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Five methods to maximise water use for greater yields

Friday June 23 2017

Workers inspect demonstration plots on which inorganic mulching technique is used at Wambugu Agricultural Training Centre in Nyeri.

Workers inspect demonstration plots on which inorganic mulching technique is used at Wambugu Agricultural Training Centre in Nyeri. The technique involves using a polythene sheet as mulch which is effective in weed control too. PHOTO | JOSEPH KANYI | NATION MEDIA GROUP 

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As water becomes more scarce and the rains consistently fail in many parts of the country, farming is becoming a costly affair due to high water prices.

It is, therefore, time for farmers to adopt various techniques that can help them use water efficiently to produce more food.

The Seeds of Gold team toured Wambugu Farm on the outskirts of Nyeri town and had a chat with John Wambugu, the chief agronomist at the institution, to explain some technologies that you can employ to maximise water use.

The technologies are:

Plastic or inorganic mulching

This involves use of a specially made white polythene material to mulch crops. The material deflects heat thus conserving water as it creates a micro-climate for the crop to grow faster.

Further, it helps to wards off insects thus increasing the crop yields.

“The sheets help conserve water and suppress weeds and also boosts the soil temperature thus effectively increasing the yields,” says Wambugu.

To employ the technology, one must first make a raised bed and apply manure on the soil. The manure helps the soil retain water.

A farmer then places drip lines on the beds for irrigation and later the polythene sheet and tucks it in the soil.

One then pokes round holes on the polythene paper, which must be in sync with the drip holes and plant any crop they intend to grow.

These include tomatoes, French beans, collard green (sukuma wiki) and cabbages.

However, the spacing on the polythene sheet depends with the crop as some require wider space. A square metre of the sheet costs Sh225.

John Wambugu explains the benefits of inorganic mulching.

John Wambugu explains the benefits of inorganic mulching as he tends crops grown using the technique on a plot at the Wambugu Agricultural Training Centre in Nyeri. PHOTO | JOSEPH KANYI | NATION MEDIA GROUP

The technology can be used both inside greenhouses and in open fields. However, in greenhouses one must use a grey polythene sheet to ensure there is no reaction with ultra-violet rays to interfere with photosynthesis.

Oasis gardens
This involves a farmer digging a two feet deep and one metre wide trench and spreading a polythene sheet on the floor of the trench.

One then lays at the centre of the bed a perforated, L-shaped PVC pipe inside the trench through which water will be supplied to the garden.

The pipe should be filled with pebbles to prevent blockage when soil is placed inside the trench.

Thereafter, soil mixed with manure is laid on the trench to create a garden. On one end of the trench there must be an opening to ensure excess waters drains away.

“The polythene sheet helps to ease flow of water in garden, where one can plant vegetables. The paper prevents seepage of water to the ground,” said Wambugu.

Sunken beds

These are the opposite of raised beds, as they are “valleys” instead of a “mountains”. The beds normally have more accumulated water and are richer in organic matter.

To create sunken beds, a farmer digs into the ground and mixes the top soil with manure. The crops will be planted in the valley.

“Sunken beds are designed to maximise water collection and store water until it can be absorbed by the soil,” says Wambugu.

The advantage of sunken beds, besides saving water, is that while crops in raised beds defrost faster in cold weather, sunken beds keep the crops warmer.

Further, the valley space helps in the accumulation of organic material and makes it harder to be washed away. This organic matter reduces water consumption and boosts soil fertility.

Multi-storey gardens

This is also referred to as bag culture, sack gardening or vertical farming. The technology facilitates growing of vegetables in areas without suitable soils or adequate space, promotes efficient and effective utilisation of available water.

Spinach grown inside 'greenhouse kadogo'.

Spinach grown inside 'greenhouse kadogo' at the Wambugu Agricultural Training Centre in Nyeri. PHOTO | JOSEPH KANYI | NATION MEDIA GROUP

You need a manila bag of desirable size, top soil and well-decomposed compost or animal manure, gravel, cylindrical can open on both ends, clean water, watering can or hose pipe, a knife or any other tool for cutting through the bag and clear plastic sheet.

The top soil and manure is mixed in the ratio of 1:1. In order to eliminate soil-borne pests and pathogens, the media should be treated by moistening the mixture, covering with clear plastic sheet and subjecting it to strong sunlight for one to two weeks.

Once the bag is filled with the soil, planting holes are prepared by making T-cuts on the sides of the sack at a regular spacing (at least 30cm apart) if one is growing collard green.

Water is applied on top of the gravel forming a column or core in the centre of the bag. This can also be utilised for fertiliser application if necessary.

Upland arrowroot technology

This technology is used in growing arrowroots away from the swamp or river. One starts with digging a trench then placing a polythene sheet on the ground and adding soil on it before planting.

The polythene is to ensure there is no water seepage to the ground.

Arrowroots grown using this technology mature in six months and a farmer only waters the crop countable times as the beds provide the required moisture for the crop to grow.

Trough farming

This is the cultivation of crops using containers and can be used to farm vegetables and fruits like strawberry on small scale.

A farmer puts a mixture of soil and manure in a trough before planting.

A storied kitchen garden

Spinach grown on a storied kitchen garden at Wambugu Farm in Nyeri. PHOTO | JOSEPH KANYI | NATION MEDIA GROUP

Each trough hosts between five and seven plants which can be a mixture of Sukuma wiki and spinach. The garden is good for people living in urban areas as they do not have space for farming.

If one gets two containers with 14 crops, for instance, a jug of water is enough for the plants a day. Unlike gunny bags which do not retain water, the containers help in efficient use of water and are good in places where water and space is scarce.

According to Mr David Kariuki, an agriculture officer in Nyeri, crops grown using such technologies require less water and save farmers from spending more.

However, he noted that polythene is biodegradable thus posing a challenge to the environment if it is improperly disposed.

“It acts as a pollutant that interferes with the environment. Farmers should ensure they dispose the polythene well to avoid degrading the environment,” he said.