Nutrient management through the different growth stages are crucial for optimal yields. 

Written by Hentie Cilliers and Dr. Chris Schmidt. 

 

Previously, we have focused on the principles and nutrients needed to achieve an optimal start. Although this is an extremely important part of plant development, many physiological processes still need to take place, each with its own unique nutrient requirement. A crop’s nutrient requirement is influenced by the crop type, growth stage, and growth conditions. In this article, we will explore the general principles that influence nutrient requirement/application in the later stage of development and plant nutrient scheduling.

 

When compiling a fertilizer program, you first have to calculate the total nutrient requirement. Often removal figures and yield estimates are used to calculate the total requirement. In addition, you also need to take practices into account that add additional nutrients to the system, as well as factors removing or limiting the availability of the nutrients. Also, keep in mind that requirements can change through the season, depending on how favorable the season is by influencing the estimated yield.

 

 

Fertilization would have been easy if we could apply all the required nutrients at once, and then rely on the plant to absorb the nutrients as needed. Unfortunately, soils have many different properties, for example, clay content, organic matter content, and pH, which all influence the availability of nutrients. It becomes necessary to implement strategies to keep nutrients available to the plant continually. One such strategy is to split fertilizer applications. 

 

As phenological stages change, so does the plants’ nutrient requirement. For example, during vegetative growth, a nutrient such as nitrogen is more important whereas potassium is more important during fruit growth. The same principle is true for all 14 essential mineral nutrients and 5 beneficial nutrients (White et al. 2010). The nutrient ratio that is required per growth stage thus changes. Careful planning is needed to ensure the correct nutrient is available at the correct time.  By linking the total nutrient requirement with the growth stages one can determine the requirement per stage. 

 

Water, temperature, light, and nutrients are the primary factors affecting growth. These four elements affect growth hormones in the plant, consequently affecting the growth speed. Thus, the time that a plant takes to develop to a specific growth stage can vary. It is important to plan fertilizer application according to growth stages and not according to a calendar or days after sowing.  This can cause large misalignments with the actual nutrient requirement. Visibility of your crop's current and upcoming growth stage gives the insight to apply fertilizers at the right moment.

 

 

 

Water, temperature, light, and nutrients are the primary factors affecting growth. These four elements affect growth hormones in the plant, consequently affecting the growth speed. Thus, the time that a plant takes to develop to a specific growth stage can vary. It is important to plan fertilizer application according to growth stages and not according to a calendar or days after sowing.  This can cause large misalignments with the actual nutrient requirement. Visibility of your crop's current and upcoming growth stage gives the insight to apply fertilizers at the right moment.

 

After the calculation of the nutrient requirement and linking it to the growth stages, consider some practical aspects that will influence the fertilizer applications. For example, under dryland conditions, one would like to match the fertilizer applications with a rain event. However, rain events can be erratic and do not always coincide with the correct time that an application needs to be made. Adjusting the timing and type/source of fertilizer would ensure that the nutrients are available at the required time. Plant height and tractor clearance also influence the timing. Under irrigation, it is easier to do multiple applications, depending on the irrigation system.   

 

Knowing the total need, and the requirement per growth stage, identifying the growth stages, and considering factors that influence the timing of application will assist with plant nutrient scheduling. This is imperative for optimal yields and quality. Please contact your local agriculturalist for assistance with your plant nutrient scheduling. 

 

References

BBCH working group. (2001). Growth stages of mono-and dicotyledonous plants. (U. Meier, Ed.) (2nd ed.). Federal Biological Research Centre for Agriculture and Forestry.

Meier, U., Bleiholder, H., Buhr, L., Feller, C., Hack, H., Heß, M., Lancashire, P., Schnock, U., Stauß, R., Boom, T., Weber, E. & Zwerger, P. (2009). The BBCH system to coding the phenological growth stages of plants-history and publications. Journal für Kulturpflanzen, 61, 41-52. http://dx.doi.org/10.5073/JfK.2009.02.01.

White, P.J. & Brown, P.H. (2010). Plant nutrition for sustainable development and global health. Ann Bot.; 105(7):1073-80. doi: 10.1093/aob/mcq085. Epub 2010 Apr 29. PMID: 20430785; PMCID: PMC2887071.