By Leonardo Gottems
Due to this dichotomy, investment in research and new technologies seeking improved soil aeration, infiltration and water availability, as well as stimulation of biological activity, and various chemical attributes that affect crop productivity, grows witheach harvest.
Soil structure has a significant influence on these issues: when in balance, it allows the soil to sustain high agricultural productivity while simultaneously performing its environmental functions. Therefore, it is essential to improve soil structure. However, this is a difficult process to achieve and quick to lose – requiring maximum attention.
In this context, a Brazilian company in the bio-inputs sector has been standing out with its "Microgeo" biological fertilization technology. It is a balanced component that nourishes, regulates and maintains the continuous production of biological fertilizer through a process called continuous liquid composting (CLC). The manufacturer claims to be the "only one in the market that manages and restores the soil microbiome."
According to them, Microgeo biotechnology is unique – and pioneering – because it has the function of "restoring the soil microbiome by increasing the diversity of microorganisms from the region itself, thus maintaining the 'biological fingerprint' through the CLC process," the company, Microgeo Biotecnologia Agrícola, told New AG International.
Microgeo biotechnology has the function of "restoring the soil microbiome by increasing the diversity of microorganisms from the region itself.”
Photo: Microgeo
This CLC process achieves its goal by ensuring the production of a customized liquid compound according to the region's needs, through the activation and replenishment of microorganisms lost due to common practices in Brazil and worldwide in modern large-scale agriculture, such as monoculture, for example.
According to the company's technical team, the biological fertilizer produced with Microgeo can be applied via spraying or fertigation, regardless of climatic conditions, and in conjunction with other inputs such as chemical or biological pesticides and fertilizers.
The manufacturers revealed that the product promotes soil structuring and plant growth and development. This is because its use ensures "greater water infiltration, storage and availability for plants, porous space for gas exchange in the root system, soil biological activity (macro, meso, and microfauna of the soil), resistance to erosion and compaction, as well as being related to the greater effectiveness of agricultural amendments in the soil."
Another important point that the company highlights is the ease and accessibility of the technology. Without complexity for implementation, maintenance and management, the biological fertilizer can be produced in biofactories installed on the farm itself. For this, Microgeo offers two models of bio-stations that meet demands starting from 10,000 litres of biological fertilizer volume. However, there is an even larger model that serves above 150,000 litres, aiming at large areas, such as those used by sugarcane mills.
Microgeo biological fertilization technology can be produced in biofactories installed on farms.
Soil problemTiago Stumpf, master and doctor in soil science from the Federal University of Rio Grande do Sul (UFRGS), explains that one of the main factors related to soil structure is compaction. "Due to soil compaction, the way nutrients come into contact with the roots is affected. High levels of compaction alter mass flow and diffusion, which are important mechanisms responsible for transporting nutrients from the soil to the roots. That is, the path that the nutrient takes until it reaches the root is affected," Stumpf explains.
The specialist also emphasizes that the greater the water retention (a characteristic found in well-structured soils), the more efficient the plant becomes in facing moments of water stress. "Periods of drought, dry spells or low nutrient levels are situations that cause stress in plants. In compacted soil, there is a reduction in pore space, and with it, less water infiltration, less retention and, consequently, less development of the root system. Therefore, it is essential to manage soil compaction so that the plant passes more smoothly through these challenges," says Stumpf.
According to Microgeo, if the physical part of the soil is doing poorly, it is a sign that the biological part also needs attention, and therefore it is essential to restore the soil microbiome through biological fertilization. They highlight studies showing that microorganisms catalyze a series of processes that occur in the plant rhizosphere and excrete some organic substances that act precisely in soil aggregation, contributing to the improvement of this physical condition. As soil compaction decreases, an increase in productivity is observed in parallel.
Master and doctor in soil and plant nutrition, specialized consultant Guilherme Anghinoni further details that "soil with good physical quality will not always have good biological quality, but soil with good biological quality will always have good physical quality."
Lucas Mendes, a doctor in biological sciences, shares important data on soil microbiology. He explains that even with the soil physics in good condition if microbiology is lagging, soil and plant health will suffer. "This is because bacteria and fungi in the soil are the ones that cycle nutrients and make nutrients available to the plant. Hence the importance of promoting soil microbiology, as this will be the tool that will increase future yields," Mendes explained.
Soil microbiology is an essential pillar for the balance of a farm’s productive system.
Mendes pointed to some studies conducted in England, in fields cultivated for over 150 years with monoculture. Even in these conditions of successive crops wearing out the same soil, productivity remained stable thanks to soil microbiology that maintained production due to bacteria that cycled nutrients. "Soil health and chemical and physical components cannot be disconnected from microbiology," he says.
According to the researcher, when the physical cannot be manipulated anymore, and the application of chemicals no longer produces effects, promoting soil microbiology will be the essential pillar for the balance of the productive system and consequently, surpassing productivity levels.
"Even before humans manipulated the microbiome, the plant itself did this through exudates in the rhizosphere to attract beneficial microorganisms. Today we already have tools for this, and we need to research more and more to understand how microorganisms can be better utilized," he said.
Integrated crop-livestock-forest systemA production strategy that is growing in Brazil is the integrated crop-livestock-forest (ICLF) integration, which consists of using different productive systems, agricultural, livestock and forestry within the same area to optimize land use, raising productivity levels, better-using inputs, diversifying production, and generating more income and employment. Last but not least, all of this is done in an environmentally friendly manner, with low emissions of greenhouse gases or even with the mitigation of these gases. And it is in this scenario that the use of biologicals emerges as an advantage for the farmer.
William Marchió, a veterinary doctor and consultant for the Sustainable Farming Division, points out pasture degradation as a serious problem in Brazil. "ICLF is a system that generates a lot of income and delivers mutual benefits such as diversification and income improvement, better technical results, soil improvement, increased biodiversity and a more efficient management modus operandi," he details.
ICLF integration consists of using different productive systems – agricultural, livestock and forestry – within the same area to optimize land use.
According to him, besides being sustainable, this economy generated with ICLF systems moves the carbon credit market. Marchió points out that when the producer implements this type of technology, they can access different credits and financing with more attractive rates than financial institutions are creating and releasing in the market. "We still have a challenge to certify these carbon credits. Today, these certifications are with international certifiers and the cost for presenting a project ends up being high. Our advice is for producers to unite in associations or even with larger companies that are already developing carbon projects to share this scope," he notes.
The idea is that carbon credits are not the focus of the producer but rather a consequence of the good practices adopted to improve the soil on their property and increase productivity, and in this context, the use of biological products is essential. Microgeo saw an opportunity in this market segment.
This is because its biological fertilizer technology enhances the efficiency of other inputs and mitigates climatic impacts that can cause crop failure, for example. "It is essential for producers seeking good results and distinction to understand that manipulating soil biodiversity impacts the physical, chemical and biological pillars of the land, and this generates important benefits such as profitability, greater plant health, greater water infiltration and retention in the soil, and less compaction," explains agronomist Elvécio Silva, master in plant production and market development coordinator at Microgeo.
"The most modern and technified ones do not give up the use of biologicals, as they add not only technical but also economic value. Producers can obtain more value per hectare, these farms are socially fair, environmentally friendly, and are generating value for themselves and the people and communities around them," Marchió concludes. ●
A barley field with saline soils resulting in no or uneven barley germination – uneven maturity, areas filled with kochia.
Photo: Lyle Cowell, Nutrien
Introduction to Soil SalinitySoil salinization is the process in which water-soluble salts accumulate in the seedbed and rooting zone in high enough quantities that are harmful to crops. Salt accumulation tends to occur in environments with low rainfall and high evapotranspiration rates and/or a source of water that transports salts to the rooting zone. Removal of salts by crop harvest is negligible in these systems and will decline as salinity reduces plant growth (FAO Irrigation and Drainage Paper NO. 48). Generally, soil salinity will involve thousands of pounds of salts per acre, a quantity well beyond the quantity associated with crop nutrient salts applied as fertilizer.
Salt composition will vary depending on regional subsurface geology and agricultural practices. In some regions (western U.S.), salinity is caused by sodium, chloride and boron, primarily coming from irrigation and water sources. In other areas (Western Canada), the salts that cause salinity are mainly magnesium sulphate and sodium sulphate that originate naturally in geological deposits.
These salts can pose direct risks to plants such as specific ion toxicities (e.g., chloride burn) and reduced water uptake, or indirect risks such as soil structure degradation and drainage problems if sodium is the dominant cation. When salinization develops, crop yield and crop quality can decline. It is generally accepted that soil salinity levels above 4 dS/m (based on a saturated paste measurement) will negatively impact plant growth, but the effects are highly dependent on soil texture, water content, the compositionof the salts as well as the crop species grown.
Sources of salinitySoil salinity is not static, but a field salt balance that is influenced by the net input and removal of salts. Additions to the system include salts in irrigation water, salts from application of compost or manures at high rates, and deposits from groundwater during evaporation. Salts are removed from the soil system by leaching driven by rainfall or excess irrigation and can be augmented with subsurface soil drainage. A general schematic for thinking about field salt balance in the soil is presented in Figure 1.
Figure 1. Sources of soil salinity inputs and removal mechanisms. The fertilizer arrow represents the localized impact of fertilizers on early crop growth (salt index) and is not a likely contributor to salinity accumulation in thebulk soil.
Source: Nutrien
Impact on yield Salinity will first damage a crop by preventing seed germination or seedling survival, which is of special concern for annual crops. For permanent crops, salinity stress can accumulate across the years, at depth in the soil, and can have a creeping negative impact on growth. Introduction of salinity stress during a growing season begins to reduce plant function and can impact yield potential within minutes of application of the stress event (Table 1). For example, a short-term reaction to salinity issues is acute water stress and an overall reduced rate of root and leaf elongation.
Table 1. Plant response to salinity stress at different time scales (Munns 2002).
Prolonged exposure to salinity stress manifests itself as leaf tissue damage, a reduction in photosynthetic rate, impaired function of the phloem and xylem, reduced nutrient and water absorption and premature tissue death. As exposure to salinity increases, yield will rapidly decline, although impact is strongly influenced by the crop being grown (Table 2).
Table 2. Crop salinity sensitivity as rated by their maximum saturated paste EC (dS/m) rating of soil before salinity induced yield declines are observed. A salinity tolerance level, based on the maximum EC, is also assigned.
Source: Rhoades et al; FAO, 1935
T: tolerantS: sensitiveMS: moderately sensitiveMT: moderately tolerant
Electric conductivity of saturated soil extract Threshold
Yield impact Salt tolerance is described as a complex function of yield decline across a range of salt concentrations (Maas and Hoffman, 1977). Salt tolerance can be measured based on two parameters: the soil salinity threshold (ECt) and the degree (%) of yield loss, which are established by field trials. Yield losses are expected to occur when a soil EC value increases past a crop specific threshold (ECt) but are not a limiting factor before the threshold is reached. Yield loss is the percentage of yield expected to be reduced for each unit of added salinity above the threshold value. Both values are unique to each crop (Figure 2).
Figure 2. Crop salinity sensitivities as rated by their EC thresholds (y axis) and observed yield declines for every one unit past the threshold (x axis). General crop salinity tolerances are provided for grain and forage crops (top) and permanent crops (bottom)for a study in contrasts.
Some extreme values on the X and Y axis have been reduced slightly for graphical clarity. Please see source document for original values.
Proactive management of salinity risk First, measure salinity – if salinity is suspected as a risk to crop production, then collect soil and irrigation water samples to help better understand the salinity issues on a field. Water samples can help predict how much salinity will be applied to a field each year or growing season through the irrigation system. This data can give you direction on where your field conditions are today and where it might be headed in the future. If you are in a region where soil salinity is often a crop yield factor, then always include soil salinity measurement with each soil sample. If soil salinity is a dominating yield factor, then it will be helpful to map the field salinity in zones to better manage the crop potential.
Fertilizer choice – in most cases, fertilizers are simple salts that provide a key resource to crop nutrition. However, the rate of nutrient salts applied as fertilizer tends to be insignificant relative to truly saline soil conditions. It is true that high rates of fertilizer applied near germinating seed can create a localized condition often called the ‘salt effect’ of fertilizers, and we often measure the solubility of fertilizers based on ‘salt index’. These effects tend to be short lived, unlike truly saline soils. A more important consideration is if the salts in a saline soil directly impact the requirement of added fertilizer. For example, if you have saline soil that is dominated by sulphate salts, then you may require less added sulphur fertilizer in a field or a portion of a field. Fertilizer rates should also reflect the yield potential of a saline soil. One last consideration is that if a crop is already affected by soil salinity, then fertilizer salts applied near the developing root system may exacerbate the problem.
Variable rate fertilizer – fields that do have saline areas offer an opportunity to use variable rate fertilizer application. Areas impacted by salinity can be detected by observation, yield monitors or satellite NDVI maps. Excess salinity can then be diagnosed and confirmed by comparing soil samples taken from high/low producing areas of the field or by using more extensive analyses involving field scale electrical conductivity or electromagnetic measurements. The goal of using variable rate fertilizers, when it comes to saline areas of the field,is to avoid excessive application on poorly producing areas as the return on investment is poor and where the
salts from the applied fertilizer may magnify the salinity issue. In short, we should always manage fertilizer rates to maximize yield on the best soil, and not apply rates that are inadequate for the most productive land, yet excessive for marginal land.
An example is Figure 3. If only a random sample were used, the soil test level would be 840 lb S per acre, and no sulphur fertilizer would be recommended. In contrast, the ‘green’ area has only 22 lb of S per acre and requires added sulphur – and this is also the area of the field with highest yield potential and profitability. The red areas, in contrast, have elevated soil salinity and additional fertilizers should be avoided until salinity is resolved. Adjusting sulphur rates (and perhaps nitrogen rates) would maximize both crop yield and the efficiency of applied fertilizer. We should always manage fertilizer rates to maximize yield on the best soil, and not apply rates that are inadequate for the most productive land, yet excessive for marginal land.
Figure 3. Understanding field scale variability in salinity risk can help create an effective reclamation planwith gypsum or elemental sulphur sources and/or help guide planting decisions on portions of the field characterized by high soluble salts.
Source: Nutrien Echelon
Crop choice – if a field is impacted by salinity and reclamation is out of the budget, another choice is to rotate into a more salt tolerant crop. For example, in Table 2, if one compares the salt tolerance of corn (maize – low soil salinity threshold with moderately sensitive rating) to that of barley (4.7x higher soil salinity threshold than corn with a tolerant rating), it may be worth switching crops to be more production on impacted acres. We know that certain forage grass or wheat have a high tolerance to salinity, and these may offer a productive solution to crop production.
Leaching fractions – in some soil and management conditions the salts can be leached though the soil and out of the rooting zone of a plant. If excess irrigation or rainfall moves through the soil profile, soluble salts can be removed from the root zone. A rough guideline to help plan leaching is below, although more complex methods can be used:
6 extra inches of applied water will leach ~50% of the salts
12 extra inches of applied water will leach ~80% of the salts
24 extra inches of applied water will leach ~90% of the salts
Reclamation plans – in some saline soils that are dominated by sodium, a source of calcium may be used to displace sodium from the soil and allow it to be leached from the root zone. Gypsum (calcium sulphate) or lime (calcium carbonate) amendments are typically applied to provide an affordable calcium choice. Gypsum is much more soluble than lime so tends to be more effective. In soils that are high in ‘free lime’ acid generating products such as elemental sulphur are applied to help free up calcium in the soil which, in turn, helps restructure soil particles and allow sodium leaching from the system.
Specialized products – a growing class of products can be used to help manage salinity, particularly under irrigated conditions where the water can serve as the carrier of the active ingredient. These products include soil conditioners and soil surfactants that 1) help water penetrate from the surface down through the root zone, which helps leach salts from the system and/or 2) helps restructure soils, which aids in the removal of salts from the soil. In non-irrigated well-structured saline soils with high soil organic matter these products may be ineffective.
Tiling – subsurface drainage with tiles can be used to remove salts, but this requires substantial investment and excess rain or irrigation water to leach the salts away (see above). In addition, water removed by tile requires a place for that water to go that is acceptable to downstream users and regulators.
Conclusion Soil salinity continues to be a challenge in global agriculture and creative solutions will need to be used to keep fields productive in environments that promote excess salt balance in soils (e.g., arid, and semi-arid farming regions). Given the broad extent of arable acres in dry regions and the potential productivity of these areas, measures should be taken to reclaim and/or maintain a reasonable soil salinity status. The strategies outlined here are a great place to get started if soil salinity is a challenge. ●
References
Soil Salinity In Western Canada | eKonomics (nutrien-ekonomics.com)
The Dirt Season 3 Ep4: Is Soil Salinity Impacting Your Crops? (nutrien-ekonomics.com)
Agricultural Drainage Water Management in Arid and Semi-Arid Areas - [PDF] Agricultural Drainage Water Management in Arid and Semi-Arid Areas | Semantic Scholar
FAO Irrigation Water Quality for Agriculture no. 29 - https://openknowledge.fao.org/items/ce9959da-7503-47c9-b393-ae50ef8780fc
Eloy, Arizona: soils with degraded structure, due to elevated sodium, showingheavy clodding when plowed.
Photo: Karl Wyant, Nutrien
CropLife Europe is launching AgriGuide, a digital navigator for farmers, generating guidance for the application of pesticides and biopesticides according to the digital label while considering the geolocation and conditions of a grower’s field.
CropLife Europe stated that AgriGuide will help farmers navigate the labyrinth of regulations, offering reliable information that streamlines administrative tasks, lessens the risk of non-compliance, and supports efforts to protect both safety and environment.
In line with Regulation 2023/564, AgriGuide promotes real time data collection for digital record keeping, paving the way towards more realistic risk assessments.
“The way it works is that a farmer would scan the label of the product and be informed of the IPM protocol, after which it registers and aggregates the application protocol based on field specific data. This way, on-field operations are easily documented, and farmers can keep track of their actions,” noted CropLife Europe in a news release.
CropLife Europe is launching the pilot phase in Q2 2024 with three countries: Germany, Italy and Romania. “Our goal is to successfully roll out AgriGuide to all 27 EU countries in the coming years.”
AgriGuide is the result of a collaborative effort between CropLife Europe and other key players in the agriculture industry. ●
