The document discusses biological soil conservation methods. It describes several methods such as contour farming, crop rotation, strip cropping, choice of crops, mulching, cover crops, reforestation, mixed crops, and wind breaks. These biological methods help maintain soil cover and reduce erosion by decreasing runoff, increasing infiltration, and reducing the velocity of water flow. The methods are effective because they are low cost and protect the soil through different planting techniques and crop choices that sustain soil productivity and quality over time.

1. SOIL GEOGRAPHY
GGY - 428
S.Lathiscumar,
A/11/427,
Department of Geography,
University of Peradeniya.

2. Topic:
Soil conservation method - Biological

3. Content
• Introduction
• Biological conservation methods
– Contour farming
– Crop rotation
– Strip cropping
– Choice of crops
– Mulching
– Cover crops
– Reforestation
– Mixed crops
– Wind breaks
• The important of biological method in soil conservation
• Conclusion
• Reference

4. 1.1 What is the soil?
o Soil is a thin layer of the Earth’s Crust.
o Formed by mineral particles, organic matter,
water, air and living organisms.
1.2 What is the soil conservation method?
Soil conservation method is a set of management strategies for prevention of
soil being eroded from the Earth’s surface or becoming chemically altered by
overuse, acidification, salinization or other chemical soil contamination.
Soil conservation method
Mechanical Biological
1. INTRODUCTION

5. 2. Biological Conservation method
Biological conservation method is various ways of maintaining a cover of vegetation
during the periods of high erosion risk.
Biological method are an effective method of soil conservation.
 Several types of biological soil conservation methods exist. Those are:
• Contour farming
• Crop rotation
• Strip cropping
• Choice of crops
• Mulching
• Cover crop
• Reforestation
• mixed crop

6. 2.1 Contour Farming
 Contour farming is the farming practice of planting across a slope following it elevation
contour lines.
 Farming on the contour creates small ridges that slow runoff water, and it increases the
rate of water infiltration, reduces the hazard of erosion.

7. 2.2 Crop Rotation
 The change type of plant grown on particular piece of land from year to year or
season to season.
Intercropping of erosion permitting crops and erosion resisting crops or their rotation.
Has been found effective for reducing soil loss.
 Return nutrients to soil.

8. 2.3 Strip Cropping
 Strip cropping is a method of farming used when a slope is too steep or too long.
 Strip cropping helps keep the soil in a long enlarge of land.
 this method becomes more effective for erosion control.
 the strip crops check the surface runoff and force them to infiltrate into the soil, thereby
facilitates to the conservation of rain water.

9. 2.4 Choice of crops
 Choice of crop is select the erosion resisting crops and cultivate.
Row crops or large growing crops such as sorghum, maize, pearl millet is not
protective in conserving soil.
 Whereas close growing crops such as cowpea, groundnut, green gram, black gram
etc., Those crops are soil erosion resisting crops. Then they very effective in reducing
soil loss.

10. 2.5 Mulching
 Mulching of soil with available plant residues reduce soil loss considerably by protecting
the soil from direct impact of raindrop and reducing the sediment carried with runoff.
 A minimum plant residue cover of 30 per cent is necessary to keep runoff and soil loss
within the acceptable limits.
 Vertical mulching also reduce soil loss
and increasing infiltration.

11. 2.6 Cover cropping
 cover cropping is good ground cover by canopy gives the protection to the land and
minimize soil erosion.
 Then conserving soil and moisture, the cover crops hold those soluble nutrients, which
are lost by leaching.
 The advantage of the cover crops is the addition of organic matter.
The legumes provide better cover and better protection.

12. 2.7 Reforestation
 Reforestation involves the replanting or regeneration of areas of forest which
have previously been damaged or destroyed.
 Forest mainly control the splash erosion. for the reason that plant canopy
decrease raindrop velocity.

13. 2.8 Mixed cropping
 Mixed cropping is the cultivation of more
than one type on a piece of land at the same time.
E.g. Corn and sugar beet.
 Here different kind of plants need different
level nutrition. Hence soil nutrition isn’t severe losses.
 Then harvest periods are different. Because different kind of plants. Always
cropping cover the surface. So soil erosion can control with mixed cropping.

14. 2.9 Wind breaks
 Wind break is a wind barriers created by planting trees that produce may
branches and leaves.
 This method is used at the edges of large farmland area to stop the wind from
blowing soil away.

15. 3. The important of biological method in soil conservation
 Maintain productive topsoil.
 Keep food safe and healthy.
 Reduce chemical fertilizers and pesticides.
 Keep farms economically possible.
 Sustainable options mimic past practices.
 prevents splash erosion and reduces the velocity of surface runoff.
 facilitates accumulation of soil particles.
 Increase infiltration.

16. 4. Conclusion
 Biological method of soil conservation is various ways of maintaining a cover of
vegetation during the periods of high erosion threat.
 Contour farming, crop rotation, strip cropping, choice of crops, mulching, cover
crop, reforestation, mixed crop, wind breaks are major biological soil conservation
methods.
 Biological method are an effective method of soil conservation. For the reason
that low cost.
 Biological method of soil conservation is reduce the surface runoff, increase the
infiltration and reduce the soil erosion.

17. 5. Reference
 Bennett, H. H., (1947) Elements of Soil Conservation, McGraw – Hill Book Company,
Inc, New York AND London.
 http://www.arkive.org/reforestation/
 https://www.blog.udemy.com/soil-conservation/
 http://www.brighthub.com/environment/science-environmental/articles/82947.aspx
 http://www.fao.org/docrep/004/y0501e/y0501e03.htm
 http://www.preservearticles.com/2012040429881/what-are-the-methods-of-soil-
conservation-18-methods.html
 http://www.teara.govt.nz/en/soil-erosion-and-conservation/page-7