Template:Chapters 5.10

5.10 - Plastic mulch prevents water loss

Galme Mumed, University of Guelph, Canada

Source:https://en.wikipedia.org/wiki/File:Plastic_mulch,_nr_Merstone,_IW,_UK.jpg

Suggested citation for this chapter.

Lanthier,C. (2022) Contour farming on hillsides to prevent erosion. In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Background

Plastic is used in agriculture for constructing tall or short greenhouses/tunnels or as mulch covers for many row crops, as protective seed beds (Wittwer 1993). The use of plastic in agriculture has propelled the development of controlled agriculture significantly over the last 40 years (Wittwer, 1993). Due to the various compositions and designs of plastic films, they can assist in mitigating some major climate and weather hazards. Some major agricultural constraints include adverse temperatures, moisture and light deficiencies, weeds, and deficiencies in soil nutrients and atmospheric CO2 (Wittwer, 1993). The following chapter will detail how plastic mulch can assist in minimizing these hazards, which crops grow best with mulch and some of its drawbacks. In general, plastic mulch is an appropriate technology for high value fruit and vegetable crops, though has been effectively introduced into grain crops including corn/maize and upland rice.

Practice

Types of Plastic Mulch - Black films made out of polyethylene are the most commonly used plastic mulch. They come in various sizes, rolling up to 2,500 feet or more in length (Schonbeck, 2012). They are often used in conjunction with drip-irrigation systems, which are installed under the films, in order to provide nutrients to the crop without watering weeds (Schonbeck, 2012). Other types of plastic mulch include clear, translucent and colored, which evidently provide more warmth to soil then black plastic. Both clear and darker films of plastic mulch speed soil warming and early crop growth (Schonbeck, 2012). Black and greyish mulches aid in effectively suppressing weeds. Alternative to the common synthetic plastic mulch is biodegradable plastic mulch. While not yet approved by the national organic program (NOP), plant-startch based biodegradable film has been shown to degrade completely.

The cost of plastic mulch varies depending on the quantity and type. Black plastic mulch can cost between $0.10 and $0.90 per meter (should be m2?) and clear mulch can be between $0.09 and $0.25 per meter (Alibaba 2016). When purchasing the film it is important to consider thickness, which can span between 0.015 to 1.5 mm (??) and each thickness may require varying application methods and equipment (Orzolek & Lamont, 2015).

Using and preparing Plastic Mulch - Before laying mulch, the soil must be in a specific condition. Specifically, the plant beds must be loose and stripped of any organic residue because it may reduce the effectiveness of the mulch. In addition, the soil has to be exceptionally moist. Once the surface is prepared, the mulch can be applied (Serrano, 2015). The application process can be done by using a mechanical layering device for medium to large scale farmers, or else manually for smaller farms. The machine “rolls over the fields laying sheets of plastic mulch over the plant beds” (Serrano, 2015). At this point, if needed the machine can also install drip irrigation. After the mulch has been placed down and sealed, farmers can then use special equipment to create holes and fill then with water and fertilizer; then finally the farmer will plant or transplant the crop in their respective holes (Serrano, 2015). When it is time to harvest, the farmer can use equipment to cut the plastic and pull the harvest out the sides. Depending on the thickness the film can last anywhere between one season to 2 years, with the more thicker mulches being more durable (Orzolek & Lamont, 2015). When the film is at the end of its life cycle it must be disposed of appropriately.

Crop production with plastic mulch- Of the various vegetables, fruits and flowers that are grown using plastic mulch, strawberries are the most extensively grown using this technology. Plastic mulch is used for winter production of strawberries in California, Japan, China, Israel, Egypt and various countries in Europe. By the early 1990s, there were 8000 ha of strawberries in California mulched with plastic (Lamenet, W, 1993). In addition, watermelons and muskmelons are very responsive to mulch, especially in China, where they are grown extensively in all provinces. Other crops include honeydews, cucumber, squash, peppers, eggplants, tomatoes, okra and sweet corn crops (Lamenet, W, 1993). Plastic mulch has proven to increase crop yield for different farm sizes around the world. For instance,

Additionally, the use of plastic mulch is becoming more popular in the production of wheat and maize (corn). Wheat and maize account for 70% of crop production in the world and demand continues to rise (Qin et al 2015). Due to all the benefits above (i.e. reduced evaporation, modified soil temperature, reduced weeds), plastic mulch is a useful technology (Qin et al 2015).

Benefits

Soil temperature- The impact that plastic mulch has on soil temperatures are heavily influenced by the color of the mulch, by regulating the amount of solar radiation absorbed and transferred to the underlying soil. For instance, black plastic mulch interrupts the sunlight so as to warm the soil (Lamenet, 1993). Soil temperatures under black plastic mulch during the daytime are 2.8˚C higher at a 5 cm depth and 1.7˚C higher at a 10 cm depth compared to bare soil (Lamenet, 1993). This warming effects promotes faster growth of crops and earlier harvesting. On the other hand, clear plastic mulch absorbs much less solar radiation, however due to the formation of water droplets, it manages to transmit between 85% - 95% of solar radiation to soil (Lamenet, 1993). Soil temperatures under clear plastic mulch are 4-7˚C higher at a 5 cm depth and 3-5˚C higher at a 10 cm depth compared to bare soil (Lamenet, 1993).

Weed management- Weeds are a problem for many small-scale farmers all around the world. For those who cannot or do not wish to use herbicides, weeding can be very time consuming. Plastic mulch physically suppresses weeds. Opaque plastic mulch reduces light penetration form the soil, and while it provides nourishing benefits for crops under the mulch it also makes it difficult for most weeds under the mulch to survive (Lamenet, 1993).

Reduction of water lost- Farmers have observed other benefits of plastic mulch. For example, farmers in Minqin County in China have remarked that water saving through plastic mulch is the main reason for its use (Ingman et al, 2015). Plastic mulch is a small-scale water conservative measure that can help to mitigate water scarcity. It has been shown to conserve water by significantly reducing the evaporation of soil moisture in the upper layer of the soil (Ingman et al, 2015). A study conducted in Nigeria found that clear polyethylene mulch increased soil moisture content by an average of 40% compared to bare soil for the duration of the growing season (Ingman et al, 2015).

Critical evaluation

While there are many benefits of plastic mulch it still requires significant financial capital and intensive management (Ingman et al, 2015). It must be available locally at a cheap price which may not be the case. As the material is heavy and is shipped as rolls, transportation may be challenging and costly, especially to remote areas. As it is a new technology and practice for many subsistence farmers, the concept of plastic mulching must first be taught to subsistence farmers, otherwise adoption rates may be low. Among plastic mulch’s major problems, disposal is problematic. For decades plastics have been disposed routinely by open burning, burial, dumping or burning in landfills, and hence they contribute to unwanted environmental degradation. Biodegradable, photodegradable and paper mulch is an alternative.

Picture Based Lesson to Train Farmers

Click on the image to access a higher resolution image as well as lessons adapted for different geographic regions.

For the South Asian version (pictures only, text for you to insert), click this link for lesson 6.10:http://www.sakbooks.com/uploads/8/1/5/7/81574912/6.10_south_asian.pdf

For the East/South Asian version (pictures only, text for you to insert), click this link for lesson 6.10:http://www.sakbooks.com/uploads/8/1/5/7/81574912/6.10e.s.a.pdf

For the Sub-Saharan Africa/Caribbean version (pictures only, text for you to insert), click this link for lesson 6.10:http://www.sakbooks.com/uploads/8/1/5/7/81574912/6.10subsaharan_africa_carribean.pdf

For the Latin-America version (pictures only, text for you to insert), click this link for lesson 6.10:http://www.sakbooks.com/uploads/8/1/5/7/81574912/6.10latin_america.pdf

For North Africa And Middle East version (pictures only, text for you to insert), click this link for lesson Chapter 5. 5.9:http://www.sakbooks.com/uploads/8/1/5/7/81574912/5.9n._africa_middleeast.pdf

Source: MN Raizada and LJ Smith (2016) A Picture Book of Best Practices for Subsistence Farmers: eBook, University of Guelph Sustainable Agriculture Kit (SAK) Project, June 2016, Guelph, Canada. Available online at: www.SAKBooks.com

Practical Tips plus future readings

Plastic mulch is available globally and can be purchased in many different countries. One online global trader is Alilbaba.com, where farmers can purchase various types of plastic mulch. Prices will depend on the scale of farming. Plastic mulch for medium to large-scale farms is often purchased at Alibab or directly from the supplier. Other websites include Indiamart.com and RobertMarvel.com, which sells biodegradable mulch as an alternative.

Further reading

1. http://ifad-un.blogspot.ca/2014/10/growing-more-food-and-using-less-water.html

2. https://www.researchgate.net/profile/Yang_Liu277/publication/273443030/figure/fig1/AS:294672233713664@1447266743945/Figure-1-Schematic-diagram-of-the-cropping-pattern-and-lateral-layout-of-the-driplines.png

3. http://www.guardandgrow.com/include/diagram.jpg

4. http://www.therockpile.com/wp-content/uploads/2010/03/Tree-planting.jpg

References

1. Alibaba. (2016). Henna Factory Supply Black Plastic Ldpe Mulch Film Mulching Film For Agriculture - Buy Ground Cover Waterproof,Mulching Film For Agriculture,Black Plastic Ground Cover Product on Alibaba.com. Retrieved December 05, 2016, from https://www.alibaba.com/product-detail/Henna-Factory-Supply-Black-Plastic-LDPE_60408197744.html

2. Fisher, P. (1995). An alternative plastic mulching system for improved water management in dryland maize production. Agricultural Water Management, 27(2), 155-166. doi:10.1016/0378-3774(95)01134-5

3. Ingman, M., Santelmann, M. V., & Tilt, B. (2015). Agricultural water conservation in China: Plastic mulch and traditional irrigation. Ecosystem Health and Sustainability, 1(4). doi:10.1890/ehs14-0018.1

4. Kasirajan, (2012). Polyethylene and biodegradable mulches for agricultural applications: a review. Agronomy for Sustainable Development, 32 (2). 501 – 529

5. Lamenet, W. (1993). Plastic Mulches for the Production of Vegetable Crops. Horttechnology, 3(1).

6. Orzolek, M., & Lamont, W., Jr. (2015). Summary and Recommendations for the Use of Mulch Color in Vegetable Production (Plasticulture). Retrieved December 05, 2016, from http://extension.psu.edu/plants/plasticulture/technologies/plastic-mulches/summary-and-recommendations-for-the-use-of-mulch-color-in-vegetable-production

7. Qin, W., Hu, C., & Oenema, O. (2015). Soil mulching significantly enhances yields and water and nitrogen use efficiencies of maize and wheat: A meta-analysis. Scientific Reports, 5, 16210. doi:10.1038/srep16210

8. Serrano, J. (2015, July 14). Using Plastic Mulch in Commercial Vegetable Production. Retrieved 2016, from http://northamericanfarmer.com/articles/plastic-mulch-vegetable-production.aspx

9. Schonbeck, M. (2012, September 12). Synthetic Mulching Materials for Weed Management - eXtension. Retrieved December 04, 2016, from http://articles.extension.org/pages/65191/synthetic-mulching-materials-for-weed-management

10. Stapleton, J., & Devay, J. (1986). Soil solarization: A non-chemical approach for management of plant pathogens and pests. Crop Protection, 5(3), 190-198. doi:10.1016/0261-2194(86)90101-8

11. Steinmetz, Z., Wollmann, C., Schaefer, M., Buchmann, C., David, J., Tröger, J., . . . Schaumann, G. E. (2016). Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation? Science of The Total Environment, 550, 690-705. doi:10.1016/j.scitotenv.2016.01.153

12. Wittwer, S. H. (1993). World wide use of plastics in horticulture production. Hort-technology, 3(1), 6-19. Retrieved 2016.