4. To get good yields from wet paddy cultivation, the farmer must
· Be In control of the water have enough water when the rice is growing, add more water at the right time, take water away (drain) at the right time, have the right depth of water.
· Make good nurseries so as to have fine seedlings for transplanting.
· Transplant at the right date, In rows
· Prepare the soil of the rice field well by tillage and level It
· Tend the rice field carefully Cultivate whenever any weeds have grown. Apply fertilizers, flood the field, protect the rice from pests.
· Harvest with care, and dry the paddy grains well.
5. Laying out a water control system in a rice field means to arrange a tract of low- lying land so as to be In control of the water.
These arrangements are not the same
· when the water comes from a river, a spring or a small stream;
· when the rice field depends on a big river or when it depends on a small stream.
We shall see how the farmer can control the water for a small field.
He can do a very large part of the work himself.
He will not have to spend much money, but he will have to do a great deal of work.
We shall study the layout of a water control system for a rice field using a stream that carries water all the year round or during several months of the year. Before starting on the work, ask advice from the technicians.
A well- made water control system lasts a long time, and the work does not have to be done again in the following years.
6. Water control system for a rice field
You will refer to this drawing frequently as you read the following pages.
Water control system for a rice field
7. Dams are small barriers across the stream. Dams hold up the water, so that the water of the stream rises. In this way, the water of the stream overflows into the low- lying land.
It is best to have concrete dams.
They cost more, but they last longer.
The good harvests of the following years will pay for the dams.
The technician will tell you where to build your dams.
Building the dams
8. When the dam is built, dig irrigation channels around the edges of the field.
These are called main Irrigation channels. Dig also, right through the middle of the field, the main drain.
The water flow starts from the dam.
It goes into the main irrigation channels.
It floods the rice field.
It goes out of the rice field into the main drain, which is the channel for the outflow of the water.
9. The main irrigation channels take water to the whole of the field.
Digging the main irrigation channels
They follow the outside edges of the field.
The channels must be big enough to let the water flow through well.
If the field has no slope, the channels must be dug deeper near the second dam.
They follow the outside edges of the field.
10. The main drain starts at one dam and ends at another dam.
It is dug with a hoe and a shovel, right through the middle of the field. Dig it as straight as possible: if it is not straight, the water is slowed up and can destroy the levees.
Levees are little walls on both sides of the drain. These walls are made with the earth dug out when digging the drain. The main drain carries away the water after it has irrigated the rice field.
Levees are little walls on both sides of the drain
11. The distribution channels carry the water to all parts of the field. They branch off the main irrigation channel. The feeder drains take away the water from the rice field, and carry the water into the main drain.
The distribution channels carry the water to all parts of the field
12. All the channels should be quite straight.
The earth dug out in making the channels is used to build the
Pack the earth down firmly on the levees so that you can walk on them.
The channels divide the whole field into small fields which are called plots.
The channels should not be wider apart than 20 metres.
All the channels should be quite straight.
The channels should not be wider apart than 20 metres
13. The field Is divided Into plots.
Often the ground of the plots slopes. With sloping ground, it is impossible to have the same depth of water everywhere. To get the same depth of water everywhere, you must have ground that has no slope.
To get ground without slope, divide your plots Into
Checks are made by building bunds.
These are small earth embankments, each 30 centimetres high and 40 centimetres wide.
If the slope is steep, make many small checks.
Pack the earth of the bunds down firmly, so that you can walk on them.
Build the bunds so that they follow the contour lines.
The field Is divided Into plots
So that you can walk on them
Build the bunds so that they follow the contour lines