unit 3:

Soil and Water Conservation Practices

Soil and Water Conservation refers to management and land use practices that protect the soil against erosion and reduce the use of and need for irrigation of the crops.

The following are conservation practices/measures common to the Guyana crop producer:

Contour Cropping
Strip Cropping
Terracing
Fallowing

Contour Cropping

This involves making ridges across the slope rather than up and down the slope. The ridges help to slow down the flow of water, reducing the amount of soil being washed away.

It:

reduces soil erosion up to 50 percent,
controls runoff water,
increases moisture infiltration and retention

In these ways it enhances soil quality and composition.

Best practiced on slopes between 15 to 20 degrees, it is a very cost effective and a sustainable practice when properly planned and applied.

It enables more efficient land use. By following the natural contours when tilling the soil, planting and cultivating, this practice mitigates climate impacts on crops, enhancing soil quality and composition.

Contour beds can be further strengthened by using one or more of the following methods:

• Plant grass barriers along alternating beds of at least 30 to 40 feet (915 to 1 220 cm) between beds.

• Construct a stone/bamboo embankment on the front edge of each bed using large stones at the bottom with smaller stones at the top (bamboo should be replaced ideally every five years).

Contour Cropping

Strip Cropping

Small strips are left uncultivated between crops to reduce/prevent water runoff. Grasses may be planted here to form a barrier strip. Strip cropping is effective on gentle slopes where the hillside is converted into a series of slopes.

This arrangement of strips reduces water and wind-induced soil erosion and reduces the transport of sediment and other water-borne contaminants so the water quality can be maintained; and thus increases soil moisture.

The effectiveness of this practice is maximized when the strips are as close as possible to the contour. Arrange crops so that strips requiring intense cultivation but which offer less protective cover are alternated with more permanent crops that offer greater protective cover during times when erosion is expected to occur.

E.g. Strip 1 would use corn, a more permanent crop, as a protective cover for strip 2 where the more intensive cultivation of vegetables can occur.

It is important to note that strip cropping is most effective when used as part of a resource management system integrating a variety of conservation practices, such as crop rotation, minimum tillage, etc.

Strip cropping is one of the least costly conservation practices to implement.

Strip Cropping

Continuous Terracing

Discontinuous (Basin Type) Terrace

Transitional Type (Convertible) Terraces

Intermittent Terraces

Broadbased Graded Terrace

Natural (Dyke) Terraces

Terracing

Hilly area are levelled in the form of steps so that planting is done on the horizontal platforms. Vertical section are used as a retaining wall.

There are several types of terracing:

Continuous type (Bench Terraces):

Bench terraces are a series of level or virtually level strips running across the slope at vertical intervals, supported by steep banks or risers. Bench terraces are used in order:

To reduce run-off or its velocity and to minimize soil erosion.
To conserve soil moisture and fertility and to facilitate modern cropping operations i.e. mechanization, irrigation and transportation on sloping land.
To promote intensive land use and permanent agriculture on slopes and reduce shifting cultivation.

Discontinuous type:

These terraces are not continuous, occurring immediately right after the other, but occur at intervals along the slope. They are used in order to:

To break up long slopes into several shorter slopes, thereby reducing erosion.
To intercept excess run-off from the land above and drain it safely.
To provide erosion control practices for orchards situated on sloping land.
To provide for moisture conservation, better weed control and fertility management of tree crops.
To serve both as access roads and as drains.

Transitional type:

Transitional terraces are bench terraces built, usually at specified intervals, over a period of time. Unlike the continuous type, they do not occur immediately after each other. Transitional types of terraces are used:

To fit in with the mixed agriculture farming systems practised by small farmers.
To allow for future development and provide flexibility for future land use.
To protect cultivated slopes with a simple terracing system by initially terracing part of the area.
To enable the farmer to spread out over a period of years the cost and labour involved in a terracing operation.
To do a quick rehabilitation job over a large area.
In semi-arid regions, to collect run-off from the slope for irrigation of crops grown on the benches.

Drainage type: - Broadbase graded terraces

These are a series of broad channels and embankments constructed at a suitable spacing along the graded contours of gentle slopes. The terraces are built with either a variable or uniform, non-erosive grade leading to a safe outlet. They are also called channel terraces. They are constructed in order:

To reduce slope length and minimize erosion.
To intercept run-off from cultivated land or rangeland at frequent intervals and divert it to protected waterways or run-off disposal areas.
To use spacings between each terrace and the ridge of the terraces for growing crops or forage.

Absorption type:- Broadbase level terraces

These terraces are constructed on a true contour with a ridge which act as an impounding reservoir when the ends are closed. Like the graded type, they are built across gentle slopes at a suitable spacing. They are also called ridge terraces. They are constructed to:

To reduce slope length.
To intercept run-off and facilitate infiltration

Soil retarding type:- Natural terraces

These are initially constructed as low contour dykes using either earth or rocks. They are employed on gentle slopes for the purpose of gradually forming level bench terraces over several years of cultivation. The terraces can have either a horizontal gradient or be level, depending on climate and soil conditions. Rock dykes can be built where rocks are available on the site. The use of rocks will not only strengthen the dyke but also help clear the field, thus facilitating better tillage. They are constructed in order to:

To break long slopes into a series of shorter slopes.
To reduce run-off and soil erosion by restraining water flow along the contour dykes.
To gradually form natural terraces for cultivation purposes.
To save on the labour required for constructing full bench terraces.

Fallowing

The practice of alternating between planting crops for three years and then leaving the land uncultivated for some time to regenerate.

It is an effective water conservation technique extremely important in very dry areas.

After the introduction of new equipment, pesticides and fertilizers, it was considered unprofitable.

However, recently it has been shown to be a sustainable practice with many benefits. These benefits are:

it replenishes nutrients lost from the soil due to uptake by plants and irrigation.
reduces soil loss by wind and erosion.
improves soil structure.
it saves money on fertilizers and irrigation.
it builds up soil organic matter which:
- improves soil moisture retention.
- increases the abundance of soil organisms.
provides a wildlife habitat for migratory birds and animals.

A cover crop can be planted or livestock can be reared on fallowed land.

Soil Conservation Practices Quiz

Match the correct definition with the correct practice

a. Practices that protect the soil against erosion and reduce the need for crop irrigation.

b. Crops are planted along the contours of a slope rather than up and down the slope.

c. Small strips of crops are cultivated with some strips being uncultivated.

d. Bench terraces built at specified intervals over a period of time

e. A series ofbroad channels and embankments constructed at a suitable spacing along the graded contours of a gently slope.

f. A series of ridges which act as an impounding reservoir constructed at a suitable spacing across a gentle slope.

g. Low contour dykes constructed for the purpose of gradually forming level bench terraces over several years.

1 Contour Cropping

2 continuous terrace

3 Soil and Water Conservation

4 discontinuous terrace

5 Strip cropping

6 natural terraces

7 ridge terrace

8 transitional terrace

9 channel terrace

Match the correct advantage with each type of terrace

intercept runoff from cultivated land or rangeland at frequent intervals and divert it to protected waterways.

break up long slopes into several shorter slopes, thereby reducing erosion.

allow the farmer to spread out the cost and labour required to construct the terrace over a number of years.

gradually form natural terraces for cultivation purposes.

promote intensive land use and permanent agriculture on slopes.

intercept run-off and facilitate infiltration.

10. Continuous terraces

11. Discontinuous terraces

12. Transitional terraces

13. Drainage type terraces

14. Absorption Type Terraces

15. Natural terraces

Write T if True or F if False...

16. Contour cropping reduces soil erosion up to 50 percent.

17. Contour cropping increases moisture infiltration and retention.

18. Contour cropping is the least costly practice to implement.

19. Contour cropping is effective on gentle slopes

20. Contour cropping can be strengthened by planting grass barriers along alternating beds.

21. Strip cropping is ineffective on gentle slopes.

22. Strip cropping reduces water and wind-induced soil erosion.

23. Strip cropping maintains soil water quality and this decreases soil moisture.

24. In strip cropping, permanent crops which offer protective cover are planted beside more intensively cultivted crops.

25. Strip cropping is the most costly method to implement.

Fallowing Quiz

Answer the following questions in your portfolio. You can also fill out the same quiz in the form below if you have the data.

What is fallowing?
Why do farmer's allow their ground to fallow?
Why did fallowing become unpopular?
What was the consequence of forsaking fallowing?
Why is fallow important to good crop rotation?
What are three benefits of fallowing?

These practices are best implemented in conjunction with each other as well as other practices such as crop rotation, hedge planting and agro-silvoculture among others.

Discussion

Let's do a review of the lesson...

Post under the appropriate topic in the Forums what you learnt, what you would like to learn and what you do not understand.

References:

Grade 9 SCCP Crops and Soils Manual
FAO. Soil Conservation: Contour Ploughing, Grenada. <http://www.fao.org/3/CA3549EN/ca3549en.pdf>
FAO. Diversified Cropping System: Strip Cropping, Grenada. <http://www.fao.org/3/CA3550EN/ca3550en.pdf>
FAO. Watershed Manual Field Manual: Slope Treatment Measures and Practices <http://www.fao.org/3/ad083e/AD083e00.htm#cont>
Larum, D. What Is Fallow Ground: Are There Any Benefits Of Fallowing Soil <https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/what-is-fallow-ground.htm >
Niesen, D. C. and Calderon F. J. 2011. Fallow Effects on Soil David Francisco <https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2396&context=usdaarsfacpub >
Contour cropping Image <http://ecoursesonline.iasri.res.in/pluginfile.php/2174/mod_page/content/1/fig-22.1.jpg>
Strip cropping Image <https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcSeKnvCKf5cRCFYq7MRQW60rJLUi1wh4-53sw&usqp=CAU>
COntinuous Terracing Image <https://ccafs.cgiar.org/sites/default/files/resize/images/Fanya%20juu%20terraces_Diagram_Eng-1300x807.jpg>
Discontinuous Terracing Image <http://www.fao.org/3/ad083e/images/m30e36.jpg>
Convertible Terrace Image <http://www.fao.org/3/ad083e/images/m30e37.jpg>
Intermittent Terraces Image <http://www.fao.org/3/ad083e/images/m30e38.jpg>
Broadbased Terrace Image <http://www.fao.org/3/ad083e/images/m30e46.jpg>
Dyke Terracing Images <http://www.fao.org/3/ad083e/images/m30e61.jpg>

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