Soil Sampling

1. Faculty of Science University of Zakho, UOZ Zakho, Kurdistan Region – Iraq Lecturer: Mr. Marwan Basheer Department of Ecology

2. Soil Sample : Amount of soil taking from the field represents natural state and most properties of the soil which take for analysis. The aim of taking samples for analysis soil " Chemical, Physical and biological'' so can be know the fertility of the soil by analysis. Soil Sampling Contd … Lab. 1: Soil Testing – Collection and Preparation of soil samples . 2

3. Objectives of soil analysis : Determination minerals and organic components of the soil. Identify origin and classification of the soil. Determination the effect of environment factors on the soil. Determination soil fertility. Determination types and numbers of micro organisms which living in the soil. Contd … 3

4. Sampling Methods 1-Randomize method: Use the wood in square field for collected the samples from different places in the field this method not represent all the field because of some areas not survey and some samples may be taken from border the field. Contd … 4

5. 2- Dividing the field to squares '' or equal length and width distances (dimensions)'' then taking the samples from contribution point of length and width'' intersection point'' so can be taking the sample from the center of each square in this method avoid taking the sample from border the field. Contd … 5

6. 3- Dividing the field to triangles: Dividing the field to squares then dividing these squares by slope lines on condition slope lines passing through the intersection point of width and length lines [vertical and horizontal lines] of squares after that take the samples on the slope lines with equal distances , avoid taking the samples from border the field. Contd … 6

7. 4-Dividing the field by two diametrical lines on condition each diameter cut others in intersection (contribution) point, then take the samples on each diameter with equal distances, avoid taking the samples from border the field. Contd … 7

8. 5- Drawing the zigzag lines , then collected the samples from these lines, avoid taking the samples from border of the field. It's a good method for collecting samples, not wanted much effort , rapid method. Generally if you taking great numbers of samples in the case you obtain best and accurate results . Contd … 8

9. Sampling depth In general, The depth of sampling depends on the purpose of soil testing. For example: For studying soil genesis, morphology and classification the soil sample should be taken from 0 – 2 m depth. For testing the availability of nutrients (N, P, K, ..etc), chemical analysis (pH, EC, O.M) and fertilizer recommendation usually the soil sample taken from 0-30 cm because most plant roots grow to that depth. A B C 30 cm Contd … 9

10. Time and frequency of sampling The correct time of sampling cannot be decisively specified. Ideally, take the soil samples 3 to 4 weeks before planting or fertilizing the crop. For annual crops , especially vegetables, test soil each year before planting. For perennial crops such as orchards, trees, alfalfa, grass seed, test soil once every 2-3 years. However, soil samples may be taken either in the fall or spring.  Early spring is a good time to take soil samples for summer crops, and summer is a good time to sample for fall and winter crops. What season of the year? Contd … 10

11. Types of samples according to location: 1-Surface samples: samples collected for chemical and biological analysis, so used for evaluating the fertility state of the soil usually take from depth (0-30) cm. 2-Sub-surface samples: samples collected for survey and classification soils, usually take from (0-200) cm Contd … 11

12. Types of samples according to Number: 1-single samples: one sample take for analysis. 2-Composite samples : consist of several single or subsurface samples, then mixed these samples and take one sample from them, in this case all single samples must be equal in volume and weight . Contd … 12

13. Types of samples according to state Disturbed soil sample: is defined as the soil that its natural status has been destroyed or disturbed during the sampling process. Undisturbed soil sample: defined as the soil that collect from the field in a natural state Without disturbing the natural conditions of a soil sample. - Usually used for studying physical properties of soil (bulk density, structure, permeability). - Usually used for studying chemical properties of soil or soil fertility (pH, EC, K, N, P ..etc) Contd … 13

14. Notes must be followed when collecting the samples : Sample volume must be equal of each layer or horizon . Avoid taking the samples from region which contain disturbed soil, Wet soil [Irrigated soil], saline regions in the field. Avoid taking the samples from up to the hill and down to the hill. Avoid taking the samples near the roads in the field, fertilizer stores. Samples must be collected at the same time. Contd … 14

15. Notes must be write on the label of sample 1- project name 2- Name of the person who collect the samples. 3- Location. 4- Date of sampling. 5- Depth of sample. 6- Land use of the field. 7- Number of sample. * Notes: Two label must be write of each sample Label pattern for collecting the samples: project name Name Location Date Depth Number of sample Land use Contd … 15

16. Equipments of collected the soil samples : 1- Auger. 2- Core or tube. 3 - Shovels. Properties of the Equipments: 1- Small volume (size) and suitable for taking the sample. 2- Easy cleaning. 3- Rust resistance. Contd … 16

17. Preparing samples for analyzing: Preparing process of samples will pass through following steps:- 1- Drying: Air drying. The samples will spread on a drying tray, or sheet paper, or plastic (Nylon) sheets, and place in a drying cabinet (room) or on laboratory until air dry for 18 – 24 hours. Notice: Samples should be kept away from water, moisture, and dust or chemical and physical factors that changes its properties. Contd … 17

18. Grinding and Sieving: After the soil samples become homogenous break down clods with a porcelain or a wood hammer, then sieve the soil through a sieve of (2 mm). Mixing: In case of single samples will not mixed together, only should be prepared singly one by one for analyzing, but in case of composite samples should be mixed single samples in order to prepare compose sample. Partitioning: by quartering Spread the sieving soil on a plastic (Nylon) sheet in one direction, divided it into four squares, take tow square and neglect the others, and carefully left one sample, then puck it in a plastic box and label it. Preparing samples for analyzing Contd … 18

19. Storage: The labeled samples should be storage in a laboratory, it's preferable to store it at 4C because at this degree of temperature, the activity of more organisms will stopped. Preparing samples for analyzing: pH, EC, K, Mn, Fe, N, O.M. measure at once because of these properties change when the sample storage. Contd … 19

20. Thanks for Listening 20