Jianrong Fu, Ho Ando and Ken-ichi Kakuda
Bulletin of the Yamagata University (Agricultural Science)
13-2, 173-180 (1999)
Summary
The beneficial effect of Si element
on the growth of rice plant had been confirmed by many researchers. However,
the information on the relationship between Si fertilizer application and
the availability of soil N was not available. Two paddy soils: 1) from
Yamagata Agricultural Experiment Station Shonai Branch Farm (Soil A) and
2) from famer's field in Tsuruoka, north-east Japan (Soil B), were collected
and mixed with different sources of Si fertilizer (Calcium silicate and
Silicic acid), and were incubated under completely closed condition, 15-N
labeled ammonium sulfate was added to evaluate the fate of N applied with
respect to Si application. From 0 to 1 week after incubation, Calcium silicate
application increased the soil pH by 0.2 - 0.3 unit as compared to no Si
application. Total accumulation of NH4-N was increased by 20%, 26% in soil
A and 9%, 11% in soil B, and the net rate of N mineralization was increased
by 26% , 35% in soil A and 13%, 13% in soil B by addition of Calcium silicate
at the rate of 1 and 2 g/kg, respectively. The difference in soil pH and
N mineralization among treatments was more significant at the first week
than at the 4th week after incubation. Silicic acid had no effect on soil
pH, ammonium accumulation and the rate of N mineralization. Data suggested
that Calcium silicate fertilizer accelerate the N mineralization not by
Si element but through its effect on soil pH.