According to the Food and Agricultural Organization of the United Nations[i], food and nutrition security of millions of farming households in Sub-Saharan Africa (SSA) are threatened. Although challenges are many and include high costs of agricultural inputs and unstable markets, climate variability is increasingly becoming more important. This is because farming households in SSA depend on rainfall and only a small percentage have irrigation technologies. Rain fed agriculture is vulnerable to climate change and climate variability, which manifest as erratic rainfall, temperature increase, prolonged drought and heat waves. It is no secret that the rains have not been coming the way they used to because of climate change. In the case of Zambia, since the 2019 drought (where man-made rivers and wells dried up, crops wilted and livestock died from the heat wave), prolonged dry spells and late onset of rain have been recorded[ii]. Rain fed agriculture in Zambia is highly unpredictable and rainfall varies from year to year especially in regions vulnerable to droughts such as the valley areas. This has led to household food and nutritional insecurity, chronic malnutrition and calorie deficit.
Depending on rain fed agriculture cannot be without its challenges and as such, whenever possible it is imperative to have an irrigation system in place as one ventures into agriculture. This article will present on simple irrigation techniques that can be applied to reduce the impact that climate change has on rain fed agriculture. Irrigation is something that can be done by anyone, even new farmers. People usually associate it with high financial requirements but there are different ways of doing it to suit different levels of income.
What is irrigated agriculture, you may ask. Irrigated agriculture is the science and art of harvesting and making the best use of water to increase agricultural productivity. There are many different techniques that are affordable and easy to use for small scale farmers. Four of them will be discussed below. These vary according to the plants you want to grow, your budget and water source.
Manual irrigation includes watering the plants by hand either using a hose, watering can or a bucket. That is what I have been using at my small vegetable garden, a bucket. It is a very common way of irrigation though time consuming and physically demanding therefore can only be sustainable on a small field. You can use this type of irrigation on any type of plants. It is the best method of irrigation for leveled fields in soils that have low infiltration. It has almost zero economic investment requirements.
Figure 1: Manual irrigation using a bucket
However, there is a lot of wastage of water with the use of manual irrigation because water reaches the crops in disproportionate quantities and may lead to water logging. Manual irrigation has an imbalance in distribution of labor which simply means that there is a possibility of one portion of the plants receiving more water when watering than the other. If one has no running water, it is important to invest in water saving devices and techniques. This may include purchasing large drums for water storage, rainwater harvesting, watering the plants with grey water (water that was used for washing plates or bathing; one must be careful not to use this type of water on seedlings as it may contain some fungal diseases that can kill your plants), digging shallow wells and mulching. It is further advisable to avoid watering your plants when it is too hot to reduce on evaporation rather the watering should be done earlier in the day or in the evening. Take note that not all plants need a lot of water. For example, spinach, peas, okra, watermelons, sunflowers and squash need less water and hence it may be ideal to opt for these crops to save water and make the irrigation process less strenuous.
Figure 2: Water storing drum for manual irrigation.
Sprinklers are a common feature on many commercial farms. There are some for small scale farming too. They are easy to use and budget friendly. These small scale sprinkler kits comprise of 3 sprinklers on tripods with pipes and rely on pressurized water supply. They can irrigate up to 250 m2. Sprinklers are attached to a hose with connectors. The water is supplied by either a water pump or water tank. One disadvantage of this system is that the water droplets going round in circles are not as efficient (meaning not all the water from the sprinklers is used by the plants, most is usually wasted) as the water coming from drip or manual irrigation.
Figure 3: Sprinklers in a vegetable garden
This kit costs about ZMW 600. The price points may differ according to the brand and pieces in the kit. For beginners, there is a Do It Yourself (DIY) way of setting up a sprinkler system. You will need an empty 2-litre bottle. Clean the bottle and poke at least 12 holes in it then connect the hose to the bottle. Make sure you tape off the bottle at the mouth so that there is no leakage. You can hang the bottle in trees or just place it on the ground. Sprinklers are suitable for cereals, vegetables and groundnuts.
Figure 4: A DIY sprinkler on the lawn
Though not common, mist irrigation is quick and irrigates a wider area as compared to drip lines. It works by spraying a mist of water onto the plants, reducing the temperatures and increasing humidity. It is similar to drip in that it uses hosepipe lines but differs in that it has misters which release water at a high pressure onto the plants whereas with drip irrigation the water droplets go directly to the roots.
A mist irrigation kit usually has a hose, misters, fittings and adapters which cost approximately ZMW 1, 250 depending on the size of the kit. In this irrigation type, the water runs through the hose from the source then when it reaches a sprinkler, the water flow is interrupted and the water is broken down into drops which are then released through the misters as mist onto the plants. It is good for propagation of rooted cuttings. Mist irrigation is recommended in fields with shallow sandy soil (has high infiltration rate), if the land is steep and if water is in short supply (as it is more efficient).
Figure 5: A misting system in a vegetable garden
This system is not as efficient as drip irrigation and may have high start-up costs if you have to purchase equipment but there is a way in which an average farmer can afford this irrigation type. This can be done by creating your own misting system using locally available resources. You will need to create tiny holes in a hose or PVC pipe and connect it to the water source. Depending on the pressure at the source, you might need to hang the pipe above your vegetables so that gravity aids the pressure. If not, there is need to get a small water pump to aid the pressure.
Another way in which mist irrigation can be achieved is by overhead watering techniques using recycled empty plastic bottles. This can be done by creating tiny holes in the lids of several bottles, cutting the other end open and tying them upside down on sticks above your plants. One bottle can cover five plants depending on how high the bottles are hung. When it is time to water the plants, just add water to the bottles and watch the mist go. This method can be used especially if you have no water tanks. Simply get water from the source to the bottles. It can also be used for drip irrigation but this time move the bottles to the base of the plants. Misting plants is a simple and effective way to boost humidity without overwatering your plants. It uses less water as compared to sprinklers.
Drip irrigation is one of the most efficient ways of irrigating and it is budget friendly too. This type of irrigation uses hose pipes with holes in it to drip feed water to the plant base. The water is transferred from the water tank to the drip lines by gravity which aids the slow movement of water. A drip system is very efficient as it reduces evaporation, water loss and overwatering. An alternative to an overhead tank is the use of a 20-litre bucket with one or two rows of lateral drip lines 5 to 10 meters in length, depending on the space available. It can irrigate up to 20 m2. The bucket can be hung from a tree or pole one meter high.
Figure 6: A DIY drip irrigation system (Source: Padala Manuel, 2011)
The irrigated area can be expanded up to 1000 m2 by using a larger drum placed at an average height of 1 to 1.5 m. It is suitable for any type of plants, including flowers. Mr. Shaba a farmer in Chongwe District has been using drip irrigation for his tomato and cabbage fields and has managed to extend his farm to grow other crops. “I now grow tomatoes all year round and I am able to educate my children,” he said. Below is a picture of his cabbage field that uses drip irrigation.
Figure 7: Mr. Shaba's cabbage field
It is important to note that costs can vary based on the availability of water, the size of the irrigation system and area you choose to use. Getting water can cost more if you have to drill a well but setting up small systems can cost about ZMW 1, 130 to irrigate a small garden of 200 m2. Setting up large fields that require pumps and piping may cost from ZMW 12, 000 up to ZMW 20, 000 depending on how large the area. Farmers are encouraged to use readily available materials around them to avoid the costs mentioned above.
There are many advantages that come with irrigated agriculture. These include all year round business thus reducing poverty while increasing the household income, better nutritional diets for the farmers that grow vegetables and employment opportunities for the youths on larger farms. Irrigation boosts production and helps crops resist insects and diseases. This will encourage agricultural led development.
Ultimately, these small scale techniques are progressive, but it is not always certain that the gains will be immediately realized because of factors such as unavailability of water and costs of equipment. Therefore, this is more of a step in the direction to recovery for any small scale farmers trying to combat the effects of climate change. Start small with what is available and then expand accordingly. With help from fellow farmers, organizations offering farmer support schemes and the government, together we can turn farming into a business through irrigation.
[i] FAO, ECA and AUC. 2020. Africa Regional Overview of Food Security and Nutrition 2019. Accra. [ii] IFRC, 2020. The World Disasters Report 2020: Come Heat or High Water- Tackling the Humanitarian Impacts of the Climate Crisis Together. Geneva. +
Palada M., Bhattarai S., Wu DL., Roberts M., Bhattarai M., Kimsan R., Midmore D. 2011. More Crop Per Drop: Using Simple Drip Irrigation Systems for Small Scale Vegetables Production. AVRDC-The World Vegetable Center, Shanhua, Taiwan.