FERTILISER GUIDELINES FOR THE WINE INDUSTRY

THE NEUTRALISATION VALUE OF LIMING PRODUCTS The reactivity of all lime types is furthermore also dependent on the fineness thereof, so that the largest possible surface can come into contact with the soil and soil water in order to neutralise soil acidity. The reactivity of microfine agri cultural lime (90% finer than 0,25 mm), therefore is significantly higher than that of agricultural lime that merely conforms to the minimum legal requirements for “ordinary” agricultural lime (50% finer than 0,25 mm).

THE TIMELY AND CORRECT APPLICATION OF LIME ON THE LAND

Lime should be broadcasted on the surface at least six months before planting and immediately incorporated into the soil, so that the pH correction can be achieved before the grapevine extends its roots into the soil. EFFICIENT MIXING OF LIME WITH THE SOIL If the soil is too moist when preparation takes place, it forms a ‘paste’ and the lime will not be thoroughly mixed with the soil particles. If the soil is too dry, large clods form and good mixing is also not obtained. The water content of the soil should be between wilting point and lower plastic limit (where a stable sausage can be rolled between the palms of your hands). THE EFFECTIVE REACTION OF THE LIME IN THE SOIL, IN ORDER TO OBTAIN THE DESIRED RESULT If soils were left fallow (i.e. soils that have not been cultivated for long periods of time) and where the pH is very low, it is recommended that lime be applied in instalments over at least two seasons. The last requirement is very important and that is to determine if the soil is fit for planting immediately after liming, or whether planting should be postponed so that the soil reaction can bring the pH nearer to the optimum of >5,5. There is a general perception that the more calcium in compound form is put into the soil, the higher the pH or soil reaction will increase. However, it is not only Ca compounds, but also magnesium, potassium and sodium compounds that have an impact on the soil’s pH levels. Excess potassium, also known as potash (K), and sodium may have a greater effect on soil pH than calcium and magnesium.

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