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Using 21st century technology to grow the oldest renewable resource: trees.

Imagine a 10,440 ha (25.800 acres) contiguous drip-irrigated farm that has 1,000 km (620 mi) of buried mainline, 30.600 km (19,000 mi) of drip line, and 34 pumping stations with 110 pumps, all installed in an area more arid than the Kalahari Desert. Now add 21st century automation technology with 1,400 sensors and 1,800 controls to irrigate this farm, day and night, with no human interaction. To handle any detrimental hydraulic conditions, add sophisticated algorithms to provide enough computer smarts to meet the challenge. Now add remote access to the system so that no matter where you are, or which mobile device you carry, you can remotely override the computer and become the person in charge. This state-of-the-science "dream farm" actually exists. It's GreenWood Resources (GWR) Boardman Tree Farm, located in eastern Oregon.

Boardman Tree Farm (BTF) is a real-world model for how technology can enable agroforestry to efficiently and economically produce fiber from one of the most renewable resources--trees--in a sustainable and ecofriendly manner. BTF covers 104 [km.sup.2] (40 m[i.sup.2]), which makes it the world's largest irrigated fiber farm and one of the largest contiguous drip-irrigated farms. In addition to the nine million Pacific Albus (hybrid poplar) trees, there are 2.225 ha (5,500 acres) of various high-value crops, including organic crops, under center-pivot irrigation. The extensive irrigation network consists of 1,000 km (620 mi) of buried pipe up to 183 cm (72 in.) in diameter--you could walk upright inside these pipes.

Single pump capacities range from 1,900 to 120,000 Lpm (500 to 32,000 gpm), with pump motors ranging in size from 22 to 746 kW (30 to 1000 hp). BTF's peak pumping power of 28,400 kW (38,100 hp) can deliver more than 852,000 Lpm (225,000 gpm) with enough capacity to produce 1.2 billion Lpd (325 million gpd). This huge volume of water is fed to the trees by nearly 27 million drip emitters, with 30,600 km (19,000 mi) of drip line--that would reach about 3/4 of the way around the Earth. With 250 sand media filters in the irrigation system, BTF has one of the world's largest sand media filter systems.

BTF produces high fiber yields through two approaches. First, BTF uses an advanced scientific irrigation management (AS1M) system, an irrigation supervisory control and data acquisition (I-SCADA) system, and an advanced hydraulic balanced irrigation scheduling (AHBIS) program, among other programs, to use water and energy resources efficiently. Second BTF plants genetically superior (high-yielding, fast-growing, disease and pest resistant) tree stock that's well suited to this particular environment.

The secret is mostly in the software

BTF uses the ASIM system to accurately predict future water demands for each age group of trees. This water demand prediction system uses localized hybrid poplar crop models, 25 years of local AgriMet hourly weather data for evapotranspiration (ET) and growing degree days, multiple independent extended weather forecasts, and real-time soil moisture sensors. Due to the high energy cost for pumping--more than $3,000,000--the ASIM system's operational objective is to pump only what the trees actually need.

The I-SCADA system, which is one of the most advanced large-scale farm automation systems in the United States, displays the irrigation schedules and keeps track of real-time operation. Each field has three soil moisture sensors at three different depths, and these sensors can be read in real-time. The ASIM and I-SCADA systems together allow BTF to replace daily ET losses, thereby maintaining optimum daily soil moisture around the root zone. This daily replacement of lost soil water produces exceptional high growth in the trees. Measured height increases during peak growth are greater than 5 cm (2 in.) a day, and annual growth rings wider than 4 cm (1.5 in.) are common. This high growth and ET have led to high evaporative cooling, as observed by NASA's thermal imaging satellite, between the irrigated trees and the surrounding pristine sagebrush habitat. The cooling ranges as high as 12[degrees]C (54[degrees]F), similar to the temperature difference between a rainforest and desert. As a result, the healthy, fast-growing trees at BTF benefit the neighboring towns and farms by increasing the humidity and moderating the temperatures of this semi-arid region.

The I-SCADA system has also allowed BTF to achieve an irrigation efficiency that is surpassed by no other large-scale irrigated farm in the nation, possibly even the world. The I-SCADA system "spoon feeds" the trees with precise amounts of water and fertilizer four times a day at different rates and start times. The 1,400 sensors and 1,800 controls in the system interact with 153 remote terminal units (RTUs). All communications to the RTUs are done by multi-spread spectrum radio telemetry on two independent licensed radio frequencies. The I-SCADA system is designed to control all devices within a radius of 30 km (19 mi) of the central office. All of the I-SCADA systems remote field actions occur within two seconds of operator command, with full control acknowledgement within five seconds of command initialization.

The I-SCADA system includes auto-shutoff programs to shut down devices independently to mitigate a hydraulic problem and thereby maintain can also be controlled remotely from any location that has internet or cell phone coverage. This is combined with a real-time alarm/pager system to alert operators of an irrigation situation that would adversely affect irrigation performance or efficiency.

BTF uses an original methodology for scheduling individual field irrigation events to maintain smooth and steady operation of the pumping stations. This methodology is incorporated into the AHB1S program, which optimizes irrigation scheduling so that no pumping changes are necessary during a particular irrigation regime. No pumping changes means a steady withdrawal rate from the irrigation canal, which helps the irrigation district maintain efficient canal operations. This approach also allows operation of this large and complex irrigation system without the use of expensive and complex pump automation programs.

The AHB1S methodology improves pumping energy efficiency, decreases irrigation system wear, and greatly improves human resource allocation. During the irrigation season, BTFs irrigation system operates around the clock, every day, with just one manager, one engineer, one water quality technician, two pump technicians, and three field assistants--a total of only eight people--for one of the world's largest drip-irrigated farms.

A combination of good ideas

The interaction of the ASIM, I-SCADA, and AHB1S programs allows BTF to micromanage irrigation scheduling at the individual 16 to 28 ha (40 to 70 acre) field level to within [+ or -]1 min. Here are some other ways that BTF has applied technology to its operations:

Closed-loop drip irrigation: BTF uses an award-winning, closed-loop design for the drip irrigation system, with drip lines fed from both sides, together with pressure-compensated emitters, to achieve efficient, uniform application at minimum pump energy costs. Automated flushing of the drip lines is programmed and scheduled days in advance, much the same way as an irrigation schedule.

Remote imagery, UAVs, GIS, and LIDAR: Satellite and aerial near-infrared images are used to improve irrigation uniformity, monitor crop growth, and evaluate disease damage and crop loss. Work is in progress to use unmanned aerial vehicles (UAVs, or drones) to evaluate irrigation, monitor crops, and provide security. GIS assists in field layout for planting (each tree has a grid reference), irrigation system and road layout, inventory control, and general mapping. BTF also uses terrestrial laser imaging detection and ranging (LIDAR) for inventory and harvest purposes.

Groundwater recharge: During winter and spring runoff, BTF's irrigation system supplies river water to a groundwater recharge basin at the edge of the property. Excess water is also bypassed to the recharge basin during certain periods of the irrigation season. The goal of the groundwater recharge project is to reverse the declining water table in the area and thereby allow the local farmers to grow high-value crops and improve their economic returns.

Bioenergy, biofuels, and biochemicals: Some of the fiber produced at BTF is used as feedstock for conversion into aviation fuel, ethanol, biochemicals (such as methyl acetate), acetic acid, and for bioplastics production. BTF's high-yielding, fast-growing trees can provide a yield per hectare that is five times the ethanol yield of corn, at a production cost of less than one dollar per gallon of ethanol.

Water use and water rights: BTF runs an unusual water rights program that involves irrigating only a 120 cm (4 ft) zone on either side of the 3m (10 ft) tree rows while maintaining a 61 cm (2 ft) wide dry zone between the tree rows. This central dry zone allows BTF to meet its water rights obligation while drastically reducing weed growth between the tree rows. To our knowledge, this level of irrigation precision, on such a huge scale, is unique.

Breeding and cloning technology: Besides using carbon isotope discrimination for selection of drought-resistant clone varieties, GWR's world-renowned hybrid poplar breeding and research station also produces planting stock in the form of high-yielding, fast-growing, disease and pest resistant trees. Breeding is on-going to produce hybrid poplar trees that have lower lignin content for efficient biofuel and bio-chemical production. Breeding is also on-going to meet the increased demand for high-yielding, fast-growing planting stock for tree farms in other regions of the world.

BTF's goal is to develop an economically and environmentally sustainable agricultural system that can produce fiber for biochemical, biofuel, bio-energy, paper, veneer, and solid wood products and that can remain productive in the long run. The adoption of 21st century technology has so far allowed BTF to achieve this goal.

ASABE member Nabil Mohamed, Water and Energy Resource Engineer, GreenWood Resources' Boardman Tree Farm, Boardman, Ore., USA,,

Photos courtesy of GreenWood Resources and the author, a Resource magazine Visual Challenge photographer.

RELATED ARTICLE: As reported on The Amusing Planet website ...

Boardman Tree Farm, an innovative poplar farm that employs more than 100 people locally, is located in Morrow County, Oregon, along Interstate 84, five miles west of the I-82 junction. Owned by the GreenWood Tree Farm Fund and operated by a Portland-based tree farm management group, its 10,117 ha (25,000 acres) consist of thousands and thousands of hybrid poplar trees. The trees are neatly arranged in evenly spaced rows, and they are about the same size, height, and thickness. It's a surreal sight, one of the most eye-catching for miles along Interstate 84.

The farm is just one of the many holdings of GreenWood Resources in North America, South America, and China, but clearly one of the most accessible, being located next to the interstate. The farm is broken up into 16 and 28 ha (40 and 70 acre) plots, with access roads separating the plots from each other on all sides. Each plot consists of about 600 trees per 0.4 ha (1 acre).

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Author:Mohamed, Nabil
Publication:Resource: Engineering & Technology for a Sustainable World
Date:Mar 1, 2014
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