Plant Sciences Commons^™

Drainage Water Quality Impacts Of Agricultural Management Practices: Effectof Manure Application Timing And Cover Crops, Brian Dougherty, Carl Pederson, Matt Helmers, Michelle Soupir, Dan Andersen, Antonio Mallarino, John Sawyer

John E. Sawyer

A primary objective of this study is to evaluate the impact of various cropping and nutrient management systems on crop yields and drainage water quality. This progress report only includes the first-year corn grain yield results. Treatment comparisons include the impact of early fall vs. late fall vs. spring application of liquid swine manure, nitrification inhibitor with late fall swine manure application, cereal rye cover crop, and gypsum application. These comparisons will be conducted for multiple years and used to develop appropriate manure and nutrient management practices to minimize water contamination potential and enhance the use of swine manure as …

Statistical And Machine Learning Methods Evaluated For Incorporating Soil And Weather Into Corn Nitrogen Recommendations, Curtis J. Ransom, Newell R. Kitchen, James J. Camberato, Paul R. Carter, Richard B. Ferguson, Fabián G. Fernández, David W. Franzen, Carrie A. M. Laboski, D. Brenton Myers, Emerson D. Nafziger, John E. Sawyer, John F. Shanahan

John E. Sawyer

Nitrogen (N) fertilizer recommendation tools could be improved for estimating corn (Zea mays L.) N needs by incorporating site-specific soil and weather information. However, an evaluation of analytical methods is needed to determine the success of incorporating this information. The objectives of this research were to evaluate statistical and machine learning (ML) algorithms for utilizing soil and weather information for improving corn N recommendation tools. Eight algorithms [stepwise, ridge regression, least absolute shrinkage and selection operator (Lasso), elastic net regression, principal component regression (PCR), partial least squares regression (PLSR), decision tree, and random forest] were evaluated using a dataset …

Understanding Anhydrous Ammonia Application In Soil, John E. Sawyer

John E. Sawyer

What happens when anhydrous ammonia is injected into soil?

Several physical and chemical reactions take place following anhydrous ammonia injection: dissolution in water, reaction with soil organic matter and clay, and attachment of ammonium ions on the soil cation exchange complex. These reactions all tend to limit the movement of ammonia, with water having the greatest initial effect. The highest concentration of ammonia is at/near the point of injection, with a tapering of the concentration toward the outer edge of the retention zone. Usually the greatest ammonia concentration is within the first inch or two of the injection point, with …

Flood Adulterated Grain - Nutrient Supply To Crops When Land Applied, John E. Sawyer, Antonio Mallarino

John E. Sawyer

Flooding has been extensive in several areas of Iowa this spring. In some cases, stored grain has been affected by flood waters. Land application of flood adulterated grain as a nutrient source for a future crop may be an option for some. See the Iowa Dept. of Natural Resources (IDNR) and Iowa Dept. of Agriculture and Land Stewardship (IDALS) publication for Proper Management of Flooded Grain and Hay. That publication states “Farms disposing of spoiled grain and feed on their own property can land apply damaged grain at the following application rates: 146 bu corn/acre and 50 bu soybean/acre”. …

Anhydrous Ammonia Application -- Spring 2019, John E. Sawyer

John E. Sawyer

It was a late harvest in fall 2018. Soils were wet and frozen when it was time to apply anhydrous ammonia. Those situations resulted in much less than normal anhydrous ammonia application last fall. Therefore, considerable anhydrous ammonia needs to be applied this spring. There is only so much capacity to switch from one nitrogen (N) fertilizer product to another. In Iowa, historically the two largest N fertilizers are anhydrous ammonia (largest) and urea-ammonium nitrate (UAN) solution, with granulated urea a distant third.

Springtime Precipitation – A Tool For Estimating Nitrogen Application Need For Corn, John E. Sawyer

John E. Sawyer

Wet springtime conditions typically raise questions about the status of applied nitrogen (N). Or the question, do I need to apply additional N to my cornfields? At this time we do not know what the weather/precipitation will be for the entire springtime, but the extended period of wet conditions this spring is of concern. A summary of long-term N rate trials with continuous corn and corn rotated with soybean conducted at seven ISU research and demonstration farms in Iowa from 1999 to 2016 has been an on-going basis for indicating the potential for needing an N rate greater than the …

Nitrogen Fertilization Options With Delayed Or Rescue Applications, John E. Sawyer

John E. Sawyer

It’s been a wait-go-stop (repeat) corn planting season this spring. Whether you planted early or are just now getting corn planted, it seems planting windows were short and rushed. In some cases this meant planting (corn/soybean) and worrying later about getting nitrogen (N) applied. And in some areas of Iowa, wetter than normal conditions are raising questions about supplemental N application. What are the options for sidedress N?

Effects Of Unharvested, Shattered, Or Hailed-Out Soybean Fields On Nutrient Supply For Corn, John E. Sawyer

John E. Sawyer

Flooded fields and wet soil conditions in the fall 2018 meant some soybean fields were not, or are not going to be harvested. Also, some fields occasionally experienced significant shattering or a hailstorm in the fall where soybean seed is knocked from the plants and thus not harvested. When the grain is not harvested, nitrogen (N), phosphorus (P), and potassium (K) nutrients returned to the soil in the soybean grain can be accounted for when planning nutrient applications for the next crop. Other nutrients will also be returned, but most are not a fertilization need in Iowa soils. An estimate …

Nitrogen Fertilizer Suppresses Mineralization Of Soil Organic Matter In Maize Agroecosystems, Navreet K. Mahal, William R. Osterholz, Fernando E. Miguez, Hanna J. Poffenbarger, John E. Sawyer, Daniel C. Olk, Sotirios V. Archontoulis, Michael J. Castellano

John E. Sawyer

The possibility that N fertilizer increases soil organic matter (SOM) mineralization and, as a result, reduces SOM stocks has led to a great debate about the long-term sustainability of maize-based agroecosystems as well as the best method to estimate fertilizer N use efficiency (FNUE). Much of this debate is because synthetic N fertilizer can positively or negatively affect SOM mineralization via several direct and indirect pathways. Here, we test a series of hypotheses to determine the direction, magnitude, and mechanism of N fertilizer effect on SOM mineralization and discuss the implications for methods to estimate FNUE.Wemeasured the effect of synthetic …

Impact Of Nitrogen Application Timing On Corn Production, John E. Sawyer, Daniel W. Barker, John P. Lundvall

John E. Sawyer

Water quality issues have renewed interest in timing of nitrogen (N) application as a means to improve use efficiency in corn and reduce losses. Improved economic return is also desired as N fertilization is one of the most costly inputs to corn production. Time of fertilizer application is a component of the site-specific 4R nutrient management stewardship programs. In Iowa, the Nutrient Reduction Strategy has a 7% (37% std. dev.) nitrate-N reduction with a 0% (3% std. dev.) corn yield change for sidedress compared to pre-plant N application (SP 0435A).

Crop Responses To Amisorb In The North Central Region, Sylvie Brouder, Robert Dowdy, Dave Franzen, Gary Hergert, Robert Hoeft, Maurice Horton, Keith Kelling, David Mengel, George Rehm, John Sawyer, Peter Scharf, Darryl Warnacke, David Whitney

John E. Sawyer

Originally used to prevent scale in boilers, carpramid or thermal polyaspartate (copoly[(3-carboxypropionamide)( 2-carboxylmethyl) acetamide)] was brought to agriculture under the trade names AmiSorb and Magnet. It claimed to increase nutrient uptake through artificially increasing the volume of soil occupied by roots through increased root branching and root hair development. Under controlled hydroponic or greenhouse conditions, the use of carpramid increased nutrient uptake, some yield determining factors such as wheat tillering and in some cases, crop yield. Extensive field testing from 1996 to 1998 under various nutrient regimes, placements, forms, and timings resulted in very inconsistent performance. Averaged across all experiments …

Nitrogen Fertilizer Rate Effects On Soil Organic Carbon In Iowa Continuous Corn And Corn-Soybean Systems, Hanna J. Poffenbarger, Daniel W. Barker, Matthew J. Helmers, Fernando E. Miguez, John E. Sawyer, Johan Six, Michael J. Castellano

John E. Sawyer

Nitrogen fertilizer rate is a key factor affecting soil organic C (SOC) in corn-based cropping systems. The objective of this study was to determine the change in SOC in response to long-term N rates for continuous corn and corn-soybean cropping systems at two sites in Iowa. Soil samples were collected to a depth of 15 cm in 1999 and again in 2014 after 15 years of corn N rate treatments ranging from 0 to 269 kg ha^-1. The soil samples were analyzed for total C and N concentrations. For continuous corn at both sites, the average annual change …

Winter Rye Cover Crop Biomass Production, Degradation, And N Recycling, J. L. Pantoja, J. E. Sawyer, D. W. Barker

John E. Sawyer

Winter rye (Secale cereale L.) as a cover crop can take up residual inorganic N between annual row crops and therefore be used to help reduce NO3 -–N loss from fields and movement to water systems. However, does the rye N uptake affect N recycling to soil and add to plant available N? The rye carbon:nitrogen (C:N) ratio could also influence N recycling. The objectives of this study were to evaluate rye biomass degradation and N recycling after spring rye termination in a no-till corn (Zea mays L.) - soybean [Glycine max. (L.) Merr.] rotation. A two year experiment (2010-2011) …

In-Season Nitrogen Fertilization Of Soybean, J. E. Sawyer, D. W. Barker

John E. Sawyer

Nitrogen (N) fertilization is not a traditional nutrient management practice for soybean production in Iowa. Soybean is a legume plant and is assumed to adequately obtain needed N through symbiotic fixation. However, there has been interest over the years in using N fertilization to increase yield and grain protein due to the recognition of the large N requirement associated with high yields. Depending on the soil residual inorganic N level and soil N mineralization characteristics, approximately 40 to 75% of the N in a mature soybean plant is derived from the soil (Shibles, 1998). Also, soybean seems to require this …

Corn And Soybean Response To Sulfur Application On Iowa Soils, J. E. Sawyer, D. W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for com and soybean production. Prior research has not determined a consistent need for S fertilization in Iowa, with field research indicating no com or soybean yield response to applied S at virtually every site studied (Thorup and Leitch 1975; Webb, 1978; Alesii 1982; Killorn, 1984; Sexton et al., 1998; Mallarino et al., 2000). The soil supply, in combination with sources such as manure and atmospheric deposition has apparently met com and soybean S needs. Sulfur deficiencies have been reported over the years in various areas of the Midwestern …

Corn Nitrogen Rate Response And Crop Yield In A Rye Cover Crop System, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker

John E. Sawyer

Water quality impairment related to N loss from crop production fields continues to be a concern in Iowa, including meeting the USEPA nitrate-N drinking water standard and reducing N export to the Gulf of Mexico. Therefore, in-field production practices would be helpful to aid in reduction of nitrate leaching and movement to water systems. One practice identified in the science assessment for the Iowa Nutrient Reduction Strategy is use of a winter cereal rye (Secale cereal L.) cover crop, where a mean 31% (29% standard deviation) nitrate-N reduction would be expected, but with a 6% (22% standard deviation) corn yield …

Dealing With Sulfur Deficiencies In Crop Production: The Iowa Experience, J. E. Sawyer, B. Lang, D. W. Barker, G. Cummins

John E. Sawyer

Research conducted for more than forty years (prior to approximately 2005) in Iowa rarely noted improved crop yield with sulfur (S) fertilization. Studies during that time period with corn and soybean found yield increase from S fertilizer application only three times out of approximately 200 trials. Research in the early 1980’s had also documented sufficient plant available S in the soil profile for crop production on most Iowa soil associations. Results of recent studies (2000- 2005) in corn and soybean were consistent with the historical research. An example is research presented at this conference (Sawyer and Barker, 2002) where there …

Nutrient Management Plan, Antonio Mallarino, John Sawyer, Barbara Stewart, John Creswell

John E. Sawyer

Management tools to help you develop a nutrient management plan and use the Iowa Phosphorus Index.

Nitrogen Application, John Sawyer, John Creswall

John E. Sawyer

Nitrogen (N) management planning for corn production.

Maximum Soil Organic Carbon Storage In Midwest U.S. Cropping Systems When Crops Are Optimally Nitrogen-Fertilized, Hanna J. Poffenbarger, Daniel W. Barker, Matthew J. Helmers, Fernando E. Miguez, Daniel C. Olk, John E. Sawyer, Johan Six, Michael J. Castellano

John E. Sawyer

Nitrogen fertilization is critical to optimize short-term crop yield, but its long-term effect on soil organic C (SOC) is uncertain. Here, we clarify the impact of N fertilization on SOC in typical maize-based (Zea mays L.) Midwest U.S. cropping systems by accounting for site-to-site variability in maize yield response to N fertilization. Within continuous maize and maize-soybean [Glycine max (L.) Merr.] systems at four Iowa locations, we evaluated changes in surface SOC over 14 to 16 years across a range of N fertilizer rates empirically determined to be insufficient, optimum, or excessive for maximum maize yield. Soil organic C balances …

Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Southwest Iowa, John Sawyer, Daniel Barker

John E. Sawyer

This project was designed to study the nitrogen (N) fertilization needs in continuous corn (CC) and corn rotated with soybean (CS) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.

Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Southwest Iowa, John Lundvall, Swetabh Patel, John Sawyer

John E. Sawyer

Water quality impairment related to nitrogen (N) is a concern in Iowa, including meeting nitrate (NO3) drinking water standards and reducing the amount of N lost to the Gulf of Mexico. The Iowa Nutrient Reduction Strategy science assessment identified a rye cover crop as an important in-field management practice for reducing N and phosphorus (P) loss from fields (31% NO3-N and 29% P), and for reducing soil erosion. However, the science assessment identified a corn yield reduction of 6 percent when grown following a rye cover crop. Lower corn yield with use of a cover crop is unacceptable to farmers, …

Corn Nitrogen Fertilization Requirement And Corn–Soybean Productivity With A Rye Cover Crop, Jose L. Pantoja, Krishna P. Woli, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Winter rye (Secale cereale L.) cover crop (RCC) has potential to reduce NO₃–N loss from corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] fields. However, RCC effects on annual crop productivity and corn optimal N fertilization requirement are unclear. The objectives were to evaluate corn and soybean yield response to RCC and corn optimal N rate. Treatments were no-RCC and RCC with six fertilizer N rates (0–225 kg N ha^-1) applied to corn in a no-till corn–soybean (CS) rotation at four Iowa sites in 2009 through 2011. The RCC biomass and …

Standardized Research Protocols Enable Transdisciplinary Research Of Climate Variation Impacts In Corn Production Systems, E. J. Kladivko, M. J. Helmers, L. J. Abendroth, D. Herzmann, R. Lal, M. J. Castellano, D. S. Mueller, J. E. Sawyer, R. P. Anex, R. W. Arritt, B. Basso, J. V. Bonta, L. C. Bowling, R. M. Cruse, N. R. Fausey, J. R. Frankenberger, P. W. Gassman, A. J. Gassmann, C. L. Kling, A. Kravchenko, J. G. Lauer, F. E. Miguez, E. D. Nafziger, N. Nkongolo, M. O'Neal, L. B. Owens, P. R. Owens, P. Scharf, M. J. Shipitalo, J. S. Strock, M. B. Villamil

John E. Sawyer

The important questions about agriculture, climate, and sustainability have become increasingly complex and require a coordinated, multifaceted approach for developing new knowledge and understanding. A multistate, transdisciplinary project was begun in 2011 to study the potential for both mitigation and adaptation of corn-based cropping systems to climate variations. The team is measuring the baseline as well as change of the system's carbon (C), nitrogen (N), and water footprints, crop productivity, and pest pressure in response to existing and novel production practices. Nine states and 11 institutions are participating in the project, necessitating a well thought out approach to coordinating field …

Why Manage Phosphorus?, John E. Sawyer, Antonio P. Mallarino

John E. Sawyer

There are 17 nutrients that are essential for plant growth and production. An insufficient supply of one or more can have an adverse effect on plant growth, maturity, and yield. Phosphorus (P)--one of three key macronutrients (nitrogen and potassium are the other two)--is present in every living plant and animal cell, and is vital in plants for harvesting the sun's energy for growth and reproduction. This requirement is the same whether the plant is growing on soil or in water (such as algae); hence, the concern regarding P levels in surface water and the accelerated aquatic plant growth associated with …

Yellow Corn, Wet Soils, And Nitrogen Loss (Part 3), John E. Sawyer

John E. Sawyer

Earlier I provided observations in two articles (June 19 and June 26, 2008) on corn growth and response to nitrogen (N) applied in an anhydrous ammonia study being conducted at the ISU research farm between Ames and Boone. Following are some final observations (July 7, 2008).

Wait Until Soil Temps Drop Before Applying Anhydrous Ammonia, John E. Sawyer, Barbara Stewart, William Ehm

John E. Sawyer

With the early harvest, Iowa’s conservation leaders are encouraging farmers to wait until soil temperatures lower before applying anhydrous ammonia (NH3) this fall. Anhydrous ammonia applied before daily soil temperatures remain below 50 degrees Fahrenheit and continue trending lower can result in the nitrogen loss that can impact crop development and have negative environmental impacts, such as enhanced leaching into groundwater and streams once converted to nitrate.

Wet Conditions And Change In Soil Profile Nitrate, John E. Sawyer

John E. Sawyer

I wrote an ICM News article February 21, 2013, that provided a summary of fall soil profile nitrate sampling results following the 2012 corn harvest. As I cautioned in that and other articles, the amount of nitrate-N that might remain for a 2013 corn crop depends on springtime rainfall. Unfortunately, much of Iowa has received considerable precipitation since soils thawed, especially the eastern two-thirds of Iowa. The two maps of the Midwest region show the total precipitation and deviation from normal since March 7, 2013. Tile lines are flowing again, and nitrate in the profile will move with percolating water. …

Sulfur Emerges As A Nutritional Issue In Iowa Alfalfa Production, John E. Sawyer, Brian J. Lang, Daniel W. Barker

John E. Sawyer

Sulfur is often classified as a “secondary” essential element, mainly due to a smaller plant requirement, but also because it is less frequently applied as a fertilizer compared to N, P, and K. This has certainly been the case in Iowa, where research had not documented S deficiency or fertilization need for optimal crop production. However, if deficient, S can have a dramatic effect on plant growth and crop productivity – more than the classification “secondary” would imply.

Uan And Preemergence Herbicide Applications On Emerged Corn, Michael D. Owen, John E. Sawyer, Robert G. Hartzler

John E. Sawyer

Planting the Iowa 2007 corn crop is somewhat behind recent years, and in efforts to stay ahead of the game, many fields will be planted before being treated with nitrogen (N) and/or herbicides. Corn in some of these fields will emerge before applications of these materials are made, raising concerns over the safety of postemergence applications of urea-ammonium nitrate (UAN) solution, with or without herbicides.