Of all the available groundwater on Earth, more than half has a salt concentration that impedes crop production. This leaves opportunities for increasing agricultural production with two options: the expensive, often unviable route of treating the water to reduce the salt content, or making the crops salt tolerant. Just how far are researchers adapting our plants? Lindi Botha spoke to the experts to find out.
The issue of salinity has progressed over time to become a far greater issue than just water availability. As farmers are left with little option than to irrigate crops with saline water when that is all they have, salt concentration in soils have increased. The Salt Farm Foundation in the Netherlands, states that 63 million hectares of all irrigated farmland is salt-affected, with the number increasing at a rate of 2,000 hectares per day.
The indiscriminate use of fertilizer has compounded the problem since nitrogen is a salt. When over applied, the salt builds up in the soil, rendering the soil too salty for optimal crop production.
Tobias Strijker, an agronomist at the Arava Research and Development Centre in Israel, notes that yield declines considerably as electrical conductivity (EC), which indicates salt content in the soil, increases. “At an EC of 2, one can expect on average 50kg of citrus per tree. At EC4 it declines to 28kg per tree, at EC8 around 12kg per tree and at EC12 there is almost no crop at all.”
Where this leaves farmers in terms of the viability of planting a crop in the first place, depends on the business model and at which point the yield no longer justifies the operation. But Strijker explains that many farmers simply have no choice since they are dependent on their own grown crops to survive. “In areas like Rwanda, farmers face very high salinity in soils and underground water. In India, fields are periodically flooded during the monsoon season, depositing large amounts of salt on the land.
“In Israel, the water allocated for farming has an EC of 2,4 to 3,1, while drinking water, which comes at a higher price, is at an EC of 1,6. Many farmers blend the two to get to a water quality that will ensure better yields, but it does push up the cost of farming.”
The other downside, he adds, is that grapevines, for example, must be replaced every nine years, compared to every 100 years in Spain, because the salt build up in the plants start clogging its cells.
Faced with myriad factors increasing saline soils, finding ways to continue, and increase crop production in this environment has been the focus of many researchers. While progress was made, the new technologies developed over the last few years are rapidly driving innovation and solving problemsfar quicker.
Globally, progress is being made on four fronts: genes using gene editing technology, grafting on salt tolerant rootstocks, seed treatments and production methods.
Working with what there isThe Salt Farm Foundation’s knowledge centre, Saline Agriculture Worldwide (SAW), believes that to make saline agriculture possible, conventional farming techniques need to be tweaked. They have identified four pillars which would need adaption, including crop and cultivar choice, irrigation, fertilization and soil management.
Since different crop species, and even cultivars within species, differ in their tolerance to salinity, a suitable crop can be identified for most levels of water and soil quality. The differences in tolerance can however be quite large which means that for saline agriculture, selecting the right cultivar is the first thing to do. SAW for example found that certain varieties of potatoes, carrots and cabbage can withstand a salinity range of five to seven EC, while only reducing yield by 10 percent, making them a far better choice than fruit trees when contending with high salinity.
Since salt concentration in soils increase when the amount of water decreases due to evapotranspiration, it is important to irrigate regularly and thoroughly when using brackish water. The latter also prevents salts from accumulating in the top layers, rather ensuring that salt is drained to deeper soil layers, or preferably, a drainage system.
The soil type is also something to take into account and SAW advises that when farmers only have saline water at their disposal, that crops
are planted in sandy soils or loamy sandy soils to aid drainage of salts.
Fertilization should be carefully considered since it raises the EC of soil already high in salt from the water. If fertilizers are not reduced, their addition can increase the osmotic stress of crops associated with salinity. SAW’s research has shown that foliar fertilizers are better suited to saline agriculture since nutrients can be absorbed through leaves and additional stress is not placed on the root system.
Additionally, salinity may lead to specific deficits in crops, or higher demands for certain minerals, and consequently these may require higher doses of application than in conventional agriculture.
In terms of soil management, SAW recommends that additional organic matter be added to saline soils.
This is because a rich and healthy soil life is important for good crop performance, especially under saline conditions, so the use of microbial-based soil additives may help boost yields. Strijker further notes that adding a layer of mulch in fields assists in reducing evapotranspiration, which will reduce the amount of salt collecting on the surface of the soil.
Adapting the plantsCountering salinity in soils is but one part of the larger puzzle that is emerging in making saline agriculture a success. Treating seeds to withstand environmental
stressors like high salinity is showing much promise, with one company in Israel producing significant results.
Salicrop in the Beit She'an Valley in Northern Israel’s Jordan Valley has developed a seed enhancement technology. Seeds are covered with a chemically formulated coating that stimulates and activates biological mechanisms in the seeds that help them cope better with abiotic stresses. The result is plants that have a greater biomass, root structure, pest resistance, stress tolerance and germination rate, when irrigated with saline water, and compared to untreated plants.
The company conducted tomato trials on 25 hectares in the Beit She'an Valley, an area known for its combination of warm, dry climate, saline irrigation water and salty soils. The results showed tomato vines that produced significant biomass, leading to improved water transpiration, increased resistance to pests and diseases, and stronger detachment tissue. Most promising was the 15 percent increase in yield when compared to untreated tomatoes planted with fresh water.
The company has since ventured into various other crops, including alfalfa, capsicums and rice in India. The treated alfalfa and capsicums planted in Israel showed a 25 percent and 32 percent increase respectively, in yield compared to untreated plants planted with saline water. The treated rice planted in India showed a 15 percent to 24 percent increase in yield.
At the Arava centre, trials are done with saline water to determine how different plants respond to different levels of salt. Strijker says that grafting is what is currently making crop cultivation near the Dead Sea possible.
“Commercial varieties have been bred for yield and taste, but are very susceptible to damage caused by high salt in water or soil. Salt tolerant varieties on the other hand, produce small fruit. By combining the two, with the salt tolerant variety as the rootstock and the commercial variety grafted on, we have seen success in tomatoes and grapes. Since salt has the interesting effect of increasing the brix level in fruit, the higher salt content in the soil makes the tomatoes sweeter.”
Strijker believes that with the advancement of grafting and other technologies, irrigating food crops using sea water could be entirely feasible in future. “But not only that, the research into making do with saline water is also uncovering a host of new crops that have never been considered food before. Some, like duckweed, even have a higher nutritional value than conventional food crops, while others can be used in medicines or for livestock feed. The very tolerant species – halophytes – have a succulent appearance and consist of a host of edible, albeit mostly unknown vegetables.”
Changing the genesThe advent of gene editing, rather than gene modification, has also brought many more opportunities for saline agriculture. Since each DNA base has a string of genes responsible for different functions, researchers are zeroing in on those that control salt uptake.
Dr. Chris Dardick, a plant molecular biologist at the United States Department of Agriculture, believes that saline agriculture is feasible through genetic selection, gene editing (GE) and genetic modification (GM). “There are a number of steps to get high production under saline conditions. The uptake of salt can be blocked completely, we can have a rootstock that is more salt tolerant take up salt, but then not the scion, or influence the plant’s cells so that it sequesters salt rather than absorb it. There is also an option of activating the plant’s natural defence to high salt. There are so many aspects that we can control to reduce salt intolerance through biotechnology.”
A particular crop Dardick has focused much attention on is apples, where his research is aimed at better understanding how plants absorb elements in the soil. This includes saline soils or saline irrigation water, and harmful residues left in the soil by mining activities.
He has turned to wild species of apples to study their genetic make-up, since they show a particular tolerance to stressful environments. “Wild apples grow in extreme environments – drought, high salinity – where domestic apples would never grow. So we are trying to tap into that germplasm to breed better apples. This process would usually take generations to do crosses and back crosses to breed in the genes, but through biotechnology, the process is dramatically sped up.”
This research is particularly important in an environment that has traditionally focused more on saline tolerance in vegetable crops than fruit trees. With the U.S.’s west coast, where the majority of fruit and nuts are produced, becoming more prone to environmental stress, Dardick’s research isespecially crucial.
He has however stumbled onto a hurdle which is set to slow down progress: acceptance and regulation of genetically modified organisms (GMOs). “We have the technology to insert the genes necessary to do the gene editing, but the problem is that when they are inserted into the apple genome, the genes carry those foreign genes, rendering it a GMO, rather than a gene edited crop. The former comes with a far more stringent regulation process which gets very complicated when looking at the export environment. So for apples, it is not really feasible to produce a GMO even if it can withstand extreme environments.”
The grafting process is showing more promise in this regard since rootstocks can be engineered to withstand salinity, leaving the scion and its fruit not only GMO-free, but able to flourish without the salt being able to reach it. With Dardick’s research into wild apples, rootstocks that are naturally salt tolerantalso present much promise sinceno engineering is necessary,only grafting.
Another avenue that biotechnology is opening up is solving the problems associated with alkalized soils. Sunil Kumar Sahu, a research scientist at the Beijing Genomics Institute in China, says that alkaline
soil (rich in sodium carbonate and sodium bicarbonate) is as much a problem as salinized soil (rich in sodium chloride and sodium sulphate). “Research into combating the former is lacking since the most widely used model plant, Arabidopsis, is typically not derived from alkaline environments and therefore lacks genetic adaptations for alkali tolerance. This makes it impossible for researchers to thoroughly investigate the mechanism of alkali tolerance in crops, making it more difficult to implement research results into production.”
Sahu therefore turned to sorghum plants, which are more prone to alkaline tolerance. A genome wide association study was conducted on 352 sorghum resources, leading to the discovery of a gene locus, AT1 (Alkaline tolerance 1). An overexpression of this gene leads to a reduction in alkaline tolerance.
Through gene editing, researchers are now focusing on removing this gene in not only sorghum, but wheat, millet and maize too. So far Sahu’s trials have shown that when the AT1 gene is removed, sorghum, millet, maize and wheat exhibited higher plant height, greener leaves and increased biomass by as much as 30 percent. Grain yield increased with 20 percent.
This discovery is set to have a substantial impact on crop production. Sahu believes that if 20 percent of the world’s salt-alkaline land use AT1-modified crops, it will produce at least 250 million tons of grain per year in addition to the existing crop yield.
This is an area which has Dardick particularly excited. “Traditionally there has been quite a bit of research into saline agriculture. But we are moving into a new era where it has become far easier to identify specific genes, know how they work and alter them to work in our favour. We are in an era where we can move from fundamental research to application and beneficial results that will have a real impact on food production.” ●
Grape vineyards in Israelare covered in mulch to reduce evaporation and the consequential build-upof salts on the surface of the soil.
An orchard that does not have mulch, like this Medjoul dates plantation, shows clear rings of salt where irrigation has fell, and water has evaporated.
Grafting commercial varieties onto salt-tolerant rootstocks is showing promise for successful saline agriculture.
Citrus yields start declining rapidly when salt concentration in water exceeds an EC of 4.
Yield declines considerably as electrical conductivity (EC), which indicates salt content in the soil, increases
SAW found that certain varieties of potatoes, carrots and cabbage can withstand a salinity range of five to seven EC, while only reducing yield by 10 percent...
By Leonardo Gottems
When it comes to recovering degraded soils, time is one of the biggest obstacles: nature needs approximately 300 years to be able to regenerate a layer of soil just one centimetre thick. With artificial methods, soil chemical attributes can be restored in a matter of years, but biologicalor physical aspects require decades.
The great challenge for the next 40 years to produce more food is to increase arable land. One of the alternatives is to expand the high-tech agricultural frontier in tropical ecosystems, which were the last areas to be incorporated into agricultural systems. The issue is that, as they are less agriculturally suited, these areas have not largely received advanced technology packages. As a result, they were relegated to occupation, with unmanaged pastures on degraded soils. To be occupied by agricultural crops, these areas will have to be submitted to practices of high technological level, which add significant value.
With the promise of recovering degraded soils in a shorter period of time, Brazilian researchers from the University of São Paulo are developing a product inspired by the geochemistry and typology of soil clays based on MOFs (Metal-Organic Frameworks). These are advanced materials, produced from the combination of metals and organic molecules, in which it is possible to use in their structure the same elements found in minerals that help fix CO2 in the soil, such as iron and magnesium, recovering ecosystem functions.
One of the main characteristics of MOFs is their great versatility in terms of structure and application. Currently, there are around 80,000 different types of MOFs catalogued: a number 330-times greater than the number of zeolites, another class of advanced porous materials, recorded. Due to this enormous variety, MOFs can be applied in gas storage technologies, pollutant removal, electricity conduction, the transformation of chemical inputs, and drug encapsulation. As far as is
known, there is still no practical application of MOFs in agriculture… until now.
The origin of everythingThe technology emerged from a meeting between two research groups from different areas, but with common interests: the group led by Professor Liane Rossi, from the Institute of Chemistry at the University of São Paulo (USP), which works with nanomaterials, and the group led by Professor José Marques Júnior, from the Faculty of Agrarian and Veterinary Sciences, at the São Paulo State University (UNESP), who researches the typology of clays.
As different as they may seem, the research carried out in the two laboratories over the last 20 years has much in common and formed the basis for the production of new materials, called “synthetic particles”, which are capable of imitating the natural particles present in the environment. soil and simulate one of its main functions: the control of soil health, or, in other words, the regeneration of ecosystem properties of arable areas.
The studies, which are expected to last three years, are carried out within the scope of the Research Center for Greenhouse Gas Innovation (RCGI) projects, a research centre funded by Shell and the São Paulo State Government Research Support Foundation (FAPESP). The commercial development of the product and access to this technological package will be carried out by two startups that originated within these research groups: Quanticum and MOF Tech.
According to the scientists involved in the research, the recovery of
degraded soils is a “crucial tool in the fight against the advance of climate change, as a 'healthy' soil sequesters more carbon dioxide than a degraded soil. In this way, the use of technology can help mitigate greenhouse gas emissions”. The application of MOFs in the soil aims to restore the properties conferred by the mineral portion of the soil, imitating what nature already does.
Unique featuresMOFs have three-dimensional structures with high porosity, similar to a sponge, however, about one million times smaller than the head of a pin. This characteristic of high porosity guarantees the formation of cavities in the structure of the material, which can house components of added value to the soil, such as, for example, macro (potassium, nitrogen and phosphorus) and micronutrients (zinc and boron) necessary for the full development of the plants.
Once applied to the soil, the “synthetic particles” decompose in a controlled manner in the soil, gradually releasing the nutrients and keeping them available for longer in the soil. These nano minerals can be applied to degraded arable land to help restore soil health, improve its water and nutrient retention capacity, and increase the productivity of crops planted there. Furthermore, taking into account the specific nutritional needs of plants, these materials can be custom designed for each different type of soil and crop.
Chemist Dagoberto Silva, researcher and CEO of MOF-Tech, says the key to soil recovery lies in the biodegradation of the product. “The MOFs end up decomposing under the action of sunlight and microorganisms, releasing the natural components of the soil and any chemical compounds stored in it.” Another great advantage of the technology is that it can be applied both in solid form, such as a powder, and in liquid form (spray), with the MOFs dispersed in water.
Fast regeneration“This set of characteristics will make it possible, with the MOFs, to regenerate a soil that has already been degraded, increasing the absorption of phosphorus and nitrogen, adjusting its pH, among other important properties for productivity”, says Rossi. “This soil renewal can take decades with the techniques currently in place. With ours, we will be able to obtain it in a matter of months, as it is a product that decomposes easily – another
positive point in preserving the environment.”
The project started at the end of 2022 and a prototype of the product has already been developed, which was synthesized in the laboratory and tested in experimental units (vegetation houses). “We are studying new formulations to maximize gains to the soil and the atmosphere, in addition to accelerating the production process. The large-scale tests will be carried out in field research units,” notes Rossi.
The agronomic studies will be carried out by the Faculty of Agronomic and Veterinary Sciences at UNESP, in Jaboticabal, and by Quanticum, which specializes in diagnosing and mapping the health of tropical soils.
Promising marketMOFs are the fastest-growing class of materials in chemistry today. Its adjustable porous structure has been explored in several application areas, such as renewable energy, catalysis, sensors and biomedicine. Studies indicate that it is a market that will grow 12 percent per year over the next 10 years. The USP project will be the first focused on the application of MOFs in agriculture, and its market potential is enormous.
According to the latest Global Land Outlook report, by the secretariat of the UN Convention to Combat Desertification, 40 percent of the planet's soil is degraded, which jeopardizes not only food and water security. Soil degradation is also associated with climate change, as the soil naturally stores CO2, one of the main greenhouse gases.
What’s next?According to the Brazilian researchers, part of the project is the development of methods for production on a larger scale (in relation to that produced in the laboratory) to meet the demand for the field tests that are foreseen in the project. “To reach the farmers, a new increase in scale will be necessary, but it is possible,” says Rossi. According to her, the next step is the proof of concept of the effect of the application of porous nano minerals in cultures in greenhouses and in experimental units in the field.
The researcher claims this technology, which has so far been tested in tropical soils, can be applied in a wide geographic range, as long as the climatic conditions and soil characteristics, indicated by the type of clay, are suitable. “However, it is important to remember that soils can vary significantly in clay type from one region to another and that different tropical crops have specific needs. That's why it's important to test and adapt MOF's formulations for each region and culture so that they can be effective in each case,” she notes.
“In addition, the application of MOFs can vary with the type of crop and cultivation method used. For example, in some cases, it may be necessary to apply MOFs directly to the soil, while in others it may be more appropriate to apply them through the irrigation water. Therefore, the geographic range of application of the MOFs tested in tropical soils is quite wide, but it is important to adapt the formulations and application methods for each region and culture, to ensure effectiveness and the best results,” she concludes. ●
Liane Rossi, Institute of Chemistry, University of São Paulo (USP)
Once applied to the soil, the “synthetic particles” decompose in a controlled manner in the soil, gradually releasing the nutrients and keeping them available for longer in the soil.
The project started at the end of 2022 and a prototype of the product has already been developed, which was synthesized in the laboratory and tested in experimental units (vegetation houses).
One of the main characteristics of MOFs is their great versatility in terms of structure and application
A limited amount of freshwater threatens agriculture production and food security, but researchers believe some crops can be grown sustainably in saline water if proper techniques are used.
The researchers are from Clemson University, the University of Florida and the United States Department of Agriculture’s Agricultural Research Service. Led by Clemson professor Raghupathy Karthikeyan, the research team has received a USD$10 million grant from the United States Department of Agriculture National Institute of Food and Agriculture (USDA NIFA) to study development of a controlled environment agriculture (CEA) platform for growing salt-tolerant crops – mustard greens, cucumbers and tomatoes – using saline water for irrigation.
“In many freshwater-scarce regions, saline water sources such as brackish groundwater are available and can be used for irrigation,” said Karthikeyan, Newman Endowed Chair Professor of Natural Resources Engineering and project director. “However, increased soil and land salinization restricts use of these water sources in traditional open field cultivation, a problem that can be reduced by using hydroponic (soilless) cultivation in CEA. Several high-value food crops are salt sensitive but can be made more salt tolerant through breeding.”
CEA covers a variety of systems, including greenhouses and modular containers, that take a technology-based approach to farming. These systems are designed to provide optimal growing conditions for crops and prevent disease and pest damage. Hydroponic agriculture is using a water-based nutrient solution rather than soil to grow plants.
“By using desalination techniques that are appropriate to the agricultural sector coupled with effective management of water, nutrients and fertilizers, as well as salinity, we believe we can grow salt-tolerant crops sustainably according to both economic and environmental metrics,” said Gary Amy, dean distinguished professor in the Clemson Department of Environmental Engineering and Earth Sciences. “We are advocating partial desalination technologies to produce tailored-quality irrigation water to match the salt tolerance of a target crop.”
The overall goal is to develop a hydroponics CEA platform for cultivating salt-tolerant food crops using saline irrigation water while ensuring no environmental impacts associated with salinity are created.
“We will do this by enhancing crop salt tolerance through breeding, developing new concepts in agricultural desalting technologies and optimizing salinity management,” Karthikeyan said.
Knowledge gained from this study will help growers use marginal quality water for year-round production.
The study is being conducted in vegetable growing areas of South Carolina and Florida and will be extended to Arizona. Objectives of the five-year research, education and extension project, which began on April 1, include developing a hydroponic CEA platform, using saline waters for irrigation, managing salinity to better align with crop responses as the crops become acclimated to high salinity and selecting mustard greens, cucumber and tomato varieties for enhanced salt tolerance. ●
Clemson researchers are leading a study to develop a CEA platform for growing salt-tolerant crops using saline water for irrigation.
Photo: Clemson University
Insights into gene and protein control systems that regulate the use of nitrogen by plant roots could help develop crops that require less nitrogenous fertilizers to produce acceptable yields.
Plant biochemist Soichi Kojima and colleagues at Japan’s Tohoku University discuss their findings and future plans in an article in the journal Frontiers in Plant Science.
Nitrogen fertilizers mostly contain nitrogen as ammonium ions (NH4 +), the chemical form in which nitrogen is most readily taken up by plant roots. However, excess nitrogen in the soil and in drainage run-off into lakes and rivers causes serious ecological imbalances, including algal blooms that de-oxygenate water and kill fish and other aquatic life.
"One of the key goals of modern agricultural research is to develop crops that can grow healthily without relying on so much added nitrogen," says Kojima. He adds there are also significant economic and environmental incentives behind this aim, pointing out: “Energy from vast quantities of fossil fuels is currently needed to convert nitrogen in the air into ammonium for fertilizers.”
The researchers worked with the small flowering plant thale cress (Arabidopsis thaliana), a common species used for laboratory studies in plant science.
"Taken together, our results reveal, at the genetic level, regulatory mechanisms at work when plants utilize nitrogenous fertilizers in their roots," says Kojima.
The team's next step is to determine if the processes they have identified in Arabidopsis are shared by other plant species, especially major crop plants such as rice and other cereals. If that is confirmed it could open an avenue for plant breeders and geneticists to generate crops that might need much less fertilizer while still producing the yields needed to feed the world. Enhancing the production or activity of the amino acid-making enzymes could be the key to success. ●
A lower level of nitrogen will improve the resistance to powdery mildew in the cultivation of gerbera, sweet pepper and cucumber. However, this effect is only achieved at the edge of nitrogen levels which affect crop growth negatively. A lower level of nitrogen has no positive effect on resistance to botrytis.
These are some of the results from a study by the Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research.
Lower nitrogen levelsWUR investigated the effect of a lower level of nitrogen on the growth and resilience of cucumber, bell pepper, chrysanthemum and gerbera. It clearly showed that nitrogen levels can be reduced seriously in all crops. For cucumber, a nitrogen reduction over 30 percent resulted in a negative effect on growth and production. The limiting value is considerably lower for chrysanthemum, gerbera and bell pepper, where the effect on growth and production occurred only from a 70-80 percent reduction in nitrogen compared to normal. The room for manoeuvre for growers is therefore much higher in those crops.
Effect on mildewThe nitrogen uptake by the plant also has an effect on the susceptibility for powdery mildew, especially in gerbera and cucumber. However, a lower level also causes less growth.
The study also examined whether the use of so-called elicitors, such as jasmonic acid or salicylic acid, substances that increase plant resistance, add anything. It turned out not to be the case, the effects were equal to the effect with just lowering the nitrogen level. The nitrogen affected the development of some pests, though the effects were not always straightforward. Aphid reproduced less and grew less rapidly at a low nitrogen level (tested in peppers). Caterpillars of Turkish moth also grew less quickly (tested in chrysanthemum). Contradictory effects were found in the development of thrips and whitefly for the various crops.
The research, which WUR is conducting together with Vertify and the Control Flowers and Food Foundation, will run until next year. In the current phase, the effects in practical situations will be investigated. The research is a PPP and is financed by the Top Sector Horticulture and Propagation Materials, Stichting Kennis In Je Kas and the crop cooperatives Gerbera, Chrysanthemum, Cucumber and Paprika. ●
Measuring temperature and nitrogen levels in soil is important for agriculture systems but detecting them apart from one another is difficult to do.
Huanyu “Larry” Cheng, James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State (U.S.), led researchers in the development of a multi-parameter sensor that can effectively decouple temperature and nitrogen signals so that each can be measured accurately. The results were recently published by Advanced Materials.
“For efficient fertilization, there is a need for continuous and real-time monitoring of soil conditions, specifically nitrogen utilization and soil temperature,” Cheng said.
Plant growth is also impacted by temperature, which influences the physical, chemical and microbiological processes in soil. Co-author Li Yang, professor in the School of Artificial Intelligence at China’s Hebei University of Technology, noted that “continuous monitoring enables farmers to develop strategies and interventions when temperatures are too hot or too cold for their crops.”
Unfortunately, both gases and temperature – along with relative humidity variations – can cause changes in the resistance reading of the sensor, so the sensor cannot tell them apart. Sensing mechanisms that can obtain nitrogen gas and temperature measurements independent of each other are rarely reported, according to Cheng.
Cheng’s team designed and fabricated a high-performance sensor to completely decouple the detection of nitrogen loss and soil temperature. The multi-parameter sensor is based on vanadium oxide-doped, laser-induced graphene foam. Vanadium oxide can adsorb and interact with nitrogen gases, and doping metal complexes in graphene have also been found to improve gas adsorption and detection sensitivity.
The sensor is encapsulated by a soft membrane that blocks nitrogen gas permeation so the sensor responds only to temperature variations. Additionally, the encapsulation can be removed and the sensor operated at an elevated temperature. Doing so removes the influence of relative humidity and temperature in the soil to allow for accurate measurement of the nitrogen gas. The combination of the encapsulated sensor and the unencapsulated sensor can completely decouple temperature and nitrogen gas without interference.
Decoupling temperature variations and nitrogen gas emissions can be leveraged to design and apply multimodal devices with decoupled sensing mechanisms for precision agriculture in all weather conditions, according to Cheng.
“The capability to simultaneously detect ultra-low nitrogen oxide concentrations and small temperature changes paves the way for the development of future multimodal electronic devices with decoupled sensing mechanisms for precision agriculture, health monitoring and other applications,” Cheng said. ●
Huanyu “Larry” Cheng, James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State (U.S.)
Seeking new tools to improve soil health, scientists at Washington State University are studying electric signals that bounce between plants and the underworld community of microbes that sustains them.
This spring, a cross-disciplinary team of WSU engineers and crop scientists sank electrodes into Washington wheat fields, as well as in soil-filled containers in the lab, in a USD$1.2 million National Science Foundation-funded research project. Their discoveries could help farmers and scientists measure and support beneficial exchanges in the soil.
“Microorganisms are essential for plants; crops need them to stay healthy,” said co-lead scientist Haluk Beyenal, professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering. “Our research uses electrochemically active microbes as proxies for soil health. Electrochemical signals can tell us what plants and microbes need.”
In the soil, bacteria make electrochemical exchanges with plant roots, grabbing free electrons for use in their metabolism. This exchange can be detected electrochemically: the team’s carbon-fiber electrodes act as an electron-producing source, with bacteria attaching themselves to the probes as a gooey biofilm.
A team led by co-primary investigator Maren Friesen, a WSU plant pathologist who is working to identify beneficial bacteria at work, are sampling and sequencing these communities, while engineers study the resulting signal data. Together, the group of faculty and student scientists aim to piece together how signals relate to soil health and plant productivity.
“We’re trying to extract the rules of soil electrochemistry: how microbes interact with the soil and the plant and what signals are being exchanged,” said co-lead investigator Anantharaman Kalyanaraman, professor and Boeing Chair of Computer Science in the Schoolof Electrical Engineering and Computer Science.
Along with a software model that can interpret signals and predict microbe activity and plant function, researchers aim to develop sensors or other technologies that could help farmers and scientists monitor the soil microbiome.
“If we can measure what’s happening in soil, we could shift microbial communities,” Beyenal said. Such control could, for instance, help growers precisely apply nitrogen fertilizer, minimizing farmer expense and environmental impact.
The four-year project launched in winter 2023 and continues through 2026. Envisioning new discoveries spinning off from the project, the team’s long-term goal is better communication on soil health. ●
Christi Webster, doctoral student in chemical engineering and bioengineering, inspects soil electrochemistry experiments at a WSU lab.
Agronomics and Economics News
Scientists have developed various machine learning models to predict the factors that produce the greatest yield in specific crop plants. However, traditional models cannot accommodate high levels of variation in parameters or large data inputs.
But now, researchers from Korea led by Professor Jung Eok Son from Seoul National University have created a novel deep-learning based crop model known as “DeepCrop”, for hydroponic sweet peppers. The model can accommodate several input variables and has fewer limitations on the amount of data it can process. Hence, it can be employed in most settings and can be extended to similar applications. The researchers tested the predictions of DeepCrop by cultivating the crop twice a year for two years in greenhouses. Their results were published in Plant Phenomics earlier this year.
We selected deep-learning algorithms as a potential solution to mitigate fragmentation and redundancy,” explained Prof. Son. “Deep learning has high applicability to broad target tasks as well as remarkable abstraction for enormous sets of data,”
DeepCrop is a process-based model that can simulate crop growth in response to various factors and environmental conditions. It can be scaled up to include many input types or greater amount of data. One reason for the high versatility of DeepCrop is that it is constructed exclusively with neural networks. Neural networks are combinations of algorithms that process the interactions between input data to make useful predictions.
Since simulations are created on a computer-based platform, DeepCrop requires minimal infrastructure. “With its applicability, a complicated task conducted at the enterprise became accessible with a personal computer,” noted Prof. Son.
Deep-learning algorithms must be fed data before they can make any predictions. DeepCrop algorithms on plant growth simulation were trained in a similar manner. However, it did not need the programming of sophisticated concepts in plant physiology or crop modeling to produce useful predictions. “DeepCrop simulation adequately followed the growing tendency from scratch according to the scores, but the model should be inspected because it has potential to be improved,” said Prof. Son.
To validate the predictions of DeepCrop, the team cultivated sweet peppers in preset greenhouse conditions. A comparison of predicted and actual plant growth patterns suggested that DeepCrop outperformed other existing process-based crop models, as indicated by its modeling efficiency. The model was also the least likely to make prediction errors.
The capacity of DeepCrop to produce useful predictions even with varying inputs and parameters suggests that it can determine relationships between input data regardless of data type. The results of this study also suggest that deep-learning models can be useful for a wide range of applications in crop science. ●
Target crop growth and morphology were abstracted as one-big organs. Averages can be calculated with total values and the number of organs. Credit: Plant Phenomics
Research from the University of Sussex (UK) shows that moths are more efficient pollinators at night than day-flying pollinators such as bees.
Studying 10 sites in the South East of England throughout July 2021, the Sussex researchers found that 83 percent of insect visits to bramble flowers were made during the day. While the moths made fewer visits during the shorter summer nights, notching up only 15 percent of the visits, they were able to pollinate the flowers more quickly.
As a result, the researchers concluded moths are more efficient pollinators than day-flying insects such as bees, which are traditionally thought of as ‘hard-working’. While day-flying insects have more time available to transfer pollen, moths were making an important contribution during the short hours of darkness.
“Bees are undoubtedly important, but our work has shown that moths pollinate flowers at a faster rate than day-flying insects,” noted Fiona Mathews, Professor of Environmental Biology at the University of Sussex and co-author of the research. “Sadly, many moths are in serious decline in Britain, affecting not just pollination but also food supplies for many other species ranging from bats to birds. Our work shows that simple steps, such as allowing patches of bramble to flower, can provide important food sources for moths, and we will be rewarded with a crop of blackberries.”
Researchers studied the contribution of both nocturnal and non-nocturnal insects to the pollination of bramble. They monitored the numbers of insects visiting flowers using camera traps, and worked out how quickly pollen was deposited at different times of day by experimentally preventing insects from visiting some flowers but not others.
Additionally, the study indicates the importance of bramble, a shrub widely considered as unfavourable and routinely cleared away, but which is in fact critical for nocturnal pollinators.
Pollinating insects are a vital part of many ecological communities and a very important part of the natural ecosystem. This research shows that both night-flying and day-flying pollinators need to be protected in order to allow natural ecosystemsto flourish. ●
