Why soil test

Soil testing to provide a balanced fertility program is a vital component of sustainable farming programs that are profitable, efficient and environmentally responsible. The right time to take soil samples is in rhythm with the crop rotation.

Most samples are taken in late summer and fall to allow ample time for planning a crop nutrition program based on the 4Rs of Nutrient Stewardship: applying the right nutrient source at the right rate, time and place. This is better for your crops and the environment. Fertiliser burn and leaves turning yellow is the outcome of over-fertilisation for crops.

It might also result in nutrient leaching, water pollution and irreversible damages to the surrounding aquatic life. Soil degradation is a threat to every farmer. It is estimated that each year 24 billion tonnes of fertile soil are lost due to erosion which is a result of unbalanced soil management.

A proper soil management is guaranteed by soil tests followed by the application of the right fertilisers at the right moment. Besides avoiding risks of soil degradation, it is a more efficient and financially more interesting practice. Moreover, soil restoration is a difficult, costly and time-consuming process.

Products Lab-in-a-Box Scanner Scoutbox. Soil sampling has always been an important management tool to help producers determine nutrient status and need.

The basic principles of what constitutes a good soil sample have not changed, but its economic importance as a risk management tool to maintain your soil's productivity while still making a profit is greater than ever.

Gary W. With a focus on industry applications and research, the online program is designed with maximum flexibility for today's working professionals. Skip to main content. Share Tweet Email. To get the most accurate fertilizer recommendations and provide for increased efficiency, you'll need: good soil samples and well-based soil sample information; and soil test calibration relationships that reflect both crop response and profit response.

Collecting Accurate Soil Samples Before Starting to Sample Take time to learn more about various soil sampling techniques and which is best for your operation. See: Guidelines for Soil Sampling NebGuide G — methods and tips for getting the most accurate samples Soil Sampling for Precision Agriculture EC — different methods of grid and management zone sampling Sample soils every three to four years for pH, organic matter, phosphorus, potassium and zinc.

Organic carbon Organic carbon is a measure of the organic matter present in soil. It assists in maintaining: soil structure the supply and retention of nutrients air water If a soil is low in organic matter, the soil test will result in a low organic carbon level.

Table 1. Available phosphorus Phosphorus is essential for plant growth and is vital for early root formation. Table 2. Table 3. Phosphorus buffering index When phosphorus is applied to soils as fertiliser, it reacts with soil components and becomes less available for plant uptake.

Table 4. Exchangeable calcium Calcium is a necessary plant nutrient. Exchangeable magnesium Magnesium is also a necessary plant nutrient. Exchangeable potassium Potassium is an essential plant nutrient and is required in larger amounts. Exchangeable potassium should be 0. The application of gypsum CaSO4 can help alleviate excess sodium in the short term. Exchangeable aluminium High exchangeable aluminium concentrations can be common in very low pH soils, and may be toxic to plants.

Aluminium levels generally fall to harmless levels once the pH water exceeds 5. If the calcium to magnesium ratio is less than , then this may indicate reduced soil stability. In contrast, a calcium to magnesium ratio of more than indicates a potential magnesium deficiency in plants and animals. Magnesium to potassium ratio The amount of magnesium should be one and a half times greater than the amount of potassium. Salinity Soil salinity is a measure of the total soluble salts present.