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Near‐Infrared Analysis of Cotton Leaves as a Guide for Nitrogen Fertilization
Author(s) -
Saranga Yehoshua,
Landa Ari,
Shekel Yehuda,
Bosak Arie,
Kafkafi Uzi
Publication year - 1998
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1998.00021962009000010004x
Subject(s) - human fertilization , fertilizer , gossypium hirsutum , field trial , agronomy , malvaceae , dry matter , nitrogen , nitrogen fertilizer , fiber crop , yield (engineering) , mathematics , horticulture , chemistry , biology , organic chemistry , materials science , metallurgy
Nitrate level in cotton ( Gossypium hirsutum L.) leaf petioles is commonly used as a practical guide to N fertilization, especially in cases of critically low N levels. The optimization of N supply to irrigated cotton requires a reliable method for monitoring the plant's N status. The feasibility of using leaf N concentrations monitored by near‐infrared analysis (NIRA) as a guide for N fertilization in irrigated cotton was examined in this study. Three field trials were conducted in three consecutive years. The NIRA data from fresh leaf disks were calibrated against laboratory N measurements expressed as g N kg 1−1 dry matter (R 2 = 0.90). Validation of the calibration showed a high correlation between NIRA estimates and laboratory data from two field trials. Dawn leaf sampling was selected for routine monitoring of plant N status. Application of NIRA‐guided N fertilization was examined in the third‐year trial. The NIRA‐guided treatment, with only 60 kg N ha −1 , resulted in only a 7.5% lower yield (statistically nonsignificant) relative to the commercial predetermined N treatment with 150 kg N ha −1 . Yield was linearly correlated with leaf N concentration. Cotton leaf N concentration was reliably monitored by NIRA. Only 30 s are required for each N determination; using 10 samples, about 7 min are needed per plot. Once its reliability under various conditions is established, this method could be used for on‐the‐spot decision‐making regarding N‐fertilizer application in irrigated cotton.