Grade 7- Water retention - Agriculture

Water retention structures to conserve surface runoff

Water Retention Structures means a structure designed to retain a large volume of water

There are various methods of water retention to conserve surface runoff, this include:

Water retention Ditches

Ditches are man-made waterbodies that are used mainly to drain the land.

Water retention Ditches

Earth Basins

is an area of land where all flowing surface water converges to a single point

Earth Basins

Water retention pits

is an artificial pond with vegetation around the perimeter and a permanent pool of water in its design.

Water Retention Pits

Water Retention Pits

Minimum tillage practices that conserve water in farming

Tillage practices refer to the tillage operations carried out between the harvest and following sowing/cultivation operation. Tillage, crop rotation and soil cover are practices related to pesticide and nutrient runoff, soil erosion, soil compaction etc.

Some of the minimum tillage practices include:

1. Use of herbicides;

2. Uprooting/slashing;

3. Use of cash crops;

4. Limiting cultivation to the point planting;

5. Proper timing of cultivation;

6. Mulching

There are other different tillage practices distinguished are:

1. Conservation tillage

2. Conventional tillage

3. Zero tillage

Conservation tillage can include the following systems:

Strip tillage or zonal tillage

Refers to a system where strips 5 to 20 cm in width are prepared to receive the seed whilst the soil along the intervening bands is not disturbed and remains covered with residues. The system causes more soil disturbance and provides less cover along the rows than zero tillage.

Tined tillage or vertical tillage

Refers to a system where the arable land is prepared with equipment which does not invert the soil and which cause little compaction. For this reason, the surface normally remains with a good cover of residues on the surface.

Ridge tillage

 is a system of ridges and furrows. The ridges may be narrow or wide and the furrows can be parallel to the contour lines or constructed with a slight slope, depending on whether the objective is to conserve moisture or to drain excess moisture. The ridges can be semi-permanent or be constructed each year which will govern the amount of residue material that remains on the surface.

Conventional Tillage

Refers to the arable land treated by conventional tillage which involves inversion of the soil, normally with a moldboard or a disc plough as the primary tillage operation, followed by secondary tillage with a disc harrow.

Zero Tillage

Refers to the arable land on which no tillage is applied between harvest and sowing. Zero tillage is a minimum tillage practice in which the crop is sown directly into soil not tilled since the harvest of the previous crop. Weed control is achieved by the use of herbicides and/or appropriate mulching and stubble is retained for erosion control.