J. Amir et al., LONG-TERM COMPARATIVE-STUDY OF SOIL NITRATE TEST, GILAT PLANT INDICATOR METHOD AND WHEAT NITROGEN UPTAKE, Plant and soil, 158(2), 1994, pp. 223-231
A long-term comparison between two routine soil nitrogen tests, soil n
itrate versus plant indicator method, was performed on the Negev Deser
t loessial soil in Israel. The Gilat plant indicator method was found
to be a better method to reflect the soil nitrogen availability for wh
eat under field conditions. It was found that 15 to 38 kg ha(-1) of NO
3-N, measured by nitrate soil test, for each 30 cm soil increment, is
not available for plant uptake. This plant unavailable NO3-N backgroun
d in the soil cannot be leached by repeated irrigation cycles of 100 m
m each, or by heavy rains.