PHOTO: THOMAS STRYDOM
PHOTO: THOMAS STRYDOM
PHOTO: THOMAS STRYDOM
INTERVIEW ▶▶▶
Lime is applied to increase the pH of the soil. Why – what is the ideal pH for the different soil types and why is it important? It is important that a holistic approach be followed when it comes to field management. • Chemical soil management must be seen as a whole and not only with regard to acidity; pH levels can indicate that soil is fer- tile, but it may not necessarily be at its full potential. Potassium levels, in topsoil and subsoil, especially for soybeans, peanuts and sunflowers, which tend to make use of subsoil fertility using their tap root systems, should also be taken into consideration.
“You cannot save your way to prosperity, but you can spend yourself broke.”
• Sandy soils, with low cation exchange capacity will become less fertile faster due to the poor holding ability of cations, as op- posed to strong clay soils. Long-term management and the gathering of relevant information is vital, then, in the following years, managing the levels according to what the fertility status indicates. In sandy soils, the physical amounts of elements are very important as they tend to get very low. In clay fields, availa- bility and relationships between elements are again very impor- tant; they need to be interpreted by an expert adviser with enough experience, understood as a whole and respected in terms of their characteristics.
• Quality of analysis as well as the source of the lime: recommen- dations and their effectiveness are often only as good as the in- formation on which they are based on, and the quality of the product used. Producers know their fields and what variations manifest themselves, not necessarily the reasons, but they can then be determined. The effectiveness of calcium also differs significantly depending on its source and has to be evaluated by means of laboratory analysis as well as the calcium carbonate equivalent, with quality controls of each product, including the reactivity of the lime.
• Different soil types with different chemical properties also play an enormous role and since the yield potential of soils differs as well as chemical extraction per crop, it is important to take grid soil analyses every 2 to 4 years and address the variations. High yields should not always be the only goal; sustainable profitabil- ity is what must be pursued. The goal is to maximise and realise the specific potential of the farm.
If it starts to rain, what should one do with the fields in preparation for the coming planting season and why? If possible, producers should collect good information and then decide what corrective action is needed and what should be planted. Information such as soil analysis, profile soil in- spections, moisture availability in the soil, crop rotation plan- ning as well as input product prices, should be taken into ac- count before deciding the way forward. Only once all the information has been obtained is it possible to decide which way to go. It is essential to determine what the most important factors are and where the greatest risks lie and save where you can without directly harming profits. Plants growing on a healthy fertile medium can handle stress conditions better and present the opportunity to realise above normal returns in good circumstances.
Poor growth due to drought conditions and incorrect cultivation in the Western Free State. Roots cannot develop further.
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Incredible root development of maize where nutrients are correctly managed.
▶ FUTURE FARMING | 1 November 2018
This shows the difference in root development of soybeans when correctly managed.
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