Performing Department
(N/A)
Non Technical Summary
High-intensity specialty crop production in sub-tropical climates is facing increased challenges due to unpredictable climate, low nutrient and water holding capacity, and high disease and pest pressures. Producers are interested in practices that improve the sustainability and resiliency of their systems. Practices including compost, cover crops, and fumigation alter the soil microbiome in ways that can be beneficial to the resiliency of the production systems to biotic and abiotic stresses. However, while fumigation is a standard practice for high-intensity specialty crop production in sub-tropical climates, compost and cover crops are less common, particularly because of challenges of three different fallow periods per year.This project will determine how combinations of cover crops, compost, and fumigation alter the soil environment to improve crop production and the resiliency of the system to biotic and abiotic stresses. Suitable cover crop species/varieties for the multiple fallow periods of sub-tropical high-intensity specialty crop production will be tested at a university farm. Field trials in commercial farms will then be conducted to examine the integration and impacts of selected cover crops and/or compost with fumigation on the soil microbiome, disease and pest incidence, and crop growth, yield and fruit quality. Providing stakeholders with information about the results will occur through a variety of extension activities to promote adoption.
Animal Health Component
60%
Research Effort Categories
Basic
40%
Applied
60%
Developmental
(N/A)
Goals / Objectives
The overarching goal is to determine how combinations of management practices (cover crops, compost, and fumigation) alter the soil environment to improve crop production and the resiliency of the production system to biotic and abiotic stresses. Our supporting objectives (SO) are to:SO1:Identify annual cover crop species suitable for use in different fallow periods of sub-tropical climates for high-intensity crop production that also alter the abundance of potentially beneficial microbial taxa and/or generate large amounts of biomass for microbial decomposition.SO2:Investigate the synergistic effect of fallow period cover crops and compost application with pre-plant fumigation on the soil microbiome, disease and pest pressure, plant growth, and crop yield and fruit quality.SO3:Promote the use of cover crops and/or compost during fallow periods to enhance the resiliency of high-intensity specialty crop production to diseases and pests and improve crop growth and production through extension activities.
Project Methods
Methods for Objective 1:We will conduct field trials at the UF/IFAS SWFREC farm to identify cover crop species suitable for the fallow summer and winter periods. Field soil will be prepared prior to planting following the standard practices used by commercial tomato producers. Cover crops will be grown in May-July for the summer fallow period, September-December for the winter fallow, and November-February for spring fallow. Three species will be grown for approximately 3 months in each period in in a randomized complete block design with 4 blocks each. The same block design will be followed for plants grown on soil supplemented with and without compost. All cover crops will be planted with a no-till seed drill. Cover crops will be terminated mowing and incorporating the fresh material into the soil for decomposition.Once per week, the NDVI index of the cover crops will be measured. Cover crop biomass will be determined on the day of termination by mowing and weighingseveral 0.5m2areasusing a quadrant system. Samples of fresh cover crop biomass will be collected for leaf nutrient analysis. The cover crops will be incorporated into the soil for decomposition and future sampling for further soil analysis after 2 weeks, 1, and 2 months.Nematode soil samples will be collected from each plotat the beginning and end of the cover crop period.For nematode analysis, a 200-cc soil sample will be extracted using a modified Baermann method at the GCREC Nematology Lab.The relative abundance of specific nematode feeding groups will be quantified as indicator organisms as to the health of the soil ecosystem. Nematodes within samples will be identified to feeding groups based on buccal cavity morphology. Plant parasitic nematodes will be further identified to genus or species level and any root damage (galls) will be evaluated at the end of the season.Soil for the assessment of the soil microbiome and physiochemical properties will be collected from each replicate immediately prior to termination. Basic properties to be assessed include soil bulk density, organic matter content, total carbon (C), and total nitrogen (N), C:N ratio, CEC, and pH.Soil DNA will be extracted and quantified from soil samples at the UF/IFAS SWFREC Soil Microbiology lab. The total abundance of specific potentially beneficial taxa,BacillusandTrichoderma, will be quantified by qPCR. The abundance of key N- and P-cycling genes will be estimated by qPCR.Growth and biomass of cover crops will be assessed using a generalized linear mixed model analysis with replicate blocks treated as random effects and standard post-hoc tests. Multivariate statistical analyses will be performed to determine the influence on cover crops with or without compost on abiotic and biotic parameters.Methods for Objective 2:Field trials will be conducted at two commercial tomato farms in Southwest Florida. Cover crops will be selected based on the results of Obj. 1 and planted in the same manner. Treatments will include cover crops alone, cover crops + compost, compost only, and a no-treatment control and will be arranged in a randomized complete block design with 4 blocks.Plant-based compost will be applied via broadcast during the fallow period either after planting of cover crops or without cover crops. When compost is applied without cover crops, it will be tilled into the soil to a depth of 30 cm.All treatments will have plasticulture beds formed using grower standard practices and fumigated with Pic-Clor 60. Trials will be conducted for two years during the summer-fall and winter-spring growing seasons, with cover crops grown during each fallow period. Tomatoes will be grown following the grower standard practices used at each farm. Similar assessments of cover crops as described in Obj. 1 will be made for each growing season.The plant height, stem diameter, stomatal conductance, chlorophyll fluorescence, and spectra reflectance will be taken on20 pre-selected plants in each treatmentonce per week and fruit yield and number of fruit per plant will be recorded during harvest.Twenty fruit in each treatment will be harvested at the same ripening stage and their nutritional quality will be determined upon postharvest storage at room temperature.Nematode soil samples will be collected from each plotat the beginning and end of the cover crop, and at planting and final harvest of the tomato crop and measured as described above.Disease incidence will be rated throughout the tomato season based on the proportion of dead or infected plants counted in each plot. Disease identification will be confirmed in the lab based on standard isolation procedures.Bulksoil samples for the assessment of the soil microbiome and physiochemical properties will be collected from each replicate at four time points.Tomato rhizosphere soil will be sampled with a soil corer. Each replicate rhizosphere sample will be collected 4- and 8-weeks after planting.Serial dilutions of additional soil aliquots will be plated onto semi-selective media to enumerateTrichodermaandF. oxysporumin soils. Representative fungal isolates will be typed based on sequencing of ITS, TEF and DNA-directed RPB2 loci.Basic properties to be assessed will be same as described in Obj. 1.Samples collected from treatments that show significant impacts on plant health or yield, disease, and/or nematode pressure will be analyzed to determine treatment impacts on the soil microbiome. Soil RNA will be extracted from soil samples at the UF/IFAS SWFREC Soil Microbiology lab, converted into cDNA, andquantified. This cDNA will be sent to an outside facility for high throughput amplicon sequencing of the bacterial V4-V5 hypervariable regions of the 16S rRNA gene using 515F/926R primers and the Illumina MiSeq platform. Fungal and Fusarium communities will be assessed based on ITS1/ITS2 and TEF1α amplicon sequencing, while specific quantification ofTrichoderma,FOL, andFoxywill use qPCR as described in Obj. 1.Similar analyses as described in Obj 1 will be performed to determine growth of cover crops. Amplicon sequence data will be analyzed in QIIME2 and R as described previously. To assess the influence of cover crops with or without compost, sampling points, and abiotic (soil physiochemical) parameters on disease incidence, nematode abundance, soil microbiome, plant growth, and yield, we will use multivariate statistical analyses.Methods for Objective 3:Results from the project will be used to develop guidelines and how-to guides for the use of cover crops and/or compost during the fallow periods of high-intensity fruit and vegetable production. Extension articles will be written for the web-based University of Florida extension article system, e-Xtension, and trade magazines. The PD and CoPIs will present results at multiple grower meetings. A full-day In-Service-Training session for county and state extension agents will be conducted at the SWFREC to provide agents with detailed information regarding the trials and results that they can also present to their growers along with factsheets developed by the PIs. These factsheets will include specific details on cover crop varieties suitable for different fallow periods, seeding rates, and termination methods. All project participants, including graduate students, will present research results to other scientists at society meetings.We will use the field trials for field day workshop events, both in-person and virtual, aimed at growers, extension agents, and industry representatives. There will be two in-person workshops held at the University of Florida SWFREC. As the management practices being examined in this project are applicable to high-intensity specialty crops other than tomatoes and other regions besides Florida, we will develop a virtual workshop and tour that will be advertised and made available via Zoom.