected information can be applied to agricultural research and facility management [13].

In the study, we aim to apply variety of possible transmission technology to collect the leaching data to the database from the lysimeters in fields to the database in labs directly and wirelessly. Ultimately, to reach the goals: real-time monitoring, reduction of labor cost, and improvement of maintenance efficiency. Secondly, along with the improvement of device, the advantages and disadvantages of diversity of transmission path are discussed, and the potential solutions of difficulties on ICT applications are assessed and suggested.

With the emergence of Arduino and Raspberry pi, the difficulty and cost of IOT development decrease. Raspberry pi has the advantage of low cost and low power consumption, which makes it relatively easy to implement [14]. However, the operation system in Arduino is comparatively easier and is much more appropriately applied on sensor communication. In this study, thirdly, Arduino is applied in the ICT system along with various communications, data storage module, and sensor. Thus, research and development are expected to be more flexible and feasible, and it is more useful for field monitoring and data transmission devices.

1. Materials and Methods

2.1. Study sites

In order to apply this study in the fields with the appropriate agricultural management with minimum input, subtropical agricultural long term ecological research (LTER) stations were targeted. LTER stations were initially established in 2006, and were set to investigate the effects of different managements and cultivated systems to biodiversity, productivity, and environment. Five stations were targeted and the locations are shown in Figure 1.

1. Two field crop ecosystems: Yuin-Lin branch station (7.0 ha, Tainan District Agricultural Research, COA) and Chi-Ko branch farm (8.0 ha, CAEB, TARI) with lowland and lowland-upland rotation.
2. Two orchard ecosystem: Chia-Yi Branch Litchi Orchard (2.5ha, CAEB, TARI) and Gukeng Branch Farm Litchi Orchard (2.5ha, CAEB, TARI).
3. One tea garden ecosystem: Ming-Jian tea garden (1.32ha) located at Tea Research and Extension Station, Ming-Jian village, Nantou County.

In these LTER stations, treatments of manage systems include both conventional agro-ecosystem management (CA) with high chemical input and sustainable agro-ecosystem management (SA) with low chemical input in different rotation systems. Field tractability, soil fertility, nitrogen leaching, production cost, disease severity of crops, pest and indicated insect, dynamic of weeds, biodiversity index, and greenhouse gases emission were collected on LTER stations as well.

Figure 1. Locations of four of Taiwan agricultural LTER stations in the central of Taiwan.

2.2. Measurement by using lysimeters

Lysimeters are used on the measurement of leaching in this study. Lysimeters are commonly in water flow and solute transport studies in soils. They are known to be of major importance in controlling and measuring water components, chemical concentration and fluxes in soil. Recently, two types of lysimeters, G2 and G3, are applied in Taiwan agricultural LTER stations (Figure 2). Lysimeters G2 and G3 are low-cost drain gauge for measuring deep drainage rate in unsaturated soils and collect soil water samples for chemical analysis to help assess potential groundwater contamination, monitor groundwater leaching, and, measure deep percolation accurately.

G2 lysimeter measures the water level and drainage frequencies in the measurement reservoir, and then to estimate the amount of leakage. G3 lysimeter directly measure the water level from the communication pipe, and the estimate the amount of leakage. G2 lysimeter takes samples with syringe negative pressure; while, G3 lysimeter takes samples directly with drainage pumpers. However, lysimeter G2 is limited by causing errors in drainage measurements when flooding measurement chambers with high water tables.

New lysimeter G3 has completely sealed system to protect from high water tables. In advanced, this new drain gauge can work in both saturated and unsaturated condition, without digging up the entire drain gauge to replace the sensor, with larger sampling reservoir, and integrated with EC sensors for allowing monitoring when solute fluxes occur. Recently, lysimeters G3 have been gradually applied to all of the LTER stations for monitoring groundwater leaching, measuring irrigation drainage, and improving the accuracy of data and durability of facilities.

 (a) (b)

Figure 2. Construction and measurement illustration of G2 (a) and G3 (b) lysimeters (source: http://www.decagondevices.eu/products/hydrology/lysimeters/)(Reproduced with permission from Decagon Devices, Inc., Drain Gauge Models G2 and G3- Operator's Manuals; published by Decagon Devices, Inc., 2014.").

2.3 Development of data transmission path

In the development of ICT data transmission facilities in agricultural LTER station, leaching data is monitored by sensors (i.e., lysimeters), collected by data logger, and then transferred to database in labs with the Internet (Figure 3). In the fields, there are two major schemes to transfer data received by lysimeters to data logger for storage, including wired transmission and RF (Radio Frequency, 2.4GHz) wireless transmission. Using wired transmission, data can be stored directly by SDI-12 communication protocol interface of data logger; while, using RF (2.4GHz) wireless transmission, lysimeters are connected to the RF(2.4GHz) wireless transmission controller, and data will be stored wirelessly by the data logger inside of the RF(2.4GHz) wireless transmission receiver. When data received by the data logger and stored within memory card or WiFi memory card, data will be periodically transferred to the terminal computer database for further storage and management. Data transmission is applied either by WiFi hotspots internet connection or by mobile internet connections (i.e., 2.5G GPRS, 3G, 4G, ect.). On the one way, data stored within the databased can be downloaded through application program or webpage for advanced analysis and researches; on the other way, data stored within the databased can be displayed as charts or tables on the webpage directly in order to monitoring the condition of instruments and the trend of data.

Figure 3. The framework of data transmission between lysimeters in the field and database in labs. The path of data transmission is replaced from labors to internet.

2.4. Data qualiy and data quantity analysis

The leaching data collected by G2 and G3 lysimeters assembled with different versions of ICT systems are examined with the precipitation records, in order to testify if the leaching data collected by lysimeters can response to the variation of precipitation record accurately. In the crop LTER stations, precipitation record is collected according to the irrigation schedule in each crop season. While, the precipitation data is collected from local agricultural weather stations where are nearby the orchard and tea garden LTER stations. For instance, in Ming-Jian tea garden LTER station, the daily precipitation record is calculated as the average of three days, including the day, the day before, and two day ago. Because, the daily leaching is influenced by the day and the previous two days. In this study, simple linear regression is applied to examine the patterns between data collected by lysimeters and from the precipitation record [15].

1. Results

The processes of ICT data transmission in different generations and the raletive challenages and solutions between different gerantions were described as following:

3.1. First version of ICT data transmission

In 2010, the first version of ICT data transmission had been developed for leaching morning in Taiwan agriculture LTER stations, including Yuin-Lin branch station, Chi-Ko branch farm, and Chia-Yi Branch Litchi Orchard. But in Ming-Jian tea garden, data was still collected and transferred by labor manually. The lysimeters in the fields were connected to the Internet for real-time monitoring (Figure 4.) The purpose of first version of ICT data transmission is to store data by using existing instruments with light and handy parts from the general vendors. In the past, 2.5G, GPRS, and 3G wireless network is not popular. It is the major limitation to provide wired internet and WiFi environment.

In order to transfer the data from lysimeters and existing data loggers in the fields to database in labs with the minimum cost, the data transmission path is relatively complicated (Figure 4). Firstly, the old exchange interface of data logger is RS-232 which needs to be exchange to Ethernet packet. Secondly, Wi-Fi compatible devices connect to the Internet via a wireless access point (WAP), and then transfer data to the database through the Internet.

Figure 4. Data transmission path of ICT first version

Multiple hardware devices were connected to each other with cables in the data transmission path of ICT first version. It’s a challenge to maintain those devices and cables inside the cabinet with small size. The space of the cabinet is compressed to those devices as well. Therefore, the operation of ICT first version had been declining quickly. In addition, WiFi signal is difficult to cover the whole region in the spacious fields, and the interruption of the Internet by WiFi happened frequently.

3.2. Second version of ICT data transmission

Because of the popularity and reasonable cost of 2.5G (GPRS) network transmission equipment, the second version of ICT data transmission had been developed by the cooperation of domestic vendors. The new version facility had been applied in five of the LTER stations. Especially, in Chia-Yi Branch Litchi Orchard, the WiFi signal is unstable because of the dense coverage to fruit tree crown. Although crown coverage is not a challenge in Gukeng Branch Farm Litchi Orchard, where is isolated and there is no WiFi provided from national wide telecommunication.

Therefore, the second version of ICT data transmission improved the limitations of first version. Data loggers, developed by domestic vendor, integrate the multiple data transmission facilities. The processes of data exchange were simplified and data received in the fields can be transferred directly to the database in labs by using GPRS (Figure 5).

Figure 5. Data transmission path of ICT second version

3.3. Third version of ICT data transmission

With the development of 3G/4G network and the strategies of removing the 2.5G(GPRS) base stations by government, the 2.5G(GPRS) signal is gradually weaken and unstable. The third generation of ICT data transmission was developed to overcome the weakness and interruption of 2.5G(GPRS) signal. New data logger provided by domestic vendors can transfer data by using 3G/4G network (Figure 6).

Figure 6. Data transmission path of ICT third version

In 2015, the ICT third version had been firstly applied in Ming-Jian tea garden. The new data transmission path is moderately adjusted from the old version (Figure 6). The old data loggers which are adapted by GPRS had been replaced by data loggers which can be adapted by 3G/4G. In this case, the unstableness and weakness of date transmission could be solved, completely. And, the new ICT facility can be operated, even though the termination of 2G in the near future.

Comparing to the first version, the data transmission paths in the second and third generations are relatively concise and the number of ICT facilities are reduced. However, data stored inside of the data logger had been compressed and encrypted; data transmitted to the databased cannot be used and extracted by SQL directly. Therefore, data needs to be downloaded from webpage provided by vendors for the advanced charts reporting and statistical analysis. The core instrument and key technology of ICT data transmission are mastered by the vendors, users cannot deal with the malfunction in real time and cannot replace or modify the facilities by themselves.

3.4. Fourth version of ICT Arduino core

Arduino is an open source microcontroller kits for building digital devices and interactive objects that can sense and control objects in the physical world. The space and allocation of Arduino cores is relatively smaller and simplified. In addition, Arduino boards are available commercially in preassembled form, or as do-it-yourself kits. Therefore, development of self-designed data logger and controllers turned to be comparatively feasible. Self-designed data logger integrated with RF (2.4GHz) can develop a wireless network transmission system for leaching monitoring by using lysimeters in a whole LTER station (Figure 7). More than 1000 network nodes come with a data logger and Arduino core device which is capable to receive all of the data from lysimeters in one LTER station.

According to the concept of Internet of Things (IOT), data logger with 4G network is applied to transmit data from Arduino in the fields directly to database in labs (Figure 7). This new version is greatly improved the convenience of wireless transmission and reduced the cost of ICT facilities [16]. The process of data management and operation of ICT facilities can be completely manipulated by users [17]. The broken ICT facilities of first version and second version were replaced by Arduino cores. In addition, fourteen Arduino were applied in Chi-Ko branch farm.

Figure 7. Data transmission path of ICT Arduino core fourth version

3.5. Qualiy and quantity of data received from ICTfor leaching moniroting

Leaching data collected by lysimeters and the precipitation records collected by local agricultural weather stations, in 2014 in Ming-Jian tea garden LTER station, are illustrated in Figure 8. The pattern of leaching data reflects to the pattern of precipitation records. It implies that data collected by lysimeters and the ICT data transmission system work well and properly. For instance, in Figure 8, on the one hand, the peaks of precipitation during heavy rain season in May and during typhoon season between July and September are reflected to the peaks of leaching. On the other hand, during the dry season in January to April and in October to December, there are off-peak in both leaching and precipitations. Therefore, the amount of precipitation is heavier; the amount of the leaching is raised accordingly. In addition, the results of simple linear regression shows that the relation between leaching (average in 3 days) and precipitations (average in 3 days) are significant positive (p < 0.001，r2 = 0.28). However, the leaching is influenced by the factors, i.e., physical property of soil, the vegetation species, growth situation, weeding management, etc. According to the results, leaching data collected by the lysimeters and ICT data transmission system is one of the most appropriate monitoring strategies. So, the quality of data is examined and the result reveals that the leaching data reflects to the precipitation records positively.

Figure 8. The daily patterns of leaching and precipitation in 2014

In addition, data quantity is examined by frequency of data received from data logger and ICT data transmission systems. Here the Data loggers developed by original factory, by vendors in Taiwan, or by Arduino, can set up the frequency of data receiving. In this study, the frequency of leaching data receiving is every three hours. In total, there are 2,920 records received by each lysimeter every year. For the advanced data analysis, each of the leaching data will be accumulated daily as one record. In generally, all of the data is accurately received and the quantity of data is plenty enough for the advanced statistical analysis.

1. Discussion

The ICT facilities for leaching monitoring have been improved from first versions to fourth versions since 2010 to present. As a result, Arduino core has been adopted to develop the data transmission path with high flexibility and feasibility. The comparison among different versions of ICT facilities are organized in Table 2. In different versions, the extensibility has been improved, the complexity of maintenance has been moderated, and the cost is decreasing. The original purpose of ICT was to minimize the cost with real-time monitoring. With the progress of ICT technology, data transmission can be developed with open source operation systems to achieve different requirements for specified circumstances.

Table 2. Comparison among different generations of ICT facilities

 1st version 2nd version 3rd version 4th version Data logger Original factory production Domestic vendor development Domestic vendor development Arduino core Network transmission mode WiFi 2.5G(GPRS) 3G / 4G 4G Extensibility Bad Moderate Moderate Good Power Consumption High Moderate Moderate Low Cost 1,000USD/Sensor 830USD/Sensor 900USD/Sensor 150-250USD/Sensor

According to the ICT developement of four versions, the potential solutions to the challenges in the fields are provided as followings:

1. Power supply

The first challenge when developing ICT facilities in the field is power supply. Power supply is required for ICT facilities, monitoring sensors, and diverse instruments. In the beginning, power supply is the essential equipment when establishing LTER stations. However, power supply is unstable and insufficient because of wire cable destroyed by lightning strike, wild animals and human beings.

One of the potential solutions is solar panels compatible with charge controllers and rechargeable batteries. The most efficient source of environmental energy is solar power [18] providing most of the energy with very high efficiency [19]. Use of solar energy could come to aid in energy supplies to batteries of the sensor nodes [20]. However, power is highly demanded by G2 lysimeters and WiFi network transmission system of ICT first version. In addition, G2 GPRS of ICT second version and data loggers with G3/G4 of ICT third version demanded more power supply than earlier versions. Therefore, after a few cloudy and/or rainy days, power supply by solar panels will be extremely limited.

Data loggers of fourth version are not only power saving with the new version sensor of ICT Arduino core, infrastructure program of fourth version is also modified to advanced power saving by setting sleep, wake-up, and data transmitting frequently for advanced power saving. Therefore, power supply by solar panels turned to be the possible solution and difficulties of developing ICT data transmission network is reduced.

1. Transmission instruments: failure rate and maintenance

In the fields, instruments are influenced by the weather, wild animals, farming practices, ect. For the ICT first version, the space of cabinet is small with pores, so the equipment inside of the cabinet is easily to be destroyed by biting, spawning, nesting, etc. In addition, the cables inside of the cabinet are crisscross and disadvantageous for maintenance.

This challenge had been overcome by the second and third ICT versions. The space of new cabinet is enlarged, closed, and durable from destroying by wild animals and the weather. However, ventilators with gauze designed by the new cabinets which may allow small-size insect coming for nesting, so the cables and equipment inside of the cabinets still have the chance to be damaged.

In order to overcoming the challenge of the second and third ICT versions, ICT Arduino core of the fourth version designed as new small case with waterproof sealed. The connections between power supplies, interface of sensor and antenna, and data loggers are completely sealed by silicon and/or rubber gasket. Therefore, ICT facilities inside of new cases are entirely separated from water and wild animal.

1. Data warehouse and database management

The development of ICT second and third versions were cooperated with system vendors, and data stored inside of the data logger which developed by vendors were compressed and encrypted. Therefore, data stored in the databased cannot be used and extracted by SQL (Structured Query Language) directly. The leaching data collected by lysimeters in LTER stations. The leaching data collected by lysimeters in LTER stations which is not required by compressed or encrypted; because of the moderation of monitoring frequencies and data size.

Therefore, data needs to be stored as exchangeable format for allowing further reading and writing in database using SQL. In addition, databased should be developed with the functions of data extraction, data analysis, chart display, etc. A webpage comes with the databased is demanded for increasing the interactions between database, applications, and users.

1. Cost control

ICT facilities can reduce the cost of data transmission. The overall profit of ICT facility establishment should be considered for cost control. The cost of first ICT version is about $1,000 US dollars and it is reasonable, because data transmission system is developed by the existing data logger and WiFi network, and new equipment is inexpensive. However, if new data logger and WiFi network could be developed by users, the cost of development would be cheaper. The costs of the second and third ICT versions are about$830 US dollars and $900 US dollars, respectively. Their costs are higher than the first version. Although the cost of data loggers developed by the domestic vendors is similar to it by original factories, the expenditure of the peripheral equipment remains high. The cost of 2G GPRS and 3G/4G network is inexpensive because transmission traffic is moderate. The cost of ICT Arduino fourth generation is about$150-250 US dollars, which is relatively reasonable because of the low-priced of assembling parts and self-designed system. 4G transmission system costs about \$100 US dollars. In addition, the new cabinet is smaller and sealed which can be compatible with solar panels, rechargeable batteries, etc. Therefore the cost of ICT facilities had been greatly reduced but the efficiency and durability had been greatly improved.

Arduino cores come with highly flexibility and feasibility to be able to connect with diverse sensors, and lysimeters are one kind of the sensors. According to the data acceptability to both analog and digital data format, the ICT data transmission can be connected to different kinds of sensors, such as weather station, soil hygrometer, soil conductance meters, greenhouse gas monitoring equipment, etc., for the potential advanced application in agricultural LTER stations in the future. The proliferation of devices with communicating–actuating capabilities is bringing closer the vision of an Internet of Things, where the sensing and actuation functions seamlessly blend into the background and new capabilities are made possible through access of rich new information sources.  The evolution of the next version mobile system will be depending on the creativity of users in designing new applications [21].

In this study, the usage of ICT data transmission is mainly designed for leaching monitoring for selected agricultural LTER stations. So far, it is under the test phase and only applied by us. In the future, whenever the system works stably and efficiently as we expected, it will be promoted to others for meeting to their needs. According to our using experiences, the ICT data transmission is feasible for limited space of cabinet because of its small size, compactness, and easy of handling. In addition, it is a low-power system, it can be powered by solar energy generation and the configuration of power line can be simplified. Therefore, the system operates well in general, the wireless transmission is speedy, and it is weather durable to be able to withstand the hot, humid, and windy in Taiwan’s farmlands.

1. Conclusions

Nowadays, ICT is properly developing. ICT facilities are applied to agricultural long term monitoring and measurement with the advantages of low-cost, instantly and remotely monitoring. According to the popularity of Open Source, users can develop the data transmission system by using monitoring equipment, transmission path, and power saving supplies by themselves, to meet the needs of different conditions in the fields. In addition, data transmission system comes with long-range transmission technologies (i.e., RF and LoRa) can develop more completely and more compactly data transmission structures. Therefore, users will be able to monitor long-term data more completely and more precisely with reasonable cost. In advanced, the basic knowledge of programming and electric hardware development is required by cooperating with other experts to achieve the specification and profession of experimental objectives. Ultimately, the feasibility, flexibility, and extensibility of ICT facilities, users can develop data transmission with diverse schemes to satisfied their desires.

Acknowledgments: This study has been implemented since 2010 and has been funded by Ministry of Science and Technology, Taiwan (Grant No. NSC-100-2621-M-055-001 and NSC-101-2621-M-055-001) between 2011 and 2012 and by Council of Agriculture, Taiwan (Grant No. 102AS-7.1.2-CI-C1, 103AS-7.1.1-CI-C1, 104AS-7.1.1-CI-C2, and 105AS-7.1.1-CI-C1) between 2013 and 2016. In addition, the authors would like to thank The Taiwan Long-Term Ecological Research Network (TERN) for assistance on the field work, data collection, and technical support.

Author Contributions: Chiling Chen developed the scope of this study, planed the system, and advised and improved the processes and progress of this study. Yankuang Chan,  Jhenghong Hu, and Chungyi Liao designed the framework of data transformation, installed the systems, collected data, and take in charge of instruments management, maintenance, and improvement. Yankuang Chan, Jhenghong Hu and Chiaoying Chou wrote the first manuscript draft. Chiling Chen and Chiaoying Chou revised the manuscript draft. All authors have read and approved the final manuscript.

Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.