NPK et cetera https://npketc.soils.wisc.edu From the Desk of Carrie Laboski Thu, 24 Mar 2022 15:33:27 +0000 en-US hourly 1 Questions about safe rates of starter fertilizer are popping up https://npketc.soils.wisc.edu/2022/03/24/questions-about-safe-rates-of-starter-fertilizer-are-popping-up/ Thu, 24 Mar 2022 15:33:27 +0000 https://npketc.soils.wisc.edu/?p=595 Questions about safe rates of starter fertilizer are popping up — pun intended. For more information check out a past article on safe rates of seed placed starter fertilizer.

Safe rates of seed placed starter fertilizer

 

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2021 Soil, Water, and Nutrient Management Update Meetings https://npketc.soils.wisc.edu/2021/11/24/2021-soil-water-and-nutrient-management-update-meetings/ Wed, 24 Nov 2021 02:19:38 +0000 https://npketc.soils.wisc.edu/?p=590 The 2021 Soil, Water and Nutrient Management Meetings will be virtual. Two identical sessions are offered. The first will be on Monday, December 6 from 12:30 to 3:55 and the second on Friday, December 10 from 8:30 to 11:55. The event is free of charge. However, registration is required by December 4.

Register at:  https://forms.gle/oK1pya2qqWrcYSB26 

There will be four speakers, with 5-minute breaks between speakers. CEUs have been requested for Certified Crop Advisers (2.0 in Soil and Water Management, and 1.5 in Nutrient Management).

Presentations Include: 

• DATCP Nutrient Management Update – DATCP staff 

• Carbon markets from a soil scientist’s point of view – Francisco Arriaga 

• Strategies for reducing soil and nutrient losses in runoff – Francisco Arriaga 

• Trends in P runoff from Wisconsin farms – Matt Ruark 

• Cover crop research update – Matt Ruark 

• Preliminary evaluation of alternative soil test methods for profitable crop production – Carrie Laboski 

• Strategies for managing nutrients when fertilizer prices are extremely high – Carrie Laboski 

Contact Francisco Arriaga (farriaga@wisc.edu), Dan Marzu (dan.marzu@wisc.edu), or Jamie Patton (jjpatton2@wisc.edu) with questions about the meeting or registration. 

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We’re back! Agronomy/Soils Field Day to be held on August 25. https://npketc.soils.wisc.edu/2021/06/25/were-back-agronomy-soils-field-day-to-be-held-on-august-25/ Fri, 25 Jun 2021 02:58:45 +0000 https://npketc.soils.wisc.edu/?p=571

The Departments of Soil Science and Agronomy in collaboration with the Arlington Ag Research Station invite you to join us at the Agronomy/Soils Field Day on August 25, 2021. After our pandemic hiatus in 2020, we are excited to see you and have put together a stellar program highlighting College of Ag and Life Sciences research on emerging technology, crops, and cropping practices that will improve the sustainability and resilience of our cropping systems.

We are trying a new format for the field day this year. The tour will consist of six stops with two speakers at each stop. We will have a shot gun start, meaning you will be able to participate in all 12 presentations.

Registration is required this year and is free. Register online at: https://go.wisc.edu/a32g16 or call 608-262-0485.

For more details, see 2021 Agronomy/Soils Field Day Flyer. We look forward to seeing you August 25!

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Considerations for Corn Sidedress Nitrogen Applications During Hot, Dry Conditions https://npketc.soils.wisc.edu/2021/06/11/considerations-for-corn-sidedress-nitrogen-applications-during-hot-dry-conditions/ Fri, 11 Jun 2021 01:01:24 +0000 https://npketc.soils.wisc.edu/?p=563 It has been abnormally dry throughout much of Wisconsin this spring. Current weather forecasts are for hot and dry conditions to persist for at least the next 10 days. A few farmers and agronomists have asked if they should make any changes to their corn sidedress N application plans based on the current, and forecasted, weather. Below are a few things to consider.

Urea or urea ammonium nitrate (UAN) are the most common sidedress N sources. Nitrogen loss through ammonia volatilization of urea is enhanced when the following conditions occur:

  • High temperature.
  • There is no rain after application. Ammonia volatilization losses will be low if 0.1 to 0.2 inches of rainfall occur with 2 to 4 days after urea application, when temperatures are 50° to 70°. If there is no rainfall with 5 days, ammonia losses may be significant.
  •  Soil pH > 7.0.
  • Relative humidity of 50 to 90 %.
  • Low soil organic matter and low clay content. Volatilization losses are more likely on sandy soils because they have a lower ability to retain ammonium on the cation exchange.
  • Greater surface residue.

Research at Lancaster and Arlington Ag Research Stations found that when urea was surface applied during warm weather, 19% of the N was lost as ammonia within two days of application (Oberle and Bundy, 1984). During warm weather, rainfall within one day of urea application is needed to limit ammonia volatilization.

Urease inhibitors (e.g. active ingredients include NBPT, Duromide, NPPT; products include Agrotain, Anvol, Limus) can be used with surface applied urea to prevent decomposition of urea and volatilization of ammonia. Urease inhibitors extend the period of time between urea application and when significant N losses occur. This provides a greater opportunity for rainfall to occur during this longer time frame. Given the current weather conditions and forecast, a urease inhibitor should strongly be considered for all surface applied urea or UAN.

Fifty percent of the N in UAN is in the form of urea, therefore 50% of the N is subject to volatilization loss and would benefit from the use of a urease inhibitor if surface applied. The amount of urease inhibitor used with UAN is typically half the amount used with urea, because only 50% of the N in UAN needs protection. If UAN is knifed in, and the soil closes behind the knife, then a urease inhibitor is likely unnecessary. Cultivation of urea or UAN into the soil, would also likely limit ammonia volatilization.

Consider delaying sidedress application by a few days when there is no rain and high temperatures are forecast. The purpose of delaying application is to reduce the length of time urea is on the soil surface before rainfall occurs. The length of time you delay application will depend upon the height of the crop and the application equipment available. Sidedress applications at V9 have been successfully used in Wisconsin where 40 lb N/a was applied at planting.

In drought conditions, water limits corn growth and yield more than N. In 2012, we found no yield increase to sidedress N fertilizer (Table 1) where dairy manure was or was not applied the prior fall. Shortly after sidedressing rainfall was very limited and drought conditions persisted for weeks. The poorly drained soil in Waterloo yielded better under drought conditions than the well-drained soil in Sun Prairie.

Table 1. 2012 corn grain yield response to sidedress UAN injected where 8,700 gallons per acre of dairy manure was or was not applied in November 2011.

Drought limit yield more than N

 

When finalizing a decision regarding sidedress N rate, remember that spring and fall and spring manure applications will supply N. A pre-sidedress nitrate soil test (PSNT) can be used to evaluate manure or forage legume N credits. For more information about the PSNT see: https://ipcm.wisc.edu/download/pubsNM/UWSoilNitrateTests_final.pdf  With extended dry conditions in the forecast, consider reducing the sidedress N application rate to limit input costs that may have no return. If it does begin to rain in a few weeks, it is possible to make a second N application if needed, assuming equipment is available to go over an even tall crop.

 

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2020 Soil, Water, & Nutrient Management Meetings – Virtual https://npketc.soils.wisc.edu/2020/11/18/2020-soil-water-nutrient-management-meetings-virtual/ Wed, 18 Nov 2020 14:23:42 +0000 https://npketc.soils.wisc.edu/?p=555 The 2020 Soil, Water, & Nutrient Management Meetings will be held virtually. Topics include:

  • The value of soil organic matter and how to build it – Dr. Matt Ruark
  • Lessons learned about corn N management in Wisconsin and the Midwest – Dr. Carrie Laboski
  • Challenges of liquid dairy manure management in Wisconsin – Dr. Francisco Arriaga

Two identical sessions will be held. Choose the session that bet fits your schedule. Ten minute breaks will occur between presentations.

  • Thursday, December 3 from 8:30 to 11:50
  • Friday, December 4 from 12:30 to 3:50

The meeting is free to all, however registration is required. Register by November 30 at this website: https://go.wisc.edu/63j338. Certified Crop Advisor CEUs have been requested.

For questions about the meeting contact Francisco Arriaga (farriaga@wisc.edu). For questions about registration contact Kimberly Schmidt (kimberly.schmidt@wisc.edu).

For more information see the meeting flyer: 2020 Soil Water NM Meeting Flyer

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Evaluating the need for rescue N applications https://npketc.soils.wisc.edu/2020/06/29/evaluating-the-need-for-rescue-n-applications/ Mon, 29 Jun 2020 09:25:08 +0000 https://npketc.webhosting.cals.wisc.edu/?p=454 This article was originally posted on June 24, 2018.

Past articles have discussed how to evaluate the need for rescue N applications for corn after excessive rainfall. A recent  study completed at the Marshfield Ag Research Station on a somewhat poorly drained soil can help when deciding how much rescue N to apply. Where wet conditions caused loss of preplant applied N at Marshfield, 40 lb N/a applied 7-10 days prior to tasseling was adequate to compensate for N loss (Figure 1). Sidedressing all of the N was more profitable than preplant or split applications. When trying to decide on a rescue N application rate, consider your cost of production and remember that the first 30 to 50 lb N/a will provide the greatest return on investment.


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A Little Fertilizer Can Result in More Forage in Pastures https://npketc.soils.wisc.edu/2020/06/04/a-little-fertilizer-can-result-in-more-forage-in-pastures/ Thu, 04 Jun 2020 17:31:50 +0000 https://npketc.soils.wisc.edu/?p=544 Recently, the USDA NASS reported that Wisconsin’s forage inventory is the lowest it has been in 70 years. Low forage inventory is a result of several seasons with excessive rainfall and winter weather that resulted not only in forage winterkill, but also higher need for cattle feed. These conditions have led farmers to investigate emergency and non-routine forage crops to help supply enough forage for cattle needs.

In the quest for additional forage production options, sometimes the lowest cost and potentially easiest options may be overlooked. A good question to ask is, “Am I managing my pasture resource to optimize forage production?” While grazing cattle will deposit some nutrients in manure and urine, the amount deposited is less than the amount removed in milk production, animal growth and maintenance. In addition, animals do not deposit nutrients evenly across a pasture and some nutrients may be lost. Nitrogen is very mobile in the environment and can be lost through leaching, denitrification, or ammonia volatilization. Low levels of soil available phosphorus or potassium or low soil pH can limit grass pasture yield and response to nitrogen fertilizer.

Whether a pasture has improved (bromegrass, orchardgrass, fescue, ryegrass, timothy) or unimproved (primarily Kentucky bluegrass) forage species, there is an opportunity to produce additional forage at a very low cost by utilizing a fertilization plan. Consult soil test results to guide applications of phosphorus, potassium, and lime. If soil test results are more than four years old, it is important to take new soil samples ahead of fertilizer application to ensure a sound investment in fertilizer and lime. When soil sampling a pasture, avoid, or sample separately, areas where cattle frequently congregate (under trees, near water tanks, etc.). Focus on sampling and applying fertilizer on the areas of the pasture where forage production potential is the highest.

Not all grass pastures are necessarily good candidates for fertilizer application. Use extreme caution when applying fertilizer to areas that are steep or wet due to multiple safety risks during application. These areas of a pasture will rarely give a return on investment worth the risk!

On soils with 2.0 to 9.9% soil organic matter, 100 or 130 pounds of nitrogen per acre is recommended on unimproved and improved grass pastures, respectively. The amount of nitrogen deposited by cattle should be subtracted from these amounts to determine the amount of nitrogen fertilizer to apply. Refer to UW Extension publication A4034 Soil Fertility Guidelines for Pastures in Wisconsin for details on manure nutrient credits. Research in Wisconsin has demonstrated that it is best to split apply nitrogen fertilizer with half applied in early June and the other half applied in mid-August. This application timing helps extend the early spring growth period and helps boost the accelerating late summer growth curve common to cool season grasses (See Figure 1).

Figure 1. Seasonal growth pattern of cool-season grasses. From UW Extension publication A3529 Pastures for profit: A guide to rotational grazing.

How much additional forage production can we expect? University of Wisconsin-Madison research conducted at Marshfield and Lancaster Ag Research Stations evaluated the efficacy of 45 pounds per acre of actual N, applied as urea, in early June and again in mid-August to increase dry matter yield of orchardgrass. Yield increased approximately 0.75 tons of dry matter per acre at Lancaster on a well-drained soil and 1.3 tons of dry matter per acre at Marshfield on a somewhat poorly-drained soil (See Figure 2).  Cattle were not grazed in this study; however, orchardgrass was clipped five times to simulate cattle grazing. In a similar trial conducted by University of Minnesota at Grand Rapids, a 1.5 ton per acre increase in yield was observed with two applications of 50 pounds of nitrogen per acre. Pasture yield response to fertilizer nitrogen will vary based on stand density and composition, soil properties, and weather. A reasonable expectation is one ton of dry matter per acre increase through an investment in fertilizer. At current prices, an investment of $60 in nitrogen fertilizer and application can yield around $120 worth of additional forage.

Established pastures that are a grass-legume mix, do not require any nitrogen beyond what is deposited by grazing animals. Applying nitrogen to a grass-legume mix pasture can result in the grass crowding out the legumes.

Once a decision has been made to fertilize a pasture, it is important to implement a grazing plan to use as much of the additional forage produced as possible. Grazing plans are customized for each farm’s unique situation. Most plans will likely involve some level of moving cattle around from pasture area to pasture area, to improve utilization of the extra growth. Plans may also include harvesting some of the pasture areas for hay and/or using drift fences in the fall to help extend the grazing season.

Fertilizer application to grass pasture may be a cost effective and easy option to increase the amount of forage available on a farm. For additional information about fertilizing pastures, collecting soil samples, and crediting deposited nutrients consult UW Extension publication A4034 Soil Fertility Guidelines for Pastures in Wisconsin.

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Safe rates of seed placed starter fertilizer https://npketc.soils.wisc.edu/2020/04/14/safe-rates-of-seed-placed-starter-fertilizer/ Tue, 14 Apr 2020 09:50:15 +0000 http://npketc.webhosting.cals.wisc.edu/?p=246 Without fail every year after planting, questions start popping up about pop-up fertilizer. The questions always occur when there are emergence or germination issues. So before planting gets into full swing, let’s think about seed placed starter. For the purpose of this article I will use seed placed, pop-up, and in-furrow interchangeably.

Why are fertilizer salts a problem?

Excessive concentrations of fertilizer salts near a germinating seed or seedling root causes injury. The injury is caused when the concentration of ions in the soil is greater than the concentration of ions within the plant cells. The high osmotic pressure created by the fertilizer salts causes water to move out of the plant cells and into the soil. As water moves out of the plant cells, the tissue dessicates and becomes blackened; hence the term fertilizer burn. The result is the eventual death of the plant tissue.

Some nitrogen fertilizers may cause more seedling and germination injury than expected based on their salt content alone if they liberate ammonia when applied to the soil. Free ammonia is toxic and can move freely through the plant cell wall (Havlin et al., 1999). Urea, UAN, ammonium thiosulfate and DAP can cause more damage from ammonia toxicity than MAP, ammonium sulfate, and ammonium nitrate (Havlin et al., 1999; Reid, 2006; Mortvedt, 2001). Moderate alkaline soil conditions, either in the bulk soil or caused by reaction of the fertilizer, will promote ammonia production.

Factors affecting fertilizer burn

Crops vary in their tolerance to salts. A list of common crops and their relative sensitivity to salts is given in Table 1.  Reid (2006) suggests that no fertilizer be placed with the seed of super sweet hybrids of sweet corn, soybean, edible beans, and peas because of their sensitivity to salts.

Table 1. Relative sensitivity of common crops to fertilizer salts.*

 

 

 

 

* Reproduced from Reid (2006).

† Least sensitive does not mean that the crop is not sensitive to salt.

Soil conditions are important for determining why injury may occur in one year and not another. Fertilizer salts diffuse away from the band in moist soils and becomes diluted, reducing the osmotic pressure. Little diffusion takes place in dry soils and the fertilizer remains concentrated with a high osmotic pressure presenting a greater risk to plant injury. Soils with low cation exchange capacity (CEC) (coarse-textured with low organic matter content) have a lesser ability to react with the fertilizer compared to high CEC soils (fine-textured) meaning that the concentration of fertilizer salts in the soil solution remains high (Reid, 2006). Thus, fertilizer burn is a bigger issue on sandy, low organic matter soils particularly in dry springs. Soil temperature also plays a role. Roots grow slowly in cold soils; thus, the root is exposed to the higher concentration of fertilizer for a longer period of time.

Concentration of fertilizer salts is another factor that determines whether or not fertilizer burn occurs. Broadcast fertilizer applications do not often injury seedlings because the fertilizer is dispersed through a large volume of soil. Banded starter fertilizers placed two inches to the side and two inches below the seed are more likely to cause injury than broadcast applications because banded applications are much more concentrated in a small area near the seed. However, at typical starter fertilizer application rates, fertilizer burn from banded starter fertilizer is unlikely.  In-furrow (pop up or seed row) placed fertilizers are typically applied at low rates but their very close proximity to the seed means that they are more likely to cause injury than 2×2 banded applications because there is little opportunity for the root to grow out of the zone of concentrated fertilizer salts before it dies. In general to avoid stand loss from fertilizer injury, no more than 10 lb/a of N + K2O should be applied in-furrow regardless of soil texure. The most suitable fertilizers for in-furrow applications will have: 1) low salt index, 2) high water solubility, 3) no compounds that liberate NH3, and 4) use potassium phosphate instead of KCl as the K source (Mortvedt, 2001).

Safe rates of in-furrow fertilizer

Salt index (SI) of a fertilizer is a measure of the salt concentration that fertilizer induces in the soil solution (Mortvedt, 2001). However, there are many steps in calculating salt index and it can be a bit confusing. South Dakota State University developed a Fertilizer Seed Decision Aid spreadsheet and web calculator based on field and greenhouse research. The Fertilizer Seed Decision Aid requires users to select the crop to be grown, fertilizer type, seed furrow width, row spacing, tolerated stand loss, soil texture and soil moisture at planting. The tool will then output a maximum rate of fertilizer to apply with the seed. The tool is really handy in assessing scenarios. For example, what if the soil was wetter or drier; what if I can accept more or less stand loss. Using the tool you will find that some relatively common practices may be a little riskier than you think. A good example of this is using ammonium thiosulfate in seed placed starters. You can access the Fertilizer Seed Decision Aid here: http://www.ipni.net/article/IPNI-3268

References

 Havlin, J.L., J.D. Beaton, S.L. Tisdale, W.L. Nelson. 1999. Soil Fertility and Fertilizers. 6th ed. Prentice Hall. Upper Saddle River, NJ.

Reid, K. 2006. Soil Fertility Handbook. Ontario Ministry of Agric., Food and Rural Affairs. Publ. 611.

Mortvedt, J.J. 2001. Calculating Salt Index. Fluid Journal. 9(2):8-11.

 

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2019 Soil, Water, and Nutrient Managment Meetings https://npketc.soils.wisc.edu/2019/10/25/2019-soil-water-and-nutrient-managment-meetings/ Fri, 25 Oct 2019 15:18:42 +0000 https://npketc.soils.wisc.edu/?p=532 Plan to attend the Soil, Water, & Nutrient Managment Meetings held from December 3 through 12 at various locations around the state. A few highlights include: comparing tillage practices and N rates for corn; evaluating N managment decisions; profitability of P and K fertilization of no-till corn and soybean; 4) biological indicators of soil health; and more. See flyer for details: 2019 Soil, Water, NM Meeting Flyer. Hope you see you around the state.

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Manganese deficiency in winter wheat is showing up in Eastern Wisconsin https://npketc.soils.wisc.edu/2019/06/09/manganese-deficiency-in-winter-wheat-is-showing-up-in-eastern-wisconsin/ Sun, 09 Jun 2019 00:17:47 +0000 https://npketc.webhosting.cals.wisc.edu/?p=526
Mn deficient winter wheat field. Photo credits: Troy Christenson

The extended cool and wet spring appears to be causing manganese (Mn) deficiency in winter wheat in some fields in Eastern Wisconsin. Wheat has a high relative need for Mn, similar to soybean, but deficiency is not often observed in Wisconsin. The deficiency manifests as lighter colored lines parallel to the leaf margins and may have some necrotic spots. It is unlikely that an entire field will be uniformly deficient.

Mn deficient winter wheat. Photo credits: Troy Christenson

Manganese deficiency is usually associated with neutral to high pH soils that are also high in organic matter. Soil tests for Mn are not accurate if soil organic matter levels are greater than 6.0%; in these soils Mn availability is considered low if soil pH is greater than 6.9. On soils with organic matter content less than or equal to 6.0%, Mn is considered low when soil test values are less than 11 ppm. Tissue testing can be used to confirm deficiency. Sample the newest fully developed leaf from 50 plants prior to heading. Manganese is considered sufficient if the tissue concentration is 25 to 100 ppm.

In the photos, the wheat is being grown on a Sebewa silt loam which is poorly to very poorly drained. In fall 2016, this field tested 6.7% organic matter (with a range of 3.7 to 10.8%) and pH of 7.8 (range 7.6 to 8.2). Because the organic matter is over 6.0%, and pH is greater than 6.9, the availability of soil Mn is considered low and Mn deficiency in soybean and wheat might be expected. However, the grower has not had issues with Mn deficiency in this field in the past, which suggests the wet fall and extended cool and wet spring may be causing low availability of Mn. The Mn level in the tissue was 6.1 ppm, which is substantially below the sufficient range of 25 to 100 ppm. Wheat grown on another field on this farm was showing similar deficiency symptoms and was growing on a well-drained Sisson fine sandy loam with a soil organic matter of 3.6 % and pH of 7.6. While Mn was not tested on this soil, the deficiency symptoms indicate that Mn availability was low.

If you suspect Mn deficiency, take plant tissue and soil samples to confirm the diagnosis. A foliar application of 1.25 lb Mn/a in a sulfate form or 0.2 lb Mn/a in a chelate form will likely increase yield. If the deficiency is severe, multiple applications at 7 day intervals may be needed to remedy the deficiency. Consider leaving a couple of strips untreated to evaluate the efficacy of the foliar application.

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