Brief Summary of Minutes of Annual Meeting

Activities of the annual meeting primarily concerned committee business, a review of contributions of individual states to overall committee objectives, and development of publication meant for practitioners and cooperative extension for the dissemination of best management practices to increase fertilizer nitrogen use efficiency, brainstorming ideas for the next project and plans for the coming year. Committee Business: P. Scharf was elected member-at-large. Committee leadership for 2005-2006 is C. Laboski  chair, D. Olk  secretary, and W. Horwath  past chair. L. Bundy announced that C. Laboski would become Wisconsins official representative to the committee. The next annual meeting will be March 8 and 9, 2006 in Kansas City. The date is subject to change depending on when the NC ASA meeting is next March. W. Horwath will arrange a meeting at the SSSA annual meeting in Salt Lake City for the committee to finalize its proposal for the next project. Committee leadership for the 2006 meeting is: Carrie Laboski Chair Dan Olk Secretary Peter Scharf Member-at-Large William Horwath Past Chair Report of Meeting Activities and Plans for Next Year: Gary Lemme presented the administrative report. Members of the committee reviewed efforts to write draft manuscripts of data collected from the previous NC218 project and current projects. These papers tentatively plan to focus on the following topics: 1. Methods and characterization of data collected during last project including crop response and field histories. 2. Potential N mineralization quick test and their relationship to thermal units. 3. Plant sensing of N status. 4. Relationship of soil mineralizable C to mineralizable N. 5. Using testing techniques to predict soil N mineralization and develop fertilizer recommendations. D. Walters presented a new maize growth model. Initial results of model simulations suggest that planting date is critical to avoid high night temperatures during the latter part of the growing season. Discussion of the protocols to be used for the new project ensued. Each state reported on their plans to conduct field experiments according to the protocol developed for NC218 studies in the previous year. There was general agreement to study the basic N mechanisms/chemistry along with looking at growing season-long dynamics. W. Horwath stated there was a need to combine techniques to show functional components such that results from an incubation type study would not be dependent on substrate/environment of the study. A tentative objective was defined as: Characterize the chemical composition of the mineralizable fraction of soil N. Sub-objectives include: 1) characterizing inter-annual variability of N mineralization as impacted by soil and crop management; and 2) estimate the turnover time of N and C in the mineralizable (or gross) pools. A potential title might be: Defining soil N fractions that contribute to N availability. Potential outputs from the project could be: 1) expand current projects outreach publication to a national scope. It was discussed to write a base proposal of research activities and then propose additional activities pending funding from a NRI/NSF grant.

Results on the Illinois Soil Nitrogen Test (ISNT), based on estimating amino sugar nitrogen (AS-N) content was presented for the third year from ongoing NC-218 research projects. As from the previous years results, this years result continue to question the value of the ISNT as a predictor of in season N availability. In a positive note, the ISNT continues to show a strong correlation with total soil organic matter (SOM) suggesting that total SOM or some fraction of SOM may be useful in developing a modified INST or new method to estimate specific field fertilizer nitrogen recommendations. Temporal variation in ISNT values continued to be inconsistent and show nonsignificant relationships to fertilizer nitrogen applications at both nonresponsive and responsive sites at all sites being examined by NC-218 investigators. The ability of the INST to predict economic response of corn to N fertilizer continued to be a major issue discussed. The NC-218 members are of the opinion that the test in its current state will not be useful as a predictive tool to address issues over application of fertilizer nitrogen. Results showing the relationship of the enzyme B-glucosaminidase (NAGase) activity to N mineralization continued to show a strong relationship. Studies on the effect of tillage systems and residue management continued to show the strong relationship between NAGase and N mineralization. The results prompted discussion by the group to hypothesize that the determination of specific fractions of soil organic matter may be useful to predict N mineralization. Analysis of the NC-218 mineralization test data set continued on a 72 site-year database evaluating the effectiveness of a suite of mineralization quick tests in estimating potentially mineralizable N (PMN) as determined by long-term aerobic incubation. Variation in extractable N and PMN was analyzed in relation to previous crop and site manure history. C mineralization showed a strong influence on N mineralization. These results confirm the notion that a specific fraction of SOM is controlling N mineralization. Results from three N response experiments showed that the PSNT had greater potential for predicting optimum N rates for corn than the ISNT. Results with archived samples from numerous N response experiments showed that the INST is not capable of predicting corn N requirements. The INST appears to measure a constant fraction of the N in soil organic matter rather than reflecting the amounts of readily mineralizable N in soils.

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