What's Cropping Up? Blog

Articles from the bi-monthly Cornell Field Crops newsletter

June 11, 2019
by Cornell Field Crops
Comments Off on Corn and Soybean Weed Control in a Wet Year

Corn and Soybean Weed Control in a Wet Year

Mike Hunter, CCE – North Country Regional Agriculture Team

small common lambsquarters

Small common lambsquarters that emerged before the soybean planted in this field. Photo taken in Jefferson County June 2019

The cool, wet month of May and start of June has created some challenging weed management situations for both corn and soybean.  Unfortunately, delayed planting seasons force growers to focus so much on getting the corn and soybean planted they may not have had the opportunity to make a timely planned preemergence (PRE) herbicide application.

Here is a common situation that we are already encountering this season.  We have a field with corn or soybeans planted and cool conditions have delayed crop emergence but the weeds have already emerged before the PRE herbicide treatment was made.  Do we stick to our original plan and apply a PRE herbicide to this field or do we need to make adjustments to the herbicide program?

If your planned PRE herbicide application has been delayed, it is very important to carefully consider your herbicide choices and make necessary adjustments if any weeds are emerged at the time of application.  With adequate rainfall, PRE herbicides can provide excellent weed control; however, once the weeds are emerged they will generally need some additional product to the tank mix.  The additional product could be another herbicide to add to the tank mix or just an adjuvant such as non-ionic surfactant (NIS), crop oil concentrate (COC) or methylated seed oil (MSO).  There will be many more options in corn than soybeans.

Corn fields not treated with an herbicide prior to crop emergence need to be looked at carefully.  If very small weeds are emerged at the time of the PRE application the answer may be as simple as adding adjuvant to the PRE herbicide.  Consult the herbicide label and follow the adjuvant recommendations based on the products in the tank mix.

If the corn has emerged and the annual grasses are over 1 inch tall and the broadleaf weeds are 2 to 3 inches tall, it may be necessary to add another herbicide to the PRE herbicide.  If the corn is glyphosate tolerant, you may only need to add glyphosate to the preemergence herbicide program.  Using this same scenario with conventional corn, you will likely need to include a postemergence (POST) herbicide to the PRE herbicide.  Examples of POST tank mix herbicides to consider for control of both emerged annual grasses and broadleaf weeds include: Revulin Q, Realm Q, Resolve Q, Capreno, Laudis, Armezon.  The effectiveness of these POST herbicides varies with the control of different annual grasses making proper weed identification critical.  Again, check the herbicide label prior to making any herbicide applications.

If you are using a PRE soybean herbicide it will likely be an Herbicide Group 2 (Pursuit, Python, Firstrate), 3 (Prowl, Treflan, Sonalan), 5 (TriCor, Dimetric, metribuzin), 7 (Lorox, Linex), 14 (Valor, Sharpen) or 15 (Dual, Warrant, Outlook).  Soon after soybeans are planted, there is a narrow window to make certain PRE herbicide applications.  Valor (flumioxazin), Sharpen (saflufenacil), metribuzin and any premixes containing these active ingredients must be applied prior to crop emergence.  Lorox (linuron) is another PRE soybean herbicide that must also be applied prior to crop emergence.  Prowl, Treflan and Sonalan are applied prior to planting soybeans.

Soybean fields not treated with a PRE herbicide after crop emergence where very small weeds have emerged can be more difficult to deal with, especially if a population herbicide resistant tall waterhemp is present.  Recently, Dr. Bryan Brown, NYS Integrated Pest Management Program, conducted tall waterhemp herbicide resistance screening trials at Cornell University.  Using tall waterhemp seeds collected from three different fields in New York, preliminary results indicate that two populations were resistant to glyphosate (i.e. Roundup, Group 9), three populations resistant to atrazine (i.e. Aatrex, Group 5) and two populations resistant to imazethapyr (i.e. Pursuit, Group 2).  Fortunately, none of the tall waterhemp screened were found to be resistant to lactofen (i.e. Cobra, Group 14).

If a population of multiple resistant tall waterhemp is present, our effective herbicide options are limited.  The PRE herbicides that will provide control of multiple resistant (Group 2, 5, 9) tall waterhemp include Dual, Warrant, Outlook (S-metolachlor, acetolchlor, dimethenamid-P), Prowl, Treflan, Sonalan (pendimethalin, trifluralin, ethafluranlin) Valor SX (flumioxazin) and Lorox, Linex (linuron).  If both the soybeans and multiple resistant tall waterhemp have emerged, our effective herbicide options are very limited.  Dual, Warrant and Outlook are the only PRE herbicides listed that can be applied POST; however, these products will not control emerged weeds.  In this situation it would be necessary to include either Reflex or Cobra (Group 14) to the tank mix to provide control of the emerged tall waterhemp.

Soybeans with the herbicide resistant technologies such as Liberty Link (glufosinate tolerant i.e. Liberty), Xtend (dicamba tolerant i.e.Xtendimax, Engenia, FeXapan) and Enlist E3 (2,4-D i.e. Enlist, glufosinate and glyphosate tolerant) provide additional options for POST control of resistant tall waterhemp.

This spring has provided very limited opportunities to plant corn and soybeans due to frequent rainfall and wet field conditions.  This challenging spring has also made it difficult to apply planned PRE herbicides in a timely manner.  It is important to carefully scout your fields before making any herbicide application to make sure the right products are included in the tank mix. And as always, check the herbicide label prior to making any herbicide applications.

 

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June 10, 2019
by Cornell Field Crops
Comments Off on Statewide Corn Trials Underway: Do We Need Neonicotinoid Seed Treatments in NY?

Statewide Corn Trials Underway: Do We Need Neonicotinoid Seed Treatments in NY?

By Jaime Cummings, NYS Integrated Pest Management

No-till corn field

(No-till corn field, photo by Ken Wise, NYS IPM)

Most corn and soybean growers in New York plant seed treated with insecticides.  But are those treatments really needed in every field?  The recent scrutiny on neonicotinoids (aka: neonics) causing harm to pollinators has brought this question to the forefront.  Given all the negative attention that neonicotinoid have received in the media in recent years regarding pollinator health, it’s no surprise that they are on the chopping block in some NY legislative bills.  These bills follow similar bans on neonics that have already taken place in Europe and Canada.  Neonics have a bad reputation as having negative effects on bee health.  Think about all the news you’ve seen or heard about the “bee-pocalypse”.  And, it’s true that they can be lethal to bees and other beneficial pollinators, especially if applied to crops at incorrect timings or under the wrong conditions.  They are insecticides, after all, and they are effective at killing insects, the good ones and the bad ones.  But, let’s not forget about the bad ones they are intended to target to help farmers raise healthy and productive crops to feed livestock and all of us.  It’s important that we consider both the positive and negative effects of these seed treatments when determining an overall need and value in our agricultural systems.

Hundreds of dead bees near a bee colony, believed to have been exposed to neonics

Hundreds of dead bees near a bee colony, believed to have been exposed to neonics (Photo courtesy of D. Schuit)

Neonic insecticides are used in many cropping systems, from fruits and vegetables to ornamentals to corn and soybeans to protect against some troubling pests.  Neonics are available as seed treatments, soil drenches or foliar sprays to various crops, depending on the target pests and formulation of the products.  And farmers everywhere have been using them for years, often as part of an integrated pest management program, to help minimize losses to some destructive pests.  They were so widely adopted because they are effective pest management tools and because they were perceived as having a reduced overall negative impact on the environment and human health compared to many of the older insecticide chemistries, such as the organophosphates.  But then it became apparent that these neonics, though safer for human health than many other insecticides, were taking a toll on beneficial insects, especially our bees that we rely on for pollinating many of our important food crops.  And we need to pay attention to that issue and determine ways to mitigate those risks.

Seedcorn maggots feeding on a corn seed.

Seedcorn maggots feeding on a corn seed. (Photo courtesy of J. Kalisch, University of Nebraska)

As mentioned above, neonics are used in various ways in many cropping systems.  But their use as corn and soybean seed treatments has received a lot of attention because of the known potential for the neonic seed treatments to drift off-target as dust during planting.  Because corn and soybeans cover such vast acreage in NY and across the country, mitigating these risks could potentially have a large impact on reducing bee mortality.  Therefore, these seed treatments seem a likely, and potentially easy target for negative attention when folks start looking to reduce overall neonic usage.  In response, the seed and seed treatment industries working with the EPA, USDA and other organizations started looking into ways that they could reduce the negative impacts that neonic treated corn and soybean seed could have on bees.  In 2013, the EPA held a Pollinator Summit to focus on reducing exposure to dust from treated seed.  Much research went into this focus group with collaborations between industry, academia and governmental regulatory agencies to address the off-target movement of dust from planting neonic treated seeds.  I encourage you to read all the details for yourself regarding what they did and what they discovered in the Dust Focus Group and the Seed Treatment Group.  For the sake of this article, I will briefly summarize their findings, conclusions and recommendations:

  1. Start with clean, quality seed with minimal dust to begin with – many major seed companies have high standards for starting with clean seed which allows seed coating to better adhere, resulting in less dust.
  2. Use improved polymers for adhering treatments to seed coats: seed coating technologies have improved dramatically over the years, meaning that less active ingredient ‘falls off’ the seed coat.
  3. Use bee-safe seed lubricants:  this minimizes the dust moving to off-target plants. New seed coating polymers and polyethylene wax lubricants for talc replacement can result in 90% total dust reduction and 65% active ingredient reduction in the dust.
  4. Eliminate flowering weeds in and around fields prior to planting – this reduces the number of flowers that may accidentally have neonic dust that bees may forage on.  The goal of many field crop growers is to ‘start clean’ meaning that they often try to minimize or eliminate competition from weeds prior to planting.
  5. Be aware of wind speed and wind direction at time of planting – be a good neighbor. Avoid planting on the windiest days (when possible) and be aware of nearby bee colonies and wind direction.  There are actually apps available to connect bee keepers with farmers to raise awareness of pesticide applications and locations of bee colonies.
  6. Re-direct the exhaust flow of vacuum planters downward to minimize off-target movement of dust.  Simple modifications can be made to some planters to re-direct the flow of the exhaust down toward the soil, which can significantly reduce dust movement.  (Many planters don’t exhaust, and most air seeders already exhaust downward).
  7. Follow labeling instructions for handing, storage, planting and disposal of treated seed and containers.
EPA Website Screenshot on Pollinator Protection

https://www.epa.gov/pollinator-protection/2013-summit-reducing-exposure-dust-treated-seed

The findings, improvements and recommendations from this summit can greatly decrease the risk of negative effects of dust from neonic seed treatments on pollinators.  However, some people are also concerned about neonics that might move through soil or water showing up in water and non-target plants. Because of these issues, neonic seed treatments might still be banned on corn and soybean in NY, so growers are concerned.

Neonic seed treatments come standard in just about every bag of corn and soybean seed planted.  Some say we do need them, others say we don’t.  If we look back in history a few decades, before the neonic seed treatments became available, farmers in NY struggled with early season pests like the seedcorn maggot, which can significantly reduce stand counts (and yields) under high pest pressure.  The seedcorn maggot is favored by situations with actively decomposing organic matter, such as manure applications and terminated cover crops.  Both of these situations are quite common in NY corn and soybean production systems.  But, since the neonic seed treatments became so widely used, the seedcorn maggot issues have decreased dramatically, and possibly faded from memory.

Skips in a corn row caused by seedcorn maggots eating the corn seed.

Skips in a corn row caused by seedcorn maggots eating the corn seed. (Image courtesy of T. Baute, OMAFRA)

But it still begs the question:  Do we have pest pressure that warrants neonic seed treatments on the vast majority of our acres of corn and soybean every year?  That is a good question.  From an integrated management perspective, it’s never recommended to rely so heavily on one tool in the tool box for as long as we have with these neonics.  We know that our insect pests can develop resistance to insecticides, just like weeds develop resistance to herbicides.  There is also some evidence from various academic studies showing that the neonic seed treatments can negatively impact predatory insects, such as ground beetles, and other beneficial insects that serve as natural biological control of some of our other pests, such as slugs.

Given those reasons, it seems like it might be a good idea to reduce our dependence on neonic seed treatments, and only use them in situations where we know we need them, right?  But, on the other hand, it’s important to keep in mind that, for now at least, it’s not easy to buy corn or soybean seed without a neonic as part of the seed treatment package.  It’s very efficient and economical for the seed industry to include these standard treatments on their seed, and it’s also important for their liability for the guarantees they may offer farmers who purchase their seed.  Not to mention that it’s not easy to anticipate when and where we need the neonic seed treatments each year.  Sure, we know that fields with a history of manure and/or cover crops may be more likely to have seedcorn maggot issues, but there’s no guarantee they won’t also show up in a clean, tilled field.  And, once the crop is planted, it’s too late to scout and determine whether or not the seedcorn maggots are going to be a problem.  This unpredictability is why the neonics are used as an ‘insurance plan’ against these sort of pests.

This conundrum is why this is such a highly polarizing debate, and why the proposed legislative bans have some farmers riled up.  It’s not that farmers want to use or pay for any more pesticides than they need, but the risk can be too high for their bottom line to just stop using them altogether.  We need local research to back up any claims for or against the use of insecticidal seed treatments in corn and soybean production, and specifically the need for neonics.  Much of the research from other states shows that they may not be necessary after all, because they don’t seem to cause a yield benefit.  But, upon closer inspection of some of those results, many of those trials didn’t have measurable insect pest pressure to produce meaningful comparisons of treatments.  And, many of the areas where those trials were conducted do not have the same practices with high organic inputs from manure and cover crops that many NY farms do.

Seedcorn maggot damage to soybean

Seedcorn maggot damage to soybean (Photo courtesy of University of Minnesota)

So, it’s complicated.  A great deal of pollinator risk research is being conducted at Cornell, including a risk assessment of neonic use.  The results of that assessment could influence the future of legislation on the availability or restriction of these products.  We know the dust from the neonic seed treatments poses a potential threat to pollinators (especially bees).  But we also know from the EPA pollinator summit that there are ways to mitigate those risks through improved seed coating and seed lubricant technologies, which have been widely implemented.  However, we still don’t know if there are other risks from these seed treatments, and we need more concrete evidence to know whether or not these neonic seed treatments are really necessary in such a large percentage of our NY corn and soybean acreage.

That’s why we decided earlier this spring to coordinate five statewide large-scale, on-farm trials with NYS IPM and Cornell Cooperative Extension specialists to try to evaluate the effect of these neonic seed treatments on 1) plant populations, 2) yield, and 3) how they compare to the anthranilic diamide seed treatments which could potentially replace them if the neonics are banned.  These corn silage trials will be located in eastern, western, northern and central NY, all on farms that have typical NY cropping practices that incorporate manure and/or cover crops.  Stand counts will be taken to measure plant populations and to determine insect pest pressure, and yields will be measured to compare the three seed treatments:  1) neonic + fungicide, 2) diamide + fungicide, and 3) fungicide only.

Regardless of our results, we will need multiple years of study to better characterize the pest pressure.  Ideally, we would determine methods to predict and monitor seedcorn maggot pressure in individual fields and years for exploring biological, cultural and genetic means for suppressing these insects.  However, this has proven challenging, as evidenced by the current situation in Canada.

Stay tuned for the results of these studies later this fall.  And, I want to extend my sincere gratitude to all parties involved for coming together to conduct this research on extremely short notice.  Thank you to Seedway for donating the seed, to Syngenta for donating the seed treatment products, to the participating farmers who are taking time out of their busy schedules to plant and harvest these trials, and to our CCE and PRO-Dairy collaborators (Joe Lawrence, Mike Hunter, Mike Stanyard, Aaron Gabriel and Janice Degni) for volunteering their time to conduct this important research.  THANK YOU!!!

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May 9, 2019
by Cornell Field Crops
Comments Off on Nitrogen Management for Forage Winter Cereals in New York

Nitrogen Management for Forage Winter Cereals in New York

Sarah E. Lyonsa, Quirine M. Ketteringsa, Shona Orta, Gregory S. Godwina, Sheryl N. Swinka, Karl J. Czymmeka,b, Debbie J. Cherneyc, Jerome H. Cherneyd, John J. Meisingere, and Tom Kilcera,f

a Nutrient Management Spear Program, Department of Animal Science, Cornell University, Ithaca, NY, b PRODAIRY, Department of Animal Science, Cornell University, Ithaca, NY, cDepartment of Animal Science, Cornell University, Ithaca, NY, dSoil and Crop Sciences Section of the School of Integrative Plant Science, Cornell University, Ithaca, NY, eUSDA-ARS Beltsville Agricultural Research Center, Beltsville, MD, fAdvanced Agricultural Systems, LLC, Kinderhook, NY

Introduction

Forage double-cropping, or growing two forage crops in a single growing season, can be a beneficial practice for dairy farmers in New York. Double-cropping corn silage with forage winter cereals, such as triticale, cereal rye, or winter wheat, can add additional spring yield on top of numerous environmental benefits including preventing soil erosion, nutrient recycling, and increased soil organic matter over time – which all promote increased soil health. Winter cereals intended for forage harvest require nitrogen (N) management to reach optimum yield and forage quality. This study was aimed at identifying field and management characteristics that can estimate yield and N needs for winter cereals harvested for forage in the spring.

Field Research

A state-wide study with 62 on-farm trials investigated the spring N needs of forage winter cereals across New York from 2013 to 2016. Each trial had five rates of N (0, 30, 60, 90, and 120 lbs N/acre) applied to farmer-managed forage triticale, cereal rye, or winter wheat at green-up in the spring to determine the most economic rate of N (MERN). All forages were harvested at the flag-leaf stage in May each year. Soil samples were taken at green-up before fertilizer was applied. Farmers supplied information about management practices and field characteristics, such as past manure applications, planting date, and soil drainage. This information, in addition to soil fertility analysis results, was used to develop a decision tree model for predicting MERN classification.

Results

About one-third of the trials did not require additional N (MERN = 0), while the remainder responded to N and most required between 60 and 90 lbs N/acre (Figure 1). Yields at the MERN across trials ranged from 0.4 to 3.0 tons DM/acre (1.8 tons DM/acre average). Yield could not be accurately predicted based on information gathered, but the lower-yielding sites (< 1.0 tons of DM/acre) tended to be poorly or somewhat poorly drained and not have a recent manure history.

Farmer-reported soil drainage, manure history, and planting date were the most important predictors of the MERN (Figure 2). Most of the winter cereals grown on fields that were described as well-drained by the farmers did not require additional N at green-up. For the fields reported as somewhat poorly- or poorly-drained, 60 to 90 lbs N/acre were required if the field had not received manure the previous fall. If manure had been applied recently, 60 to 90 lbs N/acre were required for stands that were planted after October 1 versus 0 lbs N/acre if planting had taken place before October 1.

Forage winter cereal most economic rates of N (MERN) and yield at the MERN

Figure 1. Forage winter cereal most economic rates of N (MERN) and yield at the MERN for 62 N-rate trials in New York from 2013 to 2016. Fertilizer N was applied at spring green-up and forage was harvested at the flag-leaf stag in May.

Decision tree for forage winter cereal most economic rate of N (MERN) at spring green-up

Figure 2. Decision tree for forage winter cereal most economic rate of N (MERN) at spring green-up. If the indicated site or history factor in the blue box is true, move to the left branch in the tree; if false, move to the right branch. The predicted MERN is listed in the red boxes. Recent manure history refers to manure applied within the last year (either spring or fall). This decision tree correctly predicted MERN classifications for 78% of the trials included.

Forage winter cereal crude protein as impacted by N rate applied at spring green-up

Figure 3. Forage winter cereal crude protein as impacted by N rate applied at spring green-up for 62 trials in New York from 2013 to 2016. Forage was harvested at the flag-leaf stage in May.

Most forage quality parameters were not impacted by N rate. Neutral detergent fiber (NDF) at the MERN ranged from 42 to 60% of DM (52% average), in vitro true digestibility (IVTD) at the MERN ranged from 81 to 94% of DM (88% average), and NDFD digestibility (48-hour fermentation) at the MERN ranged from 67 to 84% of NDF (78% average). However, crude protein (CP) increased with N rate for most trials, even those with MERNs of 0. Crude protein averaged 13% of DM for the 0 lbs N/acre treatment and 20% of DM for the 120 lbs N/acre treatment (Figure 3). On average, CP increases by 1% for every 15-20 lbs of N applied. These findings suggest that additional N beyond the MERN can increase the CP levels of the forage while not impacting other forage quality parameters.

Conclusions and Implications

Results from this study emphasize the importance of growing conditions for optimum forage winter cereal performance. In fields that have poor drainage and lack recent manure histories, forage winter-cereals may not yield well and will likely require additional N inputs, while fields with well-drained soil conditions and better soil fertility will support higher yields and better forage quality without needing additional N in the spring. Planting date is also a critical management consideration. Planting late in the fall (after October 1 in this study), may result in lower yields (see also Lyons et al., 2018a). Timely planting (before October 1) in fields with good soil fertility and/or recent manure histories more often resulted in MERNs for N at green-up of 0 lbs N/acre, which would save farmers time and costs in the spring. Nitrogen management at green-up did not greatly affect forage quality except for CP, which increased with N addition even if the additional N did not increase spring yield.

Additional Resources

  • Lyons, S.E., Q.M. Ketterings, G.S. Godwin, J.H. Cherney, K.J. Czymmek, and T. Kilcer. 2018a. Spring N management is important for triticale forage performance regardless of fall management. What’s Cropping Up? 28(2): 34-35.
  • Lyons, S.E., Q.M. Ketterings, G.S. Godwin, K.J. Czymmek, S.N. Swink, and T. Kilcer. 2018b. Soil nitrate at harvest of forage winter cereals is related to yield and nitrogen application at green-up. What’s Cropping Up? 28(2): 32-33.

Acknowledgements

Cornell, Nutrient Management Spear Program, and Pro-Dairy logosThis work was supported by Federal Formula Funds, and grants from the Northern New York Agricultural Development Program (NNYADP), the USDA-NRCS, and Northeast Sustainable Agriculture Research and Education (NESARE). We would also like to thank participatory farmers and farm advisors for assisting with the trials, including Cornell Cooperative Extension educators, consultants, NRCS staff, and SWCD staff. For questions about these results, contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

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May 3, 2019
by Cornell Field Crops
Comments Off on Best Timing of Harvest for Brown Midrib Forage Sorghum Yield, Nutritive Value, and Ration Performance

Best Timing of Harvest for Brown Midrib Forage Sorghum Yield, Nutritive Value, and Ration Performance

Sarah E. Lyonsa, Quirine M. Ketteringsa, Greg Godwina, Debbie J. Cherneyb, Jerome H. Cherneyc, Michael E. Van Amburghb, John J. Meisingerd, and Tom F. Kilcere

 a Nutrient Management Spear Program, Department of Animal Science, Cornell University, Ithaca, NY, b Department of Animal Science, Cornell University, Ithaca, NY, c Soil and Crop Sciences Section of the School of Integrative Plant Science, Cornell University, Ithaca, NY, d USDA-ARS Beltsville Agricultural Research Center, Beltsville, MD, and e Advanced Agricultural Systems, LLC, Kinderhook, NY

Introduction

Forage sorghum is a drought and heat tolerant warm-season grass that can be used for silage on dairy farms. Since it requires a soil temperature of at least 60°F for planting, the recommended planting time for New York is early June, unlike corn which is usually planted earlier in the spring. This would allow time for a forage winter cereal harvest in mid- to late-May prior to sorghum planting. Forage sorghum also has comparable forage quality to corn silage for most parameters except for starch, which is typically lower in forage sorghum. The main question for this research was: can forage sorghum be harvested in time for establishment of a fall cover crop or winter cereal double crop in New York? To answer this question, we conducted seven trials in central New York from 2014 through 2017 to evaluate the impact of harvesting at the boot, flower, and milk growth stages versus the traditional soft dough stage on the yield and forage quality of a brown midrib (BMR) forage sorghum variety.

Trial Set-Up

The seven trials were planted between early June and early July on two Cornell research farms in central New York. The sorghum was planted at a 1-inch seeding depth and 15-inch row spacing (15 lbs/acre seeding rate). Two N-rates as urea treated with Agrotain® (Koch Agronomic Services, LLC, Wichita, KS) were broadcast at planting (100 and 200 lbs N/acre) with the goal of having a non-N limiting scenario for these sites. Alta Seeds AF7102 (Alta Seeds, Irving, TX) was used for all trials. Forage sorghum was harvested at the boot, flower, milk, and soft dough stages. Harvest was done using a 4-inch cutting height. Measurements included dry matter (DM) yield and forage quality, including total digestible nutrients (TDN), neutral detergent fiber (NDF) analyzed on an organic matter basis with amylase, 30 hour NDF digestibility (NDFD30), non-fiber carbohydrates (NFC), acid detergent fiber (ADF), dry matter (DM), crude protein (CP), and starch content. Forage quality parameters were entered into the Cornell Net Carbohydrate and Protein System (CNCPS) version 6.55, a ration formulation software, for predicting how sorghum harvested at various growth stages would perform in a typical dairy total mixed ration (TMR) compared to corn silage. Forage sorghum, at each of the different growth stages, was substituted for 0, 25, 50, 75, and 100% of the corn silage fraction of the diet, and metabolizable energy (ME) allowable milk and metabolizable protein (MP) allowable milk were predicted.

Results

Timing of forage sorghum harvest impacted both yield and forage quality. Yield did not increase beyond the flower stage for four trials or beyond the milk stage for one trial. For two trials yield continued to increase until the soft dough stage. Averaged across all trials, yield increased from 4.8 tons DM/acre at the boot stage, to 6.0 tons DM/acre at the flower stage, and 6.8 and 7.1 tons DM/acre at the milk and soft dough stages, respectively (Figure 1). These results suggest that, in most cases, forage sorghum can be harvested at the flower or milk stage without losing a substantial amount of yield. With later harvests forage quality parameters of DM, starch, and NFC were increased while CP, NDF, and NDFD30 were decreased.

Graph of summary of yield and forage quality of BMR brachytic dwarf forage sorghum

Figure 1: Summary of yield and forage quality of BMR brachytic dwarf forage sorghum as impacted by growth stage at harvest. These are averages of seven trials in central New York from 2014-2017. Quality parameters include total digestible nutrients (TDN), neutral detergent fiber (NDF) analyzed on an organic matter basis with amylase, 30 hour NDF digestibility (NDFD30), non-fiber carbohydrates (NFC), acid detergent fiber (ADF), dry matter (DM), crude protein (CP), and starch.

Without adjusting for DM intake, 100% inclusion of forage sorghum harvested at the soft dough stage resulted in predicted ME allowable milk (90 lbs) that was similar to the 100% corn silage TMR (92 lbs) across sorghum inclusion amounts (Fig. 2A). The lower starch content of less mature sorghum resulted in reduced ME allowable milk at greater inclusion in the diet, averaging 87, 88, and 89 lbs for 100% inclusion of sorghum at the boot, flower, and milk stages, respectively. Predicted MP allowable milk for all sorghum growth stages was similar to that of corn silage (Fig. 2B).

Graph of metabolizable energy allowable milk and metabolizable protein allowable milk of forage sorghum

Figure 2: Metabolizable energy (ME) allowable milk (A) and metabolizable protein (MP) allowable milk (B) of BMR brachytic dwarf forage sorghum predicted with the Cornell Net Carbohydrate and Protein System (CNCPS) version 6.55. Harvest took place at four growth stages, and sorghum was substituted for different percentages of corn silage in a typical dairy total mixed ration. Values are averages of seven trials in central New York from 2014 to 2017.

Conclusions and Implications

Forage sorghum can be a good alternative to corn silage in double-cropping rotations with winter cereals grown for forage in New York. The BMR forage sorghum in this study could be harvested as early as the late-flower to early-milk growth stage without losing significant amounts of yield. However, early harvesting did affect forage quality, resulting in greater NDFD30, NDF, ADF, and CP, and less NFC, starch, and DM. Forage sorghum could replace corn silage in a dairy TMR but energy supplements are needed if sorghum is harvested before the soft dough stage due to a lower starch content at the earlier harvest dates. Additional forage may also be needed in a sorghum-based TMR due to changes in fiber digestibility at different growth stages. The higher moisture content of less mature sorghum may also call for adjustments in chop length and/or silage additives, such as inoculants, for proper fermentation.

Additional Resource

Lyons, S., Q.M. Ketterings, G. Godwin, D.J. Cherney, J.H. Cherney, J.J. Meisinger, and T.F. Kilcer (2019). Nitrogen Management of Brown Midrib Forage Sorghum in New York. What’s Cropping Up? 29(1):1-3.

Acknowledgements

Cornell University logo, Nutrient Management Spear Program logo, and Pro-Dairy logoThis work was supported by Federal Formula Funds, and grants from the Northern New York Agricultural Development Program (NNYADP), New York Farm Viability Institute (NYFVI), and Northeast Sustainable Agriculture Research and Education (NESARE). For questions about these results, contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

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April 25, 2019
by Cornell Field Crops
Comments Off on Challenges and Benefits of Riparian Buffers on Water Quality

Challenges and Benefits of Riparian Buffers on Water Quality

Christine Georgakakos1 and Karl Czymmek2
1Biological and Environmental Engineering, 2Animal Science and PRO-DAIRY; Cornell University

Riparian buffers are a popular practice implemented in both animal and crop agriculture.  A riparian buffer is an uncultivated area surrounding streams or saturated areas.  Saturated areas can include both perennially and temporally wetter-than-average parts of the landscape. We tend to prescribe buffers to span a certain distance from the stream, i.e. a 50 ft buffer along small headwater streams in agricultural lands.

Cattle exclusion riparian buffer

Figure 1: Cattle exclusion riparian buffer in the first season after implementation.

The purpose of a riparian buffer is two-fold.  Firstly, buffers filter soil and pollutants from water flowing over the soil surface.   Permanent grass and other plant species slow the flow of water by friction.  As water moves across a buffer, particles settle out and some water infiltrates into the soil, allowing sorption of pollutants to soil particles or otherwise slowing transport directly to a stream of soluble contaminants.   The trapped or settled pollutants can be used by buffer plants in the case of nutrients, or tightly bound by soil particles for some non-nutrient pollutants.  Some buffer biomasses are harvested as a way to remove nutrients tied up in the plant material. Secondly, when placed in livestock pastures, buffers are fenced to limit animal access to the stream to eliminate placement of urine and feces directly to surface waters or adjacent areas in addition to the benefits already outlined (Figure 1).

In practice there are a variety of factors that may reduce the water quality gains the buffer may be able to achieve.  For optimal effect, many factors need to be considered when installing buffers.  Buffers cannot filter water that does not flow over the soil surface or if too much water flows through too rapidly.  Surface features and high runoff rates that cause flow to concentrate can overwhelm the ability of a buffer to filter, effectively allowing water to by-pass the buffer.  For this reason, some conservation professionals advocate variable width buffers: extending permanent vegetation into fields or pastures to increase contact distance of flowing water within the buffer in areas likely to be saturated. Another means by which buffers can be by-passed is via ditches and subsurface drainage from fields or farmsteads where filtration is limited.

Common point sources tend to be tile line discharges, concentrated flow paths through pastures or fields, and overflow from other water routing structures. Any location where buffers are being planned should be inspected for features that can limit buffer effectiveness so that the system can be most efficiently designed for maximum pollutant removal.  Understanding details about each riparian buffer site to assess potential nutrient inputs into streams before implementing a best management practice will help more fully address these issues.

Short circuited riparian buffer

Figure 2: Sample saturated area that short circuits a riparian buffer. To maximize riparian buffer effectiveness, cattle exclusion should be extended beyond the saturated area. The left side of the fence experiences cattle grazing while the right side of the image does not.

Buffers in pasture systems raise different issues compared to crop fields.   In buffer systems where livestock exclusion is involved, fences are typically installed in a straight line(s), simplifying construction and upkeep.  Unfortunately, those lines do not always incorporate areas in the landscape that are likely to become saturated.  When these wetter than average areas are not included in the buffer system, animals tend to trample the moist, soft soil, reduce infiltration capacity, and generate swampy, wet areas within . These areas then tend to puddle, and form concentrated flow paths through the buffer. (Figure 2)  An ideal buffer would take into consideration these areas of higher saturation. Complicating management, these areas are not necessarily perennial, and can change year to year.   From a management perspective, it could be potentially difficult as moving fencing to incorporate saturated zones into the buffer is less that desired unless moveable fencing is already included in the management plan.  Meandering or movable buffer boundaries may be difficult to implement in many existing management systems, so addressing variable wet areas for animal exclusion would be most convenient if paired with other management practice changes.

Buffers are an effective water quality management tool even if imperfectly implemented.  Farmers and planners should strive to identify the areas where buffers can do the most good and locate and eliminate possible by-pass factors for best water quality results.   It is important to understand the nutrient inputs to a stream before implementing a riparian buffer so that water quality may be improved as much as possible.

Ideally, when implementing a buffer system, there are a few steps we can take to maximize buffer effectives and minimize short circuiting the buffer: (1) identify and try to address point sources flowing through the buffer system, (2) include areas likely to become saturated within the buffer zone, and (3) be prepared to modify a buffer zone as new saturated areas are developed.  These steps should help address the end goal of buffers reducing nutrient pollution to streams.

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April 5, 2019
by Cornell Field Crops
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What’s Cropping Up? Volume 29, Number 2 – March/April 2019

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