Agriculture 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 …

Predicting Economic Optimal Nitrogen Rate With The Anaerobic Potentially Mineralizable Nitrogen Test, Jason D. Clark, Fabián G. Fernández, Kristen S. Veum, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

John E. Sawyer

Estimates of mineralizable N with the anaerobic potentially mineralizable N (PMN_an) test could improve predictions of corn (Zea mays L.) economic optimal N rate (EONR). A study across eight US midwestern states was conducted to quantify the predictability of EONR for single and split N applications by PMN_an. Treatment factors included different soil sample timings (pre-plant and V5 development stage), planting N rates (0 and 180 kg N ha⁻¹), and incubation lengths (7, 14, and 28 d) with and without initial soil NH₄–N included with PMN_an. Soil was sampled …

United States Midwest Soil And Weather Conditions Influence Anaerobic Potentially Mineralizable Nitrogen, Jason D. Clark, Kristen S. Veum, Fabián G. Fernández, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

John E. Sawyer

Nitrogen provided to crops through mineralization is an important factor in N management guidelines. Understanding of the interactive effects of soil and weather conditions on N mineralization needs to be improved. Relationships between anaerobic potentially mineralizable N (PMN_an) and soil and weather conditions were evaluated under the contrasting climates of eight US Midwestern states. Soil was sampled (0–30 cm) for PMN_an analysis before pre-plant N application (PP_0N) and at the V5 development stage from the pre-plant 0 (V5_0N) and 180 kg N ha⁻¹ (V5_180N) rates and incubated for 7, 14, …

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 …