3. A step-by-step guide to the procedures

3.1 List of main steps

The main steps in land evaluation are summarized below as a guide to field work and classification. The principles, terminology and outline procedures have already been described in Chapters 1 and 2. Details of each of the following steps are elaborated in later Chapters as indicated for each step. Data record sheets (Formats) that can be filled in during the evaluation are given in Tables 4-9 (Formats 1-5) and these can be modified, enlarged, simplified or copied for field work.

A progression from a 'provisionally-irrigable' to an 'irrigable' classification is assumed in the following steps. The steps can be readily modified if an alternative approach is used. The appropriate type of classification, and the measure of suitability to be used (i.e. land productivity index, net farm income or net incremental irrigation benefit) must be decided prior to each evaluation.

3.1 List of main steps

i. Deciding the land utilization types (LUTs) to evaluate (explained in Section 4.1).

Step 1: Land is evaluated with respect to its suitability for a given land use. Decide the alternative land uses (i.e. LUTs or farming systems) of interest and prepare to evaluate each of these separately.

Step 2: Describe the LUTs. For each LUT, complete a description based on headings given in Table 10.

ii. Developing the land suitability class specification (explained in Section 4.2).

Step 3: From the list of agronomic, management, land development, conservation, environmental and socio-economic factors given in Table 12, select the relevant 'class-determining' factors that can be expected to have some influence on the suitability of land for the given LUT and that may vary from land unit to land unit.

Step 4: For each selected 'class-determining' factor, enter the appropriate land use requirement or limitation on Format 1.

Step 5: Quantify 'critical limits' corresponding to s1, s2, s3, n1 and n2 levels of suitability for individual land use requirements and limitations. These are the specifications for each factor in terms of the requirements and limitations of the LUT. These specifications may be represented by appropriate land qualities, or their representative land characteristics, together with the inputs and land improvements that influence productivity index, net farm income or NIIB. Enter the 'critical limits' on Format 1 thus separating the suitability levels for each individual factor.

iii. Field survey and mapping of 'provisionally-irrigable' classes and subclasses (see Chapters 5-7)

Step 6: Survey, delineate and describe the land units. Prepare a map of the land units, with a legend numbering the land units which can also accommodate the symbols for the land suitability classes.

Step 7: For each land unit, decide which land qualities and land characteristics are 'class-determining' with respect to the requirements and limitations of the LUT(s). For each land unit, complete Format 2 entering the appropriate values of the land qualities and land characteristics (see Procedures for Land Resource Inventory, Chapter 5).

Step 8: Match 'critical limits' of each land use requirement or limitation (i.e. from the specifications on Format 1), with the conditions found in the land unit (i.e. Format 2) to obtain a factor rating of s1, s2, s3, n1 or n2 for each combination of LUT and land unit. Enter the factor rating on Format 3. Assumptions about inputs, land improvements and their benefits and costs should also be indicated (see Example 2 in Section 6.5).

Step 9: Decide the relative 'Significance' of each 'class-determining' factor (or of a group of interacting factors) by entering Very Important, Moderately Important, Less Important or Not Important, as appropriate, in the column headed 'Significance' (Format 3) (see Section 6.3).

Step 10: Combine individual 'class-determining' factor ratings to obtain a tentative land suitability classification for each LUT on each land unit. Interactions between factors (Section 6.2) and 'Significance' (Section 6.3) must be taken into account in this step. Estimates of crop yield and economic benefit/costs, according to the guidelines in Chapter 7, may be needed to assign the classes and subclasses. Enter the tentative land suitability class and subclass (S1, S2, S3, N1 or N2 etc.) at the bottom of Format 3 or on the map.

Step 11: Where necessary, adjust the LUT description, or introduce inputs or land improvements, and repeat steps 1-10 until the most practicable cropping, irrigation and management farming system is obtained (the need for such iteration can be entered on Format 3).

iv. Presentation of the results of the 'provisionally-irrigable' classification

Step 12: Take the final set of 'provisionally-irrigable' classes and subclasses in Step 11 and present them for all the combinations of LUTs with land units on Format 4a or 4b (Tables 7 and 8). (Note that Format 4 can be presented in two ways, to show either the classes of all the land units for a single LUT or, alternatively, the suitability of a single land unit for all the LUTs.)

- describe each LUT in terms of cropping, irrigation and management systems and using descriptors given in Table 10;

- provide maps of 'provisionally-irrigable' land with legends as indicated on Format 5 (Table 9);

- indicate land development, inputs and management recommendations for each combination of LUT-land unit;

- present the results from basic surveys including maps and descriptions of land units;

- write a summary of the recommendations.

v. Determination and mapping of 'irrigable' land

Step 13: Revise the cropping, irrigation and management in an updated description of the LUT for specific land units. Revise the specifications and critical limits in the light of new information on water supply and economic data. Proceed to revise the classification to determine which areas of the 'provisionally-irrigable' land can actually be irrigated under an economically and financially viable project plan (see Chapter 7).

Step 14: Repeat mapping as in Step 6, with additional field survey as necessary, changing land unit boundaries and earlier mapped symbols as necessary.

Step 15: Complete the mapping, tabulations and present the results of the classification of 'irrigable' land.

Step 16: Based on the recommendations in Step 15, participate with other technicians in the project investigation to establish patterns of land use for the project reflecting the likely situation with the project at full development. With land use options thus reduced to a recommended and likely single LUT on each land unit for the 'with' project situation, prepare maps and tabulations of the 'irrigable' land classification for the project. The predicted economic results of each LUT can be incorporated in the overall economic analysis for the project.

Step 17: Prepare reports for investment and management such as are necessary.

The following data record sheets (Formats 1-5) are given in the succeeding pages:

Format 1: Specifications of Land Use Requirements and Limitations.

Format 2: Land Qualities and Land Characteristics Describing a Land Unit.

Format 3: Factor Ratings to Match a LUT and a Land unit. Format 4: Grouped Factor Ratings for LUTs on a Specified Land Unit.

Format 5: Land Areas by Suitability Classes for Specified LUTs (for adaptation).

Formats 1-3 are those that prove most important in carrying out the evaluation in the field. Formats 4a and 4b present the same data in alternative ways and are not essential.

Format 5 can be adapted appropriately to present the results of reconnaissance, provisionally-irrigable, or irrigable classifications.

Table 4 FORMAT 1: SPECIFICATIONS OF LAND USE REQUIREMENTS AND LIMITATIONS

LUT Name:	LUT Description
CLASS-DETERMINING REQUIREMENTS OR LIMITATIONS (Delete factors that are not selected as class-determining)	REVELANT LAND QUALITY OR LAND CHARACTERISTIC	INPUTS AND LAND IMPROVEMENTS REQUIRED	UNIT OF MEASUREMENT	CRITICAL LIMITS OR RANGES
				s1	s2	s3	n1	n2
A. Crop (agronomic) requirements or limitations
1. Growing period requirement
2. Radiation requirement
3. Temperature requirement
4. Rooting requirement
5. Aeration requirement
6. Water requirement
7. Nutritional requirements (NPK)
8. Water quality limitation
9. Salinity limitation
10. Sodicity limitation
11. pH, micronutrients and toxicities
12. Pest, disease, weed limitations
13. Flood, storm, wind, frost, hail limitations
B. Management requirements and limitations
14. Location
15. Water application management requirements
16. Pre-harvest farm management requirements
17. Harvest and post-harvest requirements
18. Requirements for mechanization
C. Land development or improvement
requirements or limitations
19. Land clearing requirements
20. Flood protection requirements
21. Drainage requirements
22. Land grading requirements
23. Physical, chemical, organic aids and amendments
24. Leaching requirements
25. Reclamation period
26. Irrigation engineering needs
D. Conservation and environmental requirements and limitations
27. Long-term salinity, sodicity hazard
28. Ground or surface water hazard
29. Long-term erosion hazard
30. Environmental hazard
E. Socio-economic requirements or limitations
31. Farmers' attitudes to irrigation
32. Others that are class-determining

Note: s1, s2, s3, n1 and n2 denote decreasing suitability levels for single factors or their interactions. See Table 12 and Section 6.5 Example 2.

Table 5 FORMAT 2: LAND QUALITIES AND LAND CHARACTERISTICS DESCRIBING A LAND UNIT WITH AN ASSESSMENT OF INPUTS AND LAND IMPROVEMENTS REQUIRED

CLASS DETERMINING FACTORS: - land quality or characteristic - inputs or improvements		UNIT OF MEASUREMENT	LAND CHARACTERISTIC OR QUALITY VALUE		INPUTS AND IMPROVEMENTS ASSUMED FOR LUT A, B, C etc.
			PRESENT	FUTURE UNDER IRRIGATION
e.g.
7. NUTRITION (NPK)
	- Total N depth 0-25 cm	%	0.05	0.5
	- Available P (Olsen)	mg/l	10
	- Exchangeable K	me/100 g	0.6
Fertilizer requirement		kg/ha
N					200 kg/ha
P					nil
K					nil

For further example of the use of this format see Section 6.5, Example 2.

Table 6 FORMAT 3: FACTOR RATINGS TO MATCH A LUT AND A LAND UNIT

FORMAT 3: Factor ratings	LUT name:
Name of evaluator:	Land unit no.
CLASS-DETERMINING FACTORS (Delete others)	LAND CHARACTERISTICS, INPUTS AND IMPROVEMENTS ASSUMED	FACTOR RATING	SIGNIFICANCE	COMMENTS
A. Crop (agronomic)
1. Growing period
2. Radiation
3. Temperature
4. Rooting
5. Aeration
6. Water quantity
7. Nutrition (NPK)
8. Water quality
9. Salinity
10. Sodicity
11. pH, micronutrients and toxicities
12. Pest, disease, weed
13. Flood, storm, wind, frost
B. Management
14. Location
15. Water application management
16. Pre-harvest farm management
17. Harvest and post - harvest
18. Mechanization
C. Land development
19. Land clearing
20. Flood protection
21. Drainage
22. Land grading
23. Physical, chemical, organic aids and amendments
24. Leaching
25. Reclamation period
26. Irrigation engineering
D. Conservation and environment
27. Long-term salinity, sodicity
28. Ground or surface water hazard
29. Long-term erosion hazard
30. Environmental hazard
E. Socio-economic
31. Farmers' attitudes to irrigation
32. Others that are class-determining
TENTATIVE LAND SUITABILITY	CLASSIFICATION TYPE:
CLASS AND SUBCLASS:
FINAL LAND SUITABILITY	NEED FOR ITERATION:
CLASS AND SUBCLASS:
s1, s2, s3, n1 and n2 denote decreasing suitability levels for single factors or for specified interactions. Significance is given as Very Important, Moderately Important, Less Important and Not Important in aggregating the factor ratings to give the land suitability class. For example see Section 6.5, Example 2.

Table 7 FORMAT 4a: GROUPED FACTOR RATINGS FOR LUTs ON A SPECIFIED LAND UNIT

FORMAT 4a: Land unit no:	Name of evaluator:
Description of land unit:
CLASS-DETERMINING FACTORS	FACTOR RATINGS
	LUT A	LUT B	LUT C	LUT D	LUT E	LUT F	LUT G
A. Crop (agronomic)
1. Growing period
2. Radiation
3. Temperature
4. Rooting
5. Aeration
6. Water quantity
7. Nutrition (NPK)
8. Water quality
9. Salinity
10. Sodicity
11. pH, micronutrients and toxicities
12. Pest, disease, weed
13. Flood, storm, wind, frost
B. Management
14. Location
15. Water application management
16. Pre-harvest farm management
17. Harvest and post-harvest
18. Mechanization
C. Land development
19. Land clearing
20. Flood protection
21. Drainage
22. Land grading
23. Physical, chemical, organic aids and amendments
24. Leaching
25. Reclamation period
26. Irrigation engineering
D. Conservation and environment
27. Long-term salinity, sodicity
28. Ground or surface water hazard
29. Long-term erosion hazard
30. Environmental hazard
E. Socio-economic
31. Farmers' attitudes to irrigation
32. Others that are class-determining
TENTATIVE LAND SUITABILITY CLASS AND SUBCLASS:
FINAL LAND SUITABILITY CLASS AND SUBCLASS:
Assumptions about inputs and land improvements:

Note that information from several Formats 3 can be assembled on this Format.

Table 8 FORMAT 4b: GROUPED FACTOR RATINGS FOR LAND UNITS FOR A SPECIFIED LUT

FORMAT 4b: Name of LUT:	Name of evaluator:
Description of LUT:
CLASS-DETERMINING FACTORS	FACTOR RATINGS
	LU 1	LU 2	LU 3	LU 4	LU 5	LU 6	LU 7
A. Crop (agronomic)
1. Growing period
2. Radiation
3. Temperature
4. Rooting
5. Aeration
6. Water quantity
7. Nutrition (NPK)
8. Water quality
9. Salinity
10. Sodicity
11. pH, micronutrients and toxicities
12. Pest, disease, weed
13. Flood, storm, wind, frost
B. Management
14. Location
15. Water application management
16. Pre-harvest farm management
17. Harvest and post - harvest
18. Mechanization
C. Land development
19. Land clearing
20. Flood protection
21. Drainage
22. Land grading
23. Physical, chemical, organic aids and amendments
24. Leaching
25. Reclamation period
26. Irrigation engineering
D. Conservation and environment
27. Long-term salinity, sodicity
28. Ground or surface water hazard
29. Long-term erosion hazard
30. Environmental hazard
E. Socio-economic
31. Farmers' attitudes to irrigation
32. Others that are class-determining
TENTATIVE LAND SUITABILITY CLASS AND SUBCLASS:
FINAL LAND SUITABILITY CLASS AND SUBCLASS:
Assumptions about inputs and land improvements:

Note that information from several Formats 3 can be assembled on this Format.

Table 9 FORMAT 5: LAND AREAS BY SUITABILITY CLASSES FOR SPECIFIED LUTs (ha) (FOR ADAPTATION)

FORMAT 5:

INTENSITIES OF INVESTIGATION 1/

RECONNAISSANCE

'PROVISIONALLY-IRRIGABLE LAND'

'IRRIGABLE' LAND VIABLE UNDER PROJECT

MEASURES OF SUITABILITY

LAND PRODUCTIVITY INDEX

NET FARM INCOME

NET INCREMENTAL IRRIGATION BENEFIT 2/

Land suitability classes

S1

S2

S3

N1

N2

S1

S2

S3

N1

N2

V1

V2

V3

N1

N2

Relative yield 3/

Net farm income $/ha

NIIB $/ha

LUT land unit combinations

1.0 to 0.9

0.9 to 0.7

0.7 to 0.6

0.6 to 0.4

<0.4

AREA IN HECTARES

LUT A

LU 1

"

LU 2

"

LU 3

"

LU 4

"

LU 5

"

LU 6

"

LU 7

"

LU 8

etc.

LUT A

Total Area

AREA IN HECTARES

LUT B

LU 1

"

LU 2

"

LU 3

"

LU 4

"

LU 5

"

LU 6

"

LU 7

"

LU 8

etc.

LUT B

Total Area

1/ Note that areas of land surveyed at increasing levels of intensity would normally diminish from reconnaissance to 'irrigable'. At reconnaissance level fewer land classes would normally suffice.

2/ V1, V2, V3, etc. denotes that the land and land use is economically viable under a plan of development, but S1, S2, S3 may be used if preferred.

3/ Relative yields indicated are examples only.