Progress 02/14/23 to 02/13/24
Outputs
Target Audience: Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for one graduate student and a postdoctoral research associate are being provided by this project, as well as several research assistants. How have the results been disseminated to communities of interest?Preliminary data from the project were presented at the annual meeting of the Soil Science Society of America in November. In addition, preliminary data was also presented to citrus and other fruit tree growers at state and regional grower meetings in Florida, including the Florida Citrus Expo in August 2023 (the largest citrus grower meeting in the state). What do you plan to do during the next reporting period to accomplish the goals?Measurements of short-term indicators and cover crop biomass will occur again in February/March 2024. Fruit harvest will occur in Spring 2024. Analyses of soil enzyme activity from preserved samples will occur throughout 2024, through the work of the current graduate student working on the project in addition to a newly recruited graduate student. This work will consist of measuring cover crop effects on soil enzyme activity through time, in addition to a comparison of soil enzyme methods to identify which methodological approach is best adapted to subtropical tree systems. Analysis of the bacterial isolates for potential PGP activities will be conducted and DNA will be extracted from soil samples collected last summer for a final amplicon sequence analysis. This activity was delayed due to the former postdoc for this project leaving and a delay in a new postdoc joining the project. Correlations and assessments of short and long-term indicators will be made to identify those to target for additional tree fruit crops. These assessments will begin during the end of summer 2024. Presentations of preliminary results will be made a regional and national scientific conferences as well as grower extension meetings.?
Impacts
What was accomplished under these goals?
During the third year of the project, we continued the field trials in two citrus orchards. Cover crops were again planted in June and November. The June mixture included sunnhemp, cowpeas, buckwheat, millet, and Egyptian wheat, and the November mixture included daikon radish, sunnhemp, black oats, Florida 401 rye, and hairy vetch. Prior to planting cover crops, the previous crops were mowed and a shallow discing of the soil was performed. The dissertation research of a PhD student is being funded by this project. SO1: In March, just before citrus harvest, soil samples were collected to assess short-term indicators and cover crop biomass was collected. The fruit was harvested during the end of March and subsamples of fruit were analyzed for fruit quality. Cover crops were then planted at the end of June. At the beginning of September, soil samples were collected for both long-term and short-term measurements from three soil depths. Leaves were also collected to assess tree nutrients. Short-term indicators were again assessed at the end of October, and cover crop biomass was collected on the same day. Cover crops were planted 6 days after the completion of the short-term indicator and cover crop biomass collections. Data analysis of the short-term and long-term indicators is ongoing as additional measurements are made each year. Cover crop biomass collected in March has been dried, weighed, ground, and sent for total C and N analysis. Cover crop biomass collected at the end of October has been dried and weighed and grinding is in progress. Germination of cover crops each season has been mixed due to the reliance on timing planting with rainfall. However, initial analysis of cover crop C:N indicates there is generally greater C:N of the cover crops compared to the weeds. Preliminary analysis of qPCR measurements of functional genes from the first two years indicates more differences in gene abundance between soil depths than between treatments. However, in the second year, there were greater differences between treatments for the abundance of the denitrification gene nosZI and archaeal ammonia oxidation for both orchards, though there was more variability in the abundances for the Young Orchard Site. Preliminary analysis of amplicon sequence data from Year 1 indicates that depth also plays a significant role in the overall microbial composition, but significant differences in the relative abundance of specific taxa are present between treatments, particularly in the fungi. Additional analyses are underway to identify taxa that may serve as potential indicators. Regarding the chemical soil health indicators measured, they were typically more sensitive to time than treatment. Significant cover crop effects in the Old Orchard Site include: 1) greater permanganate oxidizable carbon and potentially mineralizable nitrogen (only in Feb. 2023) in the legume and non-legume cover crop mix (LG+NL) compared to the grower standard control (GSC); and 2) greater in Feb. 2023 in LG+NL relative to GSC. In the Young Orchard Site, we found: 1) higher soil organic matter (Sept. 2023) and short-term C mineralization (Sept. and Oct. 2023) in LG+NL relative to GSC; and 2) greater potentially mineralizable nitrogen in LG+NL in March 2022, and Feb., Sept., and Oct. 2023. SO2: Soil samples collected at the beginning of September with the long-term indicators were used to isolate potential PGP bacteria. Over 300 isolates were collected. DNA from these isolates has been extracted and sent for Nanopore sequencing so they can be identified and functional assessments conducted. SO3: This objective will begin in 2024.?
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Castellano-Hinojosa A, Maltais-Landry G, Martens-Habbena W, Strauss SL (2023) Depth-dependent effects of cover crops in citrus orchards on soil carbon and nitrogen cyclig, greenhouse gas emissions, and soil microbial communities. Applied Soil Ecology 192; doi: 10.1016/j.apsoil.2023.105071
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Progress 02/14/22 to 02/13/23
Outputs
Target Audience:Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for one graduate student and a postdoctoral research associate are being provided by this project. How have the results been disseminated to communities of interest?The project plan and preliminary data from the proposal were presented at the Citrus Health Forum, a regional citrus grower meeting in North Florida in early 2022 and at a citrus grower meeting in South Florida in June of 2022. Preliminary data was presented by a PI and a graduate student at the 2022 Annual Soil Science Society of America conference in November in Baltimore, MD. What do you plan to do during the next reporting period to accomplish the goals?Cover crop plantings and soil collection will continue. Cover crops are scheduled to be planted twice a year at both locations. Soil sample collection for short-term indicators will occur three times during the year, and long-term collection will occur during the summer. The isolation and assessment of potential PGP microbes will begin. Preparations are in progress to begin assessments in additional tree fruit crops. Presentations of preliminary results will be made at regional and national scientific conferences, including the annual meetings of the Soil Science Society of America.?
Impacts
What was accomplished under these goals?
During the second year of the project, we continued the field trials in two citrus orchards. Cover crops were again planted in June and November. The June mixture included sunnhemp, cowpeas, buckwheat, millet, sorghum sudangrass, and Egyptian wheat, and the November mixture included daikon radish, sunnhemp, black oats, Florida 401 rye, and hairy vetch. The dissertation research of a PhD student is being funded by this project. SO1: Soil samples for short-term indicators were collected in March just prior to the orange harvest. At this time, cover crop biomass was sampled, dried, and ground. Orange harvest occurred during the last week of March and the first week of April. Subsamples of fruit were collected and analyzed for fruit quality. The next cover crop planting occurred in mid-July and included sunnhemp, cowpea, sorghum sudangrass, Egyptian wheat, hybrid pearl millet, and buckwheat. In September, leaf samples were collected for plant nutrient analysis. Soil samples were collected for both short and long-term soil health indicators, including the collection of additional surface samples sent to two commercial labs (Ward Lab in Nebraska, Waters Lab in Georgia) to evaluate their soil health analyses. At the end of October, soil samples were again collected for short-term soil health indicator measurements, and cover crop biomass was collected. The winter cover crop mixtures were planted in the beginning of November and included black oats, Florida 401 rye, daikon radish, sunnhemp, and hairy vetch. In the summer of Year 2, a novel physical indicator estimating aggregate stability with laser diffraction (long-term indicator) was developed. Data analysis has begun on the short and long-term indicators measured in Year 1 and 2 of the trial. Cover crop biomass from both years has been dried, weighed, ground, and sent for total C and N analysis. SO2: Microbial DNA was extracted from soil samples collected for long-term soil health indicator assessment in Year 1 and Year 2. The extracted DNA from Year 1 was quantified and sent for amplicon sequencing. The sequencing data is currently being analyzed to begin identification of taxa that may serve as potential indicators and candidates for future PGP isolations. Extracted DNA from Year 2 will be used for quantification via qPCR of specific nitrogen cycle functional genes. Additional samples will be collected in spring of 2023 for PGP analysis.? SO3: Objective 3 will begin in the third year of the project.
Publications
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Progress 02/14/21 to 02/13/22
Outputs
Target Audience:Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for one graduate student and a postdoctoral research associate are being provided by this project. How have the results been disseminated to communities of interest?The project plan and preliminary data from the proposal were presented at the Citrus Expo (Ft. Myers, FL), a state-wide citrus grower meeting in August 2021. In addition, preliminary data and the project plan were presented at the Florida Citrus Mutual/CRDF Education Session held virtually in Summer 2021. Preliminary data was presented by a postdoctoral research associate at the 2021 Annual Soil Science Society of America conference in November in Salt Lake City, UT.? What do you plan to do during the next reporting period to accomplish the goals?Cover crop plantings and soil collection will continue. Cover crops are scheduled to be planted twice a year at both locations. Soil sample collection for short-term indicators will occur three times during the year, and long-term collection will occur during the summer. Presentations of preliminary results will be made at regional and national scientific conferences, including the annual meetings of the Soil Science Society of America.?
Impacts
What was accomplished under these goals?
During the first year of the project, we began the field trials in two citrus groves. Cover crops were planted in June and November. The June mixture included sunnhemp, cowpeas, buckwheat, millet, and Egyptian wheat, and the November mixture included daikon radish, sunnhemp, oats, and cereal rye. A PhD student funded by this project began their studies. SO1: Baseline soil and leaf samples were collected in May prior to the planting of cover crop treatments. Approximately three months after the first set of cover crops were planted, soil samples were collected for short and long-term soil health indicators. These included POX, C and N mineralization, ACE protein content, microbial biomass P, enzyme activities, CEC, water content, SOM, pH, inorganic N, and total C and N. DNA has been extracted for baseline assessments of the abundance of N and P-cycling functional genes. In October, just prior to planting of the winter cover crops, soil samples were collected for the second set of short-term indicators. In addition, cover crop biomass was sampled, dried, and are being prepared for total C and N analysis. SO2: Preparations are underway to begin the assessment of the relationship between soil health and PGP microbes. Samples for these assessments will be collected during the next annual sampling for long-term soil health indicators in Summer 2022 after cover crops have been planted for a year. SO3: Objective 3 will begin in the third year of the project.
Publications
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