Discover the importance of combining silica and calcium.
© Copyright in this work is owned by Guano Australia Pty Ltd. All rights reserved.
When farmers think of guano products, they focus tends to be on guano as a phosphorus [P] source. Then the second question of how available is it and, what form is this phosphorus? With seabird guanos the phosphorus has a higher citric soluble phosphorus rate than non-seabird guanos that are higher in non-citric soluble phosphorus. However, when looking at Seabird guanos we need to look beyond the P % and focus a little on the calcium [Ca] and the silica [Si] and how these elements work together and interact.
By weight, calcium and silica in a good quality Guano Gold® make up over 50% of the product. Adding the calcium percentage to the silica percentage is a good test of how well the Guano Gold® you are going to buy is going to perform.
Generally, if the silica level is low then the phosphorus available, in terms of citric verses non-citric soluble, will be low. So, what are the benefits of calcium and silica? Rather than look at each element, let’s look at how they interact.
JIAN FENG MA and EIICHI TAKAHASHI from the Kyoto University in Japan used soft X-ray irradiation for detection of Silica bodies, they tested shoot and leaf from plants treated with high calcium and low silica, low calcium high silica and then equal amounts of calcium and silica.
The theory behind the testing was to show that the plant would use silica as a preference in physical structural development instead of calcium. The results showed that even if calcium levels where applied in field trails at 6.5 times the level of silica, silica was still significantly present in the flag leaves of cereals.
It concluded that increased silica resulted in reduced calcium in the shoots and developing leaves. It could be drawn from this that the addition of the silica with the calcium leaves more calcium available for metabolic functions in the plant as the silica forms silica bodies in the leaf blades.
The movement of calcium in the plant is relative to transpiration rate, increase transpiration (movement of water) slows down calcium movement. Calcium is required by the plant in fruit and grain set.
If transpiration is affected by excessive evapotranspiration (elevated temperature and water stress) then less calcium is available to increase both yield and fruit or seed quality. It logically follows that increased available silica reduces the distance calcium needs to move in the plant (long flow) and also silica due to its placement and structure reduces evapotranspiration (drought tolerance).
JIAN FENG MA and EIICHI TAKAHASHI commented that “This might mainly result from a decreased transpiration rate caused by increased Si.” Secondly it was shown that “Silica uptake was not affected when the Ca levels were increased” this indicates that by having adequate levels of both silica and calcium will result in increased silica structure in the plant and more available calcium in the plant.
So to conclude in simple terms, silica and calcium used together, such as is available in seabird Guano Gold®, increase the plants silica structure and increases tolerance to biotic and abiotic stresses but doesn’t effect available calcium, however enhances the flow and movement of calcium at critical times such as seed or fruit set.
Article 4 of 12 Written by;
Robert Drewitt | BcSc(Ag) | Agronomist
Agronomy Services Australasia Pty Ltd