Kochia control with SWAT CAM: A step-by-step guide

Kiara Lutz
Precision Agronomist
kiara.lutz@swatmaps.com

Kochia (Kochia scoparia) has grown to be a problematic weed in much of the semi-arid cropping areas of the US and Canada. The pressure it has on crops is most notable in saline and marginal areas, which are commonly found in SWAT zones 9 and 10. The rapid growth of this weed, its ability to tolerate high salinity, drought and heat, as well as growing herbicide resistance problems make it a massive threat to crops.

If kochia is left uncontrolled, at maturity and with wind the tumbleweed will spread seeds throughout the field. With each kochia plant producing at least 15,000 seeds, dense kochia patches with low crop competition can produce millions of seeds per square metre (Canola Council, 2023). However, with proper management, growers can reduce the soil seedbank and prevent kochia from reaching maturity. On top of that, farmers who bring precision ag tools like SWAT CAM into their operation find managing kochia to be a whole lot easier.

SWAT CAM is an autonomous imaging system designed to capture, assess, and evaluate crop establishment and weed pressure. It is a proprietary product for full farm SWAT MAP users that are clients of Croptimistic Technology or any premium SWAT MAPS service provider. Here’s how it works:

Step 1: The Capture
SWAT CAM is mounted onto sprayer booms (one SWAT CAM on each boom) which will then auto capture images of weeds and crop every 50 to70 feet each time the equipment enters the field.

Step 2: The Analysis
These photos are then processed using machine learning technology. During this step, crop and weeds are identified and various maps are generated. Crop and weed data are divided and presented separately, unlike satellite imagery where NDVI could represent both crop and weed biomass.​ This allows SWAT CAM to determine percent weed cover, percent crop cover, and specifically identify kochia. Once kochia has been identified in the field images, SWAT CAM can generate kochia models indicating the kochia coverage across the field.

Step 3: The Application
Since kochia is an early germinating annual weed, it requires an aggressive approach to spraying. Incorporating a previous kochia map into your early season spray jobs can get you off to a phenomenal start with your weed control. 

Effective control of kochia requires use of premium herbicide products which are expensive to apply at a flat rate across a field. However, SWAT CAM can dramatically reduce the costs of Kochia control by accurately targeting specific areas that are affected, providing a much stronger return on investment than flat rate applications. A custom spray requisition can be created using the kochia model to build an on/off herbicide application, spraying only where kochia has been found. SWAT based prescriptions can also be combined with the SWAT CAM kochia models to ensure all high risk areas are covered. Through this process, there can be huge savings as a of result only applying product to the areas with kochia patches compared to applying at a flat rate across all acres. After spraying, SWAT CAM imagery can also be used to check the effectiveness of the herbicide application.

It's important to note that reliance on herbicides alone should not be the only tool used to control kochia, or any other weeds. Crop competition is the most important tool for weed control, so variable rate seed is another valuable tool to use in these problem soils that often have high mortality and allow kochia to thrive with little competition. Increasing seeding rates 20 to40% can be an effective cultural control tactic, increasing crop competitiveness that helps reduce weed escapes.

Kochia maps are a great example to start with for SWAT CAM use cases, although it has much more to offer to your farm! Connect with your SWAT MAPS agronomist or consult our sales team to find out more about SWAT CAM’s variety of applications

Outside Source:

Canola Council. (2023, November 30). How to contain herbicide-resistant Kochia. Canola Council of Canada. https://www.canolacouncil.org/canola-watch/fundamentals/how-to-contain-herbicide-resistant-kochia/

SWAT Partner Announcement: Farm Focused Agronomy

Welcome Farm Focused Agronomy to the elite network of SWAT MAPS service providers!

After seeing the results first-hand of using SWAT MAPS on his own farm, Garrett Rockafellow, owner of Farm Focused Agronomy, knew that the SWAT ECOSYSTEM was going to be the next big step for his business.

“I couldn’t have been happier with the results of the maps, the data I was able to access, the results of the crop, and the functionality of the program,” says Rockafellow. “I immediately knew this was something I wanted to offer to growers in my area.”

Rockafellow’s background as a farmer and an agronomist allows him to understand the challenges faced by farms in his surrounding area of Crossfield, AB. With a goal to come up with the strongest agronomic plan possible for the growing season, Rockafellow will be integrating each step of the SWAT MAPS process into his service offerings to ensure growers can maximize their ROI on multiple crop inputs while improving crop quality, harvestability, and economics.

“It’s important for us to understand the logistical, economic, and time management constraints that are associated with today's farming. From managing resistance and agronomic hurdles, increasing productivity, and maximizing ROI, it’s something that drives my passion for agronomy and precision agriculture,” he says. “What excites me the most about SWAT MAPS is how much data is obtained and how many beneficial applications they can be used for.”

Rockafellow at Farm Focused Agronomy is looking forward to taking on a new edge as a SWAT MAPS service provider and plans to continue expanding services into other surrounding areas of Calgary, including south of Red Deer and east towards Drumheller.

Please join us in welcoming Farm Focused Agronomy by following @FarmFocusedAg on X.

Groundtruthing to select the correct SWAT MAP: What about peat?

A SWAT MAP is a map that sets the framework for a field’s soil potential and therefore management plan. This management could be for any or a combination of fertility, seed, or soil applied herbicides.  By understanding the potential of soils within a field, we can maximize them, but we need to ensure we have the right map. 

The first step is mapping a field with a SWAT BOX to collect electrical conductivity, elevation, and topography data which allows the creation of maps that utilize these layers in different weightings.  Depending on the soil type and geographical area, the weightings will differ.  This is where the critical step of ground-truthing comes in to determine the correct layers in a SWAT MAP.  A trained SWAT agronomist in the field analyzes the data layers to decide what map best represents the field.   

Available data layers will also include depressions, hills, and water flow paths.  The agronomist uses these layers with background imagery, soil survey information, and possibly yield data if it is available.  Then soil cores down to 2 feet are taken in several areas to determine any differences in soil color or horizons.  As the agronomist travels the field, stubble differences, weeds, or any regrowth can help indicate how certain areas should be zoned. 

Sometimes there are unique soils that are difficult to capture in the typical data layers, and this is where being in the field, looking at the soil and stubble can help identify proper SWAT zones. One example of this is Organic order or peat soils.  Because peat presents unique challenges, it needs to be managed on its own and sometimes requires a modification on the SWAT MAP to ensure it is represented well.   

Peat soils can mineralize an incredible amount of N, leading to excessive vegetative growth, lodging, and delayed maturity.  Here is an example of the total N that was measured in a field with peat soil in zones 9 and 10: 

Table 1. Organic matter, total N, and resulting estimated pounds of organic N in 0 to 8”. 

Zones OM (%) Total N (%) Total Organic N  (lbs, to 8” depth) 1% of Total N (lbs) 
1,2 0.231 6,160 62 
3,4 4.6 0.275 7,333 73 
5,6 6.9 0.325 8,667 87 
7,8 9.9 0.443 11,813 118 
9,10 27.1 0.959 25,573 256 

In this example, if only 1% of the total N is mineralized, zone 10 would potentially have 256lbs of N become available! 

The mineralization potential is impacted by organic matter as well as moisture (Schoenau, 1995).  Peat soil in a field will often correlate with lower landscape position where water tends to collect and have increased mineralization potential due to moisture availability. 

Organic matter binds copper more tightly than any other micronutrient (The Fertilizer Institute), so copper deficiencies occur more often here, and the critical levels used are higher than in mineral soils. 

Manganese, while not often tested in a routine soil test, is another micronutrient that can be unavailable in peat soils as it becomes oxygenated and is in an unavailable form.  Oats are more susceptible to this deficiency, and this has been seen in northern Alberta, where these soils are found fairly frequently.  

Table 2. SWAT Zones and correlating organic matter and Mn tissue test results in oats, N Alberta.  

Zones  OM  Tissue test Mn  
1,2  5.5  109 (high)  
5,6  7.1  57 (sufficient)  
9,10  64.0 9 (low) 

Another characteristic that differs with managing peat is the ideal pH.  While in mineral soils we don’t want to see a pH lower than 5.5 , and will adjust with amendments such as lime to target higher than this, in organic soils we don’t want to adjust higher than 5.5 or nutrient availability issues will arise (UMN Extension, 2023). 

Here is an example of a field that had an area with peat that needed to be isolated. Prior to mapping, there happened to be oats on this field which are relatively tolerant to low pH.  It was also a dry season, so low lying peat depressions were rather dry. This meant stubble was consistent across the field.  Driving across the field, the peat was evident, and soil cores revealed areas with different peat profiles.  Zones 7-8 had only about 6 inches of peat on top, whereas zone 10 had close to 18 inches of peat.  Topography and depression layers also helped to segregate these areas.  Background imagery from previously wet years was also helpful to find the edges of impacted areas for zoning. 

Figure 1. EC Layer 

Figure 2. Original SWAT MAP 

Figure 3. Modified SWAT MAP to improve management areas 

Figure 4. Soil test results from 0-8" and 8-16", NE Alberta 

This example shows the importance of all the steps that go into creating the best possible SWAT MAP, and the map accuracy is confirmed by the soil test results, where there are drastic differences between zones.   

Peat can differ in depth, how well it's drained, and its mineralization potential but in all cases, needs to be managed independently.   

All the data layers collected while mapping and compiled in SWAT MAP creation are invaluable to the framework of selecting the appropriate SWAT MAP.  Being in the field and looking at all variables is a critical step to ensure we have the most detailed map possible to base sound recommendations from. 

References  

 J.J.Schoenau, Department of Soil Science, University of Saskatchewan.  Understanding the Role of Mineralization in Supply of Plant Available Nitrogen, 1995. 

The Fertilizer Institute. (n.d.). Essential Elements; Copper. https://www.tfi.org/sites/default/files/tfi-copper.pdf 

The Fertilizer Institute. (n.d.). Essential Elements; Manganese. https://www.tfi.org/sites/default/files/tfi-manganese.pdf 

(n.d.). University of Minnesota; Liming. https://extension.umn.edu/nutrient-management/liming 

SWAT Partner Announcement: Hawk’s Agro

With seven locations across Southern Saskatchewan, Hawk’s Agro has partnered with SWAT MAPS to provide the world’s premier variable-rate fertilizer and seed service to their farm clients. The business was founded in 2009 and has since grown to 50 employees. Their core values are providing trustworthy service, loyal relationships and getting the job done right.

Dallas Funke, Director of Business Development at Hawk’s Agro, says the SWAT ECOSYSTEM is an excellent addition to their Crop 360 agronomic services.

“At Hawk’s Agro, we know a strong business is built on friendly, trustworthy service and loyal, long-term relationships. These values remain at the core of who we are today, so we continually look for ways to add to and improve the products and services we offer to growers through Crop 360, a division of Hawk’s Agro.”

Hawk’s Agro, a JGL Company, doesn’t just sell growers the products, they help growers put them to work. Their team prides itself on excellent customer service, local expertise, unparalleled knowledge, and a customized approach to give growers the advantage and convenience they need for more substantial yields and higher returns on investment.

“SWAT MAPS are another way we can help our growers gain knowledge and advantages to unlock even more potential in their fields,” says Funke.

There are seven Hawk’s Agro locations across Southern Saskatchewan: Central Butte, Gravelbourg, Neville, Moose Jaw, Rouleau, Strongfield, and Swift Current. Each of these locations are set up to provide products, service, and expertise to keep farmers growing.

The SWAT MAPS team is thrilled to recognize Hawk’s Agro and Crop 360 as a SWAT MAPS Service Provider! Join us in welcoming this dedicated team and connect with their team through the links below.

Website: https://hawksagro.com
Facebook: www.facebook.com/HawksAgroSWSK/
Twitter: @HawksAgro
LinkedIn: https://www.linkedin.com/company/hawks-agro/