Forage crops typically grow quickly, producing a large amount of vegetative growth (forage). To do this and reach their full potential, they require appropriate levels of soil nutrients and moisture.
Good soil nutrition during germination and early growth stages is critical to ensuring satisfactory establishment. Understanding soil nutrition allows for appropriate fertiliser application at sowing and influences forage crop selection with some plants being more suited to particular soil characteristics than others.
While understanding the fertiliser and cropping history of a paddock provides a useful indication of the likely status of various soil nutrients, the only way to be sure of the soil nutrient profile is to undertake a soil test.
Soil tests vary in complexity depending on producer requirements, but usually assess:
- Available phosphorus
- Available sulphur
- Nitrogen levels
- Exchangeable cations (Ca, Mn, Na and K)
Soil tests can be organised through local rural merchandise suppliers and rural consultants or a producer can order a soil test kit and take their own samples to send away for laboratory analysis.
The results from soil testing must be considered within the context of the local farm environment and it is advisable to have the results interpreted by a FertCare accredited advisor.
A key outcome of soil analysis and interpretation is a fertiliser recommendation. By analysing soils prior to application, producers can be sure that they are applying the right fertiliser for the conditions, giving their forage crop the best chance establishment.
Fertilisers vary from relatively stable and low cost single super options containing phosphorus and sulphur, to more volatile compounds containing nitrogen and high analysis custom fertilisers. Nitrogen in the form of urea is one of the most common fertilisers used on forage crops to encourage vegetative growth. Other applications, such as lime, may also be recommended through soil analysis to correct fertility issues associated with pH.
Soil testing and analysis prior to sowing not only allows soil fertility issues to be addressed prior to or during sowing but can also assist in the development of a targeted in-crop fertiliser management plan eg the application of nitrogen at a particular phase in the plant growth cycle.