Vegetable producers commonly use conventional tillage practices to prepare a seedbed that optimizes vegetable seed placement, crop germination, and emergence resulting from increased contact with loose, moist soil (Coolman and Hoyt, 1993; Sprague, 1986). Incorporating surface residues also can reduce potential weed, disease, and insect pests. Conventional tillage also facilitates incorporation of surface-applied nutrients to improve nutrient availability to crop roots. As a result of these benefits, conventional tillage has been the standard cultural practice for hundreds of years (Sprague, 1986).
With its introduction in the 1950s, conservation tillage systems have been increasingly adopted for many row crops as a result of distinct advantages in soil erosion control, soil water conservation, reduced energy and labor requirements, and enhanced crop performance (Frye et al., 1981; Phillips, 1984; Sprague, 1986). In addition, contemporary no-till planting equipment can provide for optimum seed placement, germination and emergence of most agronomic crops. Advantages and disadvantages of conservation tillage systems with agronomic crops have been well documented (Gallaher and Ferrer, 1987; Rice, 1983). An undesirable consequence of conservation tillage for vegetables includes lower soil temperature in spring resulting from surface crop residue cover that can reduce emergence and seedling vigor (Hoyt and Konsler, 1988).
In addition, increased potential for weed and pest infestations can occur with conservation tillage, requiring application of preemergence or postemergence pesticides (Hoyt et al., 1996; Hoyt and Monks, 1996). Currently, many pesticides are available for use in conservation tillage systems. Pest problems can also be minimized by fall tillage of crop debris and establishment of a grass or legume winter cover crop (Phatak et al., 1991).
Early adoption of conservation tillage systems was primarily related to concerns for soil erosion. A substantial reduction in soil loss through water and wind erosion occurs with the maintenance of surface crop residues (Follett and Stewart, 1985; Griffith et al., 1986). The use of previous summer crop and winter cover crop residues for conservation tillage planting protects the soil surface from erosion by absorbing the impact energy of raindrops, thus reducing soil particle detachment and decreasing the acceleration of surface runoff. In addition, increased water infiltration and reduced soil water evaporation under conservation tillage generally increases plant-available water and subsequent crop yield potential (Griffith et al., 1986). This increased available water is particularly important in dry land cropping systems in arid and semiarid regions where plant water availability is the most limiting factor to crop yield potential. Increased surface residue can also improve nutrient availability through increased organic matter and nutrient cycling (Doran, 1980).
With increased urbanization in rural areas and decreased availability of prime nonerodible farmland in the southeastern United States, the advantages of conservation tillage are very important to profitable crop production. Many soils available for producing farm commodities in these regions are highly erodible, especially in the Piedmont region of the southeast. In addition, much of the remaining farmland is marginal for plant growth without substantial inputs resulting from steep slopes and variable growing season conditions. Increasing surface residue cover by using conservation tillage in this region can enhance crop yield potential through protection of nutrient-rich surface soil from erosion and increased plant-available soil moisture resulting from increased infiltration and decreased evaporation (Coolman and Hoyt, 1993). The objectives of these experiments were to evaluate the yield potential and fruit quality of no-till pumpkins grown with various winter cover crop surface residues.
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Gallaher, R.N. & Ferrer, M.B. 1987 Effect of no- tillage vs. conventional tillage on soil organic matter and nitrogen contents Commun. Soil Sci. Plant Anal. 18 1061 1076
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Hoyt, G.D., Bonanno, A.R. & Parker, G.C. 1996 Influence of herbicides and tillage on weed control, yield, and quality of cabbage (Brassica oleracea L. var. capitata) Weed Technology 10 50 54
Hoyt, G.D. & Konsler, T.R. 1988 Soil water and temperature regimes under tillage and cover crop management for vegetable culture 697 702 Proc. 11th Intl. Conf., ISTRO Edinburgh, Scotland
Phatak, S.C., Bugg, R.L., Sumner, D.R., Gay, J.D., Brunson, K.E. & Chalfant, R.B. 1991 Cover crop effects on weeds, diseases, and insects of vegetables 153 154 Hargrove W.L. Cover crops for clean water. Soil and Water Cons. Soc. Ankeny, IA
Phillips, S.H. 1984 Introduction 1 10 Phillips R.E. & Phillips S.H. No-tillage agriculture: Principles and practice Van Nostrand Reinhold New York