Abstract
Rates ofN uptake by wheat (Triticum aestivum L., cv. Mexi-Pak-65) from NHS and NOf forms applied as ammonium nitrate selectively labelled with 1SN were measured in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. Both NHS and NOf forms of inorganic N were absorbed by wheat, but NOf uptake was dominant. The wheat crop used 37.7% and 54.0% oflsNH4+, 46.0% and 62.7% of "NOf, applied as ammonium nitrate at seeding time and tillering stage, respectively. Thus the uptake of labelled N showed that NOf -N was more available form of N for wheat than NOt -N. However, the effective use of fertilizer N (ratio of labelled N in grain to labelled N in whole plant) was statistically similar for the two forms ofN. The application of fertilizer N increased the uptake ofunlabelled soil N by wheat crop, a result attributed to a positive added N interaction, which varied with the time of applying fertilizer N; the dose applied at seeding caused greater added N interaction than that applied at tillering stage. Both NHS and NOf caused statistically similar added N interaction at the respective time of fertilizer N application. The A values varied with the form of N and the time of applying the fertilizer N. As the root biomass increased substantially in response to fertilizer N application and there was a significant positive correlation between added N interaction and A values (r-=0.960*), the observed added N interaction in the present study was considered to be re
A. Hamid , M. Ahmad1 . (1996) RELATIVE SIGNIFICANCE OF NH4+ AND NO3 FOR WHEAT (TRITICUM AESTIVUML.) GROWING IN FIELD FERTILIZED WITH AMMONIUM NITRATE SELECTIVELY LABELLED WITH ,5N, The Journal Soil & Environment , Volume 12, Issue (3-4).
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