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How would you manage in-season potassium deficiency in soybean?

How would you manage in-season potassium deficiency in soybean? published on No Comments on How would you manage in-season potassium deficiency in soybean?

How would you manage in-season potassium deficiency in soybean?

Dr. Rasel Parvej, LSU AgCenter Soil Fertility Specialist; Dr. David Moseley, LSU AgCenter Soybean Specialist; Dr. Josh Copes, LSU AgCenter Agronomist; and Dr. Syam Dodla, LSU AgCenter Soil Scientist

Potassium (K) is the second most yield limiting nutrient in soybean. Even though nitrogen (N) is the most limiting nutrient, soybean plant meets its own N requirement through biological N-fixation. Therefore, soybean is mainly fertilized with K and phosphorus (P) fertilizers in soils that are tested very low to medium K and P levels. Soybean is more responsive to K than P fertilizer and requires a large amount of K to maintain optimum water balance in plants, increase photosynthesis and assimilate translocation from source to sink, reduce transpiration losses of water, and improve uptake of other nutrients. A 55-bushel soybean requires about 160 pounds K2O (potassium oxide) per acre, approximately 2.9 pounds K2O per bushel grain harvested.

Potassium deficiency can decrease soybean yield more than 50% across soil types that range from sandy loam to clay loam. In addition, K deficiency decreases P uptake by soybean plants and reduces soybean seed quality by decreasing seed oil and protein content and increasing purple seed stain. Potassium deficiency can occur in any soybean field that is very low to low in soil-test K level and is not fertilized with K. Potassium deficiency, however, often occurs in coarse-textured soils with low cation exchange capacity (CEC <10) such as loamy sand to silt loam soils. Coarse-textured soils are highly prone to K leaching below the root zone. Sometimes, fall application of K fertilizer in coarse-textured soils results in late-season K deficiency due to K leaching from excessive rainfall during winter and/or spring. Coarse-textured soils are also poor in water holding capacity and drought in these soils often causes K deficiency by decreasing K uptake by plant roots.

Soybean K deficiency symptoms first appear as irregular yellowing on the edges of K deficient leaves. As growing season progress and the severity of K deficiency increases, the entire leaf edges turn brown and eventually the whole leaf dies. Potassium deficiency symptoms can occur as early as at the V3 vegetative stage (three trifoliolate leaves) mainly on the middle older leaves (Figure 1). But symptoms often occur on the upper younger leaves during the reproductive stages especially under severe K deficiency conditions (Figure 2). Soybean fields with K deficiency symptoms early in the growing season are very easy to diagnose and manage. However, most of the soybean fields often suffer from K deficiency and exhibit yield losses without showing any visible deficiency symptoms at all or at least until the later reproductive stages (beginning seed, R5 to full-seed, R6). This type of phenomenon is called hidden hunger and its most common in soybean fields that are low to medium in soil-test K level, have not received K fertilization, have high leaching potentials due to low CEC and excessive rainfall, or undergo severe drought conditions. Soybean grown in low pH (<6.0) soils also suffer from hidden K hunger effects because low pH decreases soil K availability even after fertilization.

Diagnosing hidden K deficiency early in the soybean growing season is very difficult and requires thorough scouting along with additional information such as fertilization history, soil texture, soil pH, soil-test K level, crop rotation, rainfall amount and distribution after fertilization and during the growing season, drought period, etc. Tissue sampling during the growing season is the best and perhaps the only tool to diagnose hidden K deficiency in soybean. Tissue sampling is predominantly conducted at the full-bloom (R2) stage; but can be done at the later reproductive (early pod, R3 to beginning seed, R5) stages. However, diagnosis at the early growth stages would be more effective and economical in correcting K deficiency and rescuing yield losses than diagnosis at the later growth stages.

After tissue sampling, tissue K concentration at a particular growth stage is interpreted to diagnose K deficiency. Many current tissue K interpretations, used by most of the plant diagnostic labs, only allow interpretation of K concentration for soybean leaflet (without petiole) collected at or around the R2 stage. Recently at the University of Arkansas, Parvej et al. (2016) developed critical trifoliolate leaflet and petiole K concentrations from the R2 to R6 reproductive stages (Figure 3). These critical K concentrations would allow soybean producers, agronomists, and crop consultants to sample either leaflet or petiole or both to diagnose K deficiency across the reproductive growth stages of soybean.

For proper tissue sampling, 15 to 20 recently mature trifoliolate leaves including petioles from the 3rd node from the top of the soybean plant should be collected and the date and soybean growth stage should be recorded (Figure 4). Then the leaflet of each trifoliolate leaf should be separated from the petiole and both the leaflet and the petiole or the leaflet only should be sent immediately to the plant diagnostic lab for K concentration. After receiving the results, tissue K concentrations for both the leaflet and the petiole at the specific growth stage can be interpreted using Figure 3. For example, the critical K concentration at the R2 stage ranges from 1.46 to 1.90% for leaflet and 3.01 to 3.83% for petiole and any K concentration below the critical level would be deficient and above the critical level would be sufficient. From the R2 stage, critical tissue K concentration declines linearly with the advancement of growth stage due to K translocation from vegetative to reproductive plant parts (pods and eventually seeds). Therefore, the growth stage at the time of tissue sampling should be recorded to properly interpret the tissue K concentration.

For maximum soybean growth and yield, tissue K concentration should be above the critical level across the growth stages. If the tissue K concentration falls below the critical level, especially during the early reproductive stages, soybean should be fertilized with K to make sure K is not yield liming. Soybean K deficiency can easily be corrected by applying K fertilizer during the growing season. However, the effectiveness and economics of applying K fertilizer to rescue yield loss depends on soybean growth stage and the severity of K deficiency. The earlier the growth stage for K application the more effective and economic it would be in recovering yield loss. Recently, research conducted at the University of Arkansas suggests that soybean K deficiency can be effectively and economically corrected by applying 60 pounds K2O per acre until the R5 stage or about 5-weeks past the R2 stage. This is because soybean uptakes more than 70% of the total K after blooming and maximizes (100%) K uptake near the R6 stage. Therefore, diagnosis of K deficiency followed by an immediate K application early in the growing season would allow soybean plant enough time to actively uptake K from soils or through leaves and recover significant yield losses. However, pre-plant K application is the best way to maximize soybean yield.

Both dry and liquid fertilizers can be used in correcting soybean K deficiency during the growing season. However, dry fertilizer would be more effective and economical for correcting severe K deficiency since a high amount of K would be required. Foliar application of liquid K may be effective for small amount of K requirement since K fertilizer has a high salt index that can burn soybean foliage if applied in high concentrations (Figure 5). Therefore, foliar method requires several applications to correct a severe K deficiency that would increase application cost. Also, foliar K fertilizer is more expensive than dry K fertilizer. The most effective and economical method is either by top-dressing or flying 100 pounds Muriate of Potash (0-0-60; 60 pounds K2O) per acre.

 

 

 

 

 

Figure 1. Potassium deficiency symptoms during the early vegetative growth stages of soybean.

 

 

Figure 2. Potassium deficiency symptoms during the reproductive growth stages of soybean.

 

 

 

 

 

 

 

 

Figure 3. Critical soybean leaflet and petiole K concentration from the R2 to R6 stages. (Source: Parvej, M.R., N.A. Slaton, L.C. Purcell, and T.L. Roberts. 2016. Critical trifoliolate leaf and petiole potassium concentrations during the reproductive stages of soybean. Agronomy Journal 108:2502-2518. doi:10.2134/agronj2016.04.0234; Y-axis is changed to English unit)

 

 

 

 

 

 

 

Figure 4. Steps of soybean tissue sampling during the R2 reproductive stage. Pencil in the picture indicates 3rd node from the top of the plant.

 

Figure 5. Soybean foliage damage due to sidedressing of high rate of liquid potassium.

Should You Apply Pre-Tassel Nitrogen in Corn?

Should You Apply Pre-Tassel Nitrogen in Corn? published on No Comments on Should You Apply Pre-Tassel Nitrogen in Corn?

Should You Apply Pre-Tassel Nitrogen in Corn?

Rasel Parvej, Dan Fromme, Josh Copes, and Syam Dodla

 

Nitrogen is the most yield liming nutrient for corn production. Corn requires nitrogen for amino acids, protein, and chlorophyll production. Chlorophyll is the key component for photosynthesis. Chlorophyll deficiency results in reduced yield potential. A 200-bushel corn requires about 200 to 240 lb nitrogen per acre i.e. roughly 1 to 1.2 lb nitrogen per bushel corn harvested. Applying all the nitrogen at or before planting may subject to loss to the environment through volatilization (if nor incorporated, mainly for urea), denitrification (due to water-logged anaerobic conditions), and leaching (due to excessive rainfall for coarse-textured low cation exchange capacity soils). Therefore, nitrogen management in corn is one of the biggest concerns each producer has every year. It is recommended to apply nitrogen in at least 2 splits during the growing season with 1/3 at planting and 2/3 around V5-V6 stage (5-6 leaves with visible collars and plant is about 12-inch tall). Providing adequate nitrogen plus other deficient nutrients (mainly phosphorus and potassium based on soil-test level) around V5-V6 stage is very important because corn initiates ear shoots and tassel and sets yield components at or little after V6 stage.

Although most of the researchers showed that two applications are good enough to maximize corn yield under ideal conditions for most soils having medium to high cation exchange capacity (CEC >10), sometimes it is advised to apply nitrogen in 3 splits with 1/4 at planting, 2/4 around V5-V6 stage, and 1/4 before tasseling especially for coarse-textured soils with low CEC (<10) and for years with lots of rainfall during the early corn growing season. Including pre-tassel application in nitrogen fertilization program can help reduce nitrogen loss and ensure adequate nitrogen supply during the maximum nitrogen uptake period from V10 to tasseling. It also helps adjust nitrogen rate based on crop growth, environmental forecasts, crop sensing, and tissue testing. Many land-grant university trials showed that pre-tassel nitrogen application can increase corn yield if some pre-plant and sidedress nitrogen are lost due to excessive rainfall during early growing season (Figure 1).

Corn tissue testing is one of the important tools that guides whether pre-tassel nitrogen is required. For tissue testing, about 15-20 fully developed entire leaf below the whorl should be collected around V12 stage and sent immediately to the lab for analysis. This would allow producer enough time to get the results back and make decision. The critical (normal) corn leaf nitrogen concentration around pre-tassel stage ranges from 2.75 to 3.5%. So, leaf nitrogen concentration below 2.75% would be considered low and above 3.5% would be high. One caveat about tissue testing is, nitrogen concentration in corn leaf is highly influenced by crop growth and dilution factor; so, it may not always accurately diagnose nitrogen deficiency and indicate pre-tassel nitrogen need.

Considering excessive rainfall, crop growth, and/or tissue-testing, once producer decided to apply pre-tassel nitrogen, the application rate should not be too high at this stage especially as foliar application. Broadcasting high rate of nitrogen would burn foliage (Figure 2). The pre-tassel nitrogen rate should be 15 to 25% of the total nitrogen applied i.e. roughly 50 lb nitrogen per acre. Producer can choose dry (urea) or liquid (UAN) nitrogen source. Both dry and liquid nitrogen can be flown by airplane; but it would be better to place nitrogen close to plant base, if possible, with high clearance applicator using “360 Y-drop” to facilitate rapid uptake and avoid foliage damage. A little rainfall should be expected after aerial application, which would help incorporate nitrogen fertilizer and reduce foliage burn.

Figure 1. Nitrogen deficient corn in saturated soils due to excessive rainfall. (Source: https://www.pioneer.com/us/agronomy/nitrogen_application_timing.html)

Figure 2. Corn leaf burn due to broadcasting 100 lb nitrogen per acre as UAN. Photo courtesy: John E. Sawyer, Extension Soil Fertility Specialist, Iowa State University.

Italian ryegrass is everywhere! Do not forget about it this fall.

Italian ryegrass is everywhere! Do not forget about it this fall. published on No Comments on Italian ryegrass is everywhere! Do not forget about it this fall.

How many of you had an issue with glyphosate-resistant Italian ryegrass this spring?  Did you expect clethodim to solve the problem and then found it did not?  Did you apply paraquat and were not satisfied?  Many farmers, consultants, and dealers commented to me since late January that the Italian ryegrass problem has exploded in Louisiana.  Honestly, this is not surprising because we have not been addressing this pest properly.  Mississippi has had this issue for longer than Louisiana has.  Mississippi State University weed scientists determined a good strategy to manage glyphosate-resistant Italian ryegrass five or six years ago.  LSU AgCenter weed scientists adopted their strategies and began disseminating that plan.  It starts with tillage or a residual herbicide application in the fall, which has not been adopted by many producers in Louisiana.  This article will not go into detail about Mississippi State University’s glyphosate-resistant Italian ryegrass management plan in this article, BUT it will be covered at length later this year.

I am writing this article because I would like for Louisiana farmers, consultants, dealers, and ag lenders to notice that glyphosate-resistant Italian ryegrass is still present in corn, cotton, and soybean fields on May 1st.  It may be brown following herbicide applications, but it is still competing with crops as you can see in the photo (Figure 1).

Do not take glyphosate-resistant Italian ryegrass lightly.  Remember what crop fields look like in the spring so that you will be motivated to implement good management strategies in the future.  More to come later.  If you have questions, please contact your LSU AgCenter parish agent.  Feel free to contact me at 318-308-7225.  Have a great day.

Figure 1.  Italian ryegrass competing with seedling soybean
Figure 1. Italian ryegrass competing with seedling soybean

Weed Management Thoughts: Planting cotton and soybean in 2 to 3 weeks

Weed Management Thoughts: Planting cotton and soybean in 2 to 3 weeks published on No Comments on Weed Management Thoughts: Planting cotton and soybean in 2 to 3 weeks

To manage weeds preplant, meaning two to three weeks prior, or preemergence, an application of paraquat at 0.5 to 0.75 lb/A plus a residual herbicide is needed to remove existing weeds and maintain fields weed-free.  If paraquat is applied preplant, a second application may need to be applied at planting to remove any remaining green vegetation.

If 2,4-D, dicamba, Elevore, and others may be applied, read the label because there are planting restrictions for cotton and soybean.  However, there are no planting restrictions for Enlist Duo and Enlist One in Enlist crops or Engenia, FeXapan, Tavium, and XtendiMax in Xtend crops.

Choosing a residual herbicide, whether applied preplant and/or preemergence, depends on the crop to be planted and the weed spectrum.  There are numerous choices of residual herbicides labeled preplant/preemergence in cotton, but research has shown that Cotoran at 2 pints/A is a good choice for control of numerous grass and broadleaf weeds.  If glyphosate-resistant Palmer amaranth and waterhemp are a major concern, Brake plus Cotoran, both at 1 pint/A, is an excellent choice.

In soybean, there are numerous residual herbicide options.  Many will provide control of glyphosate-resistant pigweeds; however, they differ in the other weeds they will control.  For example, if pigweed, yellow nutsedge, and grasses are the targets, Boundary at 1.5 to 2 pints/A is a good choice.  But, if morningglory or smellmelon are also an issue, herbicide formulations that contain sulfentrazone (Authority formulations, Sonic, BroadAxe, etc.) or Canopy DF at 4 to 6 oz/A plus S-metolachlor at 0.95 lb/A would provide control.  Please contact your local LSU AgCenter agent to discuss your specific weed spectrum and residual herbicide options.

The length of maximum control provided by a residual herbicide is usually 3 to 4 weeks when properly activated.  So, if applied 2 weeks prior to planting, one may only expect 1 to 2 weeks of residual control in-crop.  In contrast, if the residual is applied preemergence, 3 to 4 weeks of control may be expected in-crop.  So, the choice of preplant or preemergence residual herbicide application will influence when the first in-crop postemergence application should occur.  Remember, seedling cotton and soybean must be protected from weed competition to help maximize yield potential, so plan accordingly.

Should You Apply an In-furrow Starter Fertilizer to Corn?

Should You Apply an In-furrow Starter Fertilizer to Corn? published on 1 Comment on Should You Apply an In-furrow Starter Fertilizer to Corn?

Josh Copes, Rasel Parvej, Syam Dodla, and Dan Fromme

Phone calls have been coming in regarding applying an in-furrow starter fertilizer at corn planting. An in-furrow starter is commonly called a “pop-up” fertilizer, and is applied in the seed furrow (in-furrow). This allows for ease of application and placing the nutrients close to the germinating seed which allows the seedling to have easy access to nutrients. A good in-furrow fertilizer will contain a high percentage of phosphorus along with some nitrogen, but could also contain sulfur, potassium, or micro-nutrients. In Louisiana, ammonium polyphosphate fertilizers, 10-34-0 and 11-37-0, are commonly used in-furrow. When applied in-furrow, there is potential for salt and ammonia injury from fertilizers with high salt indexes or contain urea- or ammonium-nitrogen. Urea is, therefore, not recommended to be applied in-furrow. Adequate soil moisture at planting, however, decreases the likelihood of potential salt injury. Another starter fertilizer placement strategy is applying in a 2 X 2 band (2” to the side of the seed furrow and 2” below the seed depth). This method of application requires additional planter attachments, but allows for use of higher rates of fertilizer at planting and avoid salt and ammonia injury. In-furrow application rates in excess of 5 gallons per acre of ammonium polyphosphate in corn are not advised. If you would like to know more about salt index for fertilizers visit this web site: http://www.spectrumanalytic.com/support/library/ff/salt_index_calculation.htm.

In Louisiana, considerable research has been conducted on the use of starter fertilizers in corn, either with 10-34-0 or 11-37-0 (Mascagni et al. 2006). In five out of 15 trials (conducted from 1991 to 2005), corn grain yield was significantly increased by the use of an in-furrow starter fertilizer. It should be noted that in each year soil-test-based phosphorus levels were considered high in the test area. Therefore, corn yield increase could still occur even though soil test phosphorus levels are high. Phosphorus deficiency symptoms and yield responses to the in-furrow fertilizer were most common in light textured soils (e.g. sandy loam and silt loam soils). Mascagni et al. (2006) also documented that nitrogen only fertilizers had little effect on early season plant growth whereas, in-furrow fertilizers containing phosphorus increased early season plant growth in all trials. This demonstrates that it is the phosphorus component that improved early season plant growth. The enhanced plant growth from the phosphorus containing fertilizers, also, resulted in hastened maturity of the corn crop. Mid-silk occurred four days earlier where yield responses were observed and three days earlier when no yield response occurred.

With low commodity prices and high input costs, producers are concerned whether or not they should spend the money on applying an in-furrow starter. Situations where a positive yield response will likely occur from the use of in-furrow phosphorus containing fertilizers are: 1) Planting earlier than recommended, 2) Planting in high residue/no-till situations, 3) When there is a need to apply phosphorus fertilizer based on soil test results, 4) Years with poor early season growing conditions (low temperature and excessive rainfall). Soils, especially, sandy and silt loam soils are slow to warm in the spring. Cool soils can often result in reduced phosphorus uptake by the plant resulting in temporary phosphorus deficiency, even though soil test phosphorus levels are adequate. Therefore, when planting earlier than February 25 in south and central Louisiana and March 10 in north Louisiana, an in-furrow starter may be beneficial. High residue situations typically result in cooler and wetter soils that can result in poor early growth and phosphorus deficiencies. Also, early season nitrogen deficiencies may occur in high residue/no-till situations. When soil test levels calls for the addition of phosphorus, using an in-furrow starter would be recommended. As mentioned earlier, in-furrow application of the fertilizer allows easy access of the nutrients since it is applied in a concentrated band with the seed. Unfortunately, we cannot predict early season growing conditions, an in-furrow starter can be cheap insurance against detrimental cool and wet weather conditions often experienced in Louisiana in March.

In summary, if you are equipped to apply a fertilizer in-furrow and plan on planting as early as possible or into high residue/no-till situations then applying an in-furrow starter may be beneficial. If soil test reports call for the addition of phosphorus then an in-furrow starter would be a good method to place the phosphorus in close proximity to the developing roots. Also nutrient use efficiency may be greater compared to a broadcast application of phosphorus, especially if the broadcast application occurred in the fall. This is due in part to time, since an in-furrow application is applied at planting, there is less time for soil reactions to “tie” up phosphorus from being available for plant uptake. Soil pH should, also, be considered for the decision of when to apply phosphorus. Phosphorus is most plant available from 6.5 to 7.5 pH range. If outside this range phosphorus should be applied closer to planting. If you have any questions please contact your local county agent, Drs. Dan Fromme, Rasel Parvej, Syam Dodla, or myself.
Contact Information:

Dr. Josh Copes
Assistant Professor (Agronomy)
Northeast Research Station
Cell: 318-334-0401
Office: 318-766-3769
jcopes@agcenter.lsu.edu

Dr. Syam Dodla
Assistant Professor (Soil Fertility and Irrigation)
Red River Research Station
Office: 318-741-7430 Ext: 1103
sdodla@agcenter.lsu.edu

Dr. Rasel Parvej
Assistant Professor (Soil Fertility)
Scott Research and Extension Center
Office: 318-435-2908
Cell: 497-387-2988
mrparvej@agcenter.lsu.edu

Dr. Dan Fromme
Professor (State Corn, Cotton, and Grain Sorghum Specialist)
Dean Lee Research Station
Office: 318-473-6520
dfromme@agcenter.lsu.edu

2019 Louisiana RIce Notes #2

2019 Louisiana RIce Notes #2 published on No Comments on 2019 Louisiana RIce Notes #2

This editions covers the reasons for the poor rice germination and poor stands we are seeing, things to consider prior to fertilizing and flooding, and why fertilizing on dry ground is so important.

2018 Soybean Core Block Yield Data

2018 Soybean Core Block Yield Data published on No Comments on 2018 Soybean Core Block Yield Data

Harvest data for our soybean core block variety demonstrations have begun to come in from across the state.  The data for these 10 trials is now available on the LSU AgCenter website at the link listed below.  I will continue to update the website with incoming data from the remaining trials.

Preliminary OVT data is also beginning to come in and is currently being analyzed before being made available to stakeholders.  This information will also be available on the LSU AgCenter website when ready.

 

http://www.lsuagcenter.com/profiles/lblack/articles/page1539783075012

 

Check Soils for Compaction Layers

Check Soils for Compaction Layers published on No Comments on Check Soils for Compaction Layers

Check Soils for Compaction Layers

Josh Copes, Dennis Burns, R.L. Frazier, and Dan Fromme

 

Over the past couple of growing season, soil compaction has been a hindrance in many fields across Louisiana.  Soil compaction was evident by observing reduced crop growth and development in fields and confirmed by inserting a penetrometer into the soil. Soil compaction is the compression of soil particles that reduces pore space thus creating a dense layer of soil that can impede plant root growth. Soil compaction can be caused by heavy machinery traffic and horizontal tillage operations when the soil is too saturated. There have been instances where a deep vertical till implement was used to alleviate a soil compaction layer only to create a new one, less than four inches deep in the row middle, when the rows were rebedded. This was probably a result of rebedding when the soil was too wet. Soil compaction reduces crop rooting ability, restrict water infiltration rate, reduces the volume of soil that plant root will be able to mine essential nutrients, and ultimately can reduce yield.

Machinery size is steadily increasing and will only lead to more frequent soil compaction issues. Silt loam soils are typically prone to compaction. There is perhaps a misconception that shrink and swell type clay soils are not prone to compaction layers due to being “deep broke” as they crack open during periods of drought. Regardless soil compaction layers have been observed in cracking clay soils. Fields where soil compaction could be an issue can be identified by visual observation where a reduction in crop growth rate is evident, early season nutrient deficiency symptoms occur, wilting of crops in certain areas of the field and not in others. Compactions areas can especially be identified during periods of cool weather early in the growing season where the crop develops at a reduced rate compared with the rest of the field with a similar soil type.

You can test for compaction layers by simply probing the soil (tops of beds/rows) in several areas within a field using a soil penetrometer. In order to mark the depth of the compaction zone, push the penetrometer down to the compacted zone and place a finger where the probe meets the soil surface. As a guideline, use the penetrometer when there is sufficient soil moisture for planting. Also, make sure that deeper soil compaction layers are not present. To avoid soil compaction limit field operations when soils are too wet. This can be difficult in Louisiana but creating hardpans will reduce yield. Deep vertical tillage is the fastest method to alleviate soil compaction layers. Deep or tap rooted winter cover crops can also help loosen a compacted soil over time and may help prevent a compaction layer from occurring by increasing soil organic matter and maintaining soil structure.

Below are some photos taken this year in fields with compaction layers. Fields with soil compaction layers should be identified and deep broke this fall when soil moisture conditions are favorable to lift the soil so the hardpan can be disrupted. If you have any questions or concerns please give us a call.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Photo 1. J-Rooted Cotton due to Soil Compaction Layer

 

 Photo 2. Soil Penetrometer Reading at Field of Photo 1. Reading is over 300 lb psi.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Photo   3. Depth of Soil Compaction Layer in Field of Photo 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Photo 4. Root Restriction on Macon Ridge Silt Loam Loess Soil. Photo courtesy of Hank Jones.

Winter Cover Crops: Planning for Cover Crop Success

Winter Cover Crops: Planning for Cover Crop Success published on No Comments on Winter Cover Crops: Planning for Cover Crop Success

Winter Cover Crops: Planning for Cover Crop Success

Josh Copes, James Hendrix, Lisa Fultz, Syam Dodla, and Naveen Adusumilli

 

Crop harvest is in full swing across most of Louisiana. As we move into October, now is the time to begin planning your winter cover crop management strategy. Cover crops are used for several purposes including: protecting soil from erosion, improving soil structure, scavenging and cycling of soil nutrients, increasing organic matter, helping to alleviate hardpans, etc. Cover crop selection will depend on the goals a producer would like to accomplish by planting a winter cover crop. Having a clear objective for planting a cover crop, will also aid in cover crop management.  For example, if minimizing soil erosion is the main objective, selecting a cereal cover crop, would be a good choice. The fibrous root system of cereals will help prevent top-soil from leaving the field. Cereal winter covers are good nutrient scavengers as well. In contrast, a tap-rooted cover crop like forage/tillage radish is better suited for deep nutrient scavenging and potentially aids in loosening a soil compaction layer or preventing one. Mixes of cereal and legume covers can reduce early season N fixation issues in corn. Preliminary data collected by AgCenter scientists has shown that in soybean, legume cover crops can supply N for early growth needs until nodules develop. Other important considerations when selecting a winter cover crop includes: cash crop to be grown following cover crop termination, and winter cover crop termination. Be sure to plant only quality seed, this will help eliminate weed seed contamination issues. Seeding rates should be adjusted for germination percentage or pure live seed per pound. When planting legumes, make sure the rhizobium inoculant strain is correct for the legume that is to be planted and always inoculate. If planting pre-inoculated legume seed be sure to get pure live seed per pound and adjust seeding rates accordingly; some pre-inoculated seed are larger and therefore have less pure live seed per pound.

Cover crops should be planted as soon as possible following main crop harvest. When planted earlier in the fall, growth/biomass production will be maximized prior to cold weather which will slow growth and development of the cover crop. Planting your cover crop soon after harvest, is especially important if corn will be planted. Early cover crop termination, when planting corn, combined with late planting of a cover crop (November) will reduce overall biomass production, therefore minimizing the benefits of the cover crop. Legumes are generally slow growing if planted too late (November), and biomass production will be minimal prior to the onset of cold weather. If fields are enrolled in a NRCS conservation program, that requires cover crops, be sure to follow the NRCS’s cover crop guidelines. Below is a link that contains NRCS seeding rates and planting dates for common cover crops grown in Louisiana. The planting window for most winter cover crops will be October 1 to mid-November. Ranges for average first frost dates for Monroe, Shreveport, Alexandria, and Baton Rouge are November 15, 18, 19, and 29th, respectively (https://www.farmersalmanac.com/average-frost-dates). Posted below, hyper link 2 and 3 are some useful tools may aid in further refinement of accomplishing the intended goals for your farm.

 

  1. NRCS planting dates and seeding rates for common cover crops grown in Louisiana:

https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/lapmctn9979.pdf.

 

  1. Cover Crop and Tillage Scenarios (Potential Scenarios and their implications on incentives payments.):

http://www.lsuagcenter.com/~/media/system/b/d/4/4/bd4437aff5c14f251a1be318b8b206a6/infographic_nadusumillipdf.pdf

 

  1. Q & A of Conservation Policy and Crop Insurance Surrounding Cover Crops:

http://www.lsuagcenter.com/profiles/nadusumilli/articles/page1520011387670

 

  1. Cover Crop Economics Decision Tool:

http://www.lsuagcenter.com/profiles/nadusumilli/articles/page1533331282945

 

 

Contact Information:

 

Josh Copes

Cell: 318-334-0401

Office: 318-766-4607

jcopes@agcenter.lsu.edu

 

James Hendrix

Cell: 318-235-7198

Office: 318-766-4607

jhendrix@agcenter.lsu.edu

 

Lisa Fultz

Cell: 225-366-8863

Office: 225-578-1344

lfultz@agcenter.lsu.edu

 

Syam Dodla

Cell: 225-505-7064

Office: 318-741-7430

sdodla@agcenter.lsu.edu

 

Naveen Adusumilli

Cell: 318-884-0514

Office: 225-578-2727

nadusumilli@agcenter.lsu.edu