Reducing Soil Movement and Soil Erosion through Conservation Tillage

Many practices are used to reduce soil erosion and con serve soil. Conservation tillage is one of the most widely promoted and adopted practices around the world (Box 4).

Conservation tillage reduces the vertical movement of soil, leaving more crop residue on the soil surface, thereby reducing the soil's exposure to wind and water erosion. Most conservation tillage practices also reduce the horizontal movement of soil, which normally reduces tillage erosion.

One of the most commonly used practices in converting from conventional tillage to conservation tillage is the use of a chisel plow rather than a moldboard plow. The chisel plow leaves far more crop residue on the soil surface. Although the chisel plow reduces the risk of wind and water erosion, it may not reduce tillage erosion. This is because the chisel plow can move as much soil horizontally as the moldboard plow and it can move it to a greater distance.

Box 4 Tillage systems

The tillage operations used in preparing the seedbed define the tillage system used in producing a crop. Those systems which use the moldboard plow are often referred to as conventional tillage. Those systems which use chisel plows instead of the moldboard plow are often referred to as conservation tillage because they cause less soil inversion and leave more crop residue on the soil surface to protect against wind and water erosion. Conservation tillage systems can also include the use of the moldboard plow if it is used in the spring rather than the fall and/or if the intensity of secondary tillage operations is reduced compared to the convention, leaving more crop resi due on the soil surface for a greater length of time. Those systems which rely solely on the tools of the seeder/planter to prepare the seedbed are referred to as no till or zero till. The meaning of the terms conventional tillage and conservation tillage are relative and differ from region to region and change over time.

Table 5 Soil loss caused by the harvesting of potatoes

Study location

Years of study

Potato yield per harvest (Mgha 1)

Soil loss per harvest (Mgha 1)

United Kingdom

1967

31

30.7

Russia

1985

6

2.1

Russia

1985-86

13

0.5

Belgium

1999

47

15.3

The Netherlands

2000

53

7.8

France

2001

50

5.5

Belgium

2002

68

14.4

Belgium

1999-2001

45

2.1

Belgium

2002-03

48

3.2

Another conservation practice is the reduction in the number of passes of disks and cultivators used in second ary tillage operations. The most extreme form of conservation tillage is the use of no till or zero till systems. In these systems, both primary and secondary tillage operations are eliminated and the crop is seeded directly into the untilled soil (into the residue of the preceding crop). This eliminates tillage erosion from these operations and reduces the susceptibility of the soil to wind and water erosion by leaving crop residue on the soil surface and maintaining soil structure. Although no till and zero till systems eliminate tillage erosion from primary and secondary tillage operations, they can still result in significant soil movement and tillage erosion during seeding.

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