Benefits of Plastic Mulch - previous home page text
We organize under the major headings below and discuss everything from the differing perspectives of the home grower and the small farmer. We define the home grower as having less than 400 square feet of planting beds, and the small farmer as someone having more than this, but less than an acre of land in cultivation or without access to specialized mulch laying equipment.
- General Benefits
- Unique Flora-Flow Benefits
- DIY Instructions, growing information (coming late November 2014)
- Academic Research Links
- Environmental Issues
In this section we separately describe the most significant benefits of plastic mulch and drip irrigation systems, then describe the combined top benefits. In the end we round up other less significant benefits that the systems provide. Where appropriate we have divided the discussion into home and commercial applications. If you already understand plastic mulch and drip irrigation systems, and want to learn about the additional benefits of Flora-Flow combined products, jump here.
Home gardens can benefit every bit as much as larger growing operations from drip irrigation, but often at higher cost. The home gardener faces a few fixed costs that are spread over a smaller area as compared to a large farm: a water filter, a pressure or flow regulator and optionally, a garden timer for even the smallest installation. Nevertheless, the benefits are large, and the fixed costs typically can be spread over many growing seasons.
Drip irrigation is a superior method of delivering plant moisture in the garden environment. It reduces moisture stress, reduces plant disease and increases yield better than other watering methods. Drip irrigation delivers water where needed: directly to the soil and plant roots without wetting leaves and stems. Drip systems deliver precisely calibrated and even flow rates to avoid areas of over and under watering. Drip systems water gently and will not displace newly planted seeds and seedlings. The systems reduce moisture in non-plant areas, thereby reducing weed growth in those areas. The reduction of disease, increase in properly germinated seeds, and the ability to deliver even-watering, and the avoidance of weed growth result in significant plant yield increases.
Sprinklers deliver several problems along with water. They deliver water overhead with wild distribution variation and with significant force. The soaked area near a sprinkler contrasts sharply with much drier edge of the wetted zone. Sprinkler-wetted leaves and fruits promote and spread disease. Sprinkler water delivered is strong daylight can magnify the sun's energy and burn plant leaves. Water delivered to non-plant areas encourage weed growth. The moisture variation, leaf wetting, and time-of-day issues associated with sprinkler use result in lower yields.
On the positive side, sprinklers cost less than many drip irrigation systems and easily relocate to other areas in the yard. Sprinklers also leave exposed areas in the garden easily accessible so that the ground can be weeded and cultivated without obstructions from tubing.
Soaker hoses overcome the leaf wetting issues of sprinklers but are still prone to large variations in water delivery along their length. More moisture is often delivered near the water supply, and less at the end of the soaker. Water flow from soakers can be high enough to displace seeds and wash out small seedlings before they are established. Soakers deliver plenty of water in between-plant areas thereby encouraging weed growth there. Pulling weeds near soaker hoses is a nuisance as they overlap. These factors combined reduce plant yields when compared to drip irrigation.
On the positive side, soaker hoses cost less than many drip systems, and may have fewer maintenance issues than drip systems.
Drip irrigation systems save water. Targeted delivery points and controlled flow rates mean that water arrives at the point and with the volume needed for the plant and not elsewhere. Additionally, drip systems deliver the water close to the ground so there is not airborne loss to evaporation especially in hot, arid, and windy environments. The result is water savings. More water gets to plants, less gets to non-plant areas such as potential weed locations or garden paths and less is lost to evaporation into the atmosphere. Water saving vary with climate but consumption can be 50-75% less than sprinklers.
For the home gardener, the benefit of saving water can vary. In areas where water usage is restricted due to drought, drip irrigation can be the difference between having a garden and having none--a big value! For areas with costly water charges the value of water savings can add up. A typical recommendation for watering a garden is one inch of rain per week.
For a 400 square foot garden this is equal to 248 gallons per week (see this discussion: http://water.usgs.gov/edu/sc2.html). In a six month growing season this amounts to 6448 gallons (26 weeks * 248 gallons), so 60% savings is 3869 gallons!
No other watering system comes close to the effectiveness of drip irrigation.
Drip alone does a great deal for the home gardener, but its effectiveness is greatly magnified with the addition of plastic, or other mulches. Drip in the garden, in the presence of weeds is often a nuisance as the weeds will grow near the drip tubing and weeding around the tubing is difficult. Additionally, the most cost effective types of drip irrigation, called agricultural drip tape require either staking into place, or fairly constant repositioning as animals and wind will move the drip tape around on the surface. Staking or covering with mulch can help lock the drip tape into position, but then weeding around the tubing becomes that much more difficult.
Small farm, hoop house, and green house installations benefit from higher yields of drip irrigation systems for all the same reasons a home garden does: target, controlled water delivery and a reduction of plant disease and weed competition. Additionally, small farms can better manage all watering operations to better utilize and simplify all farm resources such as labor, water, and equipment.
Drip irrigation offers additional benefits of more value to the small grower than the home grower. Especially surprising is the ability to work in the garden when water is running, since the ground is not saturated and plants are dry you can work without compacting soils or spreading disease. And watering operations can be completed at all times of day without fear of burning crops via water droplet magnification. This translates in to the ability to easily water in different zones on the farm without taxing the water supply.
Like the home grower, small farm installations save water but since the water demands are so much larger on a larger area, these water savings can mean either real money, or the ability to open up more land for production, as the water you have will go further.
Sprinklers, and soakers on a small farm are especially problematic for all reasons drip irrigation is so beneficial. Each of these watering methods require large volumes of high pressure water resulting in big water or electricity bills for pumps. This often translates into the abililty to water only small portions of your field at one time, a reduction in the amount of land you can cultivate and loss of flexibility to work. For example, if you are sprinklering in an area, you can not weed or harvest during, or for several hours after watering due to wet ground and plant conditions.
Plastic mulch blocks weeds, saves water, increases yields and extends growing season and more. We discuss these major benefits and comment on specific areas of relevance to home gardens and small farms. Additional benefits are summarized in the Additional Reported Benefits section. Plastic mulch comes in many colors and thicknesses and these variations are discussed in the purchasing section.
Most Agricultural plastic mulches block sunlight that causes most weeds to germinate. Therefore weed germination is restricted to areas exposed to sunlight such as in holes created to plant seeds or seedlings. Almost all mid and late season weeding is eliminated. The only annual weeds seeds that germinate are those in exposed soil. The end result is that transplanted seedlings require almost no weeding, and direct planted seed require only minimal hand weeding prior to their establishment.
Plants that store significant energy underground will grow without sunlight. Nutsedge is a common example that can sprout and pierce plastic mulch as it grows. These perennial weeds must be removed prior to place mulch for effective weed control.
Plastic mulch greatly reduces evaporation and saves water as a result in both home gardens and small farm installations. The mulch can also effectively shed excess rainwater when laid on the ground with a crown in the center.
Yields for plants grown in plastic can be 3-5 times higher than conventionally grown plants. Plastic mulch generally increases yields through better moisture control and reduction of weed competition. Many plants also benefit from soil warming (see extended growing season below) that can result in better growing conditions for heat loving crops. Melons, tomato, squash and pumpkin, okra and cucumber are all benefit from warm soil.
Examples of yield increases (from Saunders, http://www.ces.ncsu.edu/hil/hil-33.html)
Yield increase above North Carolina average
Moist soil covered with dark colored plastic heats up in the sun. Plastic prevents moisture evaporation and evaporative cooling at the soil surface, and simultaneously absorbs solar energy that is transmitted to the soil. Temperature measurements of soil at 2 inch depth under black plastic are 4-5 degrees compared to bare soil, and 8 to 10 degrees under clear plastic. The net result is warmer soil earlier and later in the season. This can add several weeks of productive growing. Data from North Carolina indicates earlier harvest of 2 to 14 days for black plastic, and up to 21 days under clear plastic! (Note: clear plastic does not block weed growth) Season extension should be higher in colder climates.
Some plants do not like hot soil. While all plants benefit from relative warmth early in the growing season, others go to seed, or bolt when temperatures rise. Season extension for these crops comes in the form of mulches or additions of other materials that serve to keep soil temperatures low. Some gardeners and growers use white plastic mulch to achieve this opposite effect. White mulch reflects away solar heat to help cool weather crops growing longer. Other cooling techniques include covering dark plastics with light colored materials such as straw.
Small farms, in hoop house and green houses
There is never a shortage of work in a commercial growing operation. Plastic mulch is effective at balancing the work-load. You will spend slightly more time early in the season with bed preparation and planting, significantly less time during the height of the growing season beating back weeds, and slightly more time at the end of the season cleaning up plastic mulch.
Combined benefits of plastic mulch and drip irrigation
While drip and plastic each offer some control over weeds and water issues and help increase yields, together they do more. Plastic mulch with drip irrigation helps create a homogeneous warm, moist growing environment. The plastic reduces evaporation even more from the highly efficient drip system. The plastic greatly reduces movement of the drip irrigation system due to wind and animal action. The combined system makes each individual technology more effective through season extension and higher yields that let you cover costs more easily. If you sell your produce, earlier harvests can yield higher prices since you can deliver before the competition.
In addition to the major benefits of weed and water control, and increased yields and season extension researcher identify the following additional benefits. Some of these benefits are of more interest to specific plants. The following list of additional benefit is extracted from http://www.ces.ncsu.edu/hil/hil-33.html:
- Reduced soil compaction: Soil under plastic mulch remains loose, friable and well-aerated. Roots have access to adequate oxygen and microbial activity is excellent.
- Reduced fertilizer leaching: Water runs off the impervious mulch resulting in maximum utilization of the fertilizer.
- Reduced drowning of crops: Water is shed from the row area and excess water runs off the field thus reducing drowning and other excess soil water stresses.
- Cleaner product: [Soil does not contact or splash on to food and flowers]
- Root pruning eliminated: Cultivation is not necessary except for the area between the mulched strips. Therefore, roots are not pruned.
- Increased growth: Plastic mulch is practically impervious to carbon dioxide (CO2), a gas that is of prime importance in photosynthesis. Very high levels of CO2 build up under the plastic, because the film does not allow it to escape. It has to come through the holes made in the plastic for the plants and a "chimney effect" is created, resulting in localized concentrations of abundant CO2 for the actively growing leaves.
Flora-Flow All-in-One Mats combine plastic mulch and drip irrigation into a single packaged kit designed for hand installation and hand planting. The mats are factory assembled standard drip tape type drip irrigation joined to specially pre-perforated and printed plastic mulch. For easy hand installation and shipping the mats are folded or rolled into a compact size. This combination offers several benefits to home gardens and small farms not available with commodity plastic or drip irrigation products.
- Simple, simultaneous installation of irrigation and mulch systems and preliminary plant layout
- Built-in plant marking system
- Accurate, even plant spacing
- Lightweight, easily managed product sizes suitable for hand installation without heavy lifting or machinery.
- Available simple connector kits for home gardens eliminate many design and assembly jobs.
- Economically efficient: available in small quantities, or large. Buy what you need.
- Elimination of burning or cutting plant holes into plastic
Unlike standard plastic mulch, All-in-One Mats is printed. The printing includes:
- 1" centerline marking
- aids in installation of straight beds
- indicates position of drip tape (for single drip line products)
- Perforation indicators
- aid visualization of plant layout
- aid in locating planting holes to be removed
- Marking blocks
- provide a location for marking plant information directly on the mulch
- Edge lines
- aid in even edge sealing/securing
- provide watering data, installation guideline directly on product.
Unlike standard plastic mulch, All-in-One Mats are pre-perforated with planting holes. The 2 inch diameter holes are big enough for small seedlings and direct seeding, and can be easily stretched, without tools, to accept larger transplants. The perforated plant holes block weeds when left in place and are easily removed by tearing when it is time to plant.
Unlike flat-rolled full-width standard mulch, the 48 inch wide mats are folded lengthwise onto narrow 15" wide cardboard cores so the mats can be easily shipped and installed by one person.
Practical instructions and DIY growing information
Coming in late November 2014: This section will be a plastic mulch and drip irrigation setup guide, or manual for use in home garden and small farm installations growing vegetables, cut-flower, or berries. It serves as a DIY manual for those who want to assemble their own systems.
Published academic research
There are numerous agricultural extension service articles that cover the benefits and some details of using plastic mulch and drip irrigation in addition to those shown below. These typically are for large scale growers, but are of some interest to the small grower and home gardener.
Sanders, Douglas. "Using Plastic Mulches and Drip Irrigation for Vegetable Production." NC State University Extension. 1 Jan. 2001. Web. 10 Nov. 2014.
Peronto, Marjorie. "Bulletin #2752, Extending the Gardening Season." University of Maine Cooperative Extension Publications. Univerity of Maine, 1 Jan. 2008. Web. 10 Nov. 2014.
Ngouajio, Mathieu. "Managing Plastic Mulches Profitably." MSU Extension. Michigan State Univeristy Extension, 18 May 2011. Web. 10 Nov. 2014.
"Technologies - Plasticulture (Penn State Extension)." Plasticulture. Penn State Extension. Web. 10 Nov. 2014. This website includes many statistics and links to other research reports.
There are significant environmental benefits and a few cost to using plastic mulch and drip irrigation.
The environmental benefits of the plastic mulch and drip irrigation systems promote healthier plants and thereby help gardeners and growers avoid pesticide and herbicide. The healthier plants are able to better fend off pests. Of great importance in drought areas, the systems help reduce water consumption, and make growing more efficient. Avoidance of mechanical weeding, mowing and cultivating mean less fuel consumption and carbon dioxide emission from fossil fuels. Food grown at home, or close to consumers has a smaller carbon footprint than packaged food shipped in refrigerated trucks. These are significant environmental benefits.
Agricultural plastics and drip irrigation are genrally recyclable LDPE plastic. These are petroleum based plastics made from fossil fuel feedstocks. Properly disposed of, these plastic can be recycled into post consumer plastic products, or incinerated to release energy--no better or worse than burning gasoline or other fossil fuels, though less convenient! An offset to this environmental cost is the realization that most alternative mulches are often significantly heavier and bulkier and on all but the smallest scale or most ideal situation must be trucked to the growing location. The use of plastics in the garden or farm also are offset by the fuels not producing food in other modes and locations.
In addition to standard plastic mulches, biodegradable plastic mulch is also manufactured. These mulches are designed to be tilled into the soil and left in place, rather than removed at the end of the season. They are recycled in place, rather than repurposed or harvested for energy.
The one method perhaps superior to plastic mulching on the home or small farm garden is the use of green manures, or no-till farm methods that do not require the application of any additional materials such as plastic or other mulches to the ground while simultaneously enriching the soil with organic matter and nutrients. There is a significant additional management burden using the methods that will tax most small farmers and home gardeners at especially busy times of the growing season.
Growing with plastic mulch and plastic drip irrigation is an approved organic method according to OMRI, the Organic Materials Research Institute. Certified organic growers must remove all plastic prior to it breaking down in the soils, or use biodegradable plastic mulch that will slowly decompose in the soil.