soil & water management

MANAGEMENT OF NATURAL

RESOURCES

(SOIL,& WATER, )

Man has been relaying on the natural resources to meet

the basic requirements since time immemorial. With the

unprecedented increase in the population during the last few

decades, clearly mankind faces formidable problem to ensure

food and nutritional security for all, considering reduced per

capita land, reduced availability of water, depleting biodiversity

and need to preserve ecology and environment. The physical and

biological environment of the earth is so rich in its potential that

is can support the need of its inhabitants for a long time to come.

However, the man’s greed rather than his needs is putting

enormous pressure in the capacity of the biosphere resulting in

over-exploitation of the natural resources, as the demand is not

within the paradigm set by ecological constraints.

  The natural resource management at most places in the

world including India is inappropriate, exploitative and

unscientifically planned. Even today, land and water are being

exploited without restraint considering them inexhaustible, and

wastes are discharged freely into air and water assuming that

these have unlimited assimilative and carrying capacities. As a

result, very disturbing trends of natural resource degradation

have emerged. Human activities inflict harsh and often

irreversible damage on the environment and on the critical

natural resources. If not checked, many of our current practices

will put, at serious risk, the future that we wish for human

Society and the plant and animal kingdom.

Agenda 21 for Natural Resource management

The United Nations Conference on Environment and

Development (UNCED) at the earth summit held in Rio-deJanario,

Brazil in 1992 focused attention

on the harmful

effect of

development

of the earth’s life sustaining capacity. The

conference

also adopted Agenda 21- a global blue

print for

environmental action. It revolves around seven themes, one of

which is “Efficient use of natural resources of land, water,

energy, forests and biological resources”. This is unquestionably

the theme for the survival of humanity and for the sustainability

of future agriculture.

 Management of natural resources

 Land resource

India has only 2.4% of the land resource of the world to meet

their basic requirements of 18% of the world’s population and

over 25% of the world’s livestock. Nearly 57% of the land

resource in India is facing degradation due to water erosion,

wind erosion, loss of productivity and chemical and physical

degradation. About 5.3 million ha of topsoil is displaced every

year only through water erosion which also accounts for a loss of

8 million tones of plant nutrients. While most of the land

resource faces nitrogen deficiency, nearly 50% and 20% of the

land resource is deficient in phosphorus and potassium.

Deficiencies of micronutrients have been widely reported. It is

assessed that 8.6 million ha of agricultural land is affected by

both the problems of water logging and soil salinity. About 65%

of which is the most productive irrigated land resource. Added to

these the per capita arable land which was 0.121 ha in 1990,

0.176 ha in 1996 and 0.163 ha in 2000 is projected to be 0.121 ha

in 2025 and 0.087 ha when the population stabilizes by the year

2050 or later. Therefore, meeting all basic necessities from

degrading and low per capita arable land area of 0.087 ha is

bound to be major challenge and calls for appropriate soil

restoration and conservation technologies.

The best means of improving and maintaining soil quality which

determines soil productivity and environmental quality is

adoption of alternative agricultural practices such as crop

rotation, recycling of crop residues and animal manures, green

manures, biofertilizers and  intergrated nutrient management for

encouraging balanced use of fertilizers and manures, and reduced

use of pesticides. These are some of the components of a strategy

for obtaining sustainable high productivity in any farming

system. The relationship between the soil degradation processes

and soil conservation practices as outlined by Hamick and Parr

(1987) is shown in Fig.8.1.

Soil degradation     Soil Conservation

Processes      processes

• Soil erosion     Conservation tillage

• Nutrient     crop rotation

Runoff loss

• Water logging    Improved drainage

• Desertification    Residue 

                                                            management 

    

• Acidification    water conservation

• Salinization     Terracing

• Compaction     Contour farming

•  

Soil

productivity

NEGATIVE    POSITIVE

• Crusting     Organic fertiliser

• Organic matter loss   chemical fertiliser

• Nutrient depletion    Improved nutrient

By leaching     recycling

• Toxicant application   Improved system to

Match soil, climate

and cultivars

Relationship between soil degradation processes and

soil conservation practices

 Water resource

Water is one of the most important natural resources vital for

economic development of a nation. The per capita water

availability presently estimated at 2001 m3/annum is projected to

come down to a stress level of 1700 m3/annum in the next 2-3

decades. The ultimate irrigation potential of the country has been

estimated at 139.5 million ha comprising of 58.5 million ha from

major and medium irrigation Schemes, 15 million ha from minor

irrigation schemes and 66 million ha from groundwater

exploitation. The present irrigated area in the country is about 53

million ha. It is estimated that even after achieving full irrigation

potential nearly 50% of the total cultivated area will remain rain

fed. During 1990 the total utilization of water for all uses, was

about 51.8Mha-m or 609 m3/capita/year. The projected water

demand to meet the requirement of domestic, industrial and

irrigation is given in Table 8.1.

. Requirement of water for various uses

 Category Water (Mha-m)

2010 2025 2050

1 Irrigation 55.6 73.4 119.1

2 Domestic 6.1 7.8 10.4

3 Industires 3.7 7.9 11.6

  65.4 88.1 141.6

  Water demand for irrigation

Year Low demand Medium demand High demand

Food grains

(m tones)

Water

(Mha-m)

Food grains

(m tones)

Water

(Mha-m)

Food grains

(m tones)

2010

249 489 265 536 271 576

2025

322 619 349 688 365 734

2050

469 830 539 1088 605 1191

Water

(Mha-m)

While the water demand for irrigation to maximize agricultural

production with the maximum possible level of irrigation to

achieve self sufficiency in food grains is given in Table 8.2.

 Thus water is a limiting factor for crop production and

scientific water management is the key for sustainable

agriculture both irrigated and rain fed farming systems. Growing

demand for fresh water supplies by industry, urban & civic uses,

low water use efficiency, prohibitive costs of irrigation

development, from poor water management makes agriculture a

poor competitor for its use. Therefore the available water must

be used most efficiently. The efficient use of this resource for

crop production consists of:

i)  Water conservation- it involves two steps (a) reduction of

runoff losses and increasing its infiltration in the soil through

land shaping, tillage mechanical structures and vegetative

barriers to reduce water flow, proper crop rotations, application

of soil amendments and mulching (b) reduction of losses through

deep drainage (by increasing water storage capacity & soil

moisture retentivity), and direct evaporation from soil (by

following shallow tillage, straw mulching).

 ii) Scheduling of irrigation to crops- the timing and amount of

irrigation to crops plays a significant role in optimizing crop

production with a given amount of water and avoiding effects of

either over-irrigation or under irrigation on soil environment.

Approaches to irrigation scheduling vary depending on situations

e.g., water is adequate irrigation water is available on demand to

secure potential yield and where available  supplies fall short of

the full irrigation water requirement of crops over the entire

command area.

iii) Maximizing the utilization of resource by crop and

maximizing returns per unit resource used by the crop- The

World Bank (1999) in a working paper on irrigation sector

observed that 25% improvement both in water use efficiency and

crop yields (WUE rising from 35 to 43%)  would generate an

additional food grain production of 85 million tones, which

represents an equivalent of 44% increase in food grain

production by the year 2025. This is the latent potential which

the country needs to exploit. The ICAR experts feel that

irrigation water use from the present level of 40% is possible to

increase to 60% with the adoption of water use efficiency

technologies. Using technologies such as sprinkler irrigation and

drip irrigation in commercial and horticultural crops, a WUE of

85 to 95% can be obtained.

iv) Conjunctive use of different sources of water for increasing

the returns from available water resources and reducing soildegrading

effect. Conjunctive

use of

saline water and canal water

can

be effective in avoiding

the deleterious

effect of saline water

on

crops. Judging

from

the present trends

it can be surmised

that

water

quality will become

most

serious

constraint

in future and

agriculture

have to use more

marginal quality water.

v)

Participatory irrigation management-Promoting

participatory

irrigation

management

through establishment

of

Water

User’s Associations (WUA).

The Government of Andhra

Pradesh

has established 10292 WUA

for effective maintenance

of

irrigation-

systems

and use of waters.

For

dryland agriculture, increased efficiency

of rain-water

is

essential

and it can be achieved

in the following

ways:

1. Retain  precipitation in situ and minimize the run-off,

2. Reduce evaporation in relation to transpiration,

3. Growing drought tolerant crops that match the rainfall

pattern

4. Recycle the run-off drainage water for high value crop

adopting life saving irrigation approach

5. Watershed approach for maximization of rainwater

harvesting and recycling and

6. Ensure farmers’ cooperation by assuring equity in

distribution of benefit and maximization of the

profitability of cropping system.

The can be achieved by following practices viz., contour

cultivation, bench terracing, strip-cropping and different types

of land configuration: Storage structures viz., farm ponds, low

earthern dams, nala bunds and percolation tanks: Agronomic

practices viz., tillage practices, fallowing, crops and cropping

systems versus water availability periods, mulching,

manipulation of plant geometry etc.