TRD: Institute for Plant Production: Laboratory Services: SOIL, WATER AND PLANT TISSUE LAB
Recommendations
Nutrient requirements (i.e. the quantities of N, P and K present) are automatically recommended for small grains, pastures, vines, and fruit trees on reports issued for these crops.
The amount of lime (either calcitic or dolomitic) for acidic soils and gypsum for saline soils are also calculated. Specific trace element requirements are similarly indicated.
Fertiliser recommendations for nitrogen in the form of LAN, ammonium sulphate or urea; phosphorus in the form of double super-phosphate; and potassium in the form of potassium chloride or sulphate, are also given for these crops in the reports. Recommendations in terms of commercial compounds, blends or liquid fertilisers are only given on request.
Other crops, such as potatoes, onions, tomatoes, other vegetables, proteas, flowers, shrubs, general garden plants, sports field and bowling green grasses, are specifically catered for. The nutrient requirements for these, and practically any other crop, are given on request, along with recommended amounts of suitable, readily obtainable commercial fertilisers.
The standard analytical package forms the basis for all these recommendations. Trace elements and sulphur should be included when new land is opened up or the status of a land is unknown to the customer, or when it is known that trace elements have not been applied for a few years. It is particularly important to know the sulphur status in sandy and high pH or alkaline soils.
Particle size analysis is needed to determine herbicide application rates, the moisture holding capacity of the soil, and the likelihood of physical problems such as poor drainage, root disease, compaction, and surface crusting.
Organic carbon is needed to correct lime requirements and to estimate organic matter content. The total soil nitrogen is needed to estimate the nitrogen supplying capacity of soils.
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