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Author Linares B., Jose Clemente
Title Integrative use of perennial and annual cover crops for weed management in organic citrus
book jacket
Descript 207 p
Note Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3513
Adviser: Johannes M. Scholberg
Thesis (Ph.D.)--University of Florida, 2006
Citrus is one of the most important crops in Florida. During the past decade increased international competition and urban developments, diseases, and more stringent environmental regulations have greatly affected the citrus industry. Citrus growers transitioning to organic production may benefit from premium prices, but they also face many challenges, including development of efficient weed management strategies. Cover crops (CC) may constitute an environmentally sound alternative for improved weed management in organic systems. Two field experiments were conducted at Citra in North Central Florida, to test performance and the effectiveness of annual and perennial CC to suppress weeds in organic groves. A greenhouse trial was also implemented to evaluate potential competition between citrus and groundcovers. For annual CC, summer CC had the greatest biomass and N accumulation in comparison with winter CC. Sunnhemp, hairy indigo, cowpea, and alyceclover provided excellent weed suppression, which was superior to tillage fallow. Mono-cropped winter CC did not always perform consistently well. Use of winter CC mixtures resulted in more consistent overall CC performance, greater dry matter production, N accumulation, and more effective weed suppression. In both annual and perennial systems, weeds played a complementary role in nutrient retention and recycling. Perennial peanut (PP) showed slow initial growth and summer planting of PP was the most successful compared with spring planting. Over-seeding PP planted in summer with crimson clover reduced PP growth and its effectiveness in suppressing weeds. Initial weed suppression by PP was very poor to poor; however, effectiveness of PP to reduce weed growth improved gradually over time. Annual CC provided much better weed control than PP. For both PP and annual CC, weed biomass typically was inversely related to CC DW accumulation due to competition for resources. In a greenhouse experiment, citrus and bermudagrass appeared to compete for N during summer, while citrus and PP did not compete. Citrus, bermudagrass, and PP competed for water uptake during the spring and summer seasons. In general, perennial and annual CC treatments did not affect soil pH, C, N, and C:N ratio during the initial 3 years of field studies. Nematode populations did not reach high levels. Cover crop treatments in row middles did not affect weed growth dynamics in the tree row. However, planting cowpea in the tree row did decrease bahiagrass and crabgrass populations in tree rows. Planting tall cover crops such as sunnhemp near young citrus trees reduced initial tree growth. Cover crop treatments did not affect citrus leaf N, fruit yield, and quality during initial growth. Additional research is needed to assess long-term effects of cover crops on soil quality and fruit yield
School code: 0070
Host Item Dissertation Abstracts International 67-07B
Subject Agriculture, Agronomy
Agriculture, Horticulture
Alt Author University of Florida
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