Cotton Growth Management with Precision Agriculture

Satellite imagery cotton field-in-Brazil
From left: Satellite imagery one week before application, as applied rate, and satellite imagery one month after application of plant growth regulator in cotton fields in Mato Grosso, Midwest Brazil.

A cotton crop presents some important differences to other commodities that are widely produced in Brazil, such as soybean and corn. The first one concerns the importance of quality, since the main reason for growing cotton is the production of fibers that are used in the textile industry, which has high standards of fiber uniformity, staining, strength, length, and maturity.

The second difference is of physiological order, and is related to the origin of the cotton plant, which is perennial. When conditions are adequate, the plant prioritizes vegetative growth to the detriment of reproductive development, which is undesirable for obtaining high yields, requiring the control of plant growth through the use of plant growth regulators (PGRs) that change the hormonal balance and promote the reduction of growth and retention of vegetative structures.

Several factors can cause spatial variability in the growth and development of cotton crops. For example, differences in soil texture and fertility and occurrence of pests, diseases, and nematodes. Thus, the rates of growth regulator required to obtain a homogeneous crop and express the greatest yield potential may vary within a field.

An important feature of this variability is that, in general, it presents low temporal stability, except in areas where it is directly related to soil texture. This makes it necessary to identify the differences in season.

Some tools have been developed to measure the height of plants with high spatial resolution, initially with the use of ultrasonic sensors and more recently with the use of LIDAR technology. Although the assessment of the need for PGRs is usually performed by measuring plant height and number of nodes, this is directly related to plant vigor and has good correlations with vegetation indices obtained by active canopy sensors or satellite images. Satellite images have the advantage of low cost and high spatial resolution (3 – 5 m), but are dependent on the climatic conditions, being limited mainly by the existence of clouds. Active canopy sensors, on the other hand, have the advantage of being less dependent on climatic conditions, and can even operate at night. A comparison of these tools can be seen in TREVISAN et al. (2015).

The use of vegetation indexes presents advantages mainly in more advanced phases of crop development, since the effect of the plant growth regulator is dependent on accumulated biomass and vegetative vigor, which makes the vegetation index a better estimator of the required rate. The same is true in the case of the use of defoliants and boll openers, since the percentage of defoliation and open bolls is better correlated with the vegetation index than with the height of the plants. Once a spatial variability map of crop development has been obtained, a PGR prescription can be created using existing models or from field checks for dose determination at contrasting points and the use of regression.

The execution of the prescription depends on the availability of equipment for variable rate liquid applications, which usually presents some limitations. The most widespread form is the application with variable flow, in which a controller changes the pressure of the system, increasing or decreasing the flow and consequently the applied rate. The range of variation allowed in this system is limited because the variation in pressure may adversely affect the quality of the application. Another technology, which solves this problem, is the use of pulse width modulation (PWM) system to control flow at the nozzles. This allows wide variation of doses without changing the pressure of the system.

However, this technology is still little widespread and has a common limitation with the flow variation, which is related to the use of tank mixtures. Thus, when it is desired to apply a PGR and an insecticide in the same operation, it is not possible to only vary the dose of the PGR and keep the insecticide constant. An alternative to this is the use of direct injection systems, which inject concentrated chemicals and water into an in-line mixer on the sprayer. In general, most of these available systems have limited spatial resolution because the injection occurs on the main line and the applied rate is the same across the bar. The ideal system for this type of application could be the use of two independent spray systems on the same equipment or direct nozzle injection systems, but none of these technologies are commonly found.

It is important to match the resolution of variability mapping to that of the application. Thus, for an application where the control occurs only in the whole boom width, free satellite images such as Landsat 8 and Sentinel-2 may be sufficient, whereas for equipment with section control the use of images with better spatial resolution such as RapidEye and PlanetLabs can bring better results. With the use of PWM valves and individual control in each nozzle, the use of active sensors such as LIDAR and WeedIT can provide the best result, which also makes it possible to do a real-time application without the need of a previous map.

We have been testing, developing, and using these technologies for some years, and the tools for mapping spatial variability have evolved greatly and are no longer limiting. However, machine technologies for the application of the prescriptions, although they have existed for several years, are still not very accessible and limit the use of variable rates liquid application. In our case studies, we have observed savings from 15% to 40% in the volumes of products used, resulting in greater uniformity of areas, such as in the area of 450 ha shown in the figure above. For the creation of the prescription, the NDVI of a RapidEye image and a calibrated algorithm for these fields were used. The application was performed by a self-propelled sprayer with section control and flow variation. The prescribed application rate varied between 50 and 70 L/ha and in 18% of the area it was not necessary to apply the PGR.

The main expected results using the variable rate application of PGR, defoliants and boll openers are product savings, more uniform crop development, higher yields and better fiber quality. We are seeing these results even in areas with uniform soil characteristics, because too many factors can affect cotton development.

Topics:

Leave a Reply

Imagery/Sensing Stories
Imagery/SensingPlanet Announces New Hi-Res Imagery Products
September 21, 2017
Since our acquisition of Terra Bella, and the SkySat constellation of seven satellites, we’ve been focused on making this high-resolution Read More
Terra
Imagery/SensingAerial Imagery Aids Decision-Making
September 12, 2017
As the growing season has progressed, aerial imagery has been part of the world record setting data-collection efforts for Terra, Read More
Imagery/SensingSatshot Adds SPOT 6/7 High Resolution Imagery
August 30, 2017
Airbus Defence and Space has entered into an agreement with the GIS mapping engine operator Satshot to provide high-resolution SPOT Read More
Satshot imagery
Imagery/SensingImagery in Agriculture: Some Sage Advice
August 6, 2017
SatShot President Lanny Faleide has been a fixture on the remote imagery scene for as long as about anyone still Read More
Trending Articles
Farmer with iPad
Australia/New ZealandAgrian Expands into Australia
September 20, 2017
In line with a familiar growth trajectory, Agrian Inc. is moving into Australia with a physical support and sales presence Read More
John-Deere-labs
Tools & Smart EquipmentHow John Deere’s New AI Lab Is Designing Farm Equipment for a More Sustainable Future
September 15, 2017
On a block in San Francisco’s SoMa district, near LinkedIn’s headquarters and dozens of startups, a 180-year-old company best-known for Read More
BASF Maglis grower retailer tablet
Data ManagementWhat Will Happen to My Data? Understanding Your Rights in Precision Agriculture
September 12, 2017
The use of precision agriculture-based decision making to determine fertilizer rates and hybrid types and planting rates is becoming more Read More
Robotics/Labor SaversBlue River, Deere Deal Will Accelerate Farm Robot Innovation
September 11, 2017
No, Blue River Co-founder and CEO Jorge Heraud has not been deposed — Gaddafi-style — by big, bad corporate overlord Read More
Farming at Sunset
Business ManagementAgtech Issues: The Shiny Object Syndrome
September 6, 2017
Do you remember those cartoons where someone lures someone else by placing a piece of candy, small amount of money, Read More
AgQuip overview
Australia/New ZealandAgQuip 2017 Displays New Ag Technology in Australia
August 28, 2017
The annual AgQuip field days took place in Gunnedah, NSW on August 22-24. Being the largest agricultural field days in Read More
Latest News
deepfield-robotics-bonirob
Robotics/Labor SaversDeepfield Robotics to Showcase Precision Agriculture Te…
September 22, 2017
Deepfield Robotics is preparing to showcase its robotics and automation technologies for the agriculture market at the Agrilevante event, in Read More
Kray Drone Application
DronesCrop Spraying Drone Manufacturer Kray Technologies Gets…
September 22, 2017
Chernovetskyi Investment Group (CIG) has reached an agreement on investment into Kray Technologies company, which manufactures Kray Protection industrial robotic Read More
Imagery/SensingPlanet Announces New Hi-Res Imagery Products
September 21, 2017
Since our acquisition of Terra Bella, and the SkySat constellation of seven satellites, we’ve been focused on making this high-resolution Read More
Systems ManagementBayer Dismisses Antitrust Concerns about Digital Farmin…
September 20, 2017
Bayer said it was unable to propose the sale of any digital farming assets to allay EU concerns about its Read More
Farmer with iPad
Australia/New ZealandAgrian Expands into Australia
September 20, 2017
In line with a familiar growth trajectory, Agrian Inc. is moving into Australia with a physical support and sales presence Read More
Robotics Specialty Crops
EventsPrecision in Specialty Crops Gains Momentum
September 20, 2017
When John Deere acquired Blue River Technologies (BRT) recently, BRT’s See & Spray technology received plenty of play. Yet many Read More
Decision Support SoftwareSyngenta Helps Lead Efforts for Farm Management Softwar…
September 19, 2017
Ag data from tractors, combines, planters, and other farm machinery present a huge opportunity for growers to manage their operations Read More
Petra-Andren-Cicada-Innovations
Australia/New ZealandGrowLab’s Rocket Fuel for AgTech in Australia
September 19, 2017
Despite its superpower status as a producer and exporter of agricultural goods and services, up until now Australia has had Read More
CropIn-Team-Photo-credit-BW-Disrupt
AsiaCropIn Aims to be a Global Leader in AgTech Sector
September 19, 2017
Krishna Kumar created AgTech startup, CropIn Technology in 2010, along with co-founders Kunal Prasad and Chittranjan Jena. The trio went Read More
China-Beidou-Navigation-Satellite-System
AsiaChina’s Navigation System Gets Powerful Chip to I…
September 18, 2017
A new powerful chip technology has been introduced in China’s national satellite navigation system to provide high-precision positioning, according to Read More
Tablet Grower
Industry NewsFieldReveal Names Hesse New CEO
September 18, 2017
Matt Hesse has been selected as the Chief Executive Officer of FieldReveal, a newly launched joint venture formed to deliver Read More
John-Deere-labs
Tools & Smart EquipmentHow John Deere’s New AI Lab Is Designing Farm Equipment…
September 15, 2017
On a block in San Francisco’s SoMa district, near LinkedIn’s headquarters and dozens of startups, a 180-year-old company best-known for Read More
Wheat sunrise
Australia/New ZealandSparkLabs Group Launches an Agricultural Tech Accelerat…
September 15, 2017
SparkLabs Group, which claims to be the largest startup accelerator group in Asia, is stepping into agricultural tech with a Read More
Sensors/IoTCollaboration Leverages Internet of Things, Sensors in …
September 15, 2017
The vision of having license-free community sensor networks for agricultural users has made a giant leap closer to reality. A Read More
Young Corn Field
Data ManagementPurdue Online Tool to Help Farmers Make Precision Decis…
September 14, 2017
An innovative online tool developed by a Purdue University engineering professor will allow farmers to process data collected from their Read More
forbes-agtech-summit
Precision IrrigationImproving Water Management: Can Silicon Valley Help?
September 13, 2017
I recently attended the Forbes AgTech Summit in Salinas, CA, where roughly 50 start-up companies originating from Silicon Valley and Read More
Nate-Dorsey-Field-Trial-Curve-Compensation
Systems ManagementField Trial: Precision Application and Curve Compensati…
September 13, 2017
Several months ago I wrote an article about curve compensation in planters and how these systems can help create more Read More
Diamondback moth
Tools & Smart EquipmentTechAccel Invests in Unique Sprayable RNAi Pesticide Te…
September 12, 2017
TechAccel, the Kansas City-based technology and venture development company, has announced it has awarded the first grant under its “Path Read More