Abstract
Throughout the southeastern United States, vegetable growers have successfully cultivated pumpkins (Cucurbita pepo) using conventional tillage. No-till pumpkin production has not been pursued by many growers as a result of the lack of herbicides, no-till planting equipment, and knowledge in conservation tillage methods. All of these conservation production aids are now present for successful no-till vegetable production. The primary reasons to use no-till technologies for pumpkins include reduced erosion, improved soil moisture conservation, long-term improvement in soil chemical and microbial properties, and better fruit appearance while maintaining similar yields compared with conventionally produced pumpkins. Cover crop utilization varies in no-till production, whereas residue from different cover crops can affect yields. The objective of these experiments was to evaluate the influence of surface residue type on no-till pumpkin yield and fruit quality. Results from these experiments showed all cover crop residues produced acceptable no-till pumpkin yields and fruit size. Field location, weather conditions, soil type, and other factors probably affected pumpkin yields more than surface residue. Vegetable growers should expect to successfully grow no-till pumpkins using any of the winter cover crop residues tested over a wide range in residue biomass rates.
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.
Materials and Methods
No-till pumpkin experiments were conducted in 2001 at the Mountain Research Station (MRS) near Waynesville and the Mountain Horticultural Crops Research Station (MHCRS) near Fletcher, NC. In 2002, no-till pumpkin experiments were conducted at the MRS near Waynesville, the Upper Mountain Research Station (UMRS) near Laurel Springs, the MHCRS near Fletcher, and the Piedmont Research Station (PRS) near Salisbury, NC. Pumpkin cultivars in 2001 were ‘Magic Lantern’, a large (7.3 to 10.8 kg), powdery mildew-resistant cultivar, and ‘Oz’, a small (1.4 to 2.3 kg) cultivar. The pumpkin cultivars used in 2002 were ‘Magic Lantern’ and ‘Mystic Plus’, a small (2.3 to 3.2 kg) cultivar. Soils were a Toxaway loam (a fine-loamy, mixed, nonacid, mesic Cumulic Humaquept) at UMRS, French loam (a fine-loamy, over sandy or sandy skeletal, mixed, mesic Fluaquentic Dystrochrepts) at MRS, Comus fine sandy loam (a course-loamy, mixed, mesic Fluventic Dystrochrepts) at MHCRS, and Hiwassee clay loam (clayey, kaolintic, thermic Rhodic Kanhapludults) at PRS.
Residue treatments were arranged in a randomized block experimental design with four replications at all locations. Plots were 6.1 m wide by 13 m long. For both the 2001 and 2002 experiments, various varieties of rye (Secale cereale), wheat (Triticum aestivum), barley (Hordeum vulgare), triticale (Triticosecale), ryegrass (Lolium multiflorum), oats (Avena sativa), and crimson clover (Trifolium incarnatum) were fall-planted at 134 kg·ha−1 for small grain, 33 kg·ha−1 for ryegrass, and 25 kg·ha−1 for crimson clover using conventional tillage to prepare the experimental areas. Winter cover crops were killed with paraquat (1,1′-dimethyl-4, 4-bipyridinium dichloride) herbicide at 3.5 L·ha−1 or glyphosate [N-(phosphonomethyl) glycine] at 3.5 L·ha−1 between 2 and 4 weeks before pumpkin planting. Winter cover biomass samples (0.25 m2) were collected from each treatment at planting, oven-dried at 65 °C, then weighed to determine the amount of residue present at planting. Pumpkins were no-till-planted into the winter cover crop treatments during the third week of June for each location and year. A John Deere (Moline, IL) Maxi-merge no-till corn planter (no pumpkin seed was used) was used to open the furrows and simulate the use of a no-till planter within the plots. Two to three seeds were hand-seeded at 0.91 m in-row spacing and thinned to one plant per seeding location after seedling emergence. Between-row spacing was 1.83 m, resulting in 12 plants per pumpkin cultivar (two rows of six plants long) per plot with 1.66 m2 per plant. The small pumpkin cultivar (six plants) was planted in the front half of the plot and ‘Magic Lantern’ (six plants) planted at the back half of the plot.
Nitrogen fertilizer as ammonium nitrate (100 kg·ha−1 N) was surface band-applied 15 cm beside the row 2 weeks after planting. A single application of ethalfluralin [n-ethyl-N-(2methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl benzeneamine)] and clomazone [2-(2-chlorophenyl) methyl-4, 4-dimethyl-3-isoxazolidinone] herbicides was applied at 4.6 L·ha−1 after planting to control weeds. Esfenvalerate [(s)-cyano (3-phenoxyphenyl) methyl (s)-4-chloro-alpha-(1-methylethyl) benzeneacetate] was applied for insect control at 0.43 L·ha−1 once a week after fruit emergence. Fungicides azoxystrobin [methyl (E)-2-{2-[6-(2-cyanophenoxy) pyrimidin-4-yloxy] phenyl}-3-methoxyacrylate] applied at 0.86 L·ha−1 and chlorothalonil (tetrachloroisophthalonitrile) applied at 2.29 L·ha−1 were rotated between applications weekly starting mid-July.
Pumpkin fruit were harvested at all locations between the third week of September and the second week of October. Fruit were classified as marketable or nonmarketable (cull) and then individually counted and weighed. Analysis of variance (PROC GLM) was performed with SAS version 6.12 (SAS Institute, Cary, NC). Least significant difference tests were preformed on each yield parameter at all locations.
Results and Discussion
Residue biomass
Winter cover residue treatments just before pumpkin planting in 2001 ranged from 4156 to 11,867 kg·ha−1 over locations, cover crop species, and varieties (Table 1). At each location in 2001, wheat produced more residue biomass than rye, triticale, or ryegrass. The highest yielding wheat cultivar at both locations was Patton with 11,867 kg·ha−1 at MHCRS and 10,573 kg·ha−1 at MRS. The lowest yielding residue treatment was Gulf ryegrass at MRS with 4165 kg·ha−1 and Wheeler rye at MHCRS with 6242 kg·ha−1. All winter cover species and varieties for these two locations provided at least 75% surface cover for no-till pumpkins.
Winter cover residue for the no-till pumpkin experiments in 2001.
In 2002, Arcia triticale produced the greatest residue (12,226 kg·ha−1) at MRS among all locations and cover residue treatments (Table 2). Like in 2001, all wheat varieties produced similar biomass within each location with an average of 10,365 kg·ha−1. At MHCRS, the highest yielding cover crop residue was Wrens Abruzzi rye (5844 kg·ha−1), whereas the lowest yielding residue treatment was Arcia triticale (2377 kg·ha−1). Compared with 2001 at MHCRS, small grain residue treatments were lower in 2002 as a result of poor winter and early spring growth.
Winter cover residue for the no-till pumpkin experiments in 2002.
Wheat was the highest yielding residue species at PRS and UMRS, with ‘Pioneer 26R24’ being the highest yielding wheat cultivar. Crimson clover yielded the least amount of residue at PRS (3763 kg·ha−1) and UMRS (1577 kg·ha−1), respectively.
Rye, triticale, wheat, or barley varieties included in these studies have provided excellent residue cover for no-till summer crops when cover crops were planted at recommended fall planting dates and grown under normal winter weather conditions. These winter cover crops were allowed to grow through May, increasing the amount of residue biomass and providing excellent surface residue cover for no-till pumpkin production. Some ryegrass varieties produced residue cover that completely covered the soil surface, but in general, ryegrass cover residues resulted in lower no-till vegetable yields compared with small grain selections (Hoyt, 1999).
Pumpkin yield
Small pumpkin cultivar.
2001 experiment with ‘Oz’.
At both of the locations in 2001, there was considerable variability in pumpkin fruit yields among the various residue treatments (Tables 3 and 4). The ‘Oz’ (Harris Moran Seed Company, Modesto, CA, pumpkin Guide) cultivar ranged from 10,262 to 18,060 kg·ha−1 of pumpkin fruit yield over both locations. Residue treatments generally had no consistent effect on pumpkin yield. The Wrens Abruzzi rye residue treatment produced the highest pumpkin fruit yield (18,060 kg·ha−1) at MHCRS and Gulf ryegrass residue treatment produced the highest pumpkin fruit yield (15,080 kg·ha−1) at MRS. The lowest pumpkin fruit yielding residue treatment at MRS was Rio ryegrass and the ‘Pioneer 24R26’ wheat cultivar treatment at MHCRS. Pumpkin fruit at both locations were within the recommended size for ‘Oz’ ranging from 1.28 to 1.71 kg/fruit (Table 3). Residue treatment influenced fruit size at MHCRS, but not at MRS (Tables 3 and 4). Residue treatment had no effect on the number of fruit or total yield per hectare at either location.
The effect of winter cover residue on no-till pumpkin yield at the MHCRSz, 2001.
The effect of winter cover residue on no-till pumpkin yield at the MRSz, 2001.
2002 experiments with ‘Mystic Plus’.
At MRS, no-till pumpkin fruit total yield ranged from 40,333 kg·ha−1 in the Marshall ryegrass residue treatment to 66,774 kg·ha−1 in the Patton wheat residue treatment (Table 5). Overall, wheat, rye, triticale, and barley residue treatments had greater no-till pumpkin yields than ryegrass, oats, crimson clover, and bare soil treatments, although some varieties of wheat did result in poor pumpkin total yield.
The effect of winter cover residue on no-till Mystic Plus pumpkin yield at the MRSz, 2002.
Marketable fruit size at MRS varied between 2.46 and 3.0 kg/fruit (Table 5). The ryegrass residue treatments at MRS yielded the smallest size fruit of any treatments, whereas wheat, barley, and crimson clover residue and bare soil treatments yielded the largest no-till pumpkin fruit. The number of marketable fruit ranged from 13,948 (Coker 9663) to 21,666 fruit/ha (‘Pioneer 26R24’) and was influenced by residue treatment (Table 5). Pumpkin cull yields at the MRS location showed no statistical differences among treatments (Table 5).
At MHCRS, pumpkin total yield ranged from 27,416 to 62,067 kg·ha−1 and was influenced by residue treatment (Table 6). Arcia triticale produced the greatest no-till pumpkin total yield and number of marketable fruit/ha. The residue treatment producing the lowest no-till pumpkin total yield was Patton wheat. Cull no-till pumpkin fruit size and number of fruit ha−1 showed no differences among treatments (Table 6). Cull pumpkin yield had high variability with treatments producing from 0 to 1852 kg·ha−1 cull pumpkin fruit (Table 6). The largest amount of cull pumpkins was produced by the Marshal ryegrass residue treatment. Several treatments yielded no cull pumpkin fruit at this location.
The effect of winter cover residue on no-till Mystic Plus pumpkin yield at the MHCRSz, 2002.
At PRS, the greatest no-till pumpkin total yield (47,280 kg·ha−1) and marketable fruit number/ha (24,408 fruit/ha) was planted into Wheeler rye residue (Table 7). The other rye residue (Wrens Abruzzi) also produced a high no-till pumpkin yield (43,695 kg·ha−1). Triticale residue treatments had similar high yields with an average of 42,051 kg·ha−1. Although some wheat, ryegrass, barley, and crimson clover residue treatments produced lower no-till pumpkin total yields, all treatments had good yields. Cull pumpkin yields (kg/fruit, kg·ha−1, number of fruit/ha) at PRS showed no differences among treatments (Table 7). The marketable size fruit produced at this location also showed no differences among treatments (Table 7).
The effect of winter cover residue on no-till Mystic Plus pumpkin yield at the PRSz, 2002.
At UMRS, the greatest no-till pumpkin total yield (51,761 kg·ha−1) and number of marketable fruit (17,433 fruit/ha) were measured in the Trical 308 triticale residue treatment (Table 8). Residue treatments from the other varieties of triticale also produced high no-till pumpkin total yields with an average of 43,097 kg·ha−1. The lowest no-till pumpkin total yield was 28,989 kg·ha−1, which was planted into Patton wheat residue (Table 8). Although residue from this cultivar of wheat produced the lowest no-till pumpkin total yields, other varieties of wheat residues produced good pumpkin yields (average 41,364 kg·ha−1). The lowest number of marketable fruit at this location was 11,954 fruit/ha produced by the Marshall ryegrass treatment (Table 8).
The effect of winter cover residue on no-till Mystic Plus pumpkin yield at the UMRSz, 2002.
Cull fruit yield and fruit size were highly variable at this location, where cull yield ranged from 1120 to 11,427 kg·ha−1 and the cull fruit size ranged from 0.60- to 3.01-kg/fruit (Table 8). The wheat residue treatments (except for Vigoro RC 904) produced the greatest amount of cull pumpkins. The bare soil treatment also had high cull pumpkin yields. The lowest weight and number of cull pumpkins produced came from the Arcia triticale residue and Vigoro RC 904 wheat residue treatments, both with a 1120-kg·ha−1 cull pumpkin yield (Table 8). Marketable pumpkin fruit size varied from 2.10- to 2.65-kg fruit (Table 8). The overall pumpkin yields from the residue treatments at this location were good considering this location has the highest elevation of the four with the shortest growing season and lowest average soil temperature.
Large pumpkin cultivar.
2001 experiments with ‘Magic Lantern’.
No-till ‘Magic Lantern’ pumpkin total yields at MHCRS ranged from 34,731 to 56,915 kg·ha−1 (Table 3). The winter cover residue treatments had no significant effects on yield, fruit size, or fruit number at this site.
At MRS, no-till ‘Magic Lantern’ pumpkin total yield ranged from 32,715 to 47,280 kg·ha−1 (Table 4). Residue treatments had no significant effect on yield and fruit size, but residue cover did affect number of fruit produced, which ranged from 5429 to 7296 fruit/ha (Table 4). Results from MRS and MHCRS in 2001 indicated that all winter cover residue treatments produced excellent no-till pumpkin yields.
2002 experiments with ‘Magic Lantern’.
At MRS, no-till pumpkin total yield ranged from 105,540 (Patton wheat residue treatment) to 144,081 kg·ha−1 (oat residue treatment) (Table 9). Although the oat residue treatment had the greatest no-till pumpkin total yield for this location, a high percentage of the total were cull fruit. The residue treatments that yielded the largest and smallest marketable fruit size were bare soil (9.34-kg/fruit) and Rio ryegrass (6.66-kg/fruit), respectively (Table 9). All treatments yielded excellent pumpkin fruit weights at this location.
The effect of winter cover residue on no-till Magic lantern pumpkin yield at the MRSz, 2002.
The number of marketable fruit/ha produced at MRS was comparable with the other locations. ‘Pioneer 26R24’ wheat residue treatment had the highest number of marketable fruit (16,437 fruit/ha), whereas the lowest number of marketable fruit produced (11,954 fruit/ha) occurred with Vigoro RC 904 wheat residue and bare soil treatments (Table 9). The yields and size of cull pumpkin fruit produced at this location varied considerably. The highest cull yield produced was 22,631 kg·ha−1 (oat residue), whereas the lowest cull yield (4481 kg·ha−1) was observed with Wrens Abruzzi rye residue (Table 9). Pumpkin cull fruit size ranged from 3.31- to 7.03-kg/fruit (Table 9).
At MHCRS, no-till pumpkin total yield varied from 60,248 (crimson clover residue) to 100,798 kg·ha−1 (Wrens Abruzzi rye residue) (Table 10). Residue treatments influenced both total and marketable fruit yield. Marketable pumpkin size and numbers of fruit·ha−1 ranged from 4.59- to 9.70-kg fruit and from 4,632 to 14,171 fruit/ha, respectively (Table 10).
The effect of winter cover residue on no-till Magic Lantern pumpkin yield for the MHCRSz, 2002.
The cull fruit size and yield also were highly variable among treatments with some treatments producing no cull fruit. The greatest no-till pumpkin cull yield was 5513 kg·ha−1 from the Patton wheat residue treatment and the lowest cull pumpkin yield was zero and was produced by several residue treatments (Table 10). Overall yields were lower than those at MRS, probably as a result of landscape position, with the MHCRS field site in a river bottom landscape position that had visual wet conditions during summer, whereas the MRS field site was on an upland terrace.
Total and marketable no-till pumpkin yields were not influenced by residue treatment at the PRS location (Table 11). No-till pumpkin total yield ranged from 58,484 (Roane wheat residue treatment) to 90,975 kg·ha−1 (Wrens Abruzzi rye residue treatment). The Rio and Big Daddy ryegrass residue treatments also produced relatively high yields and marketable fruit size. Fruit size ranged from 4.89 (‘Pioneer 26R24’ wheat treatment) to 7.03-kg/fruit (Rio ryegrass treatment) (Table 11). Pumpkin cull yields ranged from 448 to 13,220 kg·ha−1 at PRS (Table 11). The Roane wheat residue treatment produced the lowest cull pumpkin yield (448 kg·ha−1) and also produced the smallest cull size (0.43 kg) (Table 11). The highest cull pumpkin yield (13,220 kg·ha−1) was produced by the Patton wheat treatment (Table 11). The largest cull fruit size was 5.21 kg and was produced by the Wrens Abruzzi rye residue treatment (Table 11), which also produced the greatest total yield in both weight and number of fruit.
The effect of winter cover residue on no-till Magic lantern pumpkin yield for the PRSz, 2002.
At the UMRS location, no-till pumpkin total yield varied from 51,313 (Crimson clover residue treatment) to 85,373 kg·ha−1 (Nomini barley residue treatment) (Table 12). At this location, the rye, ryegrass, and wheat residue treatments also resulted in good pumpkin total yields. Residue treatment also influenced yield, fruit size, and numbers of fruit for marketable and cull pumpkins parameters. ‘Pioneer 26R24’ wheat treatment produced the highest marketable fruit number (12,404 fruit/ha), whereas the Oat residue treatment produced the lowest number of marketable fruit (8220 fruit/ha) (Table 12). Marketable fruit size was generally high for this location, considering cool nighttime summer temperatures for this high elevation location, ranging from 4.67- (Crimson clover residue treatment) to 7.62-kg/fruit (Wrens Abruzzi and Wheeler rye residue treatments) (Table 12). The cull pumpkin fruit yield varied from 448 (Vigoro RC 904 wheat residue treatment) to 20,615 kg·ha−1 (bare soil treatment) (Table 12). The bare soil treatment had considerably more cull fruit than the residue treatments. The Vigoro RC 904 wheat residue treatment produced the smallest cull pumpkin fruit size (0.36 kg) and the FFR566 wheat treatment produced the largest cull pumpkin fruit size (5.39 kg) (Table 12).
The effect of winter cover residue on no-till Magic Lantern pumpkin yield for the UMRSz, 2002.
Conclusions
All residue treatments produced good no-till pumpkin yields at one location per year or another. With any of the winter cover residue types used, we did not see any residue treatments that had potential detrimental effect on pumpkin growth or yield. Because locations varied as a result of elevation, soil type, and weather conditions, these studies should represent conditions for typical pumpkin production for much of the southeastern United States. Although we did measure lower yields for some types of residue on occasion, we not see any consistent detrimental factors or yield reductions resulting from type of residue. This study did not evaluate ease of planting in these residue types. All seed were planted by hand after a no-till planter was run through the plots, so that each plant would have a 0.91-m spacing in-row. Seed placement in the soil may be an additional factor affecting no-till pumpkin yield with type of residue affecting correct seed depth.
Literature Cited
Coolman, R.M. & Hoyt, G.D. 1993 The effects of reduced tillage on the soil environment HortTechnology 3 143 145
Doran, J.W. 1980 Soil microbial and biochemical changes associated with reduced tillage Soil Sci. Soc. Amer. J. 44 765 771
Follett, R.F. & Stewart, B.A. 1985 Soil erosion and crop productivity ASA, CSSA, SSSA Madison, WI
Frye, W.W. , Blevins, R.L. , Murdock, L.W. & Wells, K.L. 1981 Energy conservation in no-tillage production of corn. Crop production with conservation in the 80s Amer. Soc. Agr. Eng St. Joseph MI. Publ 7 81
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
Griffith, D.R. , Mannering, J.V. & Box, J.E. 1986 Soil and moisture management with reduced tillage 19 55 Sprague M.A. & Triplett G.B. No-tillage and surface-tillage agriculture Wiley New York
Hoyt, G.D. 1999 Tillage and cover residue affects on vegetable yields HortTechnology 9 351 358
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
Hoyt, G.D. & Monks, D.W. 1996 Weed management in strip-tilled Irish and sweet potato production HortTechnology 6 238 241
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
Rice, R.W. 1983 Fundamentals of no-till farming Amer. Assn. Voc. Instr. Matr Athens, GA
Sprague, M.A. 1986 Overview 1 18 Sprague M.A. & Triplett G.B. No-tillage and surface-tillage agriculture Wiley New York