Agriculture Reference
In-Depth Information
Upland rice
300 mg N kg
-1
0 mg N kg
-1
BRA 02601
FIGURE 3.16
Root growth of upland rice genotype BRA 02601 at low and high N levels. Half of the N was
applied at sowing and the remaining half at the active tillering growth stage.
N ha
−1
were shown to reduce canola and durum wheat seedling emergence (Malhi et al., 2003).
McKenzie et al. (2006, 2007) reported a substantial reduction in the winter wheat stand and in mus-
tard at rates as low as 30 kg N ha
−1
. Figures 3.22 through 3.25 show N toxicity in dry bean, upland
rice, corn, and wheat. Toxicity in all the crops was observed (reductions in growth) at 400 mg N
kg
−1
, except corn. In corn, N toxicity was observed at 600 mg N kg
−1
. Toxicity symptoms in all the
crops were observed in lower or older leaves in the beginning.
3.3 SOIL TEST
Soil testing is the most common criterion to determine the nutrient and lime requirements of crop
plants. In modern agriculture, soil testing is considered as an indispensable tool essential for the
assessment of the fertility status of soils. A good soil testing program is essential to sound fertilizer
Upland rice
0 mg N kg
-1
300 mg N kg
-1
BRA 032048
FIGURE 3.17
Root growth of upland rice genotype BRA 032048 at low and high N levels. Half of the N was
applied at sowing and the remaining half at the active tillering growth stage.
