Gustavo Martins
Omono
I've been doing some reading I see many people using different NPK ratios depending on the season/tree state, etc... For instance, some say feed a high N during growing season and replace by a low N (e.g. NPK = 0-10-10) later in the season (for growing trees). Mature trees may receive a low N most of the time I suppose to control growth.
The way a see things, all this seems a bit... strange.
1. Liebig's Law of the minimum:
The Law states that the nutrient in least supply relative to the plant’s requirement will limit the plant’s growth. Although this may not be true in a strict sense as plants do have some ways to compensate, it sure does have an effect (Agren et al. 2012). As such, using a i.e. 0-10-10 will mean that no PK will be used as the plant is limited by N. So this goes against the use of specific ratios.
2. In the planted tank community, many (including myself) stand by a method called Estimative Index. This index is a simple way to make sure that all the nutrients are supplied at a level that is above the requirements of plants and thus they are never the limiting factor. To control the build up of nutrients, at least 50% of the water of the tank should be replaced every week. In bonsai, where many people use free-draining inorganic substratum, nutrient build-up should not be a problem so I suppose one could also use the same rationale of supplying every little nutrient by excess.
3. Plants need three things (other than water) to grow: Light, CO2 and nutrients. Light is by far the most important followed close by CO2. Nutrients are the least important for sure. CO2 in the atmosphere is not limiting and it is difficult to control (unlike in planted tanks where one needs to inject CO2 because it is limiting in water). However, light can be controlled (careful selection of position, using sun-cloth, etc.). So why is it that people use nutrients to limit the growth of, say, mature bonsai when this is the least important and limiting of the three (light, CO2, nutrients). It should be much mor effective to control the light (e.g. either intensity or duration).
I'd like to hear your thoughts on these
References:
A ̊gren GI, Wetterstedt JAM, Billberger MFK (2002)Nutrient limitation on terrestrial plant growth – modeling the interaction between nitrogen and phosphorus. New Phytologist 194:953-960.
The way a see things, all this seems a bit... strange.
1. Liebig's Law of the minimum:
The Law states that the nutrient in least supply relative to the plant’s requirement will limit the plant’s growth. Although this may not be true in a strict sense as plants do have some ways to compensate, it sure does have an effect (Agren et al. 2012). As such, using a i.e. 0-10-10 will mean that no PK will be used as the plant is limited by N. So this goes against the use of specific ratios.
2. In the planted tank community, many (including myself) stand by a method called Estimative Index. This index is a simple way to make sure that all the nutrients are supplied at a level that is above the requirements of plants and thus they are never the limiting factor. To control the build up of nutrients, at least 50% of the water of the tank should be replaced every week. In bonsai, where many people use free-draining inorganic substratum, nutrient build-up should not be a problem so I suppose one could also use the same rationale of supplying every little nutrient by excess.
3. Plants need three things (other than water) to grow: Light, CO2 and nutrients. Light is by far the most important followed close by CO2. Nutrients are the least important for sure. CO2 in the atmosphere is not limiting and it is difficult to control (unlike in planted tanks where one needs to inject CO2 because it is limiting in water). However, light can be controlled (careful selection of position, using sun-cloth, etc.). So why is it that people use nutrients to limit the growth of, say, mature bonsai when this is the least important and limiting of the three (light, CO2, nutrients). It should be much mor effective to control the light (e.g. either intensity or duration).
I'd like to hear your thoughts on these
References:
A ̊gren GI, Wetterstedt JAM, Billberger MFK (2002)Nutrient limitation on terrestrial plant growth – modeling the interaction between nitrogen and phosphorus. New Phytologist 194:953-960.