Tackling challenges in Sudan's agriculture sector using Cubesats
Until the discovery of oil, which led to the rise of services and industries related to the exploitation and export of oil, the agricultural sector was the most dominant sector of the Sudanese economy. Now that Sudan lost most of its oil resources due to the separation of South Sudan, the agricultural sector has regained its importance. According to data provided by the United Nations Statistics Division, the agriculture sector is estimated to represent 32% of the Gross Value Added, and it accounted for 53% of employment in Sudan.
The 2006 Khartoum Food Aid Forum outlined the constraints that beset the performance in the agricultural sector in Sudan. The lack of strategic planning is the main factor for problems encountered in the agricultural sector since independence. Also, the reduced competitiveness because of low productivity and high marketing costs (Abbadi and Ahmed, 2006) have had an impact. According to IndexMundi, a data portal that gathers facts and statistics and visualizes them, almost every product grown in Sudan has a low productivity rate. For instance, Sudan’s cotton productivity in 2019 is estimated by the United States Department of Agriculture to be 653 KG/HA compared to 1,129 KG/HA in the Syrian Arab Republic & 1,089 KG/HA in Tunisia. The literature highlights that achieving maximum production mainly depends on optimization strategies that are applied to the resources, such as irrigation water and fertilizers. Allocation of these resources according to the plants’ needs, such as water use and soil nutrients, provides the optimal and sustainable production levels, and is considered a very significant factor in a country like Sudan where farmers, due to the high inflation, have limited resources to allocated to their farms. Hence, clear, and evidence-based strategies are paramount to maximize performance.
On a national level, it is important to acquire rich data about agricultural lands and projects, which can lead to the necessary policy changes to ensure the agricultural sector is up to expectations. This approach is currently being followed by Sudan’s Ministry of Agriculture and Forest in their 4-year plan to implement E-Agriculture (“Sudan E-Agriculture Strategy” 2018-2022).
With the advent of CubeSats, space-borne remote sensing is becoming more affordable. Fortunately, many initiatives now exist to support CubeSats technology in developing nations. In 1968, The United Nations (UN) conducted the first of 3 global conferences on the peaceful use of space science and technology, with a focus on the involvement of developing nations. The UN supports this focus as it promises opportunities to bridge the gap between developing and developed countries in terms of technology, while maximizing the global benefits of space science applications (Othman, 2003). Through collaborations between institutes in developed countries and their counterparts in the less developed world, many developing countries have begun to contribute to CubeSat technology.
A notable example is a joint project between Germany, South Korea and Peru in 2008, which led Peru to launch its first satellite, the Chasqui-1 CubeSat (Wan et al., 2010). CubeSats facilitate global collaboration between countries as they are designed to be cost-effective compared to regular satellites, and can be deployed in batches, thus significantly reducing launching costs. Moreover, many space organizations fund CubeSat projects, ranging from testing and developing CubeSat payloads, to launching them into space, or even full support to reduce the development cycle. This provides young researchers opportunities to contribute to space research. With funding from local authorities and international organizations, and considering the ease of acquiring the CubeSat COTS components, and the relatively low cost of designing, constructing, launching, and operating the small satellites; problems like; pollution, environmental management, natural resources utilization, weather and climate applications, agriculture, and urban and rural planning can be tackled.
CubeSat Solutions in Sudan
Using CubeSats in Sudan will indeed help to solve major problems in agribusiness and will also push towards implementing the strategies suggested by the Sudanese Ministry of Agriculture and the FAO (“Sudan E-Agriculture Strategy.pdf” 2018-2022.).
Remote Sensing using CubeSats, through installing measurement instruments to monitor certain behaviour or phenomenon on a macro scale, have been the main application of CubeSats since 2014 (Villela et al., 2019). This section will discuss remote sensing applications that can tackle agricultural issues in Sudan, namely, land fertility assessment, irrigation, and plant health monitoring.
Irrigation and water use
The agriculture sector in Sudan can be categorized into two main branches, rain-fed agriculture and irrigated agriculture. Out of 1.09 million sq. km of land suitable for agriculture, the total irrigated area is around 195 thousand sq. km representing the six agriculture projects run by the government and the private sector in Sudan. In 2009, a report of a study of agricultural water uses in the Nile basin showed that modern and privately managed West Sennar and new Kenana schemes have good irrigation results but do not seem to be sustainable in the long term; while the El Gezira and Kassala schemes have low irrigation performances (Nil, 2009). Overall, Sudan showed wildly varying differences in irrigation performance between the LSIs.
To resolve these problems of the inadequacy of irrigation systems, a SWOT analysis was done by Sudan’s National Agriculture Investment Plan (SUDNAIP) 2016-2020. One of the main opportunities is the Sudan E-Agriculture Plan, by which the development of Information & Communication Technology (ICT) can contribute towards the achievement of the country’s agricultural vision and development objectives. In this context, ICT is used as an umbrella term encompassing all information and communication technologies including devices, networks, services and applications; these range from innovative Internet-era technologies and sensors to other technologies that have existed for much longer such as telephones, mobiles, television, radio and satellites.
Achieving ICT development objectives through CubeSat technologies is a very promising strategy. Techniques used to optimize irrigation using CubeSats are various. One of these techniques is measuring the hydric stress, which is stress that the plant undergoes in environmental conditions where the quantity of water transpired by the plant is higher than the quantity that it absorbs. Depending on the crop water stress read by the CubeSat, the optimum irrigation scheduling can set. Irrigation scheduling is the process of determining the correct frequencies and duration of plant watering.
Besides helping to determine the optimum scheduling, CubeSat data also helps in dividing the project land into specific zones, each with its suitable irrigation strategy (Veysi et al., 2017). One of the most valuable tools used in estimating water stress and irrigation scheduling is the Crop Water Stress Index (CWSI). Normally, the CSWI measures are taken manually on the field, but this process is costly, time-consuming and usually fails to provide full coverage to the field (Erdem et al., 2005).
Many methods are used to detect stress via the CubeSat. For instance, a Mid Wave Infra-Red (MWIR) sensor is a suitable option as demonstrated in the OUFTI-NEXT CubeSat of the University of Liege (Werner et al., 2018). The MWIR sensor can be embedded easily in the CubeSat and provides numerous advantages over the other alternatives. The double composition of the signal of the sensor allows it to take measurements during the day or night, via the reflective light, or the thermal emissive signal, respectively. The mechanism used by OUFTI-NEXT is quite simple, a plant without enough water closes its stomas (small apertures at the leaves surface), these stomas exchange water vapour with the atmosphere, which leads to the transpiration of the plants (transpiration is essential to conserve an ideal temperature for growing). When stomas are closed, plants heat the MWIR sensor, a sign of hydric stress.
Land Fertility
As Changwon and Jianmin described, soil fertility can be defined as the suitability of the soil to sustainably grow and develop plants and can be generally evaluated in terms of various properties, such as soil organic content, minerals content and soil moisture (Du and Zhou, 2009). Traditionally, mapping these properties is achieved through lab-based methods, where samples are taken from the soil and their physical and chemical characteristics are investigated in labs. However, this approach is generally time-consuming, especially when considered for large-scale evaluation. An alternative is to utilize remote sensing technologies, usually through spectroscopy. This section will discuss space-borne soil sensing, particularly the use of CubeSats in measuring soil organic content and moisture as they are important factors in the context of soil fertility analysis.
1 - Soil Organic Content
Soil spectroscopy is concerned with studying the reflected electromagnetic waves from soil to estimate its characteristics. In remote applications, a platform is equipped with a spectral imagery device and is operated from a distance. One of the important features of spectral imaging is the spectral resolution, which is the ability to identify different wavelength bands. The more bands a sensor can identify, the higher its spectral resolution. Based on this feature, we can classify spectral sensors into 2 categories; multi-spectral sensors, where the identifiable bands are generally between (3-10 bands), and hyper-spectral sensors which can detect even finer bands.
David J. Mulla in his 25-year review of remote sensing in precision agriculture (Mulla, 2013), highlighted the very first application of remote sensing, carried out in 1991, where Landsat imagery was used to estimate spatial patterns of soil organic matter (Bhatti et al., 1991), and later used as auxiliary data with field-wise sampling to estimate spatial patterns of phosphorus and wheat grain yield (Mulla and Bhatti, 1997).
CubeSats demonstrate significant potential in soil sensing applications compared to larger satellites, owing to their high spatial resolutions, short revisit time, and ability to form constellations of CubeSats, providing dense information about a site from multiple sensors. For instance, in 2019, a study was conducted to evaluate the measurability of soil organic carbon through several multi-spectral sensors, including space-borne sensors (Sentinel-2 and Landsat-8 satellites as well as a PlanetScope CubeSat), an unmanned aircraft system (UAS - Parrot Sequoia), as well as hyperspectral sensors CASI and SASI, used as a reference data source (Žížala et al., 2019). One important conclusion of this study is that all space-borne sensors demonstrated similar prediction capabilities, despite PlanetScope’s CubeSat having limited spectral resolution (4 Spectral Bands) compared to both Sentinel-2 (10 Spectral Bands) and Landsat-8 (8 Spectral Bands). The study highlighted the fact that UAS - Parrot Sequoia showed lower prediction performance compared to space-borne sensors, although it is the recommended alternative in this study owing to the significantly lower cost advantage. It is also worth noting the research carried out by Gerald, Daniel, Sibylle and Gird (Blasch et al., 2015), which aimed to use multi-temporal soil pattern analysis to detect soil organic matter via RapidEye time series data analysis and GIS spatial data modelling, resulting in a prediction error 1.4% for the main organic matter value range in the study site.
2 - Soil Moisture
Traditionally, soil moisture sensing was conducted using radiometry. This type of sensing could be active, where the sensing platform is equipped with a transmitter and receiver to detect the reflectance of transmitted beams, or passive, where only a receiver is involved to detect naturally emitted waves by objects or the reflectance of signals from separated transmitters. Daniel and David highlighted in their review (Selva and Krejci, 2012), that active sensing poses great challenges against its implementation in CubeSats, due to size and power limitations. To overcome this challenge, recent research efforts utilized available satellite signals and measured the reflection of these signals for various objectives. This approach is known as a signal of opportunity remote sensing (SoOp).
Equipping CubeSats with L-Band microwave antennas allows to detect soil moisture. For instance, the FSSCAT mission is a constellation of two 6U CubeSats; The first one, 3CAT-5/A, carries the flexible microwave payload which implements a GNSS-R instrument and L-band passive radiometer, while the second one, 3CAT-5/B, is equipped with a hyperspectral imager of 45 spectral bands between 400-1000 nm (Camps et al., 2018). One of the mission goals is to provide measurements for soil moisture by utilizing the combination of L-band radiometry and hyperspectral data (Munoz-Martin et al., 2020). Other radio frequencies can also play a role in soil moisture. For instance, a study (Joseph et al., 2016) was conducted to design VHF radio antennas (Very High Frequency between 240-270 MHz) for 6U CubeSat platforms. The research aims to make use of existing satellite transmitters known as transmitters of opportunity, particularly the Military Satellite Communication (MilSatCom) System’s UHF Follow-On program, to measure surface soil moisture (SM) and root zone soil moisture (RZSM). The study highlights the fact that the current observation of SM using L-band radiometers and radars (1.4 and 1.26 GHz respectively) are limited by the penetration abilities of these frequencies. Consequently, it is only possible to remotely sense surface SM while further depths can only be estimated indirectly using sophisticated extrapolations algorithms. However, with VHF (1.2 m wavelength and 250 MHz), the penetration potential increases, and it is, therefore, possible to directly measure surface SM up to root zone RZSM directly. Finally, recent research demonstrated that it is possible to implement passive radiometers in smaller CubeSats, even as small as 1U (Fernandez et al., 2020), making them considerably cheaper.
Plant Health
The term “plant health” is widely used in the field of economics and agriculture as it’s an extremely important factor for sustainability, food security and the protection of biodiversity of the ecological system. It defines the plant's ability to grow and produce in the face of diseases and environmental stresses. To achieve maximum crop production, the biophysical and biochemical properties can be monitored, as they are important for the study of the ecological and meteorological behaviour of various plants, thus they define the plant health and give good estimation in quantifying production.
One of the technologies that can be used in monitoring plant health is hyper-spectral imaging, made possible on CubeSats due to the advancement manufacturing processes. The use of hyper-spectral remote sensing was demonstrated in a study done in the Indian Himalaya Region, where hyper-spectral remote sensing is used to map and discriminate the land cover in the region, as it’s capable of mapping the vegetation class among the various classes in the land, and also has the potential to discriminate within the different classes of vegetation, as well as the ability of disease identification within a class (Upadhyay et al., 2019). The key idea in this study is the reflectance spectra of the plant. It’s well known that different surfaces reflect and absorb the sun's electromagnetic radiation in different ways, the physical and chemical properties of the surface define how the surface reflects the energy, given a specific wavelength, different surfaces will reflect different amounts of energy in different portions of the spectrum, hence it makes it possible to identify the features of these surfaces. In the Indian Himalaya study, the reflectance spectra of 11 species were analyzed. It was observed that the different tree species have the same nature of spectral reflectance but are separable due to high variation in amplitude.
The challenging issue in the use of spectral reflectance to identify the properties of the land cover is data processing. It always requires an existing library to compare the acquired data with. Hence, the development of this library is critical and a great effort should be made to provide in-situ measurements for various plants. But with the advanced development of spectra-radiometers with the capability of measuring from ultraviolet to the shortwave infrared region in very small bandwidth, generating this digital library is becoming easier and it’s now an area of interest for researchers all around the globe. Using CubeSats to provide hyper-spectral data will help determine the status of the plant's health and help to enhance it by selecting the proper method and timing of fertilization.
“Using CubeSats to provide hyper-spectral data will help determine the status of the plant’s health and help to enhance it by selecting the proper method and timing of fertilization.”
Current Situation of the Space Sector in Sudan
Using remote sensing techniques with CubeSats requires considerable effort and a good foundation in the related fields. Regarding remote sensing in Sudan, the first noted efforts dated to the 1970s, with the establishment of the National Remote Sensing Centre who aimed to set space technology policies, conduct research and studies, and undertake capacity building. With regards to research with CubeSats, three institutions are worth mentioning.
The first is the University of Khartoum Space Research Centre (UofKSRC), which was established in December 2014 to function as an umbrella for all entities involved with research on space-related fields at the university. UofKSRC is the most active institute in this matter, and have designed, fabricated and tested two prototypes successfully at the research centre, following the international CubeSat designation. Also, a fully functional ground station is installed at UofKSRC and tracks and commands other satellites and CubeSats. The ground station is actively involved in receiving many CubeSat beacons and telemetry and was one of the first ground stations in the world to receive some of these satellite data.
The second initiative is the Institute of Space Research and Aerospace (ISRA), which is one of the institutes that belongs to the National Centre of Research. It was established in 2013 to nationalize the research and development of the different fields of space science and aerospace technology in Sudan.
The third initiative is the Kush Institute of Space Technology, established in 2000 as the Space Technology Centre (STC). In May 2012, STC was renamed Kush Institute for Space Technology (KIST) to expand its mandates and operations, and to raise the level of awareness of space science and space technologies for the community, and to implement new and emerging space-related projects and programs at Future University and its international partners.
Regarding the commercial space sector, Ceres Space Technology Centre (CSTC) was founded in 2008 as a specialized centre in space technology. CSTC is a part of the Sudanese National Committee for Space (SACS). Using its ground station, the CSTC provides satellite imagery services in addition to research & training in space science and satellite engineering.
Future Directions
The UofKSRC, Kush Institute of Space Technology, ISRA & CSTC have done considerable work in space, and they provide the groundwork for research on agricultural CubeSats. Further research efforts, done individually or as a collaboration between these institutions can target space research projects related to the agricultural sector.
For instance, as a starting point, they may involve utilizing commercial CubeSat services with high spatial resolution and dense data such as the Rapid Eye, and Planet Scope projects, in conjunction with other free space-borne sensing sources like Landsat to acquire live data about water use. These services can be applied to the modern and privately managed West Sennar and new Kenana schemes to achieve sustainable irrigation results in the long term. Moreover, El Gezira and Kassala schemes have currently low irrigation performances. Utilizing such technologies will help optimize these schemes. Subsequently, Sudanese space research institutes can also launch dedicated CubeSats that focus on Sudan, providing more data in short revisit times, thus achieving the previous objectives with better output.
The suggested research projects target one of the E-Agriculture Strategy objectives, the availability of agriculture data in Sudan. The absence of statistical data has been an issue in Sudan since its independence. Although the world has shown a considerable increase in the demand for data, it could be said that the efforts done towards digitalization and data availability in Sudan are negligible. Hence, CubeSats are essential to provide digitized data for economists and policymakers and are a crucial process in prediction and decision-making.
In addition to the above-mentioned directions, initiating such projects and initiatives will enlarge the scope of space engineering in Sudan and the utilization of the space research centres at the University of Khartoum, Future University, along with Ceres Space Technology Centre & ISRA. Conducting the research related to the E-Agri project can present well-defined plans on how to improve these research centres and what type of training is needed for their personnel. It can also attract new budgets and investments that will benefit the research centres and investors. Furthermore, it can be an eye-opener for the use of CubeSats in fields other than agriculture. Mining and Geological research for instance have promising results in this direction.
Omer Mohamad
Omer is a Mechanical Engineer with a passion for designing and building electro-mechanical systems. He is currently pursuing a MSc Degree in Mechatronics as an Erasmus Mundus Scholar.
He has a deep interest in Control Engineering, being involved in the design and build of several different systems related to Robotics and CubeSats.
https://www.linkedin.com/in/omoisaac/
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