Table of Contents
Successful crop cultivation requires a balanced approach to managing resources. ‘The more, the better’ strategy often plays a nasty trick on farmers who overdo with inputs in pursuit of higher yields. Not only can it lead to undue resource waste and compromised crop growth but it can also have environmental impacts. The other extreme is neither a solution: underapplication of inputs in areas lacking nutrients or requiring crop protection agents to fight weeds is counterproductive at the very least.
The good news is that farming practices are constantly evolving to meet the challenges of the time. Modern agriculturalists are faced with a lack of land and water resources, a growing population, and climate change effects, having to produce more with less. Smart and responsible resource management is no longer an option but a necessity, and it’s where Variable Rate Technology (VRT) comes into play.
Introduced at the onset of precision agriculture back in the 1990s, VRT allows farmers to apply the whole spectrum of agricultural inputs at varying rates that respond to specific crop needs in different locations. Over time, it evolved into a modern technology in agriculture to boost field productivity through smart input allocation decisions and the use of state-of-the-art machinery.
Understanding VRT and VRA
Modern advanced agriculture technologies are focused on optimizing the return on inputs and preserving resources, and VRT is no exception. It is a system that provides a solution to the inherent variability within fields offering an individual approach to resource allocation as opposed to the traditional ‘blanket’ application where the same amount of resources is applied across the whole area. The ultimate goal of implementing variable rate technology is to achieve uniform productivity and equally high yields throughout the entire field with minimum resource wastage.
How does it work? VRT uses GPS and GIS technologies to map the area, on-site and remote sensors to collect various layers of data (on crops, soils, etc.) over time for measuring the variation within it, and specialized equipment to automate the application of the varying amounts of inputs. The process of applying such varying quantities of fertilizers, herbicides, pesticides, seeds, and irrigation water based on the specific needs of each plot is called Variable Rate Application (VRA).
VRA decisions as to where and at what rate to apply agricultural inputs are made based on a diversity of data including soil tests, yield monitoring results, UAV or satellite imagery, that can be used to break down the field into productivity zones sharing similar parameters. In map-based VRA, these zones are mapped by an agronomist using specialized software, and the resulting prescription map (also called VRA map) is further uploaded to the machinery, informing of the prescribed input rates it should apply. Sensor-based VRA represents an even more advanced farming technology where a VRT-enabled seeder, sprayer, or another piece of agricultural equipment uses in-built sensors to make input decisions right during the operation. Such real-time VRA allows to respond to precise conditions at the time of application and is most commonly used in irrigation tasks.
How VRT and VRA can benefit your farm?
As often happens with any relatively new advanced technology in agriculture, the introduction of VRT and VRA has left many skeptical about its effectiveness and unwilling to invest in the unknown. Let’s explore the tangible benefits these two can provide to a farmer and justify the invested capital and time.
- Optimized use of resources. Variable rate technology helps utilize resources in the most efficient way by applying the right amount at the right time, which translates into reduced wastage and cost savings. According to a USDA report, U.S. farmers manage to save $25 per corn planted acre thanks to the combination of VRA and yield mapping.
- Improved yields. Meeting the individual requirements of each plant and reducing human errors through variable rate application of inputs is a shortcut to boosting crop performance and securing high yields.
- Reduced environmental footprint. At the core of this advanced agriculture technology is the sustainability principle. VRT ensures maximum accuracy of input application, minimizing the odds of excessive harmful fertilizers or pesticides ending up in our ecosystems. Additionally, VRT eliminates the need for multiple applications thereby reducing the number of machinery passes and their carbon footprint.
The Many Applications of VRT
VRT and VRA are advanced agriculture technologies that can potentially be used for any agricultural input required for crop production throughout the growing season. The standard applications include:
- Variable rate fertilization (VRF): Amounts of nutrients essential to plant growth can vary greatly in different soil types and terrains, not to mention other variables that impact their availability to crops. The combination of soil sampling and VRT enables the variable rate application of fertilizers, i.e. adjustment of fertilizer dosage according to crop and soil needs. Although nitrogen is the most common fertilizer type applied via VRF, the technology can be used for other macronutrients in liquid, gaseous, granular, powder, and dung forms.
- Variable rate irrigation (VRI): Using soil moisture data coming from various sources – such as ground sensors, remote sensing data from UAVs and satellites, and weather sensors – the automated irrigation system makes real-time decisions as to how much water to apply in each field zone. Such an approach is most often used in center pivot irrigation systems proving an effective means against soil erosion, water stress in crops, excessive water, and energy waste.
- Variable rate seeding (VRS): This advanced agriculture technology became popular in the 2000s as a way to get maximum crop output with minimum seed consumption. To make it work, the seeding equipment is complemented with a VRA sensor that determines the rates of planted seeds based on available information such as soil tests and yield maps. Unlike the flat seed rate approach, variable rate seeding attempts to match the plant density to productivity zones, i.e. have more plants per fertile acres and fewer plants per poorer acres.
- Variable rate weed control: Farmers implementing precise application of herbicides save money on crop protection and increase their potential yields by effectively reducing weed pressure in their fields. The variable rate weed control is carried out either to prevent infestations or respond to the existing ones. In the first case, herbicide amounts are determined based on the field’s weed infestation history; in the latter case, the input rates are calculated from the latest drone or satellite images to detect and measure the spread of weeds.
The Variable Rate Technology adoption rates keep going up despite a number of challenges it involves, including the cost of hardware and software, learning barriers, and connectivity issues. It’s because the risks and disadvantages of VRT and VRA are outweighed by multiple benefits. In a world with shrinking lands and water resources, environmental crises, and looming famine, an advanced farming technology that enables smart usage of resources and improves yields achieved in an economically and environmentally sustainable manner is worth its weight in gold.