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Improving Crop Productivity in Saline Soils

Dealing with saline soils is one of the most challenging problems in crop production both locally and globally. A recent report by the FAO with information from 118 countries shows that more than 424 million hectares (more than 1 billion acres) of topsoil and 833 million hectares (more than 2 billion acres) of subsoil are salt-affected. It is estimated that more than 5 million acres in the Canadian Prairies are impacted by some degree of salinity. With the current challenge of feeding a growing population with limited agricultural land, finding solutions that can improve crop productivity in saline soils is critical.

What causes soil salinity?

Soil salinization occurs when water-soluble salts accumulate in the soil. This usually happens due to a combination of several factors:  the parent rock from which the soil is formed is rich in soluble salts, there is a high water table, a high evaporation rate and a low annual rainfall. Generally, if the water table is within two meters (six ft.) of the soil surface, capillary movement will carry water and dissolved salts to the surface. And if evaporation exceeds infiltration, the salts will remain in the upper layers of the soil where they can negatively affect plants.

How saline soils affect crops

Excess salts make it difficult for plants to take up water. This is because water moves into plant roots through the process of osmosis which is influenced by the difference in the salt levels of the soil water and the water contained in the plant. If the salt level of the soil water is high, water will move from plant roots to the soil instead of from soil to plant. With time, the plant will become dehydrated, growth is limited, and the plant might die. In salt-affected soils, seed germination will be poor because of low imbibition of water and salt toxicity.

Lab experiment on the effect of salinity on canola growth. Soils in the red pots were made saline by adding sodium chloride (table salt) which affected germination and growth

How to detect salt-affected soil

Saline patches in a field are often characterized by poor crop growth. For very salty soils, a whitish precipitate of salt may appear on the soil surface, especially after a long dry period. Some salt-loving weeds such as Russian thistle, Kochia and foxtail barley may also colonize the area. A routine soil test can more accurately identify the level of salinity and what kinds of salts are present.

What are some solutions to improve crop productivity in a saline soil?

Reclaiming saline soils can be difficult and expensive. Reclamation methods usually involve installing drainage and then leaching the excess salts out of the soil using sufficient rainfall or irrigation. In dryland farming, this may not be practical or economically viable.

Therefore, efforts are being directed towards more feasible alternatives. Breeding salt-tolerant varieties and developing seed treatments that help plants overcome stressful conditions are two options that are available to improve crop productivity in saline soils. A good seed treatment can complement breeding efforts and boost plant health in the early stages. Moreover, several microorganisms, phytohormones and biostimulants have been shown to enhance plant defense mechanisms and help crops thrive under abiotic stresses such as salinity. These can be incorporated into a cropping program either at seeding or as foliar applications during the season. Variable rate application of fertilizer is also useful to ensure that input is allocated to more productive areas and that saline areas are not further salinized by too much fertilizer. Long-term management of saline areas may also involve seeding them to salt-tolerant perennials that root deeply to use up a lot of the excess water thereby reducing the upward movement of dissolved salts to the soil surface.

– Ikenna Mbakwe, PhD, PAg

  Head of Research

Variable Rate Soil & Fertilizer

Would you treat these soils the same? You will probably answer no to that question, but if you are not applying variable-rate technology (VRT) on your farm, you ARE treating those soils the same. These soils came from a field with relatively flat topography and did not show a large amount of variability to the naked eye. The objective of variable-rate technology is to better distribute and customize inputs to maximize productivity.

Why Is VRT Important?

A large amount of soil on the Prairies has more than enough variability to warrant investing in variable-rate technology. Variable soils will often show variation in plant-available nitrogen (NO3-N), phosphorus (P), potassium (K), sulfur (SO4-S). The most crucial step in achieving success with a variable rate is finding/creating a representative map of the land you wish to variable-rate.

How Does VRT Work?

VR maps will break the field into multiple zones based on things such as topography, elevation, and electrical conductivity. Hilltops, mid-slopes, and depressions will be treated independently from each other. This allows you to pinpoint the strengths, weaknesses, and capabilities of each soil type. Having a detailed map to base soil sampling will give you a much more dependable soil test result. The overall goal of a variable rate fertilizer and seed prescription is to have your crop come in nice and even to reduce complications at harvest due to uneven crop stage.

How Is VRT Used?

Variable-rate maps can be used for multiple applications. Some of these examples include:

  • Seed and fertilizer applications with a drill
  • Fertilizer applications that are only needed in specific zones (applying Edge to zones with high Kochia populations)
  • Fungicide applications in the highest producing zones in the field

SynergyAG works closely with CropPro and SWAT Maps to create top of the line variable-rate maps for our customers. To learn more about VRT on your land, or start utilizing it on your farm, contact your local SynergyAG rep!

Treating Your Fertilizer

As we transition into the winter months, we move away from fieldwork and into the planning stages for next year’s growing season. With crop rotation and soil sample results in mind, a fertility plan can be formed. Decisions must be made such as what type of fertilizer you will use, how much of each product you will need to achieve your desired lbs/ac, and how you would like to apply the fertilizer and when. One should always be thinking of the 4R’s: Right Fertilizer source at the Right rate at the Right time and in the Right place. 

All fertilizers are equally important, and one should not be prioritized over any others however macronutrients such as NPK&S are required in greater quantities and environmental losses are less tolerated by the crop – especially Nitrogen and Phosphorus. 

Nitrogen

Nitrogen is a vital nutrient because it is a major component of chlorophyll: a major component of photosynthesis.  Nitrogen also produces amino acids which are the building blocks of proteins that are essential to all plant processes. 

There are a few different forms of nitrogen that are commonly used throughout the prairies. The first being anhydrous ammonia in a gaseous form (NH3), the second being a liquid form (NH4), and the third being a dry formulation such as Urea (NH2). Nitrogen must be transformed from its many different forms into a plant-available form of NH4 through nitrification. These changes are caused by exposure to oxygen and water. 

Treating Nitrogen

Nitrogen moves around in the environment readily and is transformed and lost very easily, it is important to use proper practices to ensure your crop is getting the nitrogen it needs for the growing season. Whether you are broadcasting, top dressing, or putting your nitrogen in a row it is a good idea to treat your nitrogen. There are different options for Nitrogen treatments and stabilizers that work in different ways like inhibiting enzymes and keeping nitrogen in its immobile form for longer. By treating your nitrogen, you are ensuring that 10% more nitrogen will be available to the plant throughout the growing season, increasing your overall Nitrogen efficiency. So, no matter what method of Nitrogen application you are using, treating it will provide long-lasting protection from volatilization and leaching. 

Phosphorus 

Plants need Phosphorus for pretty much all normal processes, helping the plant mature in a timely fashion, photosynthesis and many other functions. Phosphorus levels are key for the plant to be able to complete all stages of the production cycle. Phosphorus is very abundant in our prairie soils but 50-75% of the P is in an inorganic, non-plant available form. The other 25-50% is organic P, this P is transformed into plant available P through processes such as mineralization and immobilization. These processes occur in your soils naturally, but it does not supply enough P necessary for your crop. 

Treating your Phosphorus

Unlike Nitrogen, Phosphorus is not lost due to volatilization but by being fixated in the soil by other cations or (tied up). This fixation is caused by elements such as calcium, aluminum, iron which are positively charged and attract the negatively charged phosphorus ions. Phosphorus treatments work by reacting with these cations, in turn protecting the phosphorus from fixation. By treating your phosphorus, it protects your fertilizer from being fixated in the soil and allows your fertilizer to be almost 50% more plant available, ensuring your phosphorus is available for the plant when it needs it most.

At Synergy AG we want your fertilizer applications to be as efficient as possible. If you want to learn more about fertilizer treatment and your options, contact your local Synergy AG representative or agronomist today!

 

The Value of Soil Testing

As the cropping season comes to an end, it is right to look back and give kudos to every partner who worked hard these past months to ensure we continue to produce high-quality food and feed; every partner – from the resilient farmer and his patient family to the persistent input supplier and the meticulous agronomist. But perhaps in the community of farming partners, none worked harder than the ground on which our crops grew. The soil held, supplied, and recycled nutrients for plant growth, detoxified pollutants, retained water for use during the drier periods, and served as a firm structure for cropping and other agricultural activities. So, as we take stock and prepare for the next cropping season, finding out the current condition of this priceless partner is of utmost importance.

During a cropping season, several processes impact the soil nutrient status. These include crop nutrient uptake, run-off, and leaching. Over time, the soil nutrient reserve becomes depleted and will need to be replenished. Soil testing provides a way of knowing the level of this nutrient reserve as well as other soil properties affecting how nutrients are released. It is a tool that helps match fertilizer application to the needs of the crop while avoiding wastage and possible contamination of the environment. 

When To Do A Soil Test

Although soil testing just before spring seeding may provide results most closely related to conditions during seeding, fall is a great time for the activity. Soil testing in the fall allows ample time to sample soils, analyze them, examine the data, and make fertilizer plans. Besides, in late fall when soil temperature has dropped to below 10 ⁰C, soil microbial activity has slowed down, so there will be minimal change in nutrient levels between fall and the next spring. Soil testing can also be done anytime during the growing season to determine and correct nutrient deficiencies.

Without data you will have to guess your way through the growing season, and you will either be lucky or wrong. Soil testing can help you take the guesswork out of your fertilizer plans. With the advancement of technology, soil testing is becoming easier, faster, and more accurate. This is what we provide in our soil testing laboratory.  Our agronomists combine soil test results with their expertise and local knowledge to design a prescriptive fertilizer plan to increase the probability of achieving high-quality and high-yielding crops.  

At SynergyAG we treat soil as more than ‘dirt’, we recognize and respect that soil sustains life. Talk to your SynergyAG team about your soil testing needs.

-Ikenna Mbakwe, PhD, PAg
Director of Research
SynergyAG