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37th North Central Extension-Industry Soil Fertility Workshop
32nd North Central Extension-Industry Soil Fertility Workshop
44th North Central Extension-Industry Soil Fertility Conference
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Authors
Abunyewa, A
Adee, E.A
Allen, B.L
Andraski, T.W
Arriaga, F
Asebedo, A
Asebedo, R
Ashley, R
Balboa, G.R
Ballweg, M
Barbagelata, P.A
Bardella, G
Barker, D
Barker, D.W
Bauer, C.A
Becker, A.W
Behnke, G.D
Belec, C
Below, F.E
Berg, K
Beyrer, T.A
Bly, A
Boomsma, C.R
Boosma, C.R
Boring, T.J
Brouder, S
Brueland, B.A
Bu, H
Bullock, D.G
Caldwell, R
Camberato, J
Carstens, D
Carstens, G
Carter, R.I
Casteel, S
Cecchi, A.M
Chawner, M.M
Chong, S
Ciampitti, I.A
Clover, M.W
Coulter, J.A
Coyne, M
Culman, S
Cusick, P.R
Cánepa, M
Daverede, I.C
Deen, B
Diaz, D.R
Dille, J
Dunker, R.E
Dunn, D.J
Dygert, C
Ebelhar, S.A
Edwards, C
Edwards, C.L
Elwadie, M
Emmert, D
Endres, G
Fabrizzi, K
Fallow, D.J
Farmaha, B
Fehrenbacher, T.A
Ferguson, R
Ferguson, R.B
Fernandez, F.G
Flaten, D
Florence, R
Franzen, D.W
Fritschi, F.B
Gardner, T
Gehl, R.J
Gelderman, R
Gentry, L.E
Gerwing, J
Gonzini, L.C
Gordon, W.B
Grant, C
Gregory, S
Grove, J.H
Guebert, K.S
Gutierrez, M.N
Gutknecht, J
Hammond, L
Hankinson, M
Hansen, N.C
Hart, C.D
Hawkins, J.A
Heard, J
Heaton, E.A
Henderson, H.S
Henning, T
Hergert, G.W
Hoben, J.P
Hoeft, R.G
Holland, K
Hopkins, B.G
Howe, P.L
Hsu, C.K
Hubbard, V
Hubbard, V.C
Joern, B
Johnson, S
Jolley, V.D
Kaiser, D
Karanthanasis, A.D
Karlen, D
Kaur, G
Kellig, K.A
Kelling, K.A
Khan, S.A
Kitchen, N.R
Klatt, J.G
Klubeck, B
Kovacs, P
Kovar, J
Kravchenko, A.N
LaBarge, G.A
Laboski, C
Laboski, C.A
Lamb, J
Lamb, J.A
Lamond, R.L
Lange, D
Lauzon, J
Lauzon, J.D
Lawley, Y
Lindsey, L.E
Lorence, A
Lukach, J
Lundvall, J.P
Lyon, D
M Washburn, C.S
MacGuidwin, A.E
Maddux, L.D
Mallarino, A.P
Mason, S
McCallister, D.L
McKay, K
McSpadden-Gardner, B
Meier, K.K
Mengel, D
Moore, K.J
Moose, S.P
Motavalli, P.P
Mullen, R.W
Mulvaney, R.L
Munoz, G.R
Murdock, L.W
Murrell, L.J
Murrell, T.S
Myers, D.B
Nafziger, E.D
Nelson, K.A
Nielsen, R
O'Halloran, I.P
O'Neill, P.M
Oliveira, L
Oltmans, R.R
Osborne, S.L
Pantoja, J.L
Paul, L.E
Perry, C.R
Petersen, J.L
Phillips, A
Pikul Jr, J.L
Potter, D.K
Powell, J.M
Proost, R
Randall, B.K
Randall, G.W
Raudales, R
Rehm, G.W
Repking, M.J
Ritchey, E.L
Robertson, G.K
Robertson, G.P
Rosa, A.T
Rosen, C
Rosenzweig, N
Ruark, M.D
Ruffo, M
Ruiz Diaz, D.A
Russelle, M.P
Sadowsky, M
Sawyer, A
Sawyer, J
Sawyer, J.E
Scharf, P
Scharf, P.C
Schepers, J.S
Schmidt, J.P
Schmitt, M.A
Schwab, G.J
Scmitt, M.A
Shanahan, J.F
Shapiro, C.A
Sharma, L
Sheaffer, C
Sheaffer, C.C
Shelley, K
Sims, A.L
Smith, S.R
Snapp, S.S
Speth, P.E
Spray, H.C
Stammer, A
Steinke, K
Stevens, G
Stevens, W.B
Stewart, Z.P
Stone, L.R
Strock, J
Strock, J.S
Struffert, A.M
Stute, J.K
Swoish, M
Taraba, J
Tarkalson, D
Tarkalson, D.D
Thompson, A.L
Thompson, M.L
Thompson, Y.L
Tremblay, N
Uranga, M
Uribelarrea, M
Varsa, E.C
Vetsch, J
Villamil, M.B
Volenec, J
Vories, E.D
Vyn, T.J
Walker, Z.T
Walters, A
Warner, A
Warren, J.J
Wessel, J.R
West, J.R
Whitney, D.A
Wittry, D.J
Woodard, H.J
Wortmann, C
Wychen, S.V
Wyciskalla, T
Wyciskalla, T.D
Yost, M.A
Zuber, S.M
Zucco, M
von Bertoldi, A.P
Topics
Type
Oral
Year
2014
2002
2007
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Conference

Filter results96 paper(s) found.

1. 4R Phosphorus Management for Soybeans in the Northern Frontier: Rate and Placement Effects on Plant Stand, Biomass and Seed Yield

Very little research has been conducted to determine the best rate, source, placement, and timing of P fertilizer for modern soybean cultivars grown in the Canadian Prairies. Preliminary results of the two years of field studies at 10 locations in Manitoba showed that typical agronomic rates of seed row P did not decrease plant stand and seed yield at any sites; nor was seed yield increased at any site, even with Olsen P concentrations as low as 3 ppm....

2. A Case for the use of Limestone in North Dakota

Farmers in North Dakota have long believed that nearly all of the cultivated land in the state was alkaline in pH. A recent survey of the state revealed that between 27% and 50% of the fields tested below pH 7, depending on landscape position, with about 17% of the state with pH less than 6.5. In site-specific studies in fields with dominant pH above 7, nearly all fields contained at least one area with pH below 7. Herbicide carryover studies have shown that areas of even slightly acid pH can re...

3. A Crop-Based Approach for In-Season N Management of Corn

Over-application of nitrogen (N) fertilizer on corn has resulted in elevated levels of N in ground and surface waters. A major factor contributing to decreased N use efficiency and environmental contamination for traditional corn N management schemes is routine pre-season application of large doses of N before the crop can effectively utilize this N. Our long-term research goal is to reduce these over-applications by using remote sensing to direct fertilizer only to areas needing N at times when...

4. A Mechanistic Approach to Nitrogen Fertilizer Recommendations

In efforts to improve Nitrogen (N) management, many new methodologies involving advanced technology such as optical sensors are being utilized. Although these new technologies have been proven to improve N management, their use in production agriculture is relatively low. The majority of farmers are still using mechanistic equations or simply pounds per bushel to determine their N rates due to low cost and ease of use. However, most of these N recommendation equations are becoming antiquated, an...

5. Accuracy of Credits and Soil Indicies for Predicting Nitrogen Response in Corn Following Alfalfa

Corn is the most frequent first- and second-year crop following alfalfa in the upper midwestern United States. In the majority of reported cases, there is little need for additional fertilizer N to optimize yield of first-year corn following alfalfa. For second-year corn following alfalfa, fertilizer N is needed in about one-half of cases and the economically optimum N rate (EONR) has varied greatly in responsive fields. The objective of this research was to use literature data to evaluate the ...

6. Aerial Photographs to Guide Corn Fertigation Decisions

Corn producers with pivot irrigatio n have the potential to apply in-season nitrogen (N) fertilizer much more easily than their non-irrigated counterpa rts. A demonstration project was initiated in 2006 to take advantage of this potential. One advantage for in-season N application is that the risk of N loss prior to crop uptake is minimal. Another advantage is the opportunity to diagnose N n eed. A range of studies have shown that N need can vary widely from one field to another, as well as with...

7. Assessing the Benefits of Radish as a Cover Crop

Oilseed radish (Raphanus sativus L) is a popular cover crop for no-till farmers in Wisconsin, especially among those that include winter wheat in rotation since radish can accumulate large amounts of nitrogen (N). However, previously presented research in Wisconsin has not shown a clear N credit for a subsequent corn crop. Additionally, there is a lack of information that quantifies other benefits of radish, including compaction reduction and nematode suppression. The objective of this project w...

8. Changes in Crop Production Efficiency with High Yield Production

Increases in crop yields are due to changes in the genetic efficiency in the use of inputs. However, there are constraints on efficient use of resources, e-g., water, nitrogen, solar radiation, that limit consistent high yield response. The interactions of water, nitrogen, and light form a basis for understanding how crop production efficiency can be improved. Carbon dioxide is an input to crop production that has been overlooked and understanding this environmental component will help identify...

9. Changes in P Uptake and Partitioning in Soybean Cultivars Released in the Last 90 Years

Historical changes in nutrient uptake and partitioning of soybean [Glycine max (L.) Merr.] were not studied. Field studies were conducted in 2011 and 2012 to investigate phosphorus (P) uptake changes and partitioning through the growing season in 25 maturity group (MG) II, and 26 MG III cultivars. Plant samples were taken and partitioned at V4 (four trifoliates), R2 (full bloom), R4 (full pod), R6 (full seed), and R8 (physiological maturity) growth stages. In-season samples were partitioned into...

10. Comparison of Soil Properties under Long-Term Crop Rotation and Tillage

Shifts in cropping systems from long-term rotations including forages to mostly annual crops has intensified tillage, but has also led to the development of conservation tillage practices such as no-till. There is a shortage of information about the interactive, long-term effects of rotation and tillage on soil quality. The objective of this study was to assess soil chemical and physical properties after 15 years of crop rotation and tillage treatments. Continuous corn (Zea mays L.) (CCC), corn...

11. Corn and Soybean Grain Yield and Concentration of Potassium in Plant Tissues and Soil as Affected by Potassium Fertilization

Research in the Midwest has shown that K fer tilization tends to increase plant K uptake by corn and soybean and the K concentration of vegeta tive tissues. Several studies found that K fertilization usually increases the K concentrati on of vegetative plant parts, often regardless of the soil-test K (STK) level a nd grain yield response (Malla rino et al., 1999; Borges and Mallarino, 2000; Yin and Vyn, 2002a, 2002b; Borg es and Mallarino, 2003; Yin and Vyn, 2003). It is well known that the K co...

12. Corn and Soybean Response to Sulfur Applications on Iowa Soils

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Prior research has not determined a consistent need for S fertilization in Iowa, with field research indicating no corn or soybean yield response to applied S at virtually every site studied (Thorup and Leitch, 1975; Webb, 1978; Alesii, 1982; Killom, 1984; Sexton et al., 1998; Mallarino et al., 2000). The soil supply, in combination with sources such as manure and atmospheric deposition ha...

13. Corn Nitrogen Rate Response and Crop Yield in a Rye Cover Crop System

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 ...

14. Cover Crop Management for Soybean Iron Deficiency Chlorosis

Iron Deficiency Chlorosis (IDC) has been a s oybean production in the Upper Midwest for many years. A study was conducted in 2006 and 2007 to determine the effect of cover crop management under increasing soil nitrate-N concentrations. The study was conducted at two locations each year with histor ies of IDC. The treatments incl ude nitrogen rates of 0, 100, and 200 pounds N per acre applied as Ur ea with and without an oat cover crop. The oat cover crop was planted at a rate of 1 bushe l per ac...

15. Cover Crops Effects on Nutrient Cycling and Fertilizer Recommendations

...

16. Cover Crops Following Corn Silage and Winter Wheat

Cover crops are widely used in Wisconsin following corn silage or winter wheat harvest to control erosion, but effects on subsequent corn yields and their optimum N rates have not been documented. Two separate studies were conducted to: (1) determine the effect of rye as a cover or silage crop on corn yields at varying N rates and (2) determine the effect of radish on corn yields and optimum N rates. In two of three years, a reduction in corn silage yield was determined following rye silage comp...

17. Crop Potassium Uptake and Utilization

Cropping systems currently face dual challenges of maximizing yields in a sustainable approach. The importance of a balanced nutrition is critical for increasing crop production. In the past decades, comprehensive studies were performed for nitrogen (N) in corn and for phosphorus (P) in soybean. From a physiological standpoint, a synthesis-analysis on potassium (K) content, utilization, interaction with other nutrients and final impact on yield is relevant and needed for properly understanding s...

18. Delivering Continuing Education to Ag Professionals- The Crop Adviser Institute

Continuing education is essential for agricultural professionals, whether required by a certifjmg organization or completed voluntarily as a supplemental educational opportunity. Agricultural continuing education has traditionally been delivered on-site, but temporal, geographical, and other constraints often prevent individuals from attending these courses. The Crop Adviser Institute (CAI) has been established to provide an alternative method of delivering continuing education. Implementation o...

19. Developing a Natural Resource Web Site as a Training Tool for Students and Agronomists

South Dakota State University. Brookings SD Introduction South Dakota agronomists, agricultural workers, and students often require visual aids to demonstrate a field procedure or understand the interaction among natural resources that contribute to agricultural production. Suitable commercial products are available to serve this purpose, but they may be neither readily accessible to the public, nor particular to the state. An Internet site accessible to the public is required to display aspects...

20. Effect of Starter Fertilizer and Plant Date on Soybean Growth, Nodulation, and Yield

Environmental conditions at the time of planting are a crucial determinant to soybean (Glycine max) yield potential. In recent years, it has become common in Ohio to begin planting earlier in the growing season, as soon as mid- or late-April in some cases. However, soil conditions are typically cooler and wetter at this time as opposed to later planting dates, and nutrient availability may be limited. When planting soybeans into cool and wet soil, the application of a starter fertilizer may be b...

21. Effect of Tillage, Rotation (Maize and Soybean), and Nitrogen Rate in a Long Term Study on Solvita, Water Extract, H3A Extract Values

A long term rainfed tillage/rotation/N rate study was established in 1985 on a mostly Coleridge silty clay loam (fine-loamy, mixed, superactive, mesic Cumulic Haplustoll). The study is a factorial of plow, disk, and no-till under continuous corn (Zea mays) and corn following soybeans (Glycine Max) with five nitrogen rates (0, 40, 80, 120, 160 kg ha -1). Soil samples were taken from all rotation/tillage combinations and three N rates in the fall of 2013 to 0.20 m (8 in). They were analyzed using ...

22. Effects of Nitrogen Managemetn on Maize Yield and Nitrate Leachingon Irrigated Sandy Soils

Irrigated sands are some of the most productive and environmentally sensitive areas in Minnesota. Reducing nitrate leaching is critical for corn (Zea mays L.) production as ground water is a major source of drinking water in these soils. The objective of this study was to evaluate agricultural technologies that may improve nitrogen (N) management for profitable corn production and mitigate negative effects in groundwater. A randomized complete block design with four replications was established...

23. Effects of Phosphorus Fertilizer Rate, Timing, and Addition of Fertilizer Enhancer on Potato Yield and Quality

Potato plants are very inefficient in their abil ity to utilize soil phosphorus (P) on some soils (Kelling et al., 1997). The optimum soil test P category for potato is more than three times greater than for other crops (Laboski et al ., 2006). Being a high value crop, potato growers generally tend to apply more P fertilizer than recommended because it is inexpensive insurance if a yield response to applied P would occur. State nutrient management regulation requires growers to write and follow ...

24. Energy and Nutrient Supplies

A study by the Potash and Phosphate Institute on 2.5 million North American soil samples has determined that soil nutrients have been withdraw without adequate replacement for several years. Soil fertility levels have dropped below optimum. At the same time, energy prices have skyrocketed, increasing fertilizer production costs. The presentation explains natural gas supplyfdemand, and how it affects both the price for natural gas and the production costs for fertilizers. The impact of this price...

25. Enhancing Alfalfa Production Through Improved Phosphorus and Potassium Management

Addition of phosphorus (P) and potassium (K) fertilizer is vital to maintain alfalfa productivity. The objective of this study was to examine how P and K fertilizer application increases alfalfa yield. nutrient use, and plant persistence. Replicate plots of P (0, 50, 100, 150 1bs P205/acre) and K (0. 100, 200, 300, 400 Ibs K20/acre) treatments were arranged in a factorial design. Forage harvests occurred four times annually for 5 years and yield, mass per shoot, shoots per area, and herbage nut...

26. Estimating Second- and Third Year Nitrogen Availability from Dairy manure

: It is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of rnanure nutrients, it is necessary to account for the nutrients remaining in soil fiom previous years applications. A corn (Zea mays) field experiment has continued since 1998 on a Plano silt loam. Residual manure N availability was estimated for two and three years after a single rnanure application fiom differences in whole-plant N uptake using 1) fertilizer N equiv...

27. Evaluating the Interaction between Chelated Fe Source and Placement on Phosphorus Availability in Soybean

In agriculture, chelating agents are used to supplement micronutrients, such as iron (Fe). However, little research has been conducted on a field scale to evaluate chelating agent effects on phosphorus (P) uptake. The objectives of this study were to evaluate four commercially available chelated Fe sources on early soybean growth and nitrogen (N), P, and potassium (K) uptake. The study was conducted at two locations, and the experimental design was a randomized complete block with four replicati...

28. Evaluating the Removal of Corn Residue on Crop Production and Soil Quality

Removal for corn residue as a possible feedstock for the biofuels industry leaves many producers with a number of unanswered questions. These include what impact will this have on the following crop and also the impact on soil quality associated with this practice. A field study was established in 2000 to addr ess these and other questions. Experimental treatments include three corn residue removal levels (low, mid and high); corn harvested for grain and all residue remains on the soil surface,...

29. Evaluation of Adapt-N in the Corn Belt

Nitrogen is the plant nutrient required in the largest quantity, the most likely to be deficient, and the most impactful on corn yield as well as grower profit. Providing N to a corn crop in the right amount while minimizing loss is difficult because of complex biological and chemical reactions that result in the loss of N from the crop root zone via deep percolation to ground water, lateral flow, runoff and erosion to surface waters, and volatile losses to the atmosphere as ammonia, nitrogen g...

30. Evaluation of Secondary and Micronutrient for Soybean Production in Kansas

Secondary and micronutrients are being increasingly studied for their potential to contribute to yield increase. The objective of this study was to evaluate soybean response to secondary and micronutrient fertilizer application to maximize yields. A randomized complete block design was employed with four replications, at five locations during 2013 and five locations in 2014. Treatments consisted of micronutrient fertilizer as individual nutrient for B, Cu, Mn, S and Zn, in addition to a mix of t...

31. Evaluation of the Greenseeker Active Sensor for Sugarbeet Cropping System Nitrogen Management

The application of adequate, non-excessive rates of N fertilizer to sugarbeets ( Beta vulgaris L.) continues to increase in importance with rising fertilizer costs and industry transitions from yield-based payments to payments weighted towa rd crop quality. The objective of this study is to evaluate the use of an optical sensor for its potential in assessing in-season sugarbeet N status, in-season yield prediction, and total N in foliage on day of harvest. Six N fertilizer treatments, from 0 to ...

32. Evaluation of Weed Management Strategies on Grain Sorghum Nitrogen Status and Grain Yield Using Optical Sensors

Information on weed management options and relation to nutrient status is very limited for grain sorghum production. The objectives of this study were: (i) determine the effects of different weed management strategies on grain sorghum yield; and (ii) evaluate the impact on nitrogen (N) status and development of the crop. This study was established at two locations in 2014 (Smith and Reno Co in Kansas). The study used a randomized complete block design with 4 replications. Two main factors evalua...

33. Factors Affecting the Relative Benefit of Deep-banding versus Broadcast Application of Phosphorus and Potassium for Corn and Soybean

Scientifically based recommendations concerning the choice of deep banding versus traditional broadcast application of phosphorus (P) and potassium (K) for corn and soybean production in conservation tillage systems have been hampered by insufficient research and inconsistent results. Even when the decisi on is made (e.g. by strip-tillage corn farmers) to go with deep- banding of P and K, numerous questions remain about fertilizer rates, optimum deep-banding depth and frequency, whether to have ...

34. Fertilizer and Manure Management Comparisons for Corn-Soybean Rotataions in Minnesota

A study was designed to evaluate the impact of P sources (fertilizer and manure), nutrient application methods (broadcast and subsurface bands), P rates (crop removal and twice crop removal), and tillage systems (no-till and conventional) on corn-soybean response. Results to date show higher yields using manure as compared to fertilizer as the P source. This could be attributed to a higher rate of P being applied using the manure. No-till systems measured greater yields in 1999 and 2000, primari...

35. Fertilizer Placement and Tillage Interaction in Corn and Soybean Production

Different tillage systems can affect the availability of phosphorus (P) in the soil. The objective of this study was to evaluate the effects and interaction of fertilizer placement, tillage, and varieties/hybrids for corn and soybean. The experiment was established at two locations in Kansas in 2014. The experimental design was a factorial in a randomized complete block with four replications. Three fertilizer treatments were combined with two tillage systems and two varieties/hybrids of soybean...

36. Fertilizer Placement with Seed - A Decision Aid

Banding fertilizers with the seed at planting con tinues to be a popular option with producers in the Great Plains and North Central regions of the U.S. However, seed-placed fertilizer may limit germination/emergence of the seed/seedling. Nutrie nt source and rate are two factors affecting injury that are relatively simple to manage. Unfortunately, many crop producers and advisors have few rate guidelines for the many crop by fer tilizer combinations that are common to the region. The objectives...

37. Field Correlation of Tissue Testing for Phosphorus and Potassium in Corn and Soybean

Interest in tissue testing as a method of guiding fertilization and detecting nutrient deficiencies in corn and soybean in the upper Midwest is increasing. Tissue testing may be a helpful diagnostic tool for assessing in-season crop nutrients deficiencies. No current yield-response based interpretations for tissue test results are available in Iowa, although previous reports based on limited data collected during the 1990s and 2000s suggested that the value of tissue testing for phosphorus (P) a...

38. Field Measurements of Nitrous Oxide Emissions across a Nitrogen Fertilizer Gradient for Corn Cropping Systems

Significant reductions in nitrous oxide (N 2O) emissions from corn (Zea maize L.) cropping systems may be possible by reducing N fertilizer i nputs with relatively little impact on crop grain yield or economic return. To te st this hypothesis, experiments we re conducted at 4 locations in corn production in Michigan in 2007. All sites were under a corn-soybean rotation. Prior to planting, six rates of urea fertilizer (0-200 lb ac -1) were broadcast and incorporated into four replicate plots (RCB...

39. Groundwater Quality and Nitrogen Use Efficiency in Nebraska's Central Platte River Valley

In response to increasing levels of nitrate-N in groundwater in the Central Platte River Valley of Nebraska, intensive education and then regulatory efforts were implemented starting in the 1980s, to encourage adoption of nitrogen fertilizer and irrigation management practices which can reduce nitrate leaching to groundwater. Since 1988, there have been steady declines in average NO 3-N concentrations in groundwater in the Central Platte River Valley, resulting from adoption of recommended pract...

40. Improving Alfalfa Production in Wisconsin with Sulfur and Potassium Fertilizer

The longevity and quality of an alfalfa stand is an essential component for Wisconsin�s dairy rotations. A study was developed to determine the effects of sulfur and potassium applications on the growth and development of alfalfa stands. The objectives of this study were to determine the effect of i) S fertilizer rate, timing and form on alfalfa yield, ii) recommended or no K fertilizer application on alfalfa yield on soils testing optimum or low for K, and iii) S and K application on soil tes...

41. Improving Corn Yield Potential with Banded Phosphorus Fertilizer

High fertilizer costs and concerns about water quality issues have caused many Midwest corn producers to take a greater interest in improving the efficiency of phosphorus (P) fertilizer applications. The objective of this research was to determine the effects of P source, rate and placement on P use efficiency in high-yield corn production systems. The experiment was conducted in 2013 at two locations in Illinois. Two P fertilizer sources (mono-ammonium phosphate (MAP, 11-52-0) or an enhanced MA...

42. In-Season Nitrogen Management for Corn Production

Water quality impairment related to nitrogen (N) continues to be a concern in Iowa, including the nitrate drinking water standard, USEPA proposed surface water quality nutrient criteria, and the Gulf of Mexico hypoxia. Addressing these issues could include strict guidance for N input to corn and resultant N use practices that require very high level of management and risk, with unknown economic consequences. Rate of N application is an important ma nagement factor in corn production related to n...

43. Iowa Soil-Test Field Calibration Research Update- Potassium and the Mehlich-3 ICP Phosphorus Test

Iowa soil-test interpretations and fertilizer recommendations for phosphorus (P) and potassium (K) were last updated in 1999. The only change from previous recommendations (Voss et al., 1996; Voss and Mallarino, 1996) was to add interpretations for the Mehlich-3 (M3) P and K tests to existing interpretations for the Bray-1 P, Olsen P, and ammonium-acetate K tests (Voss et al., 1999). The interpretations for the ammonium-acetate and M3 K tests are similar because comparisons of amounts of K extra...

44. Management of Enhanced EfficiencyFertilizers

Phosphorus generally occurs in soils as the anions H 2PO4- or HPO4-2, depending on the soil pH. These anions readily react with soil cations su ch as calcium, magnesium, iron, and aluminum to produce various phosphate compounds of limited wate r solubility. Crop recovery of applied P fertilizer can be quite low during the season of application. Specialty Fertilizer Products 1 has developed and patented a family of dicarboxylic co-polymers that can be used as a coating on granular or mixed into l...

45. Manure Application Technology and Impact on Nitrogen Dynamics

A field study was carried out ne ar Elora, Ontario to assess the impact of manure application timing and method on ammonia volatilization a nd nitrogen availability to the crop. A novel method was developed and calibrated for quan tifying ammonia volatilization using passive dosimeter tubes, which promises to provide an economical alternative to other methods. Ammonia loss was negligible from injected manure treatments, and when manure was incorporated immediately it had smaller losses th an wh...

46. Minnesota Long-Term Phosphorus Management Trials: Phase I, The Build Period

Phosphorus (P) fertilizer recommendations are usually made using one of two philosophies, Build and Maintain or Sufficiency. In recent years, the Sufficiency approach has been questioned because of concerns of reducing soil test levels and yield sustainability and whether it has the same yield potential as the Build and Maintain approach. Trials were initiated in 2010 at six locations across Minnesota to develop various soil test P Interpretation Classes in replicated experiments. The initial ph...

47. Nitrate Leaching Characteristics for Various Nitrogen Management Strategies on Irrigated Corn

Efficient use of nitrogen (N) fertilizer for corn production is important for maximizing economic return to the producer and minimizing NO3 leaching to groundwater. This is especially important on irrigated, sandy soils due to the high infiltration and saturated conductivity and potential risk to the local water supplies. This study is being conducted to quantifL the NO3 leaching potential in the irrigated sands along Kansas' waterways under current and alternative N and water management strateg...

48. Nitrogen Fertilizer Efficiency in a Long-term Research Trial

In 1993, a long term crop rotation study (The Living Field Laboratory) was initiated at the W.K. Kellogg Biological Station, Hickory Corners, MI, designed to investigate the benefits of cover crops in various integrated systems compared to a conventional system without cover crops. Today, with the rising cost of production (i.e. energy and fertiliz er) and continued environmental concerns, there are strong incentives for corn pr oducers to accurately assess N requirements and improve fertilizer ...

49. Nitrogen Management of Bioenergy Miscanthus on Claypan Soil Landscapes

Bioenergy crop Miscanthus x giganteus has been well studied for its yield in Europe and certain parts of the US Midwest but little has been done to investigate Miscanthus production in settings economically marginal for grain production. This study was conducted to determine nitrogen (N) requirements and yield potentials of M. x giganteus in degraded claypan soils. The effects of N fertilizer rates were investigated at four different locations in central Missouri on a Mexico series soil (fine, s...

50. Nitrogen Recalibration for Wheat in North Dakota

The general formula for determining N fertilizer ra te in North Dakota for about thirty-five years has been N-rate = (2.5 X Yield Potential (or Yield G oal) less credits from previous crops and soil test nitrate-N from a 2-foot soil core composite. Historically high fertilizer N costs and the ability to fertilize within fiel ds rather than whole field N management has resulted in a reexamination of N calibration data, and an effort to expand the modern N calibration database with new field exper...

51. Nitrogen Timing, Loss, and Replacement

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52. North Dakota Corn Recommendations for Preplant and Sensor Directed Sidedress N

Nitrogen rates for preplant N application in North Dakota have been drastically revised. The former yield-based strategy may have served when N costs were stable and relatively low and high yields in North Dakota were rarely higher than 100 bushels per acre. Due to improved germplasm developed at North Dakota State University and other northern Land-Grant Universities with favorable adaptation to North Dakota climate and soil conditions corn has become one of the most planted crops in the state....

53. NUE in Practice: Will N-efficient Corn Hybrids Sell?

Efficient use of nitrogen (N) fertilizer is becomi ng increasingly important in corn production due to rising N fertilizer prices and growing concer ns about N contamination of ground and surface waters. Seed companies are also beginning to develop hybrids with N use efficiency (NUE) improved through trait introduction. The introduc tion of such hybrids will bring new questions about the value of higher NUE, and about risk ma nagement associated with decreasing, or not increasing, N use rates as...

54. Phosphorus and Water Quality Issues in Lake Erie

What are harmful algae blooms? Harmful algal blooms (HABs) are so named because they can produce toxins (or poisons) that can cause illness or irritation sometimes even death in pets, livestock, and humans. The term algae is somewhat misleading since HABs are actually cyanobacteria, which are commonly referred to as blue-green algae, and are not true algae. These organisms act like many other plant and use photosynthesis to capture sunlight but unlike most plants and algae some can fix their own...

55. Phosphorus Dynamics of Land-Applied Compost Bedded Pack Dairy Barn Product in Low and High Soil Test Phosphorus Environments

Characterizing and understanding the nutrient dynamics of land applied compost bedded pack dairy barn (CBP) products is necessary because this waste management system and its fertility use are increasingly common. An aerobic mineralization study was conducted to observe the phosphorus (P) dynamics of land-applied CBP product in low and high soil test P (STP) environments. An innovative phosphorus fractionation strategy employing UV-assisted organic P decomposition helped quantify fractions corre...

56. Phosphorus Runoff From Incorporated and Surface-Applied Fertilizer and Manure

Continued inputs of fertiher and manure in excess of crop requirements have led to a build-up of soil phosphorus (I?) levels, creating an environmental rather than agronomic concern (Sharpley et al., 1994). The objective of this study was to evaluate the effects of soil test P level, source of P amendments, tillage, and manure application method on P runoff from agricultural soils. The treatments consisted of swine manure surface applied and injected at rates of 29 and 59 Ib acre-' of P, and tri...

57. Phosphorus Sorption Behavior of Kentucky Soils with Varying Indigenous Phosphorus Content

The risk of phosphorus (P) losses from agricultural lands through surface transport to waterways increases with increasing levels of soil P. Agricultural soils in the Inner and Outer Bluegrass of Kentucky have high indigenous P content. This study investistigates the phsophorus sorption characteristics that influence the soils potential for P loss to water bodies. Four soils from the Inner Bluegrass and four soils from the Outer Bluegrass were identified as eing agriculturally significant soils ...

58. Phosphorus Stratification- is it Relevent to P uptake by Soybean

Stratification of nutrients, observed in soils under continuous no-till management, remains an issue. Two experiments were conducted during 2001 and 2002 to evaluate the effect of stratification on P nutrition of soybean (Glycine nzax (L.) Merr.). At the fist site there were five blocks with stratified and unstratified main plots and five levels of soil test P as subplots. In the second trial there were four blocks with two stratification treatments as main plots, the absence and presence of in...

59. Plant Population Influences on Maize Physiological Responses to Nitrogen Application

Past genetic improvements in maize ( Zea mays L.) have led to the creation of modern hybrids that are increasingly tolerant to a variety of stresses and, in particular, to high plant populations. However, high plant densities can adversely a ffect overall grain yield due to greater intra- specific (within species) competition for lim iting resources. This competition increases barrenness and plant-to-plant variability for grain yield (GY CV) and other morpho-physiological traits. In this study, ...

60. Planting Date, Nitrogen Rate, and Nitrogen Timing Interactions to Optimize Winter Wheat Production

Winter wheat (Triticum aestivum L.) planting date is a large contributing factor for high yield production systems located within the central Great Lakes Basin, and nitrogen (N) rate and timing strategies offer the opportunity to improve both the production and efficiency of winter wheat when considered in combination with planting date. A field study was initiated in East Lansing, MI to determine the effects of planting date, N application timing, and total N application rate on winter wheat y...

61. Potassium Management, Soil Testing and Crop Response

New field research is conducted in Iowa as issues or questions arise to assure that nutrient management guidelines are up to date and to address new issues. This article briefly summarizes two major projects with potassium (K) whose results are useful to improve the efficacy of nutrient management and crop production. One project focused on correlating soil-test K methods with response of corn and soybean to fertilization and on obtaining better estimates of the concentration of K in corn and so...

62. Predicting Relative Yield of Corn in Indiana Using an Active Sensor

Fine-tuning N fertilization is important for impr oving the economic and environmental impact of corn production. This importance is highlighted by ever rising fertilizer prices and increased public scrutiny. Reflectance measurements usi ng an active sensor during the growing season may be useful for determining the need for additio nal N. This is the second year of a multi-year study to evaluate canopy reflectanc e as an N management tool across a variety of Indiana soil types. The objectives o...

63. Profile Distribution of Available Potassium in Des Moines Lobe Soils

Plant potassium (K) concentrations and soil fertility evaluations to predict available K have received renewed attention during the past few years due to increasing interest in harvesting crop residues as feedstock for production of bioenergy and other bio-products [e.g., button mushroom (Agaricus Bisiporus) compost]. Interest in K crop nutrition has also increased as more producers adopt reduced or no-tillage production practices. This latter situation is not new, because the potential for K de...

64. Quantifying the Effects of Nutrient Management and Cover Crops on Soil Microbial Communities and Soybean Production

Agricultural productivity relies upon microbial communities to cycle nutrients from soil to plant yet little information is available concerning how nutrient management and cover cropping practices influence microbial activity and crop production. Lack of consistent soybean (Glycine max L.) yield response to applied fertilizer has resulted in a need to further investigate management practices focused upon enhancing soil biological activity which in turn may feed the crop. A field study was init...

65. Relationship Between Soil P and P in Surface Runoff and Subsurface Drainage- An Overview of Ongoing Research

Nonpoint source pollution fiom agricultural fields has the potential to accelerate eutrophication of fieshwater ecosystems. In a report of water quality in the United States, the Environmental Protection Agency sited agriculture as the primary source of pollution in 60% of impaired river miles, 30% of the impaired lake acres and 15% of estuarine square miles @PA, 1998). Phosphorus, in particular, has received much attention due to its role as limiting nutrient in many fieshwater ecosystems (Cor...

66. Remote Sensing of Corn Canopy Dynamics and Biophysical Variables Estimation in Michigan

This study was initiated to evaluate sensor-based nitrogen and water application for corn (Zea mays L.) in Michigan. The specific objectives of this study were: 1) to identi@ wavelengths that are more sensitive to N deficiency in corn, 2) to determine when to predict corn grain yield fiom spectral remote sensing data, and 3) to estimate biophysical variables ofcorn such as leafareaindex (LAI) and fractional cover (Fc) fiom spectral vegetation indices (SVI) obtained fiom radiometric measurements ...

67. Skip-Row Configuration and Plant Density Effects on Sorghum Grain Yield and Yield Component in Southern Nebraska

Equal spacing of sorghum rows typically results in the highest grain yield when soil water is adequate throughout the season, but skip-row plan ting may be a means to reduce water deficits during reproductive growth stages. We evaluated the effect of skip-row planting configuration and plant population density on grain yield, yield components and water use efficiency at five locations in a transect across southern Nebras ka where annual mean precipitation ranges from 300 to 900 mm yr -1. Three r...

68. Soil Mineralogy and Potassium Availability

In this talk, I will try to answer four questions. The outline below gives the overall framework for the presentation. 1. What are the mineral sources of potassium? Primary minerals crystallize from the magma. Those that contain K are: Feldspars (microcline and orthoclase)  Micas (biotite and muscovite) Primary minerals weather  decompose  by several mechanisms. Chemical bonds are destabilized by acid attack. Al ions are complexed by orga... M.L. Thompson

69. Soil pH and Manganese Effects on Roundup Ready Soybeans

Soybean 'flas'h is a general yellowing of th e upper soybean canopy thought to be associated with high rates of glyphosate and reduced levels of manganese (Mn) with glyphosate-resistant soybeans. Several field sites varying in soil Mn levels and some with within field variable pH levels were evaluated between 2004 and 2006 for re sponsiveness of soybeans to glyphosate rate and Mn treatments. The objectives of this study were to 1) evaluate the effects of foliar applied Mn and soil applied Mn on ...

70. Soil Phosphorus Spatial Distribution in Pastures Receiving Poultry Litter Applications

Environmentally-based P management strategies could be improved by debeating management zones incorporating the effects of landscape position on soil morphology, hydrology, and soil P distribution. Three farm pasture sites in SW Missouri receiving long-term poultry litter applications were sampled by landscape position (summit, shoulder, upper backslope. middle backslope, lower backslope, footslope, drain) for soil P (Bray 1 P, CaCl2 P, total P) at two depths (0-5 cm, 5- 15 cm). Low landscape po...

71. Soybean Response to Nitrogen Applications

Soybean yield increases due to N fertilizer have been reported recently, particularly for N applications during the reproductive stages. It is also known that nitrate inhibits nodulat ion and nodule activity and could potentially reduce yield. Our objective was to evaluate the effect of N fertilizer on soybean yield. Forty-six experiments were conducted with N fertilizer applied at times ranging fiom planting to late reproductive stages. Some experiments had significant positive or negative resp...

72. Soybean Whole Plant, and Trifoliate Phosphorus Concentration Relationships to Yield and Phosphorus Removal Rates

Plant tissue analysis is becoming a more popular tool to diagnosis nutrient deficiencies. Whole plant samples may be taken early ( corrections. Leaf samples taken just before grain fill may be used to diagnose problem spots in a field. Benton Jones Jr. et al. (1991) reports that the phosphorus (P) sufficiency range for upper most developed trifoliates is between 0.26 and 0.50 percent P. There is no published data on whole plant P sufficiency ranges from V4 to V6. Nutrient grain analysis is valua...

73. Stand Age Affects Fertilizer Nitrogen Response in First-Year Corn Following Alfalfa

Through a symbiotic relationship with soil bacteria, alfalfa can acquire nitrogen (N) from the atmosphere, use the N for its own growth, and contribute large amounts of N to subsequent crops. To estimate this N contribution, most land-grant universities use book-value N credits based on alfalfa stand density at termination. However, a recent literature analysis indicated that alfalfa stand density is not a reliable predictor of grain yield response to fertilizer N in first-year corn. That analys...

74. Starter Fertilizer Application Effect on Reduced and No-tillage Grain Sorghum Production

This experiment was conducted at the North Central Kansas Experiment Field, located near Belleville, on a Crete silt loam soil. Soil test P was in the high@ range. Treatments consisted oftillage systems and starter fertilizer placement and composition. Tillage systems were no-tillage and minimum tillage (spring disc and harrow treatment). Methods of starter fertilizer application included placement 2 inches to the side and 2 inches below the seed at planting (2x2) and dribbled in a band on the s...

75. Starter, Nitrogen Management and Nitrogen Calibration- Localizing Management Practices

When I first started consulting with some of the fertilizer dealerships in my area, they hired me to make them different from the dealership down the road. The best way to do this was to become a local expert on scientifically-based best management practices for growing corn and soybeans in my territory. This included knowing how best to manage nutrients to grow productive and profitable crops. University and soil test laboratory recommendations provided a good starting point. However, these dat...

76. Strip till Nitrogen Placement, and Starter Fertilizer Effects on Corn Growth and Yield

Strip tillage, a system where residue is removed and small ridges are formed in the fall in the position of next year's rows, has become an increasingly popular alternative to 0-till for corn in Illinois. Over three years and eight environments in Central and Northern Illinois, tillage had no effect on grain yield: conventional tillage, strip tillage, and 0-till produced 1 1.67, 11.67, 1 1.57 Mg/ha, respectively. There were also no differences in yield due to N timing, N placement, or starter fe...

77. Sulfur Fertility for Kentucky Agriculture

Sulfur (S) fertility concerns are becoming more common in Kentucky due to the reduction in atmospheric deposition resulting from more stringent air quality concerns. The most likely crops where S deficiency would first occur are winter wheat and alfalfa, due to mineralization rates or high removal rates. Currently few, if any, fields in Kentucky show consistent S deficiency problems. Tissue surveys were conducted in alfalfa fields during 2013 and 2014 to assess S status in alfalfa. Twenty-one pe...

78. Sulfur Influence on Corn and Soybean Yields in Eastern South Dakota

Clean air legislation, the increasing use of conservation tillage, and the manufacture of phosphorus fertilizers without sulfur have all contributed to lowering soil sulfur (S) availability to crops. Soil S availability has been affected to some extent by all three issues in eastern South Dakota. Hilltop erosion has exposed subsoil in which the pH is higher and organic matter content is lower than at lower landscape positions. In some eroded shoulder positions of the landscape in no-till fields....

79. Sulfur Responses and the Wisoconsin Alfalfa Sulfur Survey

For more than 30 years, agronomists, soil scientists, consultants and farmers have recognized the potential for significant responses to applied sulfur fertilizer in northern and western Wisconsin on lighter textured, low organic matter soils that had not recently received manure (Rand et al., 1969; Hoefi and Walsh, 1975; Schulte, 1976; Peters and Kelling, 1987). More recently, crop consultants and others have reported seeing sulhr responses on soils or in locations where they typically were no...

80. Sustainable Vegetable Crop Production Using Vermi-Compost

This research intends to utili ze earthworm castings as an alternate nutrient source, especially nitrogen, for vegetable crop production. The experiment was conducted in the greenhouse and 'Mountain Fresh' tomato ( Lycopersicon esculentum Mill.) was used as the test crop. The main objectives were (1) to identify the optimum app lication rate of earthworm castings (EC) for tomato growth, and (2) to compare tomato res ponse under different treatments. Three different textural soils, namely sandy s...

81. Swine Manure Applications for Soybean Production - Environnmental and Pathological Implications

Soybeans are leguminous plant sp ecies capable of fixing nitrogen (N) from the atmosphere to support their growth and development. Despite th e fact that soybeans can fix their own N, in a soil environment rich in inorgani c N they will scavenge for available N decreasing the level of root nodulation (Schmidt et al., 2000; Hester man and Isleib, 1991). Studies conducted to measure the impact of N fertilization of soybean s reveals that crop response to commercial N fertilizer does not result in ...

82. Switchgrass Rhizobacterial Community Structure as a Function of Cultivar and Nitrogen Fertility at Two Sites in Minnesota

Biofuel production using native perennial grasses such as switchgrass (Panicum virgatum) has potential to reduce U.S. dependence on foreign oil and curtail greenhouse gas emissions. Switchgrass can also provide significant ecosystem services, such as nutrient loss reduction and carbon sequestration. Best management practices (BMPs) for switchgrass fertility are being established on a regional basis, yet little work has been done to examine the intersection of soil fertility with soil biology in ...

83. The Effect of Tillage and P Fertilizer Placement on P Runoff from Sugar Beet Production Systems

The objective of this study was to determine the differences in the amount of phosphorus (P) in runoff fiom land under sugar beet production caused by different management practices and phosphorus fertilizer placement. The study was set up as a split plot experimental design, replicated three times. The whole plot treatments were: 1 ) codsoybean rotation, with moldboard plow as primary tillage before soybean; 2) corntsoybean rotation, with chisel plow as primary tillage before corn; 3) sugar bee...

84. Triple-Stacks, Genetics, and Biotechnology in Improving Nitrogen Use of Corn

Genetic improvement in N use efficiency (NUE) is a clear strategy fo r enhancing yield and fertilizer N management of corn ( Zea mays L.), and has been the subj ect of our ongoing research. Calculation of the N requirement (N fertilizer usage/grain yield) based on statewide average grain yields and fertilizer sales shows a stead y decrease since the mid 1980's, suggestive of a genetic improvement in N use. Direct comparis on of the response to N for a 1980�۪s hybrid with its modern counterpar...

85. Update on the Illinois N Test

Estimation of plant-available N is complicated enormously by the dynamic nature of soil N, owing largely to the effects of temperature and moisture supply on N-cycle processes. Numerous biological and chemical methods have been proposed as an index of soil N availability (Brernner, 1965; Keeney, 1982; Stanford, 1982; Bundy and Meisinger, 1994), but none has been adopted widely for soil testing. Biological methods are necessarily time-consuming because of the need for incubation, and the results ...

86. Use of Chlorophyll Flourescence Techniques to Detect Stresses in Corn

Increased efficiencies in the use of water and fertilizer will require better methods of monitoring crop stress. This study was conducted to determine whether chlorophyll fluorescence was more sensitive to detecting water and nitrogen stress than chlorophyll meters in corn (Zea mays). The experiment was carried out near Shelton, NE in 2000, 200 1, and 2002. Treatments consisted of a factorial combination of 12 corn hybrids (1 1 Pioneer Hi-Bred internationali and B73 x M017), two water levels (de...

87. Use of Fly Ash as as Alternative Liming Source for Irrigated Corn Production

Fly ash from the Gerald Gentleman Power Station in west central Nebraska can potentially serve as an alternative liming source without reducing corn grain yields. A study was conducted to assess the use of fly ash as an alternative liming source on three acid sandy soils of west central Nebraska where conventional limmg sources can be uneconomical due to transportation costs. Corn grain yield, and soil pH change over time were assessed. Lime sources failed to raise the soil pH in the upper 8 in...

88. Use of Nitrogen Fertilizer Sources to Enhance Tolerance and Recovery of New Corn Hybrids from Early Season Soil Waterlogging

Corn (Zea mays L.) production losses due to temporarily flooded or saturated soils resulting from excessive precipitation are a persistent problem in Missouri and the Midwest Region of the United States. In 2011 alone, monetary losses for corn and soybean (Glycine max) production due to excessive flooding in the Midwest were calculated to be more than $1.6 billion. Application of different sources of nitrogen (N) fertilizer may promote increased flood tolerance and recovery in interaction with d...

89. Using Reflectance Sensors to Predict Nitrogen Needs of Cotton

Objectives 1) Develop on-the-go N recommendations based on analysis of the reflectance sensor readings. 2) Determine the sensor model, height, and wa velength that give the best prediction for sidedress N. 3) Determine the best growth stag e for sensor-based sidedressing Relevance There is great spatial variability of N in the soil. Cotton fields that receive a blanket rate of nitrogen, ignoring the vari ability, will have areas of excessi ve growth. This unnecessary growth raises production cos...

90. Value of Tillage Practices and Nitrogen Rates for Corn Production

Most N recommendations for corn (Zea mays L.) production in the U.S. Midwest do not consider tillage as a factor when an appropriate N rate is determined. Our objectives were to determine the response of grain yield and RTN to increasing rates of fertilizer N for corn grown in three tillage systems. Tillage by N rate experiments we re conducted at eight Central Illinois site-years at three locations and years (1998-2000). Tillag e systems employed were: zero-till, where no tillage was performed ...

91. Variable Nitrogen Rate Management

It is now more or less acknowledged that lime and N are potentially more profitable than P and K variable rate management. There is a lot of variability in optimal N rates within fields so that there is a need for variable N management. The benefits related to variable N management are generally ranked as: o Less N fertilizer used per unit yield. Savings of 15 USDIac on average for small grains. up to 41 USDIac. o Greater uniformity in crop stand, yield, grain humidity, specific weight and prot...

92. Variable Rate Nitrogen Fertilizer for Corn Grown in Kentucky

In Kentucky, nitrogen recommendations for corn have historically been based on soil type. soil drainage class, and previous crop rather than on an anticipated yield or yield potential. Because of the growing popularity of yield monitors and GPS technology, corn producers are now accurately mapping yield variations within fields. A three year study was conducted in the karst region of western Kentucky to determine if past yield history (collected with a yield monitor using GPS) could be used as a...

93. Variable Seeding Rates in Twin Row Planting and Micro Management of Nutrients

A large scale study to determine if twin row planting, utilizing particular fertility concepts and conservational practices, out produces conventional methods of planting and fertilizing. The primary goal of the study was to increase fmer profitability and promote methods of conservational tillage. ...

94. Varying Nitrogen and Seeding Rates of Corn Across Productivity Regions in Fields

A field study was conducted fiom 1999 to 2001 to determine the effects of variable seeding rates and variable nitrogen rates on corn (Zeu muys L.) in southern Ihois. In whole field experiments, variable seeding rates ranging fiom 18,000 to 38,000 seeds ac-' in 4.000 seed increments were planted in randomized strips (in a randomized complete block design) across the field that had soils with varying productivity based upon historical yield maps. From the yield data it was determined that the opti...

95. Visual Correlation of Aerial Imagery with Topography and Crop Yield

A study is currently being conducted on several farms to evaluate the usefulness of aerial imagery of soil and of a growing crop to delineate within-field management zones for the purposes of site-specific management. Presented is information for one site in Kent county Ontario for which correlations between aerial images taken of the soil and of the growing crop with the spatial patterns of measured topography, soil texture, and corn yield were examined. Visual interpretation indicated a very g...

96. Zinc Deficiency Response of Sorghum, Wheat, and Corn

Zinc (Zn) deficiency in corn (Zea mays L.) is more common than in sorghum (Sorghum bicolor (L.) Moench) or wheat (Triticum sp.). The ability of wheat to withstand low soil Zn conditions is related to increased release of phytosiderophore, a natural chelate, fiom its roots. The reasons for sorghum's ability to utilize low levels of soil Zn have not been adequately explored. The objective of this research was to: 1) ascertain if Zn deficiency can be induced with sorghum, wheat, and corn grown in a...