Agriculture Reference
In-Depth Information
Silicon Effect on Soil
The application of Si soil amendment has positive effect on the chemical and physical
properties of cultivated soil. Most investigations of Si soil amendments or Si fertilizers on soil
properties concern their interaction with phosphates (Matichenkov, 2008; Matichenkov and
Ammosova, 1996).
The thermodynamic calculations showed that the reaction of displacing phosphate-anion
by silicate-anion from slightly soluble phosphates and formation of the corresponding
silicates is possible (Matichenkov and Ammosova, 1996). The model and field experiments
have completely confirmed this suggestion (O'Relly and Sims, 1995).
CaHPO
4
+ Si(OH)
4
= CaSiO
3
+ H
2
O + H
3
PO
4
2Al(H
2
PO
4
)
3
+ 2Si(OH)
4
+ 5H
+
= Al
2
Si
2
O
5
+ 5H
3
PO
4
+ 5H
2
O
2FePO
4
+ Si(OH)
4
+ 2H
+
= Fe
2
SiO
4
+ 2H
3
PO
4
Our laboratory and field tests conducted in various countries have demonstrated that the
application of Si fertilizer positively effects soil plant-available P and makes possible to
reduce the traditional P fertilizer rates by 25-50% (Table 2; Matichenkov, 2008; Matichenkov
and Bocharnikova, 2001; Matichenkov et al., 2011).
On the other hand, Si fertilizers or Si soil amendments usually possess good adsorption
capacity. Field demonstrations on sandy soils (deep sandy Entisol) in Florida have shown that
the application of Si soil amendment provided the reduction in P leaching by 200-300% and
keeping P in plant-available forms (Figure 5; Chimney et al., 2007). The leaching of N, K,
and organic matter by Si was reduced as well (Matichenkov, 2008).
Table 2. Effect of Si fertilization on plant-available P in soil (Matichenkov, 2007).
Soil and location Plant-available P (0.1 n HCl-extracted),
mg kg
-1
Before Si application After Si application
Soddy Podzolic Soil, Moscow region, Russia 37.9±2.7 59.6±1.5
Chestnut Soil, South Russia 28.2±1.4 42.4±3.5
Mullisoil, South Russia 11.0±0.6 14.6±0.6
Alluvial Soil, Jordan River valley 63.8±3.5 104.8±6.8
Grey Soil, Tajikistan 16.2±1.1 36.6±2.5
Calcareous Soil, Andalusia, Spain 15.3±1.0 46.0±3.1
Spodosol, Florida, USA 123±13 142±12.5
Histosol, Florida, USA 13.2±0.3 23.9±1.4
Active Si applied to soil initiates the formation of the secondary clay minerals, which results in
increased soil water-holding capacity, exchange capacity and improved soil texture (Table 3;
Matichenkov et al., 1994).
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