January-February 2002
The topics in this newsletter
are considered to be timely and of interest. Comments and suggestions are
invited. The use of trade names in this newsletter is not an endorsement of any
company or product by the Maryland Cooperative Extension, University of
Maryland, College Park.
David S. Ross, Extension Agricultural Engineer
Using
a Small Water Source for
Irrigation
Recently a farmer requested advice on setting up irrigation for a vegetable operation on about 6 acres; his well driller was able to get only 12 gallons per minute (gpm) of water. The driller found 2 gpm yield in another well. The farmer proposed drip irrigation for brambles and other more permanent plantings. Overhead sprinkler irrigation was proposed for most of the rowcrops. What can be done with 12 gpm?
First, the 12 gpm is a very small water supply and will not water very much in direct use from the well. We need to determine how much water is available in 24 hours for irrigation. The maximum benefit from the well comes from incorporating intermediate storage. Intermediate storage allows the well water to be collected into storage tanks or a pond all day to provide water for several hours of irrigation during the next day. This method requires a pump in the well to raise water to the storage tanks and then a second pump at the storage facility to pressurize the water for the irrigation system.
In 24 hours the well will yield 12 gpm x 60 minutes/hour x 24 hours/day equals 17,280 gallons per day. The second well would yield 2 gpm x 60 minutes/hour x 24 hours/day equals 2,880 gallons, a small contribution.
A crop will use 0.05 to 0.10 inch of water per day early in the season and 0.20 to 0.25 inch of water per day at maturity. This evapotranspiration (ET) amounts to 1.4 to 1.75 inches per week for a maturing crop with lots of foliage. One acre-inch of water (one acre of land covered by 1 inch of water) is 27,152 gallons. The well yields only 17,280/27,152 or 0.64 acre-inch on a daily basis.
Water applied by overhead sprinkler on a hot, dry day may have an application efficiency of only 70 to 80 percent due to evaporation in the air and from the ground or plant surfaces. This means that to get one inch of water into the ground, 1.0/0.75 or 1.33 inches of water may need to be pumped. Drip irrigation is 90 to 95 percent efficient, meaning more of the water makes it into the ground to benefit the crop. Using drip irrigation, 1.0/0.95 equals 1.05 inches of water must be pumped.
If the goal is to apply one inch of water per week (1.33 inches pumped for overhead sprinklers), then the daily well yield of 0.64 acre-inch will only provide half of that required for one acre by overhead sprinkler irrigation. Therefore, one-half acre of crop can be irrigated each day at the rate of a gross 1.28 inches. In one week, 3.5 acres can be irrigated. Using drip irrigation, 0.64/1.05 or 0.6 acre can be watered per day or 4.2 acres per week.
Water can be accumulated for 24 hours into the storage and then utilized in 6 hours of daily application. The stored water will give 48 gpm of flow for 6 hours. An overhead system of 12 sprinklers, each discharging 4 gpm, can be used for five hours and then the drip system could be used elsewhere for an hour each day. Or, the mix could include more drip irrigation and less sprinklers. The average daily application is about 0.15 inches, which will meet the requirements of most crops until near the final peak demand at maturity.
This illustration shows that a small water supply and intermediate storage can fully utilize the available water to irrigate a limited number of acres. A decision must be made on the amount of crop acreage to irrigate, knowing that water will have a large influence on the quality and quantity of the product produced. The water may be used for intense cultivation on limited acreage to maximize profitability.
Trickle
Irrigation for Cut Flowers,
Vegetables,
and Small Fruit
Thinking of using trickle or drip irrigation and need to learn more about it? Maryland Cooperative Extension Bulletin 356 titled Trickle Irrigation for Cut Flowers, Vegetables, and Small Fruit is available through county Extension offices for $2.00. The booklet covers system planning and design, water management and irrigation scheduling, and basic hydraulics of water flow and pressure in pipes.
More specifically, covered are water sources – sources, quantity of water and quality of water; laying out the trickle system; plant-soil-water relationships for irrigation; system components; preparation for system design; sizing water pipes; and water management and irrigation scheduling. These topics to get you started are covered in the booklet.
To purchase Trickle Irrigation for Cut Flowers, Vegetables, and Small Fruit, contact your local Maryland county Extension office to obtain a copy. The cost is $2.00.
Hay
Fires -- Spontaneous
Combustion
A hay fire isn't a minor incident, particularly if it is inside a storage building. Storing hay when it is wet can result in problems later, either moldy, low quality hay or spontaneous combustion. Hay stored at more than 22 percent moisture in a barn or in a stack is at risk.
Chemical reactions occur in high moisture haystacks and these lead to heat building up in the pile. Hay acts as an insulator to hold the heat inside. When the internal temperature of the hay reaches above 130 degrees Fahrenheit (55 degrees C), a chemical reaction begins to produce flammable gas that can ignite if the temperature goes high enough.
Hay fires generally occur within six weeks of baling. Heating occurs in all hay above 15 percent moisture, but it generally peaks at 125 to 130 degrees F, within three to seven days, with minimal risk of combustion or forage quality losses. The temperature in the stack then declines to safe levels in the next 15 to 60 days, depending on bale and stack density, ambient temperature and humidity, and rainfall absorbed by the hay, if stored outside.
To avoid hay fires, small, rectangular bales should not exceed 18 to 22 percent moisture, and large round bales should not exceed 16 to 18 percent moisture for safe storage.
In addition, you should check your hay regularly. If you detect a slight caramel odor or a distinct musty smell, chances are that your hay is heating. At this point, monitor the temperature.
A simple probe inserted into the haystack can accurately monitor temperature. Make the probe using a 10-foot piece of pipe or electrical tubing. Close the end of the pipe with a pointed dowel and drill several ¼-inch holes behind the dowel. Drive the probe into the hay and lower a thermometer on a string into the probe. The thermometer should be left for 10 minutes in several areas of the stack to ensure an accurate reading.
Watch for the following temperatures:
150 degrees F - This is the beginning of the danger zone.
160 degrees F - This is dangerous. Measure temperature every four hours.
175 degrees F - Call the fire department. Wet the hay down. Remove it from barn.
185 degrees F - Hot spots and pockets may be expected. Flames may develop if hot hay comes in contact with air.
212 degrees F - Critical temperature has been reached. Temperatures rise quickly about this point. Hay will almost certainly ignite.
When entering a barn, place long planks on top of the hay. Do not attempt to walk on the hay mass itself. Always tie a rope around your waist and have a second person on the other end in a safe location to pull you out if the surface should collapse over a fire pocket. Have the fire company on hand or someone with a good fire hose standing by. Be careful if the hay was treated with preservatives as poisonous gas may be formed at 240 degrees F. Be aware of the type chemical additive and its properties.
Dry ice, liquid nitrogen or carbon dioxide gas can be pumped into the hay to eliminate oxygen, thus preventing combustion.
(Adapted from Cash, D. and R. Johnson. 1999. Keeping Hay Fires from Spontaneously Combusting, Montana State University Communications Services, Bozeman, MT)
Consumers -- What is ENERGY STARTM?
Have you noticed signs in your local appliance store with the label ENERGY STARTM? If you are planning to buy a new appliance, computer, home, or other product, this label is one to watch for and to become familiar with in advance of your purchase. As a symbol, watch for the word "energy" followed by a star symbol, both are under an arch.
ENERGY STARTM is a voluntary labeling program in a dynamic government-industry partnership. The program offers businesses and consumers energy-efficient solutions, making it easy to save money while protecting the environment for future generations. In the past decade, ENERGY STARTM has been the driving force behind the more widespread use of such technological innovations as LED traffic lights, efficient fluorescent lighting, power management for office equipment, and low standby energy use.
Recently, energy prices have become a hot news topic and a major concern for consumers. ENERGY STARTM provides solutions. ENERGY STARTM provides a trustworthy label on over 30 product categories (and thousands of models) for the home and office. These products deliver the same or better performance as comparable models while using less energy and saving money. ENERGY STARTM also provides easy-to-use home and building assessment tools so that homeowners and building managers can start down the path to greater efficiency and cost savings.
Major milestones in ENERGY STAR's history include efficient lighting systems in 1991, and in 1992 EPA introduced the first ENERGY STARTM labeled product line, including personal computers and monitors. Maybe you remember seeing the symbol on monitors and computers that had low energy resting modes. Since then many more products have achieved the ENERGY STARTM label.
The National Appliance Energy Conservation Act of 1987 (NAECA) mandates that manufacturers make use of readily available technologies in building appliances 10 – 30 percent more efficient than previous models. The standards set by NAECA and its subsequent revisions are benchmarks for how much energy a particular appliance needs to use. By law, manufacturers must provide detailed yellow EnergyGuide labels on all new refrigerators, freezers, water heaters, dishwashers, clothes washers, room air conditioners, heat pumps, furnaces, and boilers for sale. Consumers who compare these Energy Efficiency Rating (EER) statistics should have all the information needed to calculate the long-term energy costs – not just the short-term purchase expense – of items under consideration.
ENERGY STARTM products meet a higher performance standard for energy efficiency than typical products on the market. For example, refrigerators that qualify for the program must use 10 percent less energy than the 2001 NAECA standard for a refrigerator of that size and configuration. While the standards will continue to change with product improvements, the message is that new appliances operate at much lower energy consumption than older models, so money will be saved on the energy cost of new models. The added energy savings will pay for the additional cost of the most energy efficient model.
Indeed, consumers who buy appliances end up saving hundreds of dollars on utility bills. Refrigerators made to meet the latest Department of Energy efficiency standard, which was issued in April 1997 and took effect in the year 2001, cut consumer's energy costs by 30 percent compared to the previous (1993) standards. And, a family replacing a 1972-vintage model with a product that meets the new standard will see their utility bills drop by over $120 a year. There are super-efficient refrigerators currently on the market that save even more. If every household in the United States had the most efficient refrigerators available, the electricity savings would eliminate the need for more than 20 large power plants.
Efficient appliances are good for consumers and the environment. By themselves, they won't solve our energy woes, but they are an important step in the right direction. More information is available on the web at http://www.epa.gov/nrgystar/about.html or http://www.energystar.gov/default.shtml.
