SABI Magazine | Page 31

How to... results and the application of remedial strategies to ensure the maintenance of optimum conditions for crop growth. The objectives of soil analysis are based on the need for information, which will determine the timing of the sampling procedure. Initial sampling provides an input to soil preparation prior to planting as well as the determination of management units, areas of similar soil form, depth and level of coarse material which require similar management strategies. Maintenance sampling provides input to the quality and effectiveness of the irrigation scheduling and fertilisation regimes. PREPARATION Once the decision has been taken to conduct a soil analysis, the following preparation has to be undertaken in order to achieve accurate results. The first step is the preparation of a sampling plan. This plan indicates where the samples are to be taken as well as the depth of the samples and is based on the specific objectives of the analysis. For example, the sampling plan for soil preparation will be very different to a maintenance sampling exercise. Also obtain sampling tools as well as suitable containers for the gathered samples. Planning: Initial profile pits should be dug on a 50x50m grid in order to evaluate the soil conditions so as to determine the borders of cultivation or management units. Should large variances in soil conditions exist between the trial pits, intermediate pits should be dug in order to establish where the soil transitions are. These units will be chosen on soil form, depth and coarseness as they will require similar management strategies. Thereafter the collection of representative samples for analysis from each of the management units may be undertaken. For tree and vineyard crops, separate samples should be taken from the topsoil and subsoil. I