Simon Blackmore 2015-02-23 23:30:05
Mechanized agriculture uses massive amounts of energy in myriad forms, from the energy associated with chemical pesticides and fertilizers, to the tractors and implements and the fuel needed to power them. This energy is often wasted when it goes off-target. It’s also expensive and will become more so in the future. Smart machines should use the minimum amount of energy to turn the natural environment into useful agriculture, thus saving energy and reducing costs. Let me give an example of how the current system uses too much energy. I estimate that up to 90% of the energy going into traditional cultivation is needed to repair the damage caused by the machines themselves. Each horizontal kilonewton of draft requires a vertical kilonewton for traction, which causes soil compaction. Therefore, without vehicle trafficking, 60% to 70% of the tillage energy would not be needed. If we retain just the 20% to 30% that is used for occasional deep loosening of the soil, we can see that there should be significant energy savings by not compacting the soil in the first place. In other words, if we can find a way to avoid dragging metal through the soil, we can nullify the compaction problem. Currently, tractors, combines, and other agricultural machines are increasing in size due to economies of scale. However, as the machines get bigger, the opportunity to work the fields gets smaller due to the fragile structure of the soil, especially when wet. This cycle can only be broken by making the machines significantly lighter so as not to damage the soil, and thus expand the time available for field operations. Most new large tractors have autosteer systems that allow much more accurate positioning to avoid overlap and skip in field treatments. That improvement saves 10% to 15% of the time and operating costs. In addition, many tractors now use a CAN bus for internal system management and an ISOBUS to communicate with attached implements. Instead of the tractor controlling the implement, the implement controls the tractor. Telemetry is another innovation that allows new levels of management. New combine harvesters are x-by-wire, so a lot of data about the machine is digitally available. Some models can even transmit this information back to the factory for analysis. If the machine starts to operate outside of normal tolerances, say a belt starts to slip, the driver can be alerted via mobile phone before the problem becomes a disaster. There are many other examples like this. So how do we take advantage of these new technologies? One way is to continue making incremental improvements to the current system. An alternative approach would be to start with a whole new paradigm. We know that farmers today have conflicting pressures—new legislation, environmental regulations, and commodity price fluctuations, to name a few. All of these pressures push farmers toward more efficient production. Combining these pressures with the opportunities presented by new technologies can lead to a new mechanization system that addresses all the concerns—environment, economics, and energy efficiency—in a new way. Such a system would also be based on plant needs, using precision agriculture to address the temporal and spatial variability of crops. Can we develop a new system of agricultural mechanization that can assess crop variability in real time and use only the minimum amount of energy required to support crop development? The answer is a qualified yes. We have not yet developed all the technologies needed, but many have been prototyped, and we can start to visualize how such a system would look. My vision for the future is one where small smart machines move around the field independently, establishing, tending, and selectively harvesting the crops. Call it agricultural robotics. Ten years ago, I developed an autonomous tractor that could mechanically remove weeds, thus achieving 100% chemical reduction. Back then, the tractor was too big and used more energy than was needed. More recently, one of my former doctoral students has developed a laser weeding system that uses machine vision to recognize the species, biomass, leaf area, and position of the meristem (growing point). A miniature spray boom only a few centimeters wide can then apply a microdot of herbicide directly onto the weed, thus saving 99.9% of the spray. Alternatively, a steerable 5 W laser can heat the meristem until the cells rupture and the weed becomes dormant. These devices could be carried on a mobile robot no bigger than an office desk, working around the clock, without damaging the soil or crop. Another application is selective harvesting. Currently, many vegetable crops are harvested by hand, which is expensive even with the cheapest labor. In addition, up to 60% of the harvested crop is not saleable to supermarkets because it does not have the desired quality attributes—too small, too large, incorrect cutting, blemishes, etc. Selective harvesting involves using a robot to assess all of the quality attributes and only harvest the produce that has ideal saleable characteristics. If some plants are too small, they can be left until they grow to the correct size. By knowing the position, size, and expected growth rate, we can schedule an accurate second or even third harvest in the field. Looking at all the operations needed to establish, care for, and harvest crops, while minimizing inputs, we can see how such a mechanization system could evolve over time and adapt to changing circumstances. That adaptability is the key. We must stop defining what we do now by the way we have done it in the past, and instead look at the fundamental problem. Only then can we create new ways of meeting the economic and environmental requirements of crop production—and do a better job of caring for the planet. ASABE Member Simon Blackmore, CEng, Professor and Head of Engineering, Harper Adams University, Newport, U.K. (www.harperadams.ac.uk/engineering), Director of the National Centre for Precision Farming (www.harper-adams.ac.uk/NCPF), and Project Manager of FutureFarm (www.futurefarm.eu); email@example.com. Top photo Kwiktor | Dreamstime. Inset photo by the author.
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