Development of sustainable vegetable production systems for south Florida and Virginia based on use of cover crops and precision irrigation

Development of sustainable vegetable production systems for south Florida and Virginia based on use of cover crops and precision irrigation

Summary

Florida Component.  1. An automated drip irrigation system was devised during the summer and fall of 2003. Given the high porosity of the soil, the system provides frequent low volume water applications. Two different types of soil moisture sensors are utilized, as well as several different approaches to meeting the crop’s evapotranspiration requirements.  Tomatoes were transplanted into the beds, and the collection of yield data is complete.
2. A cover crop-snap bean-squash rotation is being grown on a commercial farm.  This is a completely randomized block experiment with 4 replicates. The treatments and marketable bean yields, kg/ha, in brackets were fallow (5220), sorghum sudangrass (6401), velvetbean (6605) and sunn hemp (6902).
3. A cover crop-okra-snap bean rotation was initiated on a commercial farm as a demonstration. The cover crop treatments and the marketable okra yields, kg/ha, in brackets were sorghum sudangrass (6187), sunn hemp (6367), and velvetbean (8011).
4. Bell peppers have been grown on a commercial farm in a completely randomized block experiment with 4 replicates. The treatments were fallow, sorghum sudangrass, sunn hemp and velvetbean with plastic or organic mulch, and with some plots fumigated with methyl bromide chloropicrin (MC-33). The plots were harvested 4 times. Yield data have not been analyzed.
5. A cover crop-grape tomato rotation was grown on a commercial farm. This is a completely randomized block experiment with 4 replicates. The treatments were fallow, sorghum sudangrass, sunn hemp and velvetbean with plastic throughout, and with some plot fumigated with methyl bromide chloropicrin (MC-33), methyl iodide, and KPAM. High and low irrigation rates were planned. However the grower has irrigated so sparingly that a lower rate could not be applied. Yield data are being collected weekly.

Virginia Component.  On 3 October 2003, cover crops were established on preformed raised beds at (1) the Kentland Agricultural Research Farm (KARF), Blacksburg, VA; and (2) two certified organic farms in southwest Virginia. In late April 2004, certified seed of “Elba” Irish potato will be planted in all plots (cover-crop mulched vs. bare-soil control), using a no-till planter (Subsurface Tiller-Transplanter, SST-T). These organic no-till experiment/on-farm demonstration plots will serve as a basis for development and dissemination of organic-based systems for Irish potato.

Objectives/Performance Targets

1. Develop sustainable production systems for tomato, pepper, potato, snap bean, squash and okra each based on use of nematode- and pathogen-resistant cover crops (cowpea, oat, sorghum sudangrass, sunn hemp, velvetbean) instead of chemical soil sterilants such as methyl bromide.  
2. Assess the effects of a cover crop based system on (a) crop yields and (b) population densities of plant parasitic nematodes, weeds and other serious pests.
3. Conduct research to reliably attain major gains in crop yields through science-based management of irrigation, fertigation and improvement of soil quality.  Study the feasibility of using automated irrigation system and soil moisture sensors to maintain the optimum moisture level in the root zone, and prevent leaching of nutrients.
4. Develop enterprise budgets of the cover crop-based production systems vs. those based on use of methyl bromide. Determine social or economic constraints to adoption of advantageous systems, and identify appropriate measures to facilitate adoption if warranted.
5. Disseminate research findings and facilitate adoption of sustainable vegetable production systems in Florida, Virginia and other southern states.

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