The Most Important Reason for Regular Soil Analysis

Ines Marjanovic

Agronomy Expert

Successful farm production starts with quality soil. The soil is one of the farmer’s most important and valuable tools. It provides a reservoir of water and nutrients that is required by crops. Each type of soil has a variety of properties that cannot be changed, such as texture. However, soil quality can be improved by following exceptional farm management practices, i.e. a soil analysis.

Soil analysis is a valuable farm practice that determines the exact amount of available crop nutrients that are in the soil, including nitrogen, phosphorus, potassium, pH, humus content, available lime, and organic matter. It also provides a visible snapshot of various chemical, physical, and biological soil properties.

Why Is Soil Analysis so Important?

Soil analysis presents information that is essential for the improvement of soil quality. By tracking the exact amount of soil nutrients, a farmer can easily adjust fertilization in accordance to soil and crop requirements. Additionally, soil analysis facilitates fertilization management, by also revealing the current soil pH level.

Soil pH is important due to its influence on the uptake of soil nutrients. The intention of managing soil pH is to be able to adjust the acidity, as needed, to the point where there are no toxic metals exposed to the crops, as well as to ensure that nutrient availability is at its maximum. Every crop has its own optimal pH range. Because of this, some crops grow better and can achieve their full potential in acid, while for others, this takes place in a more alkaline-based soil. The optimal pH levels for the most common crops are shown in the table below.

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The Best Time to Complete Soil Analysis

A quality and balanced soil leads to higher yields. A farmer should collect soil samples frequently to detect any changes that could affect crop yields. It’s recommended to perform a soil analysis every 3-4 years. However, considering improvement of soil quality, it is ideal to execute an analysis as often as possible, especially when growing annual crops in a crop rotation. In this case, it is recommended that analysis of the soil should take place after every third crop in the rotation.

Other important aspects to consider are the best time to complete an analysis, as well as the amount of time that should be allocated to do so. For example, soil sampling for annual crops should be taken after the harvest. In doing so, a farmer is left with plenty of time to plan for sufficient fertilization management. On the other hand, the best time for a soil analysis of perennial crops is during the dormancy stage.

What Happens After the Soil Analysis?

Depending on the analysis results, a farmer can easily manage the soil requirements for a certain crop, with the results indicating to him whether he needs to add lime to manage soil acidity. Liming rates are usually determined by taking into account soil type, depth of tillage, and limestone quality. The following table shows the lime rates according to the measured soil pH and its structure.

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Alkaline soil can be managed by adding elemental sulfur or nitrogen fertilizers. Aluminum sulfate also lowers pH, but its use is not recommended because of potential harmful side effects (aluminum toxicity to plant roots).

Although a chemical soil analysis is an expensive farm measure, it is the only way to ensure the management of proper soil nutrients, leading to eventual achievement of higher yields. Fertilizing crops without knowing their requirements and available soil nutrients is equivalent to driving a car while blindfolded. Finally, how often a farmer analyzes his soil depends entirely on him; whether he is ready to invest in soil quality and a higher yield or not. Do you know the levels of your soil pH?

 

Text and image sources: Ontario || FAO || NSW DPI