Cover crops have been used in agricultural systems for thousands of years and are still an important part of vegetable production in the Northeast. Winter rye (Secale cereale) is by far the dominant cover crop species on conventional vegetable farms in the New England states. It is use is primarily for erosion control. Winter rye is popular since it is cheap, easy to establish, can overwinter in the harsh winters of northern New England, is efficient in “capturing” excess nitrogen at the end of the cash crop season, and it can produce substantial amounts of organic matter in the spring. As many positive attributes that winter rye has, it is important to be aware of many of the other potential cover crop species that are available to us. For example, many conventional growers are exploring the use of leguminous cover crops as an alternative to chemical nitrogen fertilizers which are more readily leached and are only going to get more expensive. Cover crops can also be seeded and managed in innovative ways to suppress weeds and other pests, add organic matter and conserve soil moisture.
Production of carrots for cut-and-peel processing has increased to >400 ha in the past 5 years in the Holland/Bradford Marsh area (44°5' N, 79°35' W) of Ontario. To provide carrots best suited for the new industry, growers needed information on the best cultivars and production practices. Trials with cultivars from four seed companies were conducted on muck soil (60% organic matter, pH 6.0) for 3 years (1997-1999) and on mineral soil (5% organic matter, pH 7.2) for 2 years (1998-1999). Carrots were seeded on raised beds at three seeding rates—25, 40, and 55 per foot—at two or three seeding dates and were harvested at two or three dates at 15-day intervals. Plant stand was always less than the seeded rate because of hot, dry growing conditions during the years of the trials. Carrots were hand-harvested and assessed for total yield, marketable yield, oversized carrots (>0.75 in diam.), length, width, and uniformity. The seeding rate of 55 seeds/ft and harvest 100 to 110 days after seeding resulted in the highest yield of carrots suited for cut-and-peel processing. Cultivar HM03 consistently had the highest score for quality, but low yields. Other cultivars, such as `Indiana', `Caro Pride', and `Vita Treat', also had high scores for quality. Carrots grown on mineral soil were longer than those grown on muck soil; however, yields were higher for the muck-grown carrots.
'Macoun'/Budagovsky 9 apple (Malus ×domestica Borkh.) trees were planted in May 1998 in one of four preplant treatments that were soil incorporation of: 1) control, no phosphorus (P); 2) 90 g P per tree; 3) 128 kg compost per tree; and 4) 90 g P and 128 kg compost per tree. Preplant addition of P had no effect on soil organic matter, P, magnesium (Mg), and calcium (Ca) in the first three seasons after planting, but lowered soil potassium (K) in the second season. Foliar nutrients, tree growth and flowering were also not affected by P. The addition of compost increased soil organic matter and P in the first season after planting, and pH, K, Mg, and Ca in the first three seasons. The addition of compost increased foliar nitrogen and K in all three seasons, and decreased foliar Mg in the first season. Compost incorporation increased shoot length in the first season, trunk cross-sectional area in the first two seasons, tree height and the number of growing points in third season, and flowering in the third and fourth seasons. Compost addition was more effective than P fertilization for increasing tree growth during the establishment years.
The objective of this study was to determine the persistence and leaching of the herbicide oxadiazon in five substrates. The substrate mixtures consisted of the following: peatmoss, compost, and sand in the following proportions: 1:1:0, 3:3:2, 1:1:2, 1:1:6, and 0:0:1 in 5-liter containers. Rates of oxadiazon used were 4 and 8 kg a.i./ha on two separate split-split plots. Each experimental design had three factors: five substrates, four harvest times (24 h; 1, 2, and 3 months) and five soil depths (0–2, 2–4, 4–6, 6–8, 8– cm). Only herbicide persistence and leaching from the various substrates were investigated in this experiment; therefore, we did not remove plant material. Substrate oxadiazon residues were determined by gas chromatography analysis, and it was shown that leaching was more evident in media with a lower percentage of organic matter. In addition, oxadiazon did not leach below 4 cm in conventional substrate (1 peatmoss: 1 compost: 1 sand, respectively). The persistence of oxadiazon was affected by soil composition and herbicide persisted more in substrates with great percentage of organic matter.
Under heavy pressure to prolong the life of landfills, cities have been asked to reduce the amount of trash deposited in them. Yard grass clippings and prunings contribute greatly to filling up local land fills. Since green waste can be easily composted, municipalities are looking into agriculture as a potential candidate in disposing of composted material. It is common knowledge that compost is good for plants. However, most information seems to be anecdotal or testimonial. Therefore, the need for scientific-based information is highly needed if compost is to be used successfully in agricultural lands. To generate hard data, replicated test plots were conducted in watermelons, sweet corn, and tomatoes in which 10 and 20 tons per acre of community-derived, green waste, composted material was used in addition to a commercial fertilizer rate and nontreated check. Soil and tissue analyses were run three times during the season to check nutrients in plants(N, P, and K). Organic matter, electrical conductivity, and pH were analyzed from soil samples. Yields and quality determinations also were taken from all crops for comparisons. Organic matter from compost treatments increased significantly in corn and tomatoes. Electrical conductivity was lower in the composted treatments, and K increased as well. Trials are being funded by the California Integrated Waste Management Board, and it will continue for at lease 1 more year.
A 7.5 cm layer (.1 m3) of fresh or 8-year-old oak sawdust was applied to 1.7 m2 plots as a mulch or tilled in to a depth of 10 cm. Saw dust-treated and control plots received 0.45 or 227 g of nitrogen applied as ammonium nitrate. Five one-year-old `Lynwood Gold' forsythia plants were planted in each of the 90 plots in the experiment in September 1992 and were pruned in March 1993 to 20 cm above the soil surface. Plant height, soil pH and levels of Na, organic matter, P, K Ca, Mg, NO3 and NH3 in the soil were determined following the 1993 growing season. Fresh and aged saw dust reduced plant growth by 40 and 31% respectively when incorporated without supplemental nitrogen. Adding the high rate of nitrogen overcame the inhibition caused by aged but not fresh sawdust. Both materials significantly reduced soil nitrate content even when used as a mulch and reduced phosphorus when incorporated. Organic matter content of sawdust-amended plots averaged over twice that of control plots. Neither material had a significant influence on pH as determined one year after incorporation.
The benefits of composted yard waste applied as a mulch were demonstrated in a field study at two locations and supporting greenhouse research. Compost was applied to eroded roadside slopes of about 12° and 27° to determine the influence on soil displacement and establishment and/or enhancement of permanent roadside vegetation. Treatments consisted of compost rates of 5 cm and planted with asiastic jasmine (Trachelopermum asiaticum), 5 and 10 cm, seeded with 110 or 220 kg·ha–1 80:20 bahiagrass (Paspalum notatum Flugge): bermudagrass (Cynodon dactylon L.) seed mix by weight, straw erosion control mats, and bahiagrass sod. Compost treatments effectively controlled soil displacement regardless of compost rate or seeding with turfgrass at both locations. Effects on roadside vegetation and visual quality varied with location. Asiatic jasmine did not establish at either site. Compost mulch applications increased total vegetation, turfgrass density, and quality at the site with 27° slope and 4% initial soil organic matter content, but resulted in a decline in cover at the site with a 12° slope and <1% organic matter content. Compost mulch can effectively prevent soil displacement from roadside slopes, but may not promote establishment or enhancement of permanent vegetative cover.
A composting facility in New Milford, Conn. (NMF), utilizes food-processing residuals, including spent tea leaves, coffee grounds, cocoa shell and cleanings, wastewater treatment sludge from a food ingredients manufacturing plant, and past-expiration processed vegetable products. Materials are composted in aerated, frequently turned windrows under cover. The range of inputs, combined with time constraints on the composting process, has resulted in a variable, immature compost product with a high rate of microbial activity. Users have expressed concern about potential phytotoxicity or nutrient immobilization from using NMF compost. Therefore, research was conducted to determine the influence of cured and uncured NMF compost amendments on potentially sensitive crops with high nutrient requirements. Arugula (Eruca vesicaria) and green bibb lettuce (Lactuca sativa) were grown on two Connecticut organic farm research sites in 1998 and 1999. Both sites have soils classified as coarse loamy over sandy or sandy-skeletal, mixed, mesic, typic, Dystraudepts. Farms differed in the length of time under organic farm management. One farm has been an organic farm since 1988 and consequently has high soil fertility, while the other was a first-year organic farm in 1998, and had relatively low soil fertility. Three amendment types were applied: cured compost, uncured compost, and organic fertilizer (5N-3P2O5-4K2O). Amendment application rates were estimated to provide a comparable range of plant-available nutrients for the amendments and a control without fertilizer. Compost application rates were 3.4, 6.8, 20.2, 35.8, and 71.7 Mg·ha-1 (dry-weight basis) in 1998 and 11.2, 22.4, 44.8, and 89.6 Mg·ha-1 (dry-weight basis) in 1999. Organic fertilizer application rates were 1.34, 2.68, 5.36, 10.72, and 21.44 Mg·ha-1 in 1998 and 1.34, 2.68, 5.38, and 10.72 Mg·ha-1 in 1999. Soil organic matter and nutrients increased with amendment application rate at both locations. Crop yields increased with amendment rate at the new, lower-fertility farm, but yields did not respond to amendments at the older, higher-fertility farm. Yield differences were minor between the uncured and cured compost treatments at both locations. This indicates that either cured or uncured NMF food-processing residual compost can be successfully used as an organic soil amendment for salad green production.
Summer cover crops can improve soil fertility by adding organic matter, supplying nutrients through mineralization, reducing nutrient leaching, and improving soil water and nutrient holding capacity. Other benefits include weed suppression and reduction of soil parasitic nematodes. A series of field experiments have been conducted at the UF IFAS Tropical Research and Education Center in Homestead, Florida to evaluate several summer cover crops for use in vegetable production in South Florida followed by field demonstrations conducted in the growers' fields. Best performing cover crops were legumes: velvet bean (Macuna deeringiana) and sunn hemp (Crotalaria juncea L. `Tropic Sun') providing 13 and 11 Mt of dry matter/ha, respectively. Sunn hemp supplied 330 kg N/ha followed by velvet been with 310 kg N/ha. Traditional summer cover crop sorghum-Sudan produced 4 Mt of dry matter/ha and retained only 36 kg N/ha. In addition Sunn hemp significantly reduced soil parasitic nematodes for successive crops. Limitations in use of Sunn hemp by more vegetable growers in South Florida include cost and availability of seeds.