Agriculture Reference
In-Depth Information
C
H
O
Rainfall
H
2
O
Rainfall
H
2
O
Rainfall
H
2
O
Macronutrients
PK
Mg
N
Ca
S
Micronutrients
Zn
Mn
Cu
Mo
Fe
B
Cl
Ni
FIGURE 3.1
(
See color insert.
) Essential nutrients for plant growth and development. (Adapted from
Fageria, N. K. 1989b.
Tropical Soils and Physiological Aspects of Crops
. EMBRAPA: Brasilia, Brazil.)
man, animals, and many species of microorganism, which additionally need organic foodstuffs to
provide energy (Mengel et al., 2001).
Among essential nutrients, N is the most yield limiting in crop production around the world. The
deficiency of N in crop production is widely reported in the literature (Marschner, 1995; Fageria
et al., 2001; Brady and Weil, 2002; Fageria and Baligar, 2005b; Fageria, 2009, 2013). More research
has been done with N than any other mineral nutrient, because the world's ecosystems are probably
influenced more by deficiency or excess of N than by those of any other essential element (Brady and
Weil, 2002). However, still there is a gap of information for the best management of N in the sustain-
able cropping systems. Hence, more information is required to know the quantity of N required to
increase its availability in the soil to achieve crop yields to a designated level in different cropping
systems. The objective of this chapter is to discuss diagnostic techniques for nitrogen requirements
in crop plants. This information will be helpful in identifying nitrogen disorder in crop plants and
consequently in improving the management of nitrogen fertilization for maximizing crop yields.
3.2 NITROGEN DEFICIENCY, SUFFICIENCY, AND TOXICITY DIAGNOSTIC
TECHNIQUES
Diagnostic techniques for nutrient disorders, including N, refer to the methods for identifying nutri-
ent deficiencies, toxicities, or imbalances in the soil-plant system (Fageria and Baligar, 2005a).
Nutritional deficiency can occur when there is insufficient nutrient in the medium or when it cannot
be absorbed and utilized by plants as the result of unfavorable environmental conditions. Nutritional
deficiencies are very common in almost all field crops worldwide. The magnitude varies from crop
to crop and from region to region. Even some cultivars are more susceptible to nutritional deficien-
cies than others within a crop species.
