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

Virginia Component. A unique organic raised-bed (185-cm wide) zone production system was studied at Virginia Tech. On 20 July 04, bed tops (75-cm wide) were drill-seeded with three different summer cover crops: sunn hemp (SH), lablab (LL) and bell bean (BB), compared to a control, no cover crop (NC). Alleyways (bed shoulders and bottoms, 110-cm wide) were seeded with sorghum sudangrass (SSG) in all plots except the control. On 26 April 05, potato seed pieces were no-till planted in twin rows (50-cm apart) and grown without using chemical fertilizers or pesticides.
Weed suppression was best in plot areas covered with SSG, SH and LL residues; weed suppression was particularly poor in no-cover plots. Tuber yields were excellent in all treatments, averaging 25.4 t/ha; however, yield was 14% higher in SH and LL plots than in BB and NC.
Florida Component. Additional progress was made in developing an alternative pepper production system without the use of methyl bromide soil fumigant. Yields (kg ha-1) of peppers obtained by growing a nematode-resistant summer cover crops and covering the beds with a thick layer of compost with fallow as a control were as follows: A. Soil Treatments: (1) compost, 16,492 a, (2) MC-33, 9,384 b, (3) no fumigation, 8,631 b; B. Cover Crops (4) sunn hemp, 12,466 a, (5) velvetbean, 13,605 a; (6) sorghum sudangrass, 10,765 ab and (7) fallow, 9,176 b However this system failed to suppress yellow nutsedge on the compost plots, which had to be hand-weeded twice.
An automated precision irrigation system was developed and evaluated for production of tomato and other high value horticultural crops on highly porous soils with poor water-holding capacities. Various aspects of the system were described in 3 extension publications.

Objectives/Performance Targets

Objectives (Virginia): Assess the effects of an organic-based (high residue no-till cover crop mulch) on tuber and pest incidence of Irish potato. Disseminate research finding and facilitate adoption of high residue no-till systems for production of organic potatoes.
Performance targets(Virginia): We anticipated that (1) cover crops would produce a high residue mulch that would suppress weed growth and lower incidence of Colorado potato beetle below crop-yield limiting levels; and (2) tuber yield would be equal or exceed that obtained in the control plots.
Objective/Performance Targets (Florida): 1. Develop sustainable production systems for tomato, and pepper each based on use of nematode- and pathogen-resistant cover crops (cowpea, 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.

Accomplishments/Milestones

Virginia Component: Second year-year organic tuber yields following sunn hemp and lablab were excellent; and they averaged 14% higher than conventional plots or in plots on which lablab had been grown. Suppression of weeds was best on plots with winter-killed residues of sorghum sudangrass, sunn hemp and lablab and on the no-cover crop control.
Florida Component: 1a. Development of an alternative tomato production system.
We have reached our end-points and have documented our accomplishments on feasibility of profitable tomato production using nematode-resistant cover crops or automated high frequency low volume irrigation in part as follows:
Abdul-Baki, A. A.,W. Klassen, H. H. Bryan, M. Codallo, B. Hima, Q. R. Wang, Y. Li, Y.-C. Lu and Z. Handoo. 2005. A Biologically-Based System for Winter Production of Fresh-Market Tomatoes in South Florida. Proc. Fla. State Hort. Soc. 118: 153-159.
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006a. Low cost injection system combined with soil-moisture-based irrigation for precision fertigation of vegetable crops. EDIS.
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006b. Selecting and calibrating Venturi injectors for fertigation of vegetable crops. EDIS.
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006c. Fertigation methods for soil moisture-based irrigation of field-grown tomatoes on coarse soils in Florida. EDIS.
1b Development of an alternative pepper production system.
We applied for a one-year no-cost extension in order to repeat some of the experiments and to develop the economic data.
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.
For tomato this work was completed, but for pepper it will be brought to closure in the next winter growing season.
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.
This work has been largely completed and documented in a number of publications. Several publications are in preparation.
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.
Enterprise budgets have been prepared for tomato but not for pepper. Also more needs to be done with respect to constraints.
5. Disseminate research findings and facilitate adoption of sustainable vegetable production systems in Florida, Virginia and other southern states.
We need to post results on our web page and prepare additional extension publications.

Impacts and Contributions/Outcomes

Virginia Component: Based on data from 2005 and previous research, we are confident that organic potato growers can use high-residue no-till systems to produce profitable potato yields and better maintain the production capacity (sustainability) of their soil than with conventional inversion tillage/cultivation systems. The field work has been completed. Presentations were given by Dr. Ron Morse on various aspects of organic no-till production of vegetables – including potato – at state and regional meetings. An economic assessment will be completed. A manuscript is being prepared.
Florida Component: The feasibility of using a biologically-based system for winter production of fresh-market tomatoes in south Florida fields with light to moderate infestations of the root knot nematode, and yellow nutsedge was evaluated. The system consisted of a cropping rotation in which nematode-resistant cover crops [cowpea cv. Iron Clay, velvetbean, and sunn hemp cv. Tropic Sun] were each followed by tomato, and a standard methyl bromide/chloropicrin (MC-33) treatment preceded by a summer sorghum sudangrass. Each treatment was replicated four times in all years. Economic analysis shows that all treatments resulted in positive net returns in all years. Returns in 2003/04 were the highest of all study years due to high yields and high market prices. Among the cover crops, sunn hemp produced the highest yields and net returns of all treatments over the two years it was used.
Abdul-Baki, A. A.,W. Klassen, H. H. Bryan, M. Codallo, B. Hima, Q. R. Wang, Y. Li, Y.-C. Lu and Z. Handoo. 2005. A Biologically-Based System for Winter Production of Fresh-Market Tomatoes in South Florida. Proc. Fla. State Hort. Soc. 118: 153-159.
A new irrigation controller was developed with readily available components, coupled with an inexpensive dielectric soil water probe. The electronic controller was designed to be easily adapted to existing commercial irrigation systems that currently use time clocks with a pressurized water supply. Total cost of components used in this controller was US$124 including the US$60 sensor. The new device was field tested against other common automatic scheduling methods (fixed timer and variable timer based on historical evapotranspiration) on a drip irrigated plastic mulched tomato field in South Florida. The soil moisture feedback irrigation control with this new device saved up to 74% water with respect to the typical irrigation rates applied by commercial tomato growers in the area based on a fixed irrigation schedule for the winter tomato season in 2003-04. Comparisons with evapotranspiration based application rates for the area also showed water savings of up to 61%. Although similar savings (up to 79%) were obtained with switching tensiometers, these devices are difficult to maintain in the coarse soils of South Florida. The new controller proved reliable and simple to use although field adjustment of the water set point from laboratory calibration was necessary.
Muñoz-Carpena, R., M.D. Dukes, Y.C. Li and W. Klassen. 2006. Design and field evaluation of a new controller for soil moisture-based irrigation. Applied Engineering in Agriculture (accepted, Manuscript no. SW-06008-2005, August 2005).
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006a. Low cost injection system combined with soil-moisture-based irrigation for precision fertigation of vegetable crops. EDIS.
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006b. Selecting and calibrating Venturi injectors for fertigation of vegetable crops. EDIS.
Munoz-Carpena, R., J. Schroder, M. Dukes, Y. Li and W. Klassen. 2006c. Fertigation methods for soil moisture-based irrigation of field-grown tomatoes on coarse soils in Florida. EDIS.

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