Frost Injury on Corn

Matt Foster, LSU AgCenter Corn Specialist

Article Highlights:

1. Corn planting is moving at a fast pace in Louisiana, with some growers already finished.

2. A late-season frost is of concern.

3. The effect of frost on emerged corn is mainly damage to the leaf tissue.

4. Corn growth stage is the most important factor determining recovery after a frost event.

With corn planting occurring rapidly throughout the state, I’ve received numerous questions about how an Easter cold snap may impact emerged corn. The effect of frost on emerged corn is mainly damage to the leaf tissue. Within the first 24 hours after the frost event, corn leaves may turn yellow or brown and exhibit a water-soaked appearance. Fields should be scouted 3 to 5 days after the frost event to assess recovery potential. After 3 to 5 days, surviving corn plants should be showing new leaf tissue expanding from the whorls. Corn growth stage is the most important factor determining recovery after a frost event. The growing point of a corn plant remains below ground until around the V5/V6 growth stage and is generally protected from the effects of an aboveground frost. Research has shown that young corn plants can easily recover from frost damage and suffer no yield loss.

Examining Input Costs, Margins, and Return on Investment ahead of the 2023 Planting Season

Michael Deliberto, LSU AgCenter Economist

Article Highlight:

• The LSU AgCenter has published interactive one-page enterprise budgets for corn, soybeans, cotton, and rice that allow growers to examine cost structures relative to their expected market price, yield, margin, and return on investment (ROI).

While many input costs have retreated from historic highs in early 2022, costs for both fertilizer and farm diesel fuel remain elevated, continuing to inflate 2023 total production costs. Even though commodity prices remain relatively robust, margins will be stretched thin for many crops this year and prices are expected to decline from the 2022 averages for corn, soybeans, cotton, and rice.In late February, the USDA released a set of price projections for the 2023/24 marketing year. In their outlook, USDA projects 2023 prices for corn at $5.70 per bushel, soybeans at $13.00 per bushel, cotton lint at $0.80 per pound, and long grain rice at $15.00 per cwt.

In early January 2023, the LSU AgCenter released detailed enterprise budgets. Given the fact that inputs (and commodities) continue to experience price volatility, updates to these farm management planning tools can assist growers in re-evaluating their cost of production, margin, and return on investment (ROI) for the 2023 crop year.

One-page enterprise budgets for corn, soybeans, cotton, and rice are available at the web extension https://lsuagcenter.com/portals/our_offices/departments/ag-economics-agribusiness/extension_outreach .

These worksheets allow growers to enter their farm acreage, expected market price they anticipate receiving, expected yield, rent, fuel, fertilizer, labor, and several other farm input parameters as to calculate direct expenses on both a per-acre and whole-farm basis. For each direct expense, the expected output (e.g. bushels, pounds, or cwt) is calculated so that a final breakeven yield is presented. In a whole-farm perspective, total direct expenses, crop revenue, gross revenue, cost per bushel, margin, and ROI are estimated subject to the grower-supplied data points.

Cells containing blue numerals can be changed by the grower to reflect their specific production situation. Those cells containing black numerals contain formulaic notation and must not be altered.

Evaluating Soybean Planting Dates in Louisiana

David Moseley, LSU AgCenter Soybean Specialist

Article Highlights:

• Recent data suggest the optimum planting timing for soybean in central and north Louisiana is between late-March to mid-April.
• The LSU AgCenter continues to research soybean planting dates to see if it is economical to plant earlier or later than the optimum time.

A soybean planting date was initiated by Dennis Burns at the LSU AgCenter Northeast Research Station. The first planting date was on March 1 in a no-till field following cotton with 15-inch row spacing (Figure 1). Soybean seeds were sown 1.25 inches deep at a rate of 140,000 seeds per acre and the soil temperatures were 67 degrees Fahrenheit at planting. One variety with a maturity group of 4.8 was planted. Subsequent planting dates are planned for every two weeks until approximately mid-May.

Figure 1. A soybean planting date location at the LSU AgCenter Northeast Research Station. The soybean seed was planted on March 1, 2023, in a no-till field after cotton. On March 6, the seed had not yet emerged.

On March 6, the seeds had germinated and were approximately half an inch from emerging (Figure 2). The days between planting and emerging were slower than in later planting dates due to cooler soil temperatures. The soil temperature at planting was above the recommended 60 degrees Fahrenheit, but the seed will still take longer to emerge than in warmer temperatures when seed can emerge within three to five days. Soybean seed should not be planted if the soil temperature is expected to be below 50 degrees Fahrenheit within 48 hours after planting to avoid seedling damage during the rapid water imbibition stage.

Figure 2. A soybean seedling that was planted 1.25 inches deep on March 1, 2023. On March 6, the seedling was approximately half an inch away from emergence.

Planting equipment and soil conditions should be considered when planting. Seed should be planted approximately 1 to 2 inches deep, depending on soil moisture conditions with good seed-to-soil contact. Planting into wet soil conditions can cause compaction of the seed furrow side walls and limit outward root growth.

Data from planting date trials conducted in 2020 and 2021 at the LSU AgCenter Dean Lee Research Station suggest the optimum planting timing for soybean is between the last week of March and mid-to-late April (Figure 3). Data suggest planting earlier than late-March or later than mid-April can result in lower yield potential. The amount of yield loss when planting earlier or later than the optimum timing will depend on the environment of the growing season. The yield difference in 2020 was greater than in 2021 due to an ideal environment from late-March to mid-May. In 2021, there was cool and wet conditions during late-March to mid-May and then there were mild temperatures and timely rainfall events in the summer months of 2021.

Figure 3. Data from soybean planting date trials conducting at the LSU AgCenter Dean Lee Research Station in 2020 and 2021. Each data point is the average of 12 varieties planted on the same date.

Even though the yield potential for a mid-March and late-April to mid-May seem to be similar (earlier and later than optimum planting timings), the plant can grow faster in warmer temperatures. In 2021, the canopy coverage at the R4 growth stage was 78% when planting in late-April to early-May versus 52% when planting in mid-March (Figure 4). The faster canopy coverage can help with weed control.

Figure 4. Canopy coverage and yield data from a 2021 planting date trial conducted at the LSU AgCenter Dean Lee Research Station. Each data point is the average of 12 varieties planted on the same date.

Last year the majority of soybean acres planted in Louisiana during April suffered significant damage from rain. Planting in April can help maximize yield potential; however, decreasing the risk of a severe weather event by spreading out the planting dates may be one strategy to consider. Planting in early-to-mid-March can help extend the planting season and prevent planting into mid-May or later. Planting in March does come with the threat of freezing temperatures that can kill plants. The National Centers for Environmental Information shows a map of the expected last freeze across the United States. The map shows the areas in north Louisiana can have a last freeze between March 16 – 30.

Additional information can be found in a “Science for Success : The Best Soybean Planting Date” factsheet on the Soybean Research and Information Network website.

Register to Join a National Team of Soybean Extension Specialist and Discuss Soybean Production!

David Moseley, LSU AgCenter Soybean Specialist

Register to join a webinar series on early soybean management. The webinars will be conducted by a national team of soybean specialist, and will cover new research and recently published extension material. Each virtual webinar will include a live Q&A session!

Please use the links to register and for more details. All are welcome, and registration is free. Each webinar will be held at noon Central/1:00 PM Eastern time.

MARCH 17, 2023 WHEN EARLY PLANTING DOESN'T WORK OUT - DO I REPLANT, REPAIR-PLANT OR LEAVE THIS PITIFUL STAND? CCAs will earn 0.5 CEUs in Crop Management.

Register: Webinar: When early planting does not work

MARCH 24, 2023 WHAT'S NEW IN PLANTER TECHNOLOGIES. CCAs will earn 0.5 CEUs in Crop Management.

Register: Webinar: Planter technologies

MARCH 31, 2023 N-FIXATION AND SULFUR FERTILITY IN SOYBEANS

Register: Webinar: N-fixation and sulfur fertility

Additional information on the Science for Success team and soybean cultural practice factsheets can be found on the Soybean Research and Information Network website.

Are you applying enough starter nitrogen at corn planting for maximizing yield components?

Rasel Parvej, LSU AgCenter Assistant Professor and State Soil Fertility Specialist

Article Highlights:

• Corn requires around 30 lb N/acre from planting to V6 stage to maximize the total number of kernel rows per ear.
• The most frequently used starter fertilizer (10-34-0 or 11-37-0) mainly contains P but little amount of N that cannot fulfill this early-stage N requirements.
• The best option is to apply 9 to 13 gal/acre of UAN (32-0-0, 30-0-0-2S, 28-0-0-5S) at planting.

Louisiana corn producers mostly use 4-5 gal/acre of ammonium polyphosphate (10-34-0 or 11-37-0) as starter fertilizer and apply it in the seed furrow or in a 2 by 2 band. The main purpose of applying starter fertilizer is to help the germinating corn seedling boost up early-season growth by easily accessible nutrients placed near the seeds. However, corn grain yield response to 5 gal/acre of 10-34-0 or 11-37-0 starter fertilizer is very inconsistent with no yield response being common across the mid-South and Midwest. This is because 5 gal/acre of in-furrow starter fertilizer (10-34-0) contains 19.8 lb P (P₂O₅) but only 5.8 lb N per acre, which is a very small amount to make any yield difference by N at planting. The additional P from the starter fertilizer (10-34-0) can only be beneficial for soils that are deficiency in P and did not receive any P fertilization either in fall or spring. If the producers already applied P based on soil-test P concentrations (less than 20 ppm or 40 lb/acre P at 0- to 6-inch soil depth), there may be no benefit of using 10-34-0 or 11-37-0 starter fertilizer. This is also true for high P testing soils (more than 35 ppm or 70 lb/acre P) where additional P is not needed. Sometimes, cold soil temperature causes reduced P uptake by young corn plants, due to slow root growth, resulting in temporary P deficiency especially in sandy loam soils, even though soil-test P levels are adequate (21-35 ppm P or 42-70 lb/acre P). But this early season P deficiency especially in soils with sufficient P level can go away with warmer soil temperature and adequate moisture and usually does not negatively affect corn yield.

Corn sets the total number of kernel row per ear, one of the important yield components, from planting to V6 stage i.e., 6 visible collar leaves and plant is about 12-18 inches tall. To maximize this important yield component, corn requires 30 to 45 lb N during this early growth stage, which can only be fulfilled by applying around 9 to 13 gal/acre of urea ammonium nitrate (UAN; 32-0-0, 30-0-0-2S, or 28-0-0-5S) at planting. UAN (32-0-0) can be applied as 2 by 2 banding or dribbling on the top of the bed at planting. Urea (46-0-0) can also be used but it should be broadcast followed by incorporated at or before planting. If 10-34-0 or 11-37-0 starter fertilizer is used, producers need to apply at 26 to 39 gal/acre rate to fulfill the early-season N demand, which would not be economically sound. In addition, when corn is planted in high plant residue with or without cover crops, high plant residue sometimes results in early-season N deficiency due to N immobilization by soil microbes. Providing 30 to 45 lb of N using UAN during planting as a starter would offer more benefits in these soil conditions than 5.8 lb of N using ammonium polyphosphate (10-34-0 or 11-37-0). Overall, corn producers should use UAN as a starter fertilizer during planting to provide the need of 30 to 45 lbs N from planting to V6 stage and come back with the rest of the N rate as a sidedress during V6-7 stages. Note that producers should subtract the starter N rate from the total N rate during sidedressing. The total N rate depends on corn yield goal and soil type. LSU AgCenter recommends 1 lb of N per bushel of yield for sandy to silty soils and 1.25 lb of N per bushel of yield for clayey soils. Therefore, producers should apply 30 lb of N for sandy to silty soils and 45 lb of N for clayey soils during planting.

Soon to Be Released: Irrigation Scheduling Webtool

Stacia L. Davis Conger, LSU AgCenter State Irrigation Specialist; April Divine, LSU AgCenter Extension Associate; Carol Friedland, LSU AgCenter Director of LaHouse Resource Center; Robert Rohli, LSU Professor and Climatology Scientist

Agricultural drought can occur in any crop season and for any length of time; even 2-3 weeks of no rainfall during critical growth stages can be detrimental to yield outcomes. Thus, irrigation can be seen as a method for improving agricultural resiliency by mitigating drought risk. Soon, an Irrigation Scheduling webtool, developed with help from an advisory panel made up of producers and industry professionals, will be released to assist farmers in scheduling irrigation to manage agricultural drought.

While some have focused on soil moisture sensors for irrigation scheduling, most extension systems support at least one weather-based option that does not require hefty price tags to make irrigation decisions across large acreage. The 2022 drought conditions provided the necessary prioritization of funding to make this happen for Louisiana.

To be released by the end of March 2023, this webtool can aid in making daily irrigation decisions, checking site-specific evapotranspiration and rainfall estimates, and alerting to the drought status determined by the U.S. Drought Monitor. The development of the webtool has been guided by a producer-led advisory process that continues to prove invaluable to understanding the best ways to interact with the webtool and visualize the information so that it is usable by the irrigator.

While this version will be very specific to the project’s goals, the advisory group continues to identify opportunities for future improvements. One suggested update was to target irrigation recommendations based on the goal of the irrigator. For example, irrigation decisions may require minor adjustments to meet a goal of maximizing profits compared to a goal of maximizing yields. While we will continue to work and improve the tool outside of the crop season, the upcoming release will focus on functionality, reliability, and supporting irrigators through technical support and educational opportunities.

Interested in trying this webtool? Sign up now to be informed when it goes live by using this link: https://forms.office.com/r/A4KL9Xapf9. Also, we will be announcing its release through LSU AgCenter media channels and the social media accounts for the irrigation program: @geauxwater. Stay tuned!

LSU AgCenter Specialists