Agriculture Soil Science Important Study Table (6)

Agriculture Soil Science Study Point For Competitive Exam

Agriculture Soil Science Study Point For Competitive Exam

 1.Soil Orders (as per Soil Taxonomy) representing different soil groups

 2.Six categories were adopted for this system 

Note:- The smallest unit of soil classification is the soil series
Soil orders in the 7^th approximation and their derivation

 3.12 Soil orders With Characters 

 4.Land Capability Classification 

• Land capability classification (LCC) may be defined as a system of grouping land in to various classes based on inherent limitations imposed on sustained use by soil attributes, topography, drainage and climate.

The capability classes falls in two groups:-

1. Suited for cultivation a
2. Not suited for cultivation.

The subclasses are further divides in to unit based on a specific management practice.

1. Thus land is classified in to eight land capability classes under two broad groups as:Land suitable for agriculture and other uses which include class I to class IV lands.
2. Land not suitable for agriculture but very well suited for forestry, grass land and wild life which include class V to class VIII lands.

 5.On map, the capability classes are indicated in different colours 

 6.Detailed characteristics of Land Capability Classes (LCC) 

7.Composition Of Sand Silt & Clay Related To Textural Class

Soil Texture:-
Soil texture refers to relative proportion of mechanical / soil separates below 2 mm in diameter (viz. sand, silt and clay).
Three size classes are particularly important:

1. Sand (size as in beach sand)
2. Silt (size like talc/talcum powder)
3. Clay (small particles which stick together, like modeling clay).

Soil Structure and Consistency:-

• The term soil structure refers to the arrangement of primary and secondary particles in to a certain structural pattern.
• The primary particles are sand, silt and clay whereas the secondary particles are the cluster of the primary particles which are called aggregates and peds.
• Structure can be modified by cultivation and tillage operations while texture is an inherent property of soil and cannot be modified within short period of time.

Soil structure is most usefully described in terms of:-

1. Type of aggregates (form),
2. Class (average size) and
3. Grade (degree of aggregation)

Types of Soil Structure:-
Based on the shape and arrangement of peds or aggregates, soil structure is classified into four principle type –plate like, prism like, block like and spheroidal structure.

1. Plate like:-

• In this type, the aggregates are arranged in relatively thin horizontal plates or leaflets. The horizontal axis or dimensions are larger than the vertical axis
• It is commonly found in forest soils, in part of the A- horizon, and in claypan soils. When the units/ layers are thick they are called “ platy” and when they are thin then it is “ laminar”.

2. Prism-like:

• In prism like structure, the vertical axis is more developed than horizontal, giving a pillar like shape. They are commonly found in the subsurface horizons of semiarid and arid regions.
• The prisms having rounded tops are called columnar and mostly occur in subsoils of salt-affected soils. When the tops are flat or level the structure is termed as “ prismatic”.

3. Block like:-

• The structure is blocky when soil particles cling together in nearly square or angular blocks having more or less sharp edges.
• The peds have sizes varying from 1 cm to 10 cm. There are two types- angular blocky and sub-angular blocky.
•  They are commonly found in the B-horizon where clay has accumulated.

4. Spheroidal:-

• Here the individual particles of sand, silt and clay are grouped together in small, nearly spherical grains.
• When the peds or aggregates are relatively non-porous, they are called granules and porous granules are termed as crumbs.
• They are commonly found in the A-horizon of the soil profile.

Agriculture Soil Science Study Point