The mobility and transformation of soil nitrogen and the relationships between soil and plant nitrogen and yield at different times following application of various nitrogen fertilizers to sweet corn [maize]
1992
Salardini, A.A. | Holloway, R.J. (Tasmanian Dept. of Primary Industry, Devonport (Australia). Vegetables and Allied Crops Branch) | Sparrow, L.A. (Tasmanian Dept. of Primary Industry,. Kings Meadows (Australia). Land Management and Chemistry Branch)
The concentration of NH4-N, NO3-N and their sum (mineral N) were monitored 12 times in 1 or 2 weekly intervals in the soil under a sweet corn crop. Under the low rainfall and optimized irrigation of this trial the concentration of mineral N in soil to the depth of 400 mm or more was a good predictor of yield response to application of N at 10 of the 12 sampling times. The concentration of mineral N in the top 200 mm of soil 1 or 2 weeks after top-dressing of N was highly correlated to yield. The concentration of sap NO3-N and midrib NO3-N decreased continuously until harvest. Both these concentrations were significantly correlated with the rates of basal and top-dressed N in most sampling times. These were also strongly correlated to yield 1 or 2 weeks after N top-dressing. Ammonium sulfate, ammonium nitrate and urea gave similar responses in sap NO3-N and midrib NO3-N and in soil nitrogen after 5 weeks when nitrification of fertilizer NH4-N was complete. These observations indicated that soil mineral N, sap NO3-N and midrib NO3-N all offer potential as techniques to predict the yield response of sweet corn to N application. The sap NO3-N test was simpler, quicker, cheaper and more consistent than other tests.
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