loss) or 4 replicates standard error of the mean. Plant N uptake is the sum of N in
roots, straw, and grain at harvest.
Mass balance (harvest)
(% of applied N)
Water management
CF AWD
A. NH3 volatilization 20.8 1.8 12.9 2.4
B. N2 emission 0.4 0.1* 2.5 0.3*
C. Plant N uptake 53.9 4.8 58.4 3.7
D. Soil N accumulationa
0e15 cm depth 10.1 0.7 11.9 0.9
15e30 cm depth 4.8 0.3 5.3 0.5
30e50 cm depth 4.7 0.3 5.2 1.1
E. Unaccounted forb 5.3 3.1 3.8 3.3
* denotes significant difference between CF and AWD (p 0.01, unpaired t-test).
a denotes total fertilizer-derived N in different soil horizons at harvest.
b denotes nitrogen not accounted for.
Table 3
Crop production indices of rice at harvest. Roots were sampled to 15 cm depth. The
results are means of 4 replicates standard error of the mean.
Crop production indexes (harvest) Water management
CF AWD
Yield (kg dry matter m2)
- Root biomass 0.55 0.01* 1.44 0.31*
- Straw biomass 0.66 0.01 0.62 0.03
- Grain yield 0.60 0.04 0.57 0.03
Harvest index (HI) 0.47 0.01 0.48 0.01
N harvest index (NHI)
- Total N 0.36 0.04 0.28 0.05
- Fertilizer15N 0.45 0.02 0.44 0.02
* denotes significant difference between CF and AWD (p 0.05, unpaired t-test). HI:
proportion of grain to aboveground biomass (dry matter weight), NHI: ratio of N
content in grain to total N content in plant