Agriculture Reference
In-Depth Information
by the least significant difference (LSD) and were considered significant
at p ≤ 0.05.
7.3 RESULTS AND DISCUSSION
In all four seasons and across the biofertilizer treatments, grain yield in-
creased with increasing amounts of applied fertilizer (Table 4, Figure 1).
However, this increase was not always statistically significant and the
yield increase varied considerably between seasons. Overall, the lowest
grain yields occurred in the 2009 WS, ranging only from 1.9 to 2.7 t·ha
−1
.
Generally, low yields in that season were due to a typhoon that caused con-
siderable damage through flooding of the experimental field and lodging
of the crop. For this reason, the crop was harvested prematurely by about
1 week, which further reduced attainable yields.
Grain yields in the other three experimental seasons were similar and
ranged from 4.0 to 5.2 t·ha
−1
in the 2009 DS, from 3.4 to 5.1 t·ha
−1
in the
2010 WS, and from 3.8 to 5.6 t·ha
−1
in the 2010/11 DS. These ranges al-
ready indicate a relatively low yield increase due to fertilizer application
in the 2008/09 DS (up to 1.2 t·ha
−1
for the full fertilizer rate of 120-60-60
kg N-P
2
O
5
-K
2
O ha
−1
) and the 2009 WS (up to 0.8 t·ha
−1
for the full fertil-
izer rate of 90-30-30 kg N-P
2
O
5
-K
2
O ha
−1
). A higher response to inorganic
fertilizer was achieved in the 2010 WS (up to 1.7 t·ha
−1
for the full fertil-
izer rate of 90-30-30 kg N-P
2
O
5
-K
2
O ha
−1
) and the 2010/11 DS (up to 1.8
t·ha
−1
for the full fertilizer rate of 120-60-60 kg N-P
2
O
5
-K
2
O ha
−1
).
The effects of biofertilizer treatments on grain yield, depending on the
inorganic fertilizer treatment, are shown in Table 4 and Figure 1. Signifi -
cant yield increases due to biofertilizer use were observed in all experi-
mental seasons with the exception of the 2008/09 DS. In the 2010/11 DS,
no signifi cant difference between the three biofertilizers tested was detect-
ed, but all three achieved better yields than the Control. The biofertilizer
achieving the highest average grain yields across all four inorganic fertil-
izer treatments and in all four seasons was BN. Statistically signifi cant
interactions between biofertilizer treatment and inorganic fertilizer treat-
ment could not be detected in any season (at p ≤ 0.05), suggesting that the
effect of the biofertilizer was independent of the inorganic fertilizer rate.
