northern New England, however, short growing seasons can limit opportunities to establish productive cover crops between cash crop growing periods, particularly in vegetable crop rotations ( Snapp et al., 2005 ). In these cases, living mulch (LM) systems, a
Nicholas D. Warren, Richard G. Smith and Rebecca G. Sideman
Daniel C. Brainard, John Bakker, D. Corey Noyes and Norm Myers
Cover crops growing below crop canopies provide several potential benefits in vegetable cropping systems. During extreme rainfall events, these “living mulches” protect the soil from degradation and reduce the risks of nutrient and pesticide runoff
James Leary and Joe DeFrank
An important aspect of organic farming is to minimize the detrimental impact of human intervention to the surrounding environment by adopting a natural protocol in system management. Traditionally, organic farming has focused on the elimination of synthetic fertilizers and pesticides and a reliance on biological cycles that contribute to improving soil health in terms of fertility and pest management. Organic production systems are ecologically and economically sustainable when practices designed to build soil organic matter, fertility, and structure also mitigate soil erosion and nutrient runoff. We found no research conducted under traditional organic farming conditions, comparing bareground monoculture systems to systems incorporating the use of living mulches. We will be focusing on living mulch studies conducted under conventional methodology that can be extrapolated to beneficial uses in an organic system. This article discusses how organic farmers can use living mulches to reduce erosion, runoff, and leaching and also demonstrate the potential of living mulch systems as comprehensive integrated pest management plans that allow for an overall reduction in pesticide applications. The pesticide reducing potential of the living mulch system is examined to gain insight on application within organic agriculture.
Annual ryegrass (Lolium multiflorum), which grows prolifically during the strawberry production season in the Gulf South, has the potential to serve as a living mulch if its growth is controlled. Sublethal dosages of Embark, a plant growth regulator, and the herbicides Poast and Rely were determined on ryegrass. Growth retardation was rated from 0 = none to 6 = dead. In 1993, all Poast dosages (1/8X – 1X, where X = 8 ml·L–1) were lethal. Embark regulated ryegrass growth, but its study was discontinued because of the unlikelihood that it could be labeled for use on strawberries. Results of the 1994 study suggested that prime oil in the spray may cause an inordinate amount of vegetative browning. In 1995, three levels of oil (1/256X, 1/64X, and 1/32X, where X = 8 ml·L–1) were used with each of four levels of Poast (0, 1/32, 1/64, and 1/128X). Increased levels of oil generally caused increased browning at each level of Poast, but no browning occurred where oil only was applied in the spray. In contrast to results in 1995, oil at 1/32X with no Poast caused considerable browning (score = 3.25) in 1996. The most desirable control (score = 2.75) was accomplished by a spray containing 1/128X Poast and 1/64X oil. The most desirable control by Rely (score = 3.25) was accomplished by 1/64 and 1/32X sprays. Rely is not labeled for strawberries although it is labeled for other fruit crops. Chemical names used: 2-[1-(ethoxylmino)buty1]-5-[2-(ethylthio)propy1]-3-hydroxy-2-cyclohexen-1-one (Poast); Paraffin Base Petroleum Oil + polyol Fatty acid Esters (Prime oil); N-[2,4dimethyl-5-[[(trifluoromethyl)-sulfony]amino]phenyl] acetamide (Embark); ammonium-Dl-homoalanin-4-yl-(methyl) phosphinate (Rely).
Kim Patten, Gary Nimr and Elizabeth Neuendorff
Blueberry production is enhanced by the use of an organic mulch. An alternative to off-farm sources of mulch is the production of winter and summer living mulch cover crops grown in the row middles of the blueberry planting. These crops are mowed and then windrowed for use as a mulch. We evaluated living mulch crops for blueberries for the following parameters: adaptation to low soil pH, mulch production, ease and cost of stand establishment, mowing tolerance, allelopathic weed control, and N contributed by mulch. Rye, ryegrass, and crimson clover were the most overall suitable crops for the winter; while for summer, pearl millet was best adapted. Nitrogen was the major limiting factor that affected nonlegume production. Legume yields were limited by deer foraging and low soil pH. Pearl millet had the greatest allelopathic response on weeds of all cover crops tested. Maximum dry matter production for the living mulches ranged from 6000 kg/ha for elbon rye in the winter, to 30,000 kg/ha for pearl millet in the summer. With the appropriate cover crop selection and adequate soil fertility living mulches appear to be a efficacious practice to aid blueberry production in the south.
Laura K. Paine and Helen Harrison
Since the domestication of the first crop species, farmers have dealt with the problem of soil depletion and declining crop yields. Fallowing of land was the first approach to restoring soil fertility, and is still the most commonly used method among indigenous farmers. Alternatives to fallow, such as crop rotation and green manures, developed in a number of areas. The earliest record of their use is in Chinese writings from ca. 500 B.C. Discussion of these practices is found in European agricultural publications dating from the 16th century. While these ancient techniques have proven value for soil conservation, their use in modern agriculture is quite limited. Renewed interest within the agriculture community in recent decades has resulted in a greater research effort in the areas of green manures, cover crops, and living-mulch cropping systems.
Laura Paine, Astrid Newenhouse and Helen Harrison
Seedlings of Syn 4-56 hybrid asparagus were planted in May, 1990 on loamy sand in the irrigated Central Sands region of Wisconsin. Treatments were unsuppressed living mulches of perennial ryegrass, Dutch white clover, a mixture of ryegrass and clover and cultivated bare ground. Ammonium nitrate was banded at rates of 90, 45, and 0 kg/ha across all treatments. Measurements of weed populations, asparagus growth, and soil and tissue nitrogen levels were made in 1990 and 1991. Soil nitrate and ammonium levels were measured in 30 cm increments to a depth of 90cm. In 1990, asparagus fern growth was greater in the bare ground controls than in any of the mulch treatment plots. In 1991, asparagus growth in the clover-based mulches was greater than that in the ryegrass mulch, although also still less than that of the bare ground control. Total accumulated nitrogen in clover-based mulch plots at the end of each season was more than twice the level of that of either the grass mulch or the cultivated plots. Percent nitrogen in asparagus tissue varied with mulch treatment: in 1991, the %N was higher in the asparagus tissue grown with clover than either that grown with the grass or on bare ground. Weed control in all mulch plots was good; in clover plots it was nearly 100%.
Dru Bernthal*, Elsa Sánchez and Kathleen Kelley
A field trial investigating the use of living mulches for weed management in edamame (Glycine max), also known as vegetable soybean, was conducted in 2003 at the Russell E. Larson Agricultural Research Center, Rock Springs, Pa. Edamame was direct seeded on 24-25 June 2003. Seven weeks later, the living mulch treatments were broadcast seeded. The living mulch species were white clover (Trifolium repens), buckwheat (Fagopyrum esculentum) and a control with no living mulch (bare ground). Each living mulch plot was divided into a weeded and non-weeded subplot. Weed pressure was evaluated every 2 weeks from the time living mulches were sown. Data collected included the total number of weeds present, number of different species present, number of broadleaf and grass species and number of annual and perennial species. The total number of weeds in weeded and non-weeded subplots was lowest in the buckwheat and highest in the clover. Species diversity in weeded subplots was lowest for the control and highest in clover while species diversity in non-weeded subplots was lowest in buckwheat and highest in the control. Overall, most weeds present were broadleaf annuals including pigweeds (Amaranthus spp.), shepard's purse (Capsella bursa-pastoris), common lambsquarters (Cheno-podium album) and common purslane (Portulaca oleracea). Based on this 1-year study, which will be repeated in 2004, the buckwheat treatment is likely the most effective in managing weeds in edamame field production for consideration by Pennsylvania growers.
Hector R. Valenzuela and Joseph DeFrank
Living mulches offer a low-input alternative to achieve weed control while minimizing herbicide applications, decreased fertilizer leaching, insect and nematode management. and improved soil texture. A study was conducted to evaluate the effect of a Rhodes Grass (Chloris gayana cv. Katambora) living mulch on the growth and productivity of ten eggplant. Solanum melongena, cultivars grown under fertigation. The living sod was established at the Univ. Hawaii Waimanalo Experiment Station in June 1992. Soil analysis was taken before experiment initiation. Ten eggplant cultivars were transplanted on both living-mulch and control (woven-polyethelene mulch) plots on 4 March 1993. Weekly or bi-weekly harvests were conducted for six months. beginning on 19 May 1993. In addition plant height and canopy dimensions were determined on 16 April. and 10 Nov. Plant growth was monitored throughout the experiment. Soil samples were taken from the eggplant rhizosphere, hare-ground and in Rhodes grass monoculture, for nematode count determinations. Soil samples were also taken for nutrient determination after completion of the experiment. Overall yields were greater in the polyethelene mulch than in the living mulch plots. A differential response was observed on the response of cultivars to cropping system. However the most vigorous cultivars performed well in both systems. The living mulch system showed potential for nematode management in eggplant agroecosystems.
Stephen Reiners and Olga Wickerhauser
The possibility of using annual grain rye (Secale cereale L.) as a living mulch between rows of black plastic mulch was investigated. Rye was seeded immediately after plastic was laid and ≈30 days before transplanting bell pepper (Capsicum annuum L.) seedlings. Rye growth was controlled by postemergence herbicides and mowing or was left unmowed. These treatments were compared to a weedy control, cultivation, and standard preemergence herbicides for their effect on weed control and bell pepper yield. Within the rye treatments, the unmowed rye provided the best weed control and significantly decreased the number and size of weeds between crop rows. The rye cover crop also significantly reduced the yield of peppers. In both the mowed and unmowed rye treatments, total marketable yield was reduced 50% compared to clean cultivated and herbicide-treated plots. Further work is needed to minimize the competition between the living mulch and the crop.