Source: MISSISSIPPI STATE UNIV submitted to
SUSTAINABLE AGRONOMIC SYSTEMS FOR CROP PRODUCTION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
1017113
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Sep 7, 2018
Project End Date
Jul 31, 2022
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Project Director
Shankle, MA, W..
Recipient Organization
MISSISSIPPI STATE UNIV
(N/A)
MISSISSIPPI STATE,MS 39762
Performing Department
North Mississippi Research & Extension Center
Non Technical Summary
Most crop production in the "hill section" of north Mississippi is non-irrigated and prone to inconstant yields due to the lack of adequate soil moisture during critical stages of the growing season. In 2017, an estimated 2.25 million acres of soybeans were planted in Mississippi with a farm gate value of over 1.1 billion dollars (MSU-DAFVM 2017), which is 3rd in value only behind forestry and poultry. An estimated 42% of these acres were planted in a dryland environment (Heatherly 2017) that are prone to yields that are typically more than 15 bu/ac lower than irrigated soybeans (USDA-NASS 2012). Although dryland soybeans have a lower yield potential, they will remain an important production practice in Mississippi and across the United States because irrigation is not feasible due to technical and financial limitations in some areas (Popp et al., 2002). For example, the depth of an irrigation well could be 45 feet below land surface in the Delta of Mississippi compared to 675 feet in the "hill section" (USDOI-USGS 2018). Therefore, an alternative to irrigation is to focus on development of sustainable dryland systems to achieve more consistent crop yields. Identifying affordable cover cropping systems coupled with early planting in a no-tillage environment to minimize inconsistent yields due to lack of timely rainfall events could provide more than $40 million across the state of Mississippi in dryland soybean production based on a 10% increase in yield. Another challenge in crop production is weed management. Research indicates that corn and soybean yields could be reduced by 50% if weeds are left uncontrolled (Soltani et al., 2016, 2017). In the United States and Canada, this would be an estimated $43 billion loss in revenue just for these two crops. There are many herbicides labelled for use in major row crops, but only a hand-full are registered in specialty crops such as sweetpotato and sesame. There is a need for tolerance studies in specialty crops to identify potential herbicides that could be utilized for weed management. This will also require applied research to determine the appropriate use rate, tank-mix partner, and application time for specific herbicides in order to establish guidelines for the federal registration process. Sustainable and efficient crop production will be even more important for future generations and management of soil nutrients will play a vital role in achieving this task. Nutrient management would not be possible without soil test correlation and calibration research to provide the information necessary for interpretation and support of recommended fertilizer inputs (SERA-IEG-6 2014). The majority of soil test correlation and calibration studies in the southern states were conducted at state agricultural experiment stations between the 1950s through the late 70s (Jones 1979). Data collected from this early research serves as the basis for current fertilizer recommendations in reports from soil testing laboratories. Currently, most private laboratories utilize the Mehlich-3 method as a soil test extractant, while the soil testing laboratory at Mississippi State University (MSU) uses the Lancaster method (Cox 2001). In the 1970s, Dr. James D. Lancaster, an agronomist with MSU developed the Lancaster extraction method, commonly referred to as the Mississippi method (Cox 2001). Producers and consultants have expressed concerns over different soil test based fertilizer recommendations between Mehlich-3 and Lancaster extracted samples. Research information that correlates Mehlich-3 extractable nutrients to sweetpotato yield is very limited. Also, it is unclear when the Lancaster soil test method for potassium or phosphorus was correlated with sweetpotato yield in Mississippi or when fertilizer recommendations were last updated. In addition, it is important to note that Dr. Lancaster utilized cotton in research to set soil test ranges and fertilization recommendations for the Lancaster method. Some states have verified their calibration research over time, but new soil fertility research is limited, especially for sweetpotato. This suggests that soil testing practices should be reviewed and validated with calibration field plots. The use of auxin technologies in row crop production was launched in 2017 and the use of auxin herbicides in genetically enhanced tolerant crops is expected to increase over the next several years, which will increase the risk of injury to non-tolerant crops such as sweetpotato. Identifying the potential level of sweetpotato plant injury and yield reduction associated with the interception of off-target auxin herbicide movement during different stages of plant development will help the in-season, decision-making process to replant or take the crop to yield. Also, sweetpotato varieties may differ in their tolerance to abiotic stress linked to exposure to synthetic auxins and other herbicides. Understanding the level of injury expected with off-target exposure, coupled with the discovery of less susceptible varieties will help manage and mitigate risk to sweetpotato as it relates to the current landscape of evolving technologies.
Animal Health Component
50%
Research Effort Categories
Basic
25%
Applied
50%
Developmental
25%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1022410106030%
2131450114040%
2051450105030%
Goals / Objectives
Evaluate sustainable cover crop systems for dry-land crop production. Crops are prone to inconsistent yields due to inadequate rainfall at the appropriate crop development stage. Therefore, a systems approach will evaluate the use of cover-crops, source of fertilizer, and crop planting date in a no-tillage environment to help improve soil health and provide more stable soil conditions for crop production.Determine weed control strategies to manage problematic weed species and mitigate herbicide resistant weed bio-types. Major row-crop production continues to advance with new crop resistant herbicide systems. However, herbicide registration for weed management in specialty crops such as sweetpotato is limited and they are not typically included in herbicide resistant crop breeding programs. Therefore, herbicide systems will be evaluated that include PRE-plant, Delayed-PRE, POST, and POST-directed applications in order to maximize control of problematic weed species and minimize risk of crop injury.Determine the optimum amount of phosphorous and potassium for sweetpotato production in using both Lancaster and Mehlich-3 extraction methods. Some states have verified their calibration research over time, but new soil fertility research is limited, especially for sweetpotato. Therefore, this project will investigate fertilizer inputs for sweetpotato with calibration field studies.Investigate off-target movement of auxin herbicides to specialty crops such as sweetpotato. Herbicide resistant crops have introduced a new dimension of weed control to manage herbicide resistant weeds in row-crop production systems. But it has also created the risk of injury to specialty crops planted due to volatility, drift, and tank contamination of auxin herbicides. Therefore, studies will be designed to simulate off-target movement of auxin herbicides to sweetpotato at different growth stages.
Project Methods
Objective 1. Studies will be conducted at the Pontotoc Ridge-Flatwoods Experiment Station in Mississippi to evaluate the effects that different cover cropping systems have on soybean growth/development and yield. Also, the effects on "soil health" (physical and chemical characteristics, microorganisms, soil moisture, and other parameters) will be evaluated. Site selection will be confined to dryland soybean production fields. Standard agronomic practices for soybean production in the area will be applied. Treatments will include 4 cover crops, 3 fertilizer treatments, and 3 soybean planting times. Baseline soil samples will be taken at the beginning of the project. A standard commercial fertilizer rate based on soil test recommendations will be made from the baseline soil samples. A nutrient analysis will be utilized to determine poultry litter application rates that coincide with the amount of K applied in the standard commercial fertilizer treatments. Experiments will be split-split plot arrangement replicated in a randomized block design. In addition to simple ANOVA and means separation, we will utilize SAS software for computations of correlation and regression analyses that best describe results (other methods will be employed if warranted).Objective 2. Herbicide systems will be evaluated for specialty crops such as sweetpotato. Treatments will include PRE-plant, Delayed-PRE, POST, and POST-directed applications in order to maximize control of problematic weed species and minimize risk of crop injury. Some greenhouse studies will be included when appropriate, but most evaluations will be conducted as field studies. Treatments will be arranged in a randomized complete block design with at least 4 replications. All studies will utilize the Agronomic Research Management software to record observations, plant measurements, and to calculate statistical formulas. Data will be interpreted and prepared for the appropriate avenue of dissemination.Objective 3. Fertilizer studies will be conducted at the Pontotoc Ridge-Flatwoods Branch Experiment Station and at cooperator locations where commercial sweetpotato production occurs. Site selection will be based on soil that has a low to very-low soil test P and K nutrient level and of the same soil type typically used for sweetpotato production. Baseline soil samples will be collected from each plot and analyzed for available nutrients using both Mehlich-3 and Lancaster extraction methods. Treatments will include an unfertilized check and a range of K2O rates such as 60, 120, 180, 240, 300, and 360 lb/ac and P2O5 rates such as 40, 80, 120, 160, 200, and 240 lb/ac. All studies will be designed as a randomized complete block with 4 replications. Sweetpotato growth will be monitored during the growing season. The two center rows of each plot will be harvested with a chain-digger at 90 to 110 days after transplant. Sweetpotatoes will be graded and yield determined for US no. 1, canner, jumbo, culls, and total marketable grades. Statistical analyses will be conducted and interpreted to determine the target P and K level to optimize yield of US no 1 grade sweetpotato.Objective 4. Investigate off-target movement of auxin herbicides to specialty crops such as sweetpotato. Field studies conducted at the Pontotoc Ridge-Flatwoods Branch Experiment Station will include drift and tank contamination treatments with dicamba formulated with diglycoamine (DGA) salt and 2,4-D formulated with choline salt at rates such as 0x, 1/8x, 1/16x, 1/64x and 1/512x of the registered labeled rate at several application times such as Pre-transplant and 1, 3, 5, and 7 weeks after planting (WAP). The experiment design will be a randomized complete block with a minimum of four replications. Visual injury ratings will be recorded 1, 2, and 4 weeks after treatment applications on a scale of 0 to 100% (no injury to plant death) according to injury type (chlorosis, necrosis, stunting, epinasty). Data will be subjected to statistical analyses followed by interpretation of results to determine the extent of crop injury as it relates to plant exposure at a specific growth development stage and herbicide dose.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:The target audience for this project consists of dryland crop producers, students that have an interest in agronomic systems, and other scientists and extension personnel with universities and federal agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Preliminary research results have been presented to growers, ag company representatives, and others scientists at the American Society of Agronomy, Mississippi Chapter. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Research to evaluate sustainable dryland soybean systems continued in 2020 with cover crops, fertilizer sources, and early/late planting dates. Cover crop biomass was greater with later termination for all species in the study. In addition, biomass with grass species was greater than vetch and native vegetation. Soybean yield was not increased with cover crops, but yield with poultry litter was greater than inorganic fertilizer at the soil testing lab recommended rate. In addition, yield with the addition of both sources of fertilizer was greater than no fertilizer. The costs associated with cover crop establishment were Elbon cereal rye ($40.70/A), Elbon cereal rye + mustard ($92.20/A), hairy vetch ($51.80) and wheat ($29.64). The costs of fertilizer treatments were poultry litter at 2 ton/A ($90.00/A) and inorganic fertilizer at 0N-120P-30K-20S ($77.24/A). Net profit with any cover crop + fertilizer source was greater than any system that did not include fertilizer. There were two IR-4 studies conducted in 2020. A plant-bed study and a POST to row-middle study. The plant-bed study evaluated a product to manage slip uniformity. This product was applied after storage roots sprouted/emerged from the bed and immediately after removed of plastic bed cover. The concept was to burn-down vegetation and allow a more uniform establishment of slips. This would provide similar slip size/length at cutting for transplanting in commercial production fields. In addition, slips from this study were also cut and transplanted to evaluate yield and quality of storage roots after harvest. The POST to row-middle study was conducted to evaluate a contact herbicide applied at 14 days after transplant or at lay-by (20-25 days after transplant). Competitive treatments, a commercial standard, and untreated check were included for comparison. Results submitted to IR-4 regional director. Field research was repeated in 2020 to evaluate the effect of potassium fertilizer rates on two sweetpotato cultivars. Rates of phosphorus fertilizer were added this year. The Orleans variety replaced Bayou Belle and Beauregard remained as the commercial standard. Incremental fertilizer rates were based on soil testing laboratory recommendations. Leaf tissue samples were collected 35 days after transplant and analyzed for plant nutrient concentration. Sweetpotatoes were graded to determine US No.1, canner, cull, and jumbo yield grades. Total marketable yield was recorded as the sum of US No.1, canners, and jumbo grade yields. Data is being collected, analyzed, and interpreted. This research will impact net profit and enhance environmental stewardship by applying the appropriate amount of fertilizer that achieves the maximum yield in-line with the law of diminishing returns. Field trials were conducted in Mississippi in 2018, 2019 and 2020 to determine the effect of diluted applications of dicamba on sweetpotato crop tolerance and yield, simulating off-target movement or a contaminated sprayer tank. Four rates of dicamba, 1/8X, 1/16X, 1/64X, and 1/512X were applied at 1, 3, 5, and 7 weeks after planting and plant injury ratings were taken 1, 2, 3, and 4 weeks after treatment application. Yields were reduced at 1/8X and 1/16X rates compared to the untreated check, however there was no yield differences between the untreated check and 1/64X rates and 1/512X rates. Despite similar injury among dicamba rates, yield was typically higher with treatments that were applied 1 and 3 weeks after planting compared to those applied later in the growing season (3 and 5 weeks after planting) suggesting that earlier treated plants had time to recover from injury and that early exposure to dicamba might not result in a complete crop loss despite foliar injury. Based on the current study, care should be taken to avoid sweet potato exposure to dicamba especially at 1/8X and 1/16X rates during the growing season.

Publications


    Progress 10/01/18 to 09/30/19

    Outputs
    Target Audience:The target audience for this project is primarily dry-land crop producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training was provided at grower workshops. How have the results been disseminated to communities of interest?Outreach activities include inverviews and popular press articles that descibe research objectives have been conducted and will be provided to the general public. What do you plan to do during the next reporting period to accomplish the goals?Present research results at professional scientific meetings and local grower meetings.

    Impacts
    What was accomplished under these goals? A large-scale study was established in 2018 and repeated in 2019 to evaluate cover crops, fertilizer source, and planting date systems for dry-land soybean production sustainability. Soil was collected to determine changes in nutrient status and microbial population diversification. Measurements of soil moisture, leaf nutrients, and plant height were collected. Plots have been harvested and a soybean seed sample was collected from each plot for nutrient analysis. Preliminary results indicate there is no yield benefit of any cover crop at this stage in the study when compared to the native cover crop check. Soybean yield was greater in the early planting than in the late planting date. The addition of organic or inorganic fertilizer sources increased yield over the no fertilizer check. Weed control and plant tolerance studies were conducted in sweetpotato. Treatments with the herbicide fomesafen were evaluated since this product became available for use in sweetpotato for 2019 in the state of Mississippi. This product will be registered as a Section 24c. Also, linuron herbicide was evaluated for use with other herbicides to develop a POST weed control system for sweetpotato. This data will be submitted through the IR-4 program. Field Research was conducted at the Pontotoc Ridge-Flatwoods Experiment Station in Pontotoc, Mississippi to determine the effect of potassium fertilizer rates on two sweetpotato cultivars, Bayou Belle and Beauregard. 8 potassium rates were used in 2019, 0, 60, 120, 180, 240, 300, 360, and 420 ai lb/a. Leaf tissue samples were collected 35 days after transplant and analyzed for plant nutrient concentration. Sweetpotatoes were graded to determine US No.1, canner, cull, and jumbo yield grades. Total marketable yield was recorded as the sum of US No.1, canners, and jumbo grade yields. This is the second year the experiment has been conducted. Preliminary results showed Beauregard did not need as much potassium fertilizer applied before planting as Bayou Belle for No.1 and total marketable yield. Data for 2019 is being analyzed and will be presented. Field research was conducted at the Pontotoc Ridge-Flatwoods Experiment Station in Pontotoc, Mississippi to determine the effects of a simulated dicamba drift on sweetpotato in 2018 and repeated in 2019. The trial was a randomized complete block (RCB) with 4 or 5 replications. Plots were 3.33 X 30 ft. having one 40-inch row with a guard row separating treatments. Treatments were applied pre-transplant (PRE) and post-transplant (POST) at 1, 3, 5, and 7 weeks after transplant (WAT). Treatments include XtendiMax®PRE at 22 oz/ac (1X), and tendiMax®PRE and POST at 2.75 oz/ac (1/8X), 1.375 oz/ac (1/16X), 0.34 oz/ac (1/64X), 0.043 oz/ac (1/512X). Ratings for crop tolerance (injury) were made at 1, 2 3, and 4 weeks after application for each treatment. Sweetpotatoes were harvested and graded to determine US No.1, Canner, Cull, and Jumbo yield grades. Total marketable yield was recorded as the sum of US No.1, Canners, and Jumbo grade yields.

    Publications


      Progress 09/07/18 to 09/30/18

      Outputs
      Target Audience:The target audience for this project is primarily dry-land crop producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Research studies were presented and discussed at a field-day event. How have the results been disseminated to communities of interest?Outreach activities that include a field-day event and a workshop for regional K-12 teachers to promote public awareness about the concept of a systems approach for a more sustainable dry-land crop production system. What do you plan to do during the next reporting period to accomplish the goals?Present research results at professional scientific meetings and local grower meetings.

      Impacts
      What was accomplished under these goals? A large scale study was established to evaluate cover crops, fertilizer source, and planting date systems for dry-land soybean production sustainability. Soil was collected to determine changes in nutrient status and microbial population diversification. Measurements of soil moisture, leaf nutrients, and plant height were collected. Plots have been harvested and data is being analyzed. Weed control and plant tolerance studies were conducted in sweetpotato. Treatments with the herbicide fomesafen were evaluated since this product will become available for use in sweetpotato for 2019 in the state of Mississippi. This product will be registered as a Section 24c. Also, linuron herbicide was evaluated for use with other herbicides to develop a POST weed control system for sweetpotato. This data will be submitted through the IR-4 program. Incremental potassium fertilizer treatments were applied based on STK levels in the soil to determine the appropriate amount to use for production of B-14 Beauregard and Bayou Belle sweetpotato varieties. Leaf tissue samples were collected and roots were harvested. Data is being processed for interpretation of results. Sweetpotato tolerance to off-target movement of dicamba and 2,4-D was evaluated in field research studies. Herbicide treatments at different rates were applied at several growth stages during the life cycle of the sweetpotato plant. Visual observations for injury was accessed through-out the season for both herbicides, but only the roots were harvested for dicamba treatments.

      Publications