Delineating prime Farmland Module description

Thursday, April 16, 2020 2:17:00 PM

Land capability assessment is done to find out the general capability of the resources of an area for agricultural crops, forestry and other uses. In this assessment, the mapping units occurring in an area are grouped according to their limitations they pose for cultivation, the risk of damage if they are used for the identified use, and the way they respond to management interventions. Normally the criteria used in grouping the units don’t take into consideration any major and costly reclamation measures or conservation techniques that change the slope, depth or characteristics of the soils. This system is not aimed to find out the suitability of the land resources for specific uses or crops. Though the classification was evolved originally to help the soil conservation efforts, but now this system can be used for identifying priority areas, which requires immediate attention and development within a watershed or project areas.

The capability grouping is based on the inherent soil characteristics, external land features and environmental factors that limit the use of the land for different purposes (I.A.R.I., 1971 and Soil Survey Division Staff, 1993). The following land and soil characteristics are used to group the land resources identified in an area into various classes, subclasses and units.

Soil characteristics: Soil depth, texture, gravelliness, soil reaction, water holding capacity, calcareousness, salinity/ alkalinity etc.

Land features: Slope, erosion, rock outcrops and drainage.

Climate: Rainfall distribution and length of growing period.

In the capability system, mapping units are generally grouped at three levels – capability class, subclass and unit. Depending on the level of available information, grouping can be done at any one of the above levels. If the information available for an area is of general nature, then the classification can be done only up to class or subclass level and if it is detailed and site-specific then the classification can be done up to the unit level, which is an equivalent of a management unit for the survey area. Since site-specific and comprehensive database is generated through the Land Resource Inventory for all the watersheds in the project districts, the land resources can be grouped into various land capability units for each watershed area.

Structure of the classification

Capability classes, the broadest groups, are designated by roman numerals I to VIII. The numerals indicate progressively greater limitations and narrow choices for practical use. The eight classes used in the classification are:

Class I	The mapping units have few or very few limitations that restrict their use.
Class II	Mapping units have moderate limitations that reduce the choice of the crops or that require moderate conservation practices.
Class III	Mapping units have severe limitations that reduce the choice of the crops or that require special conservation practice, or both.
Class IV	Mapping units have very severe limitations that reduce the choice of the crops or that require very careful management, or both.
Class V	Soils in the mapping units are not likely to erode, but they have other limitations, impractical to remove that limit their use.
Class VI	The land area has severe limitations that make them generally unsuitable for cultivation.
Class VII	The land area has very severe limitations that make them unsuitable for cultivation.
Class VIII	Soils and miscellaneous areas have limitations that nearly preclude their use for any commercial crop production

Capability subclasses are formed based on the dominant limitations observed within the capability class. They are designated by adding a lower-case letter like e, w, s, or c, to the class numeral. For example, in subclass IVe, the letter ‘e’ shows that the main hazard in class IV land is the risk of erosion. Similarly, the symbol ‘w’ indicates drainage or wetness as a limitation for plant growth or cultivation (in some soils the wetness can be partly corrected by artificial drainage); the symbol ‘s’ indicates shallow depth, calcareousness, salinity and sodicity or gravelly nature of soil as limitations and ‘c’ indicates climate or rainfall with short growing period as a limitation for plant growth.

The land capability subclasses have been divided into land capability units based on the kinds of limitations present. Ten land capability subclass units are used in grouping the resources of an area, which are indicated below with their symbols

Stony or rocky
Erosion hazard (slope, erosion)
Coarse textures (sand, loamy sand, sandy loam)
Fine texture (cracking clay, silty clay)
Slowly permeable sub soils
Coarse underlying material
Salinity or alkali
Stagnation, overflow, high groundwater
Soil depth
Fertility problems

Capability units have almost similar soil and other land characteristics that influence the use of the land resources at the field level. Accordingly, each capability unit is expected to respond uniformly to a given level management. (Note: Under Sujala project, land capability assessment is done only up to land capability subclass and not up to land capability unit levels)

By following the Land capability classification system, the phases mapped or the map units identified at the watershed level can be grouped into various land capability classes, sub classes and land capability units. The various parameters to be considered and their ratings to be used in grouping the land parcels/areas into land capability units are given in the table below.

Source:

United States Department of Agriculture (USDA), 2012, Soil Survey Manual, Handbook No:18, USDA, USA.
Natarajan, A., and Dipak Sarkar, 2010, Field guide for soil survey, National Bureau of Soil Survey and Land Use Planning (NBSSLUP), ICAR, Nagpur, India.
IARI (1971) Soil Survey Manual, IARI, New Delhi

Table Parameters and their ratings to be used for land capability units/classes

Sl No	Climate, soil and site parameters/features affecting LCC				Land capability ratings
					Suitable for Agriculture				Suitable for forestry, sylvipasture, wildlife etc.				LCC
	Parameters	Value	Classes	Code	Class I	Class II	Class III	Class IV	Class V	Class VI	Class VII	Class VIII	LCC
1	Climate			Humid with well distributed rainfall	√								I
2	Climate			Humid with occasional dry spells		√							IIc
3	Climate			Sub humid-yields frequently reduced by droughts		√							IIc
4	Climate			Semi-arid			√						IIIc
5	Climate			Arid				√					IVc
6	Slope	Red	0-1	A	√								I
7	Slope	Red	1-3	B		√							IIe
8	Slope	Red	3-5	C		√							IIe
9	Slope	Red	5-10	D			√						IIIe
10	Slope	Red	10-15	E				√					IVe
11	Slope	Red	15-25	F				√					IVe
12	Slope	Red	25-33	G						√			VIe
13	Slope	Red	33-50	H						√			VIe
14	Slope	Black	0-1	A	√								I
15	Slope	Black	1-3	B		√							IIe
16	Slope	Black	3-5	C			√						IIIe
17	Slope	Black	5-10	D				√					IVe
18	Erosion		e1	Slight	√								I
19	Erosion		e2	Moderate		√							IIe
20	Erosion		e3	Severe			√						IIIe
21	Erosion		e4	Very severe				√					IVe
22	Drainage			Excessive						√			VIw
23	Drainage			Well drained	√								I
24	Drainage			Moderately well drained		√							IIw
25	Drainage			Imperfect			√						IIIw
26	Drainage			Poorly drained				√					IVw
27	Drainage			Very poorly drained					√				Vw
28	Soil Depth		>100	>100	√								I
29	Soil Depth		50-75	50-75		√							IIs
30	Soil Depth		25-50	25-50			√						IIIs
31	Soil Depth		10-25	10-25				√					IVs
32	Soil Depth		<10	<10						√			VIs
33	Soil Depth		10-25	10-25						√			VIs
34	Soil Depth		75-100	75-100		√							IIs
35	Soil Depth		100-150	100-150	√								I
36	Soil Depth		50-100	50-100		√							IIs
37	Soil Depth		>150	>150	√								I
38	ST		sl	Sandy loam	√								I
39	ST		scl	Sandy clay loam	√								I
40	ST		cl	Clay loam	√								I
41	ST		l	Loam	√								I
42	ST		sicl	Silty clay loam	√								I
43	ST		sc	Sandy clay		√							IIs
44	ST		sic	Silty clay		√							IIs
45	ST		c	Clay			√						IIIs
46	ST		ls	Loamy sand				√					IVs
47	ST		s	Sand						√			VIs
48	SG		g0	<15	√								I
49	SG		g1	15-35		√							IIs
50	SG		g2	35-60			√						IIIs
51	SG		g3	60-80				√					IVs
52	SG			>60				√					IVs
53	SG		g4	>80				√					IVs
54	Rock outcrops		R0	<2		√							IIs
55	Rock outcrops		R1	2-10			√						IIIs
56	Rock outcrops		R2	10-25				√					IVs
57	Rock outcrops		R3	25-50				√					IVs
58	Rock outcrops			10-50				√					IVs
59	Rock outcrops		R3	50-90						√			VIs
60	Rock outcrops		R4	>90								√	VIIIs
61	EC		<2	<2	√								I
62	EC		0-2	0-2	√								I
63	EC		2-4	2-4		√							IIs
64	EC		4-8	4-8			√						IIIs
65	EC		8-16	8-16				√					IVs
66	pH		<4.5	Unfavourable reaction (exceedingly difficult to modify)				√					IVs
67	pH		4.5-5.54	Unfavourable reaction (difficult to modify)			√						IIIs
68	pH		5.5-6.5	Unfavourable reaction (easy to modify)		√							IIs
69	pH		6.5-7.5	Favorable Reaction	√								I
70	pH		7.5-8.5	Unfavourable reaction (easy to modify)		√							IIs
71	pH		8.5-9.5	Unfavourable reaction (difficult to modify)			√						IIIs
72	pH		>9.5	Unfavourable reaction (exceedingly difficult to modify)				√					IVs
73	Permeability		vs	Very slow			√						IIIs
74	Permeability		s	Slow		√							IIs
75	Permeability		ms	Moderately Slow	√								I
76	Permeability		r	Rapid			√						IIIs
77	Permeability		vr	Very rapid							√		VIIs

Note: While assigning the land capability class for any unit based on soil and other land features, the property that acts as a major limiting factor for production is given importance.

Step By Step Process

The web page will have the drop down for selecting District, Taluk, Village, Watershed name, Survey Number.
User will select the District, Taluk, Village, Micro Watershed and Survey number.
System will Fetch the information related to selected Survey number.
System will fetch the Slope, Erosion, Drainage, Soil depth, Texture, Rock out Crops, EC, pH, Permeability for the respective Survey Number.
System will fetch climate_data to find the climate condition for the respective area.
System will execute the query on Master Land capability Table to find
- Class for Climate category against Climate value.
- Class for Slope category against the slope value.
- Class for Erosion category against Erosion value.
- Class for Drainage category against Drainage value.
- Class for Soil Depth category against Depth value.
- Class for Soil Texture category against Texture value.
- Class for Gravels category against Gravel value.
- Class for Rockout crops category against Rockout_Crops value.
- Class for EC category against EC Value.
- Class for pH category against pH Value.
- Class for Permeability category against Permeability Value.
If the for all Class Value comes as ‘I’ then update the LCC as ‘I”.
If any class value is greater than ‘I”, Get highest class value from all above for deciding the LCC. And add the lower case letter like e, w, s, or c to the Class number. e.g, IIIw , the letter ‘w’ shows that the drainage or wetness is limitation in class III land. Below symbols will be used to show the limitations.
- e – Erosion limitation
- w – Drainage Limitation
- s - Depth, Texture, gravel, rockout crop, EC,pH, Permeability limitation
- c – Climate Limitation

Save the result in Land_Capability Table with Id, Cadastral_ID, LCC, Limitation.
Fetch the Farmer Name from Land_Parcel_Information table against the selected survey Number. This table will be populated using the web service from BHOOMI.
Display the result in a table showing the information such as Survey number, farmer Name, area in hectare, Land Capability Classification, Limitation, Arable/Non Arable.