Progress 10/01/06 to 09/30/11
Outputs
OUTPUTS: Across the time period for this project, the following research efforts were conducted. 1) Field-based N rate trials to measure corn response to applied fertilizer N rate. 2) Field correlation and calibration determination for the amino-sugar N test and determination of the fraction of total soil N measured. 3) Incubation of soils to study addition of urea and biochar on soil total C, total N, extractable P and K, pH, and ammonium and nitrate-N. 4) Field-based N rate trials to study soil mineralization potential and soil N supply to corn and evaluate corn plant N stress sensing as a means to determine N fertilization need. 5) Leaching soils amended with legume residues (green manure) in a laboratory study to measure the organic N addition effect on production of ammonium, nitrate, and nitrite-N. 6) Field-based trials studying the effect of biochar addition to soil on the N requirement, grain yield, and N recovery in corn. 7) Incubation of soils amended with biochars produced with different feedstock and reactor conditions to study effect on biochar characteristics and reaction with soils related to production of ammonium and nitrate-N, and soil total-N and total C. 8) Laboratory study of eleven diverse biotechnology byproducts to assess chemical composition and organic and inorganic compounds, including sugars, protein, and low molecular weight organic acids. 9) Field-based N rate trials to study soil N supply to corn, corn response to applied fertilizer N, corn canopy N status by sensing with various active canopy sensors, and N rate calibration of the canopy sensors. 10) Soil incubation to study specific enzyme activity as a potential index for soil N mineralization potential, including six amidohydrolases involved in N cycling and four glycosidases involved in carbon (C) cycling in soils. 11) Incubation of biochars produced from corn stover and switchgrass with varying feedstock and reactor conditions to study how biochars react with soils and effect on soil ammonium-N, nitrate-N, total N, and total C. 12) Study mechanisms of nitrate removal and N cycling by perennial vegetation strips located at the toe and shoulder slope positions within corn-based cropping systems. Results of studies were published in scientific journals, published in extension publications, presented at the American Society of Agronomy annual meetings, presented at soil fertility and bioenergy conferences, and included in conference proceedings. PARTICIPANTS: R. Killorn, principal investigator; J.E. Sawyer, principal investigator; D.W. Barker, assistant scientist; M.A. Tabatabai, principal investigator; M. Ekenler, graduate research assistant; Z.N. Senwo, graduate research assistant; M. Castellano, principal investigator; M. Perez-Suarez, co-investigator; H. Asbjornsen, co-investigator; M. Helmers, co-investigator; R. Kolka, co-investigator; M.M. Al-Kaisi, co-investigator; J.P. Lundvall, extension program specialist; R. Unger, graduate research assistant; D.E. Dodor, graduate research assistant; J.A. Hawkins, graduate research assistant; D.A. Ruiz Diaz, postdoctoral assistant; L.N. Nakhone, Fulbright Fellow Collaborator; C. Brewer, graduate research assistant; A.P. Mallarino, research and extension specialist; C.A.M. Laboski, Univ. of Wisconsin; D.T. Walters, Univ. of Nebraska; L.G. Bundy, Univ.of Wisconsin; R.G. Hoeft, Univ. of Illinois; G.W. Randall, Univ. of Minnesota; T.W. Andraski, Univ. of Wisconsin; L. Hendrickson, John Deere Company; G. Ostermeier, John Deere Company. TARGET AUDIENCES: Activities are designed to provide research based information for scientists and other researchers working in this topic area, for the North Central Region Experiment Station Directors NC-1032 committee, for bio-energy industry personnel, and for agribusiness and certified crop advisers providing recommendations to crop producers regarding N management, bioenergy by-product management, and soil testing. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
1) Field based N rate trials provided crop producers and crop advisers an understanding of the soil N supply for corn production; economic optimum N fertilization rate; lack of specificity in the amino-sugar N test to determine mineralization of soil organic N, supply of crop-available N, or help with adjustment in corn N fertilization rate; and correlation of active canopy sensors for determination of N stress deficiency in corn and calibration to in-season N rate adjustment. This information will help alleviate the potential for misapplication of N fertilizer, provide understanding of N rates for optimal profitibality, and reduce the potential for nitrate reaching water systems. 2) Studies with biochars provided new fundamental scientific findings and will help guide potential use of biochar for carbon sequestration and N availability to crops, and provided information to help identify the quality of biochars that will have the maximum positive effect on soil processes. The different biochars studied significantly affected soil total N, total C, and pH, but did not influence cycling of ammonium-N or nitrate-N. The conditions during pyrolysis and feedstock influenced how the biochar reacted with soil and resulting influence soil chemical properties. Biochar applications in the field did not improve corn production. 3) Studies with incubation of legume green manure crops provided new fundamental findings that explain N mineralization with these crops: net cumulative N mineralized correlated with the total polyphenols and polyphenol:N ratios; net cumulative N mineralized and percentage N mineralized correlated with residue C:N ratios and net cumulative N mineralized correlated with (lignin + polyphenols):N ratios, and with lignin contents; N mineralization varied among leguminous crops, being related to the chemical composition of C and N. Nitrogen mineralization of leguminous crop residue in soils should be compared from the added organic N and not on a residue weight basis. 4) Studies with soil incubation and enzyme activity measurement showed that among the enzyme activities studied, NAGase activity was the most correlated with the cumulative N mineralized; cumulative N mineralized were also correlated with arylamidase and L_aspartase activities; because NAGase activity is involved in both N and C cycling, the cumulative N mineralized were also correlated with the activity of this enzyme and with b_galactosidase; activities of other N enzymes correlated with cumulative N mineralized were L_asparaginase, urease, amidase, and L_glutaminase. It seems that the activity of NAGase can be used as an index of N mineralization in soils. 5) Research on diverse biotechnology byproducts has shown that the products vary in characteristics (pH, solids, organic C, and total N); contained significant concentrations of phosphorus and sulfur; other organic chemical constituents were protein, total sugars, aliphatic acids, and aromatic acids. Therefore, application of biotechnology byproducts to agricultural land may alter some of the chemical and biochemical processes in soils, but with proper management any negative impacts can be alleviated.
Publications
- No publications reported this period
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Research was conducted to assess the relationship between nitrogen (N) mineralization in soils and enzyme activities using six amidohydrolases involved in N cycling and four glycosidases involved in carbon (C) cycling in soils. Enzyme activity was assayed and related to N and C mineralization for 20 weeks at two temperatures. Specific enzyme activity was then evaluated as a potential index for N mineralization potential in soils. Multiple field-based N rate response trials across multiple years and locations were used to evaluate corn canopy N status sensing with various active sensors as a means to determine corn plant N status calibration and provide N fertilization need estimation. Nitrogen fertilizer was applied at multiple rates in equal increments from 0 to 270 kg N/ha before or at corn planting. Several active sensors and canopy indices were evaluated, including the Minolta SPAD-502 chlorophyll meter (Konica Minolta, Japan), Crop Circle ACS-210 (Holland Scientific, Lincoln, NE), and GreenSeeker 505 and 506 (NTech Industries, Ukiah, CA). The corn canopy was sensed at mid-vegetative growth stages. An investigation was conducted on how feedstock and reactor conditions will affect biochar characteristics and how biochars produced react with soils. Biochars were produced from corn stover and switchgrass by fluidized bed fast pyrolysis, slow pyrolysis, and gasification. These chars were mixed with soil at a rate equivalent to 36 Mg/ha along with the equivalent of 224 kg fertilizer N/ha. The N source was urea. The mixtures were incubated for 1, 2, 4, 6, and 8 weeks at 25C and then analyzed for ammonium-N, nitrate-N, total N, and total C. Perennial vegetation strips located at the toe and shoulder slope positions in watersheds with corn-based cropping systems have been shown to reduce downstream nitrate losses. However, mechanisms of nitrate removal remain unclear. Nitrate availability and cycling rates are being indexed in perennial vegetation strips and cropped areas of watersheds with toe and shoulder slope perennial grass buffers. This research will determine how these perennial vegetation strips impact down-slope N availability, cycling rates, and nitrate losses. Dissemination Results of studies were published in scientific journals, published in extension publications, presented at the American Society of Agronomy annual meetings, presented at soil fertility and bioenergy conferences, and included in conference proceedings. PARTICIPANTS: R. Killorn, principal investigator; J.E. Sawyer, principal investigator; D.W. Barker, assistant scientist; M.A. Tabatabai, principal investigator; M. Ekenler, graduate research assistant; Z.N. Senwo, graduate research assistant; M. Castellano, principal investigator; M. Perez-Suarez, co-investigator; H. Asbjornsen, co-investigator; M. Helmers, co-investigator; R. Kolka, co-investigator. TARGET AUDIENCES: Activities are designed to provide research based information for scientists and other researchers working in this topic area, for the North Central Region Experiment Station Directors NC-1032 committee, for bio-energy industry personnel, and for agribusiness and certified crop advisers providing recommendations to crop producers regarding N management, bioenergy by-product management, and soil testing. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Laboratory soil incubation and enzyme activity measurement results showed that among the enzyme activities studied, NAGase activity was the most significantly correlated with the cumulative amounts of N mineralized in 32 soil samples at 20oC (r = 0.87***) and at 30oC (r = 0.95***). The cumulative amounts of N mineralized at 30oC were also significantly correlated with arylamidase and L_aspartase activities, with r values of 0.61*** and 0.52**, respectively. Because NAGase activity is involved in both N and C cycling, the cumulative amounts of N mineralized at 30oC were also significantly correlated with the activity of this enzyme (r = 0.80***) and with b_galactosidase (r = 0.58***). Activities of other N enzymes that were significantly correlated with the cumulative amounts of N mineralized at 30oC in 20 wks were those of: L_asparaginase (r = 0.61***), urease (r = 0.57***), amidase (r = 0.54**), and L_glutaminase (r = 0.41*). It seems that the activity of NAGase can be used as an index of N mineralization in soils. Field correlation/calibration of active canopy sensors is needed in order to correctly relate sensor measurements and calculated indices to N stress and N rate deviation from economic optimum N rate in corn production systems. The new findings from the sensor calibration work show that monitoring the plant canopy N status is a viable option to aid in determination of corn plant N status, in-season N fertilization need, and application rate adjustment. These results provide crop producers and crop advisers in Iowa an understanding of active canopy sensors, sensor indices, calibrated sensor technology, and model algorithms for adjusting N fertilization rate. This information will alleviate the potential for misapplication of N fertilizer based on use of N stress sensing, provide an understanding of N rates for optimal profitability, and reduces the potential for nitrate reaching water systems.
Publications
- Tabatabai, M.A., M. Ekenler, and Z.N. Senwo. 2010. Significance of Enzyme Activities in Soil Nitrogen Mineralization. Communications in Soil Science and Plant Analysis, 41:595-605.
- Barker, D.W., and J.E. Sawyer. 2010. Using active canopy sensors to quantify corn nitrogen stress and nitrogen application rate. Agron. J. 102:964-971.
- Sawyer, J.E., and D.W. Barker. 2010. Quantifying corn nitrogen deficiency and application rate with active canopy sensors. p. 97-108. In Proc. Fortieth North Central Extension-Industry Soil Fertility Conf., Des Moines, IA. 17-18 Nov. 2010. Vol. 26. International Plant Nutrition Inst., Brookings, SD.
- Castellano, M.J. 2010. Shifting human diets and agricultural nutrient management. J. Soil and Water Conserv. 65(3):63A-65A. doi:10.2489/jswc.65.3.63A.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: An investigation was conducted on how feedstock and reactor conditions will affect biochar characteristics and how biochars produced react with soils. Biochars were produced from corn stover and switchgrass by fluidized bed fast pyrolysis, slow pyrolysis, and gasification. These chars were mixed with soil at a rate equivalent to 36 Mg/ha along with the equivalent of 224 kg fertilizer nitrogen (N)/ha. The N source was urea. The mixtures were incubated for 1, 2, 4, 6, and 8 weeks at 25C and then analyzed for ammonium-N, nitrate-N, total N, and total carbon (C). Research was conducted on 11 diverse biotechnology byproducts to assess the chemical composition, organic and inorganic, including sugars, protein, and low molecular weight organic acids by using wet chemistry, ion chromatography, and gas chromatography-mass spectrophotometry. Multiple field-based N rate trials were conducted to study the soil N supply to corn, measure corn response to applied N, and evaluate corn canopy N status sensing with various active sensors as a means to determine corn N fertilization need and to provide N fertilization rate calibration with corn canopy sensing. Nitrogen fertilizer was applied at multiple rates in equal increments from 0 to 270 kg N/ha before or at corn planting. Active sensors, Minolta SPAD-502 chlorophyll meter (Konica Minolta, Japan), Crop Circle ACS-210 (Holland Scientific, Lincoln, NE) and GreenSeeker 506 (NTech Industries, Ukiah, CA), were used to sense the corn canopy N status (N adequacy/deficit) at the V10-V12 vegetative growth stages. Results of studies were published in scientific journals, published in extension publications, presented at the American Society of Agronomy annual meetings, presented at soil fertility and bioenergy conferences, and included in conference proceedings. PARTICIPANTS: R. Killorn, principal investigator; R. Unger, graduate research assistant; J.E. Sawyer, principal investigator; D.W. Barker, assistant scientist; M.A. Tabatabai, principal investigator. Collaborators: C. Brewer, graduate research assistant; A.P. Mallarino, research and extension specialist. TARGET AUDIENCES: Activities are designed to provide research based information for scientists and other researchers working in this topic area, for the North Central Region Experiment Station Directors NC-1032 committee, for bio-energy industry personnel, and for agribusiness and certified crop advisers providing recommendations to crop producers regarding N management, bioenergy by-product management, and soil testing. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The research on soil application of biochars is providing results that are new, fundamental scientific findings that will help identify the quality of biochars that will have the maximum positive effect on soil processes. The biochar applications in this study did not influence cycling of ammonium-N or nitrate-N. Addition of the biochars increased total soil N and C, although not differentially. The research on diverse biotechnology byproducts has shown that the products vary in characteristics; pH values ranged from 0 to 8.2, solid contents from 25 to 706 g/kg, organic C from 132 to 568 g/kg, and total N from 14 to 100 g/kg. The byproducts contained significant concentrations of phosphorus and sulfur. Other organic chemical constituents were protein (0.2-20 g/kg), total sugars (4-90 g/kg), aliphatic acids (0.06-1200 g/kg), and aromatic acids (0.03-35 g/kg). Therefore, application of biotechnology byproducts to agricultural land may alter some of the chemical and biochemical processes in soils, but with proper management any negative impacts can be alleviated. Field correlation/calibration of corn canopy N status sensing is needed in order to correctly relate sensor measurements and calculated indices to N stress and N rate deviation from economic optimum N rate (needed in-season N fertilization rate) in Iowa corn production systems. The new findings from the sensor calibration work show that monitoring the plant canpy N status is a viable option to aid in determination of available soil N supply, in-season N fertilization need, and application rate adjustment. These results provide crop producers and crop advisers in Iowa an understanding of corn N stress with sensing tools, calibrated sensor technology, and model algorithms to adjust N fertilization rate. This information will alleviate the potential for misapplication of N fertilizer based on use of N stress sensing, provide an understanding of N rates for optimal profitibality, and reduces the potential for nitrate reaching water systems.
Publications
- Unger, R., and R. Killorn. 2009. The effect of different biochars on selected soil chemical properties. In Annual Meetings Abstracts CD-ROM, ASA, Madison, WI.
- Barker, D.W., and J.E. Sawyer. 2009. Optimizing nitrogen fertilizer application in corn using green technology. In Annual Meetings Abstract CD-ROM, ASA, Madison, WI.
- Sawyer, J.E., and A.P. Mallarino. 2009. Fertilization decisions in uncertain times. p. 21. In 2009 Proc. Crop Advantage Series. Iowa State Univ., Ames, IA.
- Sawyer, J.E. 2008. Fertilizing crops in the new price age - nitrogen. p. 253-260. In Proc. 20th Annual Integrated Crop Management Conf., Ames, IA. 10-11 Dec. 2008. Iowa State Univ., Ames.
- Tabatabai, M.A. 2009. Chemical composition of biotechnology byproducts produced in Iowa: Selected organic and inorganic forms. Journal of Food, Agriculture Environment 7:793-798.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Activities, Events, Services, Products: 1) Multiple N rate trials were conducted to study the mineralization potential and soil N supply to corn, evaluate the amino-sugar N test, measure corn response to applied N, evaluate corn plant N stress sensing as a means to determine the soil mineralization potential and N fertilization need, and to provide N fertilization rate calibration from N stress sensing. 2) Organic N production by legumes is a key benefit of growing cover crops and green manures. Five soils were mixed with five legume residues commonly used as green manure. The soil was packed in a leaching tube and leached every two weeks with calcium chloride solution and incubated for a total of sixteen weeks. Leachate was analyzed for ammonium, nitrate, and nitrite-N. 3) Completed the second year of a field experiment studying the effect of application of biochar on the N requirement, grain yield, and N recovery of corn. A field study was conducted in 2007 and 2008 to measure the effects of biochar on crop production. Biochar was applied at rates of 0, 4.5 and 18 Mg/ha. Nitrogen rates of 0, 56, 112, and 224 kg/ha as urea were applied on top of the biochar plots. The crop was continuous corn. Dissemination: Results of studies were published in scientific journals, published in extension publications, presented at the American Society of Agronomy annual meetings, presented at soil fertility and bioenergy conferences, and included in conference proceedings. PARTICIPANTS: Participants: J.E. Sawyer, principal investigator; D.W. Barker, assistant scientist; J.A. Hawkins, graduate research assistant; J.P. Lundvall, extension program specialist; D.A. Ruiz Diaz, postdoctoral assistant; R. Killorn, principal investigator; R. Unger, graduate research assistant; M.A. Tabatabai, principal investigator; and L.N. Nakhone, Fulbright Fellow. Collaborators: C.A.M. Laboski, Univ. of Wisconsin; D.T. Walters, Univ. of Nebraska; L.G. Bundy, Univ.of Wisconsin; R.G. Hoeft, Univ. of Illinois; G.W. Randall, Univ. of Minnesota; T.W. Andraski, Univ. of Wisconsin; L. Hendrickson, John Deere Company; and G. Ostermeier, John Deere Company. TARGET AUDIENCES: Activities are designed to provide research based information for scientists and other researchers working in this topic area, for the North Central Region Experiment Station Directors NC-1032 committee, for bio-energy industry personnel, and for agribusiness and certified crop advisers providing recommendations to crop producers regarding N management, bioenergy by-product management, and soil testing. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
1) Field correlation/calibration of the amino-sugar based N test on Iowa soils indicated an inability of the test to predict corn responsiveness to applied fertilizer N, soil supply of crop-available N, or economic optimum N fertilization rate. The test was found to be extracting a constant fraction of total soil N rather than the specific amino-sugar N fraction. The test was found to not be of use in Iowa cropping systems to aid in N rate management. Corn N stress sensing was calibrated to N rate deviation from economic optimum N rate in Iowa corn production systems. Monitoring the plant N stress is a viable option to aid in determination of available soil N supply, in-season N fertilization need, and application rate adjustment. These results provide crop producers and crop advisers in Iowa an understanding of the soils ability to supply crop-available N, the soil N mineralization potetial, determine corn N stress with sensing tools, and adjust post-sensing N fertilization based on N stress sensing. This information will alleviate the potential for misapplication of N fertilizer based on use of N stress sensing, provides for understanding of N rates for optimal profitibality, and reduces the potential for nitrate reaching water systems. 2) The results indicated new fundamental findings that explain N mineralization from legume green manure crops. Analyses showed that net cumulative amounts of N mineralized from individual legume residues was correlated with the total polyphenols and polyphenol:N ratios. Analysis of the pooled data showed that net cumulative amounts of N mineralized and percentage N mineralized were correlated with C:N ratios of the residues and that net cumulative N mineralized was correlated with (lignin + polyphenols):N ratios, and with lignin contents. Mineralization of N in legumes used for green manure varies significantly among leguminous crops. This is related to the chemical composition of carbon and N in the plant materials. Nitrogen mineralization of leguminous crops in soils should be compared from the added organic N and not on a weight of residue basis. 3) These results are new fundamental scientific findings and will help guide potential use of char for carbon sequestration and N availability to crops. Corn grain yield increased from 4.5 to 5.9 Mg/ha in 2007 and from 4.9 to 11.5 Mg/ha in 2008 due to addition of N fertilizer. Application of biochar had no measurable effect on grain yield in either year.
Publications
- Hawkins, J.A., Sawyer, J.E., Barker, D.W., and Lundvall, J.P. 2007. Using relative chlorophyll meter values to determine nitrogen application rates for corn. Agron. J. 99:1034-1040.
- Hendrickson, L., Ostermeier, G., and Sawyer, J. 2007. Use of aerial imagery in making effective nitrogen recommendations. In Annual Meetings Abstract CD-ROM, ASA, Madison, WI.
- Barker, D.W. and Sawyer, J.E. 2007. Evaluation of crop canopy sensors for in-season N rate management in corn. In Annual Meetings Abstract CD-ROM, ASA, Madison, WI.
- Laboski, C.A.M., Sawyer, J.E., Walters, D.T., Bundy, L.G., Hoeft, R.G., Randall, G.W., and Andraski, T.W. 2008. Evaluation of the Illinois soil nitrogen test in the north central region of the United States. Agron. J. 100:1070-1076.
- Nakhone, L.N. and Tabatabai, M.A. 2008. Nitrogen mineralization of leguminous crops in soils. J. Plant Nutr. Soil Sci. 171:231-241.
- Ruiz Diaz, D.A., Hawkins, J.A., Sawyer, J.E., and Lundvall, J.P. 2008. Evaluation of in-season nitrogen management strategies for corn production. Agron. J. 100:1711-1719.
- Sawyer, J.E., Lundvall, J.P., and Hawkins, J.A. 2007. In-season nitrogen management for corn production. p. 38-45. In Proc. Thirty-Seventh North Central Extension-Industry Soil Fertility Conf., Des Moines, IA. 14-15 Nov. 2007. Vol. 23. International Plant Nutrient Inst., Brookings, SD.
- Unger, R. and Killorn, R. 2008. Bio-char and nitrogen effects on corn grain yield. Agron. Abstracts. Amer. Soc. Agron. Madison, WI.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: 1) Multiple N rate trials were conducted to measure corn response to applied N and to provide correlation/calibration of the amino-sugar N test. Field correlation/calibration on Iowa soils indicated an inability of the test to predict corn responsiveness to applied fertilizer N, soil supply of crop-available N, or economic optimum N fertilization rate. The test was designed as a simple and routine laboratory test that would provide information on the mineralization potential of a specific soil organic matter form, amino-sugars, and exchangeable ammonium-N that were suspected to be related to soil supply of crop-available N. However, the test was found to be extracting a constant fraction of total soil N rather than the specific amino-sugar N fraction. 2) The effect of addition of urea fertilizer and char created by pyrolysis of corn stalks was studied by incubating char created by fast pyrolysis, pyrolysis with 10% atmosphere, and pyrolysis with 25% atmosphere with two Iowa
soils for 8 weeks. Samples were collected weekly and analyzed for total C, total N, extractable P and K, pH, NO3-N and NH4-N. Dissemination: Results of studies were published in scientific journals, presented at the American Society of Agronomy annual meetings, and presented in conference proceedings.
PARTICIPANTS: J.E. Sawyer, principal investigator; D.W. Barker, assistant scientist; M.M. Al-Kaisi, co-investigator; J.P. Lundvall, extension program specialist; R. Killorn, principal investigator; R. Unger, graduate research assistant; M.A. Tabatabai, principal investigator; D.E. Dodor, graduate research assistant.
TARGET AUDIENCES: Activities are designed to provide research based information for scientists and other researchers working in this topic area, for the North Central Region Experiment Station Directors NC-1032 committee, and for agribusiness and certified crop advisers providing recommendations to crop producers regarding nitrogen management and soil testing.
Impacts
1) These results provide crop producers and crop advisers in Iowa an understanding of the soil N supply for crop production, corn response to applied N, and economic optimum N fertilization rate. Results also provide information on the lack of specificity in the amino-sugar N test to determine mineralization of soil organic N, supply of crop-available N, or help with adjustment in corn N fertilization rate. This information will alleviate the potential for misapplication of N fertilizer based on use of the test, provides for understanding of N rates for optimal profitibality, and reduces the potential for nitrate reaching water systems. Based on these results, the amino-sugar N test is not recommended for use on Iowa soils to predict soil N mineralization or adjust N fertilization rates for corn production. 2) These results are new fundamental scientific findings and will help guide potential use of char for carbon sequestration and N availability to crops. The
different chars significantly affected the total N, total carbon, and pH in both soils at all rates of urea applied. The total N in char 1 treatment increased over time. The total N in char 2 and 3 treatments decreased at the second week of sampling and increased thereafter. During the study, the amount of total carbon decreased in chars 1 and 2, but remained steady in char 3, which had the lowest total carbon when the study began. The pH of the char and soil mixtures decreased over time. The conditions during pyrolysis, with respect to air, influence how the char reacts with the soil.
Publications
- Killorn, R. 2006. Environmental implications of corn stover utilization. In Proceedings of the 1st annual mtg. of the Green Crop Network. Dec. 4-5. McGill University, Montreal, Quebec, Canada.
- Unger, R. and Killorn, R. 2007. The effects of corn char on two different soils. Agron. Abstracts. ASA, Madison, WI.
- Dodor, D.E. and Tabatabai, M.A. 2007. Arylamidase activity as an index of nitrogen mineralization in soils. Communications in Soil Science and Plant Analysis 38:2197-2207.
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Progress 01/01/06 to 12/31/06
Outputs
Multiple N rate trials were conducted to measure corn response to applied N and to provide correlation/calibration of the amino-sugar N test. Field correlation/calibration on Iowa soils indicated an inability of the test to predict corn responsiveness to applied fertilizer N, soil supply of crop-available N, or economic optimum N fertilization rate. The test was designed as a simple and routine laboratory test that would provide information on the mineralization potential of a specific soil organic matter form, amino-sugars, and exchangeable ammonium-N that were suspected to be related to soil supply of crop-available N. However, the test was found to be extracting a constant fraction of total soil N rather than the specific amino-sugar N fraction. Based on these results, the test is not recommended for use on Iowa soils to predict soil N mineralization or adjust N fertilization rates for corn production.
Impacts
These results provide crop producers and crop advisers in Iowa an understanding of the soil N supply for crop production, corn response to applied N, and economic optimum N fertilization rate. Results also provide information on the lack of specificity in the amino-sugar N test to determine mineralization of soil organic N, supply of crop-available N, or help with adjustment in corn N fertilization rate. This information will alleviate the potential for misapplication of N fertilizer based on use of the test, provides for understanding of N rates for optimal profitability, and reduces the potential for nitrate reaching water systems.
Publications
- Barker, D.W., Sawyer, J.E and Al-Kaisi, M.M. 2006. Assessment of the amino sugar-nitrogen test on Iowa soils: I. Evaluation of soil sampling and corn management practices. Agron. J. 98:1345-1351.
- Barker, D.W., Sawyer, J.E., Al-Kaisi, M.M. and Lundvall, J.P. 2006. Assessment of the amino sugar-nitrogen test on Iowa soils: II. Field correlation and calibration. Agron. J. 98:1352-1358.
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