Soil Analysis

Introduction

Soil analysis is a set of various chemical processes that determine the amount of available plant nutrients in the soil, but also the chemical, physical and biological soil properties important for plant nutrition. Chemical soil analysis determines the content of plant nutrients; nitrogen (N), phosphorus (P2O5), potassium (K 2 O), pH, humus content, total CaCO3, available lime, organic matter, total sulphur (S), Sodium, micro nutrients, and other physical characteristics (capacity, permeability, density, pH  value).

Reasons for doing soil analysis

1.  To determine the level of availability of nutrients or the need for its introduction. 
2.  To predict the increase in yields and profitability of fertilization (poor soils do not always provide yield increase due to fertilization because of possible limiting factors). 
3.  To provide the basis for calculating the required fertilizing of each crop. 
4. To evaluate the status of each nutrient element and simultaneously determine how to manage the nutrients. 
5. To improve economic planning and decision making for a farmer.

According to the content of nutrients in the soil obtained by soil analysis and the requirements of a particular crop, it is easier to determine the amount of required fertilizers to achieve high and quality yields. High quality soil analysis is the basis of planning of fertilizing (what fertilizers to use, what amount and when to use) and thus the quality of the entire production cycle, which results in a high quality and yield and better farm managerial decisions.

when is the best time to do a soil analysis? 

Taking soil samples for analysis is greatly advised to be done after harvesting of crops and before any fertilizing, at optimum soil moisture. The soil must not be depressed, along the edge of the farm or where mineral fertilizers are unevenly scattered, because the sample will not be representative of the whole field and the resulting data will not be a reflection of the real status of the soil in the entire field. In the case of permanent crops such as orchards and vineyards analysis is carried out periodically. 

How to properly perform sampling

Samples are taken using an auger, but can also be taken using a shovel.

Important factors to put into consideration when taking soil samples: 

 Depth of sampling.

Depth of sampling is critical because tillage and nutrient mobility in the soil can influence nutrient levels in different soil zones. Sampling depth depends on the crop, cultural practices, tillage depth and the nutrients to be analyzed. 

 Soil type. 

In the event that ones farm has different soil types it is recommended that different samples from the different soil types be taken separately. 

 Previous cropping. 

The previous crop that was occupying the particular field should be put into consideration. If different crops were in different fields, separate samples should also be taken from those different fields and not one sample be taken for fields where different crops were grown. 

 Previous lime and or fertilizer applications. 

In a case where there were different fertilizer programs being used for different fields. The same should also be put into consideration when taking soil samples for analysis by taking different soil samples separately for the different fields. 

Slope or topography of the land. 

Different soil samples should be taken if for example in a field part of it is sloppy while the other part is a gentle slope.