Mineral N (nitrate and ammonical form) is highly dynamic, and is generally not measured by most of the researchers, who most of the time take total N or available N in consideration for evaluating the response. Depending upon the net mineralisation (which is complex function of edaphic environment), mineral N becomes available from the available N pool.
If we have to use soil survey data for regional analysis, it becomes difficult to compute the mineral N values, as only info on total N or available N is available. Most of the crop modeller do expert judgement or sensitivity analysis for setting the value of mineral N (layerwise).
Is there any research group working on this aspect, we understand the mineral N will depend on so many factors, including the inputs, management, cropping system, climatic conditions alongwith total (or available N), but to get a near estimate of mineral N is the requirement.
regards
For the reasons you have given I question why one would want to produce regional estimates of mineral N?
No, depends on the soil, the gramulometry, etc. You should measure nitrate, and the ratio total N/nitrate should give a better indication. But the values can change considerable after one cropping, season, etc. Therfore, to evaluate organic matter content will give you a better idea
i agree with you all, since mineral N is not commonly evaluated by agricultural scientists, in literature available N or Total N is there, through SOC also we deduce the vales of avail or total N, but for really relating the response of crop growth and yield, mineral N is imp and moreover it is theinput for most of the models to run, that is why i raised this question.
regards
My advise is to measure the N not in the soil, but in plants during the growing season if our interest is how much can be taken up by plants from the soil. On how to go about is, please see attached.
Article Nitrogen and phosphorus limited production of cereals and se...
thanks Hein for providing this nice article, but to me the question is to provide mineral N at the time of sowing which is required for most of the models
definitely through plant measurements, we can have some idea or develop the transfer function
regards
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