Essential nutrients must be available at critical times to ensure necessary hormone activation during plant growth.
A plant with correctly activated hormones will withstand extreme climatic conditions better. Also, this will aid in recovery from frost, pollination maintenance, help with stronger root development, survival in salty conditions and to the improvement of fruiting quality.
Typical hormone activity would include Gibberellic acid, Indole Acid, Ethylene, Cytokinin, and Abscissic Acid.
Plant’s (in general) demand for essential nutrients to facilitate growth balance can be summarised as follows:
- Germination and plant establishment Ca, Fe, Mg, Mn, N, P, Zn
- Vegetative growth B, Ca, Cu, Fe, K, Mg, Mn, Zn, Amine N
- Flowering and reproduction B, Ca, Cu, K, Mg, Mo, Amine N
- Fruit sizing and maturity B, Cu, K, Mg, Mn, Mo, P, Amine N
Although fertiliser coatings can provide a method to ensure a more complete nutrient level is available in granular fertiliser, it must be understood that soil pH, climatic influence, soil structure and specific crop types may need additional corrective measures later in the cycle of the crop’s growth.
Equally important and yet sometimes overlooked is the importance of seed and fertiliser placement in a manner to reduced nutrient loss and that added nutrients to the fertiliser are plant available.
A further consideration and a relatively new concept is the analysis of seed nutrient content as seed development runs to a time line critical to completing its design cycle. Analysis of seed grain can also determine the post-harvest nutrient status of its paddock source while the seed critical nutrient levels are able to give emerging plants a good start.
Proximity of the seed in the root zone improves the chance of early nutrient interception and efficiency. This is particularly applicable in systems of reduced tillage. Much of this understanding is revolved around solubility and mobility of nutrients and the use of low salt index fertilisers which if high would impact on a poor germination and delayed emergence. Coating fertilisers in this case would be a typical management tool essentially to reduce rapid conversion to ammonia.
Nutrient stewardship can therefore be summed up as to continually adapt practices in applying the right nutrient source, at the right rate, right time and place.