The art of engineering has had a major impact on agricultural production. Agricultural mechanization has been cited as one of the twenty most significant fetes of engineering in the 20th century. As we look through the titles of articles published in
The art of engineering has had a major impact on agricultural production.
This article highlights some of the engineering innovations made in the peanut industry during the past 50 yr and looks ahead at what engineering obstacles must be overcome in the next 50 yr.
Much of the engineering research in the late 1950's and early 60's related to peanut production was focused on land preparation, seed placement, and plant spacing. Early research on tillage with a moldboard plow to turn crop residue under prior to planting peanuts resulted in increased yields by 224 - 336 kg/ha due to reduced impact of diseases (Boyle and Hammons, 1956;
Just as planting patterns and mechanical planters have changed, the size of the planters has increased from one- or two-row planters to six- and twelve-row planters. Each row unit on the planter has a seed hopper that holds approximately 22 kg of peanut seed which is approximately one bag of commercial seed. Planting at a rate of 112 kg/ha requires that the seed hopper be refilled every 400 m. An 81-ha field requires 9,065 kg or 9 MT of seed, all which would have to be manually lifted and poured into each seed hopper. A bulk seed tender is a portable hopper equipped with either an auger or conveyor belt to load seed hoppers on the planters and are used when planting other commodities such as soybean, wheat, and corn.
One of the major engineering innovations in peanut production has been the introduction and adaptation of global positioning systems (GPS) into the agricultural sector. Equipment manufacturers have developed automated steering guided by precision GPS technology that has improved precision of various field operations, reduced operator errors, and reduced operator fatigue (
Fifty years ago, management decisions were made strictly on rules of thumb, keen observation by growers, and instinct. The development of sensors and wireless instrumentation systems has had profound effects on management decisions made by growers. Sensor technology and interpretation of data from those sensors has evolved considerably over the last 50 yr. The development and progression of Irrigator Pro, an irrigation management tool for peanuts is an excellent example. Irrigator Pro for Peanuts was originally developed and released in 1991using the maximum and minimum soil temperature measured under the plant canopy using a bimetal recording maximum/minimum thermometer. Since then, sensors to measure soil water potential have become simpler to use, more reliable, and relatively inexpensive. These sensors had to be visited and data manually recorded and entered into Irrigator Pro to develop an irrigation recommendation. Engineers began developing small, battery-powered, field-deployable data acquisition systems to record and transmit these data to a central location in the field (
In the early 1900's, it took approximately 3074 man-hours to harvest a hectare of peanuts (
Peanut combine developed by
John Deere two-row self-propelled peanut combine circa 1964 (picture used by permission)
A 6-row peanut combine (photo provided by Kelley Manufacturing Company, Tifton, GA).
An 8-row self-propelled peanut combine manufactured as a joint venture between Amadas Industries and John Deere (photo provided by Amadas Industries, Suffolk, VA).
As the size of the combine increased, so did the harvest capacity. Peanut combining typically began each d shortly after noon and lasted until dusk. A two-row combine could harvest 4 to 6 ha per d. The harvest capacity increased nearly proportional to the header width, and a 6-row combine could harvest 14 to 17 ha per d. However, the mechanisms for threshing and cleaning also improved allowing ground speeds to increase as well as begin harvest earlier in the d. The development of conveyors that allow the operators to offload on-the-go reduce dead time in the field required to unload. These improvements have increased overall harvest capacity of the modern 6-row peanut combine to 16 to 20 ha per d.
Prior to the development of the towable peanut combine, peanuts cured in the stackpole and the moisture was reduced to safe storage levels prior to harvest. The peanuts were bagged 57-kg bags and stored. With the development of the towable peanut combine, a mechanical curing system was developed to match the capacity of the new harvester. A four-wheeled wagon with a perforated floor installed 23 cm above the wagon floor was developed as a peanut drying wagon. The space between the solid bottom of the wagon and the perforated floor formed a plenum into which heated air could be introduced and forced up through the peanuts. The early commercially available peanut drying wagons had a holding capacity of approximately 3.6-4.5 MT of peanuts and were primarily used in on-farm drying facilities. However, as peanut production grew and harvest capacity increased, the drying operation moved from the farm to the centralized peanut buying point. Today, most peanuts are dried at the peanut buying point capable of drying as many as 200 wagons simultaneously. Increased harvest capacity on the farm pushed dryer manufacturers to increase the length of the drying wagons from 4.3 m, to 6.4 m, then to 8.5 m. In 1994, Longshot peanut buying facility in Seminole, TX constructed stationary drying containers capable of drying approximately 21 MT of farmers stock peanuts. This allowed growers to load directly into hopper-bottom semi-trailers in the field then transport them to the peanut buying point reducing the amount of equipment, drivers, and trips required to move peanuts from the field. The large fixed drying containers were costly to build, and the logistics of unloading the peanuts into the dryers was unwieldy and failed to catch on. However, the idea of the large peanut drying container resulted in the conversion of surplus 14-m semi-trailers into peanut drying wagons capable of drying in excess of 18 MT of peanuts at a time (A.
Considerable research was conducted to develop windrow drying models to optimize number of days in the windrow and minimize harvest losses during combining and subsequent energy costs for curing (
After drying, each load of farmers' stock peanuts is graded to establish its quality and market value. Much of the development of the equipment currently used in obtaining a representative sample and evaluating that sample can be attributed to Mr. James W. Dickens, an agricultural engineer with the USDA, Agricultural Research Service (
Considerable research has been conducted to eliminate peanuts contaminated with aflatoxin from the edible stream of peanuts. Many researchers conducted research to determine the primary source of aflatoxin contamination in peanuts and found that prolonged drought stress during the pod filling stage of reproduction was the primary cause for pre-harvest contamination. However, contamination was not always predictable. A multi-disciplinary team including engineers designed and constructed rainout shelters with the capability of not only inducing drought stress, but also manipulating the soil temperature in the pod zone (
Several innovations in post-harvest processing and shelling have occurred in the last 50 yr as well. The development of computer-aided design and manufacturing (CAD/CAM) has streamlined the design and layout of peanut shelling and processing plants. The 3-dimensional modelling facilitates visualization of the finished construction and design, reducing design time and changes during the construction process (
Three dimensional rendering of a small peanut shelling plant. (Image provided by LMC, Donalsonville, GA)
Equipment within the shelling plant has changed. Shellers consist of sheller bars rotating around a central shaft a specified distance away from the shelling grate (
Cutaway view of modern peanut sheller (Image provided by LMC Donalsonville, GA).
Over the past 50 yr, shelling plant operations have changed. Prior to about 1997, the peanut crop harvested in the fall of one year was shelled by April or May of the following year. Shelled peanuts were stored in ambient dry storage or in cold storage depending on how soon they would be shipped to the manufacturer for further processing. The peanut shelling industry began to consolidate, reducing the number of operational shelling plants and the shelling season increased in length. Today, plants are shelling peanuts almost year-round and increasing the length of time that farmers' stock peanuts are stored in warehouses prior to shelling. This increases the probability of post-harvest insect infestations, warmer peanuts, and potential storage problems. Engineers have been involved in conducting research on packaging for shelled peanuts (
The rapid development and deployment of sensors to measure crop progression and health as it grows creates many challenges. The sheer volume of data collected from the sensors is overwhelming. Precision agriculture is developing massive amounts of spatially and temporally variable data from the field. However, the greatest challenge is to use that data to answer the question, 'So what?' Engineers and other agricultural practitioners must develop methods to extract the important data and massage it down to a single concept and make a single recommendation for a management decision. Decisions related to when to plant or replant; when and how much to irrigate, when and what herbicides, fungicides, insecticides to apply; and when to dig could all be driven by plant-based measurements and be optimized to maximize yield and quality while minimizing the cost of production.
Similar amounts of data are produced when peanuts are purchased from the farmer. There are many characteristics such as market type, cultivar, size, chemistry, flavour, and aflatoxin contamination generated from the official grade and additional tests for each load of peanuts. The challenge for the buyer is to acquire and assimilate that data within 24 hours of receiving those peanuts and decide how to best segregate and where to store each load of peanuts. The goal of such decisions must be to optimize the available physical storage resources and facilitate efficient operation of the shelling plant when those peanuts are shelled maybe as long as a yr in the future. When the peanuts are finally unloaded from a warehouse, the data regarding the moisture, oil chemistry, and size of individual kernels can be measured. Engineers have the challenge of taking all that single kernel data and integrate it into decisions about blending peanuts from other sources and operating the shelling plant so that manufacturer specifications can be met the first time the peanuts are processed with minimal remilling.
Advances in measuring physical and chemical properties of the peanuts are needed. There are methods to measure properties such as moisture content while the peanuts are still in the shell (
Finally, developing and implementing new technology will not be our biggest challenge. Our biggest engineering challenge will be to apply technology as appropriate especially in developing countries where small changes can have tremendous impacts in improving food safety and food security. Something as simple as planting peanut seed in rows may increase peanut yields dramatically enough to significantly raise the standard of living for an entire community or introducing mesh bags to store in-shell peanuts may reduce post-harvest losses due to aflatoxin contamination enough to eliminate the health risks associated with consuming contaminated peanuts. The technology of engineering is the expansion of technology to solve a problem, while the art of engineering is recognizing and implementing the appropriate technology to solve a problem.
The art of engineering has touched almost every aspect of solving problems for the peanut industry from the laboratory to the field to the kitchen cupboard. Sometimes engineers have solved problems in isolation, but in most cases in connection with a multi-disciplinary team of researchers and practitioners. As technology advances, the volume of data that must be interpreted, summarized, and distilled into a single decision. Sensors, machinery, and systems have been our greatest achievement over the last 50 yr and will continue to be a big part of the success of the peanut industry.
Research Agricultural Engineer, USDA ARS National Peanut Research Laboratory, Dawson, GA 39842 and Executive Director (