Temperature and root length at selected locations within a raised bed under black polyethylene, hairy vetch (Vicia villosa Roth) residue, or bare soil were measured and correlated with tomato (Lycopersicon esculentum Mill.) growth. Early in the season, before the tomato leaf canopy closed, soil temperature was influenced more by vertical depth in the bed than by horizontal position across the bed. Maximum soil temperatures under black polyethylene averaged 5.7 and 3.4C greater than those under hairy vetch at 5 and 15 cm deep, respectively. More hours at optimum temperatures for root growth (20 to 30C) during the first 4 weeks of the season probably accounted for greater early root and shoot growth and greater early yield of tomatoes grown with black polyethylene than hairy vetch residue or bare soil. After canopy closure, soil temperatures under tomato foliage within the row were reduced by an average of 5.2 and 2.2C at 5 and 15 cm deep, respectively, compared to those on the outer edge of the beds. Most tomato roots were in areas of the bed covered by the tomato canopy where temperatures in all treatments remained in the optimum 20 to 30C range almost continuously. Soil temperature, therefore, did not explain why tomato plants in the hairy vetch treatment had equal or higher total yields than the black polyethylene or unmulched treatments.
John R. Teasdale and Aref A. Abdul-Baki
Alvin D. Rutledge
Research yields of conservation tillage (CT) snap beans (Phaseolus vulgaris L.) and sweet corn (Zea mays L. var. rugosa Bonaf.) have been less than those produced under conventional tillage. This has been due to soil conditions at planting, the cover crop used, weed control and a lack of proper design in equipment for CT. However, some growers have been successful with CT for sweet corn using hairy vetch (Vicia villosa Roth.) as the cover crop. On-farm demonstrations of CT with cabbage (Brassica oleracea L. Capitata Group), pumpkins (Cucurbita pepo L.), tomatoes (Lycopersicon esculentum Mill.) and watermelons [Citrullus lanatus (Thunb) Matsum. & Nak.] have been successful and with good management it is commercially feasible under Tennessee conditions. Advantages include reduced soil erosion, cleaner products, more efficient application of crop protection chemicals, quicker planting after rainfall, lower energy costs and facilitation of harvest in wet weather. Disadvantages include reduced weed control, modifications of existing equipment, less uniformity in seed coverage and problems with transplanting, cover crop residue in mechanically harvested crops, possible delays in early harvest of fresh market crops due to delayed maturity and limited application of soil protective chemicals.
Harbans L. Bhardwaj
Winter legume cover crops have been successfully used to meet N needs of many summer crops, but they are not being used extensively in Virginia and the mid-Atlantic region, especially for specialty crops such as muskmelon and sweet corn. The objective of these studies was to determine the potential of winter legume cover crops in meeting N needs of muskmelon (Cucumis melo L.) and sweet corn (Zea mays L.). Comparisons of performances of muskmelon and sweet corn, grown after lupin (Lupinus albus L.), hairy vetch (Vicia villosa Roth.), Austrian winter pea ([AWP] Pisum arvense L.), and control fertilized with 112 kg N ha–1, and unfertilized control were made during 1999, 2000, and 2001. The interactions between cover crop treatments and years were, generally, significant. The muskmelon fruit yields were 53.6, 45.0, 23.1, 13.0, and 5.6 Mg·ha–1 during 1999; 27.8, 26.3, 8.6, 5.8, and 2.2 Mg·ha–1 during 2000; and 41.1, 39.9, 25.5, 21.4, and 2.1 Mg·ha–1 during 2001 respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. Similar results were obtained for number and size of muskmelon fruits. The sweet corn ear yields (Mg·ha–1) were 8.5, 5.6, 3.1, 1.5, and 0.7 during 1999; 5.2, 3.9, 4.0, 4.8, and 1.2 during 2000; and 2.6, 2.4, 1.9, 2.0, and 0.9 during 2001, respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. White lupin and hairy vetch, as winter cover crops, were superior than AWP and 112 kg N ha–1 for sweet corn ear number and size, and plant height. These results demonstrated that winter legume crops, especially lupin and hairy vetch, can be excellent winter cover crops for meeting N needs of muskmelon and sweet corn.
Upendra M. Sainju, Bharat P. Singh, Syed Rahman, and V.R. Reddy
The influence of tillage [no-till (NT) vs. moldboard plowing (MP)], cover crop [hairy vetch (Vicia villosa Roth) (HV) vs. no hairy vetch (NHV)], and N fertilization (0 and 180 kg·ha–1 N) on root distribution and growth rate of tomato (Lycopersicon esculentum Mill.) transplants was examined in the field from May to August in 1996 and 1997. Experiments were conducted on a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Kandiudults) in central Georgia. Root growth was estimated every 1 to 2 weeks with minirhizotron tubes installed in the plot. Roots were well distributed at soil depths between 1 and 58.5 cm and a maximum root count of 3.14 roots/cm2 soil profile area was found at 19.5-cm depth with MP and no N fertilization in 1996. In general, NT with HV or with 0 kg·ha–1 N increased root proliferation at a depth of 6.5 to 19.5 cm, while MP with 180 kg·ha–1 N increased root proliferation at greater depths. Total root count between 1 and 58.5 cm was not influenced by management practices, but increased linearly at rates of 0.35 roots/cm2 per day from 20 June to 11 July 1996, and 0.03 roots/cm2 per day from 16 May to 5 Aug. 1997. Root growth thereafter was minimal. Because of the higher temperature during early development, growth rate and number of roots were greater in 1996 than in 1997. Superior moisture conservation, accompanied by increased N availability, may have increased root proliferation in the surface soil in NT with HV or with 0 kg·ha–1 N compared with NT with NHV or with 180 kg·ha–1 N, and MP with or without HV or with or without N fertilization. Root growth, however, was not related with aboveground tomato yield.
Sven Verlinden, Louis McDonald, James Kotcon, and Silas Childs
In 1999, West Virginia University (WVU) established an organic farming systems project with a market garden section consisting of 32 plots measuring 16 × 25 ft arranged in a completely randomized design. Sixteen of these plots were managed as high-input and 16 as low-input plots. High-input plots received 10 tons/acre per year of dairy manure and a rye-vetch (Secale cereale and Vicia villosa) cover crop during each winter season since the inception of the experiment in 1999. Fertility in low-input plots was managed solely with an annual rye-vetch cover crop while both treatments also received 5 tons/acre of mixed species hay used as mulch in 2 of every 4 years. A 4-year rotation of crops, green bean (Phaseolus vulgaris), zucchini (Cucurbita pepo), tomato (Solanum lycopersicum), green pepper (Capsicum annuum), and lettuce (Lactuca sativa) in the Fabaceae, Cucurbitaceae, Solanaceae, and Asteraceae families, was established in 1999 and has been maintained ever since. Soil organic matter (SOM) in the upper 6 inches of the soil profile (4.4% in 1999) has remained unchanged in low-input plots at 5.2% in 2004 and 5.4% in 2014, the year following transition and most recent data collection, respectively. During this same time period, significant increases in SOM from 6.4% in 2004 to 8.7% in 2014 were observed in high-input plots. Bulk density was lower in high-input plots than low-input plots in 2014. Despite these improvements in soil quality, high-input plots showed very high levels of phosphorus and potassium. Over the duration of the experiment, yearly manure application increased yields by 22% in all crops combined; however, individual crops responded quite differently. The yield was 9%, 25%, 24%, and 24% higher in high-input plots than in low-input plots for tomato, pepper, zucchini, and green bean, respectively. Manure application in addition to green manures and hay mulch incorporation was found to result in significant economic returns.
Lidia M. Carrera, Aref A. Abdul-Baki, and John R. Teasdale
Cover crops combined with conservation tillage practices can minimize chemical inputs and improve soil quality, soil water-holding capacity, weed suppression and crop yields. No-tillage production of sweet corn (Zea mays var. `Silver Queen') was studied for 2 years at the USDA Beltsville Agricultural Research Center, Md., to determine cover crop management practices that maximize yield and suppress weeds. Cover crop treatments were hairy vetch (Vicia villosa Roth), rye (Secale cereale L.) and hairy vetch mixture, and bare soil (no cover crop). There were three cover crop killing methods: mowing, rolling or contact herbicide paraquat. All plots were treated with or without atrazine and metolachlor after planting. There was a 23% reduction in sweet corn plant population in the rye-hairy vetch mixture compared to bare soil. Averaged over both years, sweet corn yield in hairy vetch treatments was 43% greater than in bare soil, whereas yield in the rye-hairy vetch mixture was 30% greater than in bare soil. There were no significant main effects of kill method or significant interactions between kill method and cover crop on yield. Sweet corn yields were not different for hairy vetch or rye-hairy vetch treatments with or without atrazine and metolachlor. However, yield in bare soil without the herbicides atrazine and metolachor were reduced by 63% compared to bare soil with these herbicides. When no atrazine and metolachlor were applied, weed biomass was reduced in cover crops compared to the bare soil. Regression analysis showed greater yield loss per unit of weed biomass for bare soil than for the vetch or rye-hairy vetch mixture. This analysis suggests that cover crops increased sweet corn yield in the absence of atrazine and metolachlor not only by reducing weed biomass, but also by increasing the competitiveness of corn to weeds at any given biomass.
Laura Avila, Johannes Scholberg, Lincoln Zotarelli, and Robert McSorely
Poor water- and nutrient-holding capacity of sandy soils, combined with intense leaching rainfall events, may result in excessive N-fertilizers losses from vegetable production systems. Three cover cropping (CC) systems were used to assess supplemental N-fertilizer requirements for optimal yields of selected vegetable crops. Fertilizer N-rates were 0, 67, 133, 200, and 267; 0, 131, and 196; and 0, 84, 126,168, and 210 kg N/h for sweet corn (Zea mays var. rugosa), broccoli (Brassica oleracea), and watermelon (Citrullus lanatus), respectively. Crop rotations consisted of sunn hemp (Crotalaria juncea) in Fall 2003 followed by hairy vetch (Vicia villosa), and rye (Secale cereale) intercrop or a fallow. During Spring 2004, all plots were planted with sweet corn, followed by either cowpea (Vigna unguiculata) or pearl millet (Pennisetum glaucum), which preceded a winter broccoli crop. Hairy vetch and rye mix benefited from residual N from a previous SH crop. This cropping system provided a 5.4 Mg/ha yield increment for sweet corn receiving 67 kg N/ha compared to the conventional system. For the 133 N-rate, CC-based systems produced similar yields compared to conventional systems amended with 200 kg N/ha. Pearl millet accumulated 8.8 Mg/ha—but only 69 kg N/ha—and potential yields with this system were 16% lower compared to cowpea system. For a subsequent watermelon crop, trends were reversed, possibly due to a delay in mineralization for pearl millet. Because of its persistent growth after mowing, hairy vetch hampered initial growth and shading also delayed fruit development. Although CC may accumulate up to 131 kg N/ha actual N benefits, N-fertilizer benefits were only 67 kg N/ha, which may be related to a lack of synchronization between N release and actual crop demand.
Nancy G. Creamer, Mark A. Bennett, Benjamin R. Stinner, and John Cardina
Four tomato production systems were compared at Columbus and Fremont, Ohio: 1) a conventional system; 2) an integrated system [a fall-planted cover-crop mixture of hairy vetch (Vicia villosa Roth.), rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), and barley (Hordeum vulgare L.) killed before tomato planting and left as mulch, and reduced chemical inputs]; 3) an organic system (with cover-crop mixture and no synthetic chemical inputs); and (4) a no-input system (with cover-crop mixture and no additional management or inputs). Nitrogen in the cover-crop mixture above-ground biomass was 220 kg·ha-1 in Columbus and 360 kg·ha-1 in Fremont. Mulch systems (with cover-crop mixture on the bed surface) had higher soil moisture levels and reduced soil maximum temperatures relative to the conventional system. Overall, the cover-crop mulch suppressed weeds as well as herbicide plots, and no additional weed control was needed during the season. There were no differences in the frequency of scouted insect pests or diseases among the treatments. The number of tomato fruit and flower clusters for the conventional system was higher early in the season. In Fremont, the plants in the conventional system had accumulated more dry matter 5 weeks after transplanting. Yield of red fruit was similar for all systems at Columbus, but the conventional system yielded higher than the other three systems in Fremont. In Columbus, there were no differences in economic return above variable costs among systems. In Fremont, the conventional systems had the highest return above variable costs.
Kyle E. Bair, Robert G. Stevens, and Joan R. Davenport
Concord grape (Vitis labrusca L.) accounts for a majority of juice grapes produced in Washington State. Because synthetic nutrients are not permissible in USDA organically-certified production systems, legume cover crops are used to supply nitrogen (N) to the crop. In order to supply a sufficient amount of N, the cover crop must successfully establish and produce large quantities of biomass. This study evaluates how the planting date influences emergence and biomass production of hairy vetch (Vicia villosa subsp. villosa L.) and yellow sweet clover [Melilotus officinalis (L.) Lam.] when used as legume green manures. The research was conducted on a commercial vineyard and a research vineyard from 2003–05. Treatments for the study consisted of yellow sweet clover and hairy vetch planted in both the spring and fall. Plots receiving soluble N sources were planted with wheat (Triticum aestivum L.) or rye (Secale cereale L.). Because of the large relative seed sizes of rye, wheat, and hairy vetch compared to yellow sweet clover, these treatments established faster with good stands in 2004. In 2005, clover plots had high emergence and biomass production because of water management modifications. Biomass data from the commercial vineyard in May 2005 indicates that fall-planted vetch produced more biomass than spring-planted vetch. Fall-planted hairy vetch and yellow sweet clover in the research vineyard showed higher biomass production than spring- and fall-planted hairy vetch and yellow sweet clover. When hairy vetch and yellow sweet clover are planted in the fall, they generally have better seedling emergence and biomass production due to the heightened aggressiveness exhibited by competing weed species during late spring and summer.
W.F. Whitehead and B.P. Singh
Conventional production of tomatoes (Lycopersicon esculentum Mill.) requires substantial investments, intensive management and high inputs of nitrogen. High N rates invariably leave residual soil NO3-N with the potential of polluting ground water and posing health hazard to humans and animals. The objective of this study was to examine the value of cover crops as a substitute to synthetic N fertilizer in growing of tomatoes. The experimental treatments consisted of control (no N fertilizer or cover crop), Abruzzi rye (Secale cereale L), hairy vetch (Vicia villosa Roth), or crimson clover (Trifolium incarnatum L.) cover crop, and fertilization of N at 90 or 180 kg·ha-1. The treatments were replicated four times over 2 years in a randomized complete block experiment for growing `Mountain Pride' tomato on a Greenville fine sandy loam soil. The parameters used to evaluate the performance of tomato consisted of leaf area index (LAI), gas exchange (GE), above ground plant dry weight, number of fruits, dry weight of fruits, and marketable fruit yield. Tomato LAI was similar under legumes and N fertilizers. Hairy vetch and applied N at 90 kg·ha-1 influenced net photosynthesis (Pn) and transpiration (E) the most in both years at all stages of growth. Highest number of tomatoes were produced in hairy vetch and applied N at 90 kg·ha-1 plots. There was no significant difference in the above ground plant dry weight, fruit yield and dry weight of fruits between legumes and N fertilizers. The results suggested that the legume cover crops compared favorably to N fertilizers in promoting tomato growth and development and may have potential of substituting N fertilizers in fresh-market tomato production.