Summer cover crops for weed management and yield improvement in organic lettuce (Lactuca sativa) production

Abstract

Over the last two decades, the demand for organic products has grown rapidly in the world due to increased concern about side effects of pesticides on the environment and human health. Studies were conducted in organic lettuce (Lactuca sativa L.) from 2004 to 2005 at the Black Sea Agricultural Research Institute in Samsun, Turkey, to determine the suppressive effects of summer cover crops on weeds. The experiment was arranged in a randomized complete block design with four replications. Treatments consisted of grain sorghum [Sorghum bicolor (L.)Moench.], sudangrass [Sorghum vulgare Pers. var. sudanense (Piper) Hitchc.], hairy vetch (Vicia villosa Roth.), grain amaranth (Amaranthus cruentus L.), pea (Pisum sativum L.) and bare ground with no cover crop. Weed density and total weed dry biomass were assessed before and at 14, 28, and 56 days after incorporation (DAI) of the cover crops. The cover crops produced between 1.2 and 3 t ha −1 biomass and grain sorghum produced more dry matter than any other species in both years. After incorporation of the cover crops, hairy vetch and sorghum treatments showed fewer weed species, and lower weed density than the other cover crops in both years. Hairy vetch, grain sorghum, and sudangrass were the most effective cover crops and reduced total weed dry biomass by 90. 3%, 87.4%, and 86.9% in 2004, and by 88%, 86.3%, and 85.2% in 2005, respectively. Cover crop residue suppressed many broadleaved weed species but failed to control grass weeds. Hairy vetch treatments produced the highest yield, followed by sudangrass and grain sorghum. Yields with grain amaranth and pea were similar to that of the control. These results indicate that hairy vetch, grain sorghum, and sudangrass can be used to suppress weeds in early season of organic lettuce production.

Use of Living, Mowed, and Soil-Incorporated Cover Crops for Weed Control in Apricot Orchards

“…The suppressive effects of hairy vetch on weeds have been well-reported previously, and this could suppress the weeds by more than 60% [30,31]. This cover crop (hairy vetch) was also effective in suppressing weeds in organically grown lettuce and pepper [32,33]. Cover crops' biomasses were reasonably good to suppress the weeds.…”

Effects of Cover Crops, Compost, and Vermicompost on Strawberry Yields and Nitrogen Availability in North Carolina

“…In the 2nd year of the study, however, PM decreased total strawberry yields and PM and CP treatments decreased marketable yields compared with the NOCC controls. Although other studies have found yield benefits from summer cover crops in lettuce [Lactuca sativa (Isk et al, 2009)], spring muskmelon [Cucumis melo (Wang et al, 2008)], and 'Sanibel' tomato [Solanum lycopersicum (Wang et al, 2005)], specific cover crop species and combinations can have different impacts on the subsequent cash crop. These studies were conducted in hot and subtropical climates that lead to rapid residue decomposition, similar to conditions in eastern NC.…”

Molecular, Genetic and Agronomic Approaches to Utilizing Pulses as Cover Crops and Green Manure into Cropping Systems

“…var. ), hairy vetch ( Viciavillosa ) and grain amaranth ( Amaranthuscruentus ) [ 157 ]. It seems that its efficient use especially in the winter is related to the climatic conditions.…”