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ARS Home » Research » Publications at this Location » Publication #69896
Title: WATER, NITROGEN AND WEED STRESS ON CORN (ZEA MAYS L.): SHOOT GROWTH AND DEVELOPMENT

Author
item EPHRATH, J - J BLAUSTEIN INST, ISRAEL
item ALM, D - J BLAUSTEIN INST, ISRAEL
item Hesketh, John
item Huck, Morris

Submitted to: Biotronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Nitrogen fertilization of crops must be more finely tuned in the future to minimize pollution of surface runoff of ground water. N-levels in ground water have exceeded recommended levels for drinking by small children with increasing frequency in recent years. We explored possibilities for using the nitrogen content of corn leaves as an indicator of whether additional N-fertilizer applied as a side-dressing during the growing season might be useful for increasing grain yield and quality, or whether the additional fertilizer would simply be stored in vegetative tissue and subsequently be lost to the environment. We found small differences did exist in leaf N content but these differences in leaf N content became smaller as the crop was stressed for water. This study indicates that crops used by corn producers to help decide on fertilizer application amounts would benefit by including information on leaf N content. This modification would help reduce N runoff into drinking water supplies without reducing corn yields.

Technical Abstract: Nitrogen (N) balances of soil-crop systems must be monitored more closely in the future to minimize ground water pollution. Maize was grown in rain-sheltered plots on a Flanagan slit-loam soil under three moisture regimes: Wet (W, weekly irrigations equal to water lot by a standard evaporation pan); Limited irrigation (L or 1/2 W) and Dryland (D, no irrigation). For each soil moisture regime, supplemental nitrogen (NH4NO3) was applied at 0, 125, and 250 kg N ha**-1. Seedlings of common lambs quarter were transplanted 0.15 m apart into the maize rows in sub-plots of each soil moisture regime at the medium N level or 124 kg N ha**-1. Soil moisture profiles were measured twice weekly, leaf stress was monitored with a leaf pressure bomb and root growth was followed at weekly intervals using minirhizotron tubes. Generally yield correlated well with either leaf water potential or N per plant. Higher N or water applications led to less negative leaf water potential values, one stress substituting for the other in controlling crop stress or yield. Leaf percent N as an indicator for yield was compromised by small differences among treatments within sampling dates and the N x leaf water potential interaction; leaf water potential as an indicator for when to irrigate was not compromised.