Using plastic mulches and drip irrigation for vegetable gardens

NC STATE UNIVERSITY Horticulture Information Leaflet 8033 Revised 1/01 ~ Author Reviewed 1/01 College of Agriculture & Life Sciences Department of Horticultural Science USING PLASTIC MULCHES AND DRIP IRRIGATION FOR VEGETABLE GARDENS Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating. Douglas C. Sanders, Extension Horticultural Specialist Muskmelons, tomatoes, peppers, cucumbers, squash, eggplant, watermelons, and okra are vegetable crops that have shown significant increases in earliness, yield, and fruit quality when grown on plastic mulch. Some less- valuable crops such as sweet corn, snap beans, southern peas, and pumpkins have shown similar responses. Some of the advantages and disadvantages of using plastic mulches are outlined below. Advantages 1 . Increased soil temperature — At a 2- inch depth: 4 to 5°F under black mulch, 5 to 8°F with infrared transmitting (IRT) (clear green), or 8 to 10°F under clear mulch. 2. Reduced soil compaction — Soil under plastic mulch remains loose, friable and well-aerated. Roots have access to adequate oxygen and microbial activity is excellent. 3 . Reduced fertilizer leaching — Water runs off the impervious mulch, resulting in maximum utilization of the fertilizer. 4. 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. 5. Reduced evaporation — Soil water does not escape from under plastic mulch. Plant growth on mulch is often at least twice that on bare soil. The resulting larger plants will require more water, so mulching is no/ a substitute for irrigation. 6. Cleaner product — A mulched crop is cleaner and less subject to rots due to elimination of soil splashing on the plants or fruits. Note: Beds should be firm and tapered away from the row center. Plastic should be tight to promote run¬ off. There should be no puddles on the mulched beds! 7. Root pruning eliminated — Cultivation is not necessary except for the area between the mulched strips. Therefore, roots are not pruned. 8. Reduced weed problems — Black and IRT plastic mulch provides good weed control in the row. Clear plastic will require useof aherbicide, fumigation or lifting the mulch and cultivating. Often, weeds between mulch strips can be controlled by a herbicide. 9. Earlier crops — Black plastic mulch can result in 2 to 14 days earlier harvest while clear plastic can result in a 2 1 -day earlier harvest. 10. Increased growth — Plastic mulch is practically impervious to carbon dioxide (CO,), a gas that is of prime importance in photosynthesis. Very high levels of CO, build up under the plastic, because the film does not allow it to escape. It has STATE UNIVERSITY A&T STATE UNIVERSITY COOPERATIVE EXTENSION Helping People Put Knowledge to II