By James Kamau
With the weather forecasts indicating less than normal rains this season, farmers must conserve enough water to cater for the whole season.
Effective water collection is determined by available storage, method of irrigation, type of crops grown and the farm’s terrain.
Most farms rely on surface water sources such as rivers and lakes, ground water such as springs and aquifers or municipal water, which is stored in tanks or dams.
Some farmers have built their own ponds to collect excess runoff or floods from surface water bodies.
When conserving water consider the following factors:
1. Never allow water to flow in and out of your farm
When it is raining the most important task of the farmer is to stop, sink and spread water slowly. Do not allow water to flow in and out of your farm. Ensure it gets ample time to sink into the soil. Add compost to your soil to enable it to hold more water for longer periods.
Also, use techniques such as retention ditches, furrows and dams to trap your runoff water (TOF edition 175).
2. Protect your natural sources of water
Natural sources such as rivers, lakes, springs, soaks and waterholes need to be protected from pollution, salinisation and evaporation and careless human activities.
Chemical waste from factories, effluence from sewerage or other human activities can make the water common sources unfit for humans, plants and animals. Therefore, water sources should be protected from contamination.
A poorly managed water source will have poor quality water and poor habitat with little or no vegetation and lots of algae. They are usually exposed to direct access by animals.
A well-managed water body will have good water quality. To do this the following can be done:
- Restrict animal access to your water source. Instead, pump or feed to external troughs through gravity for redistribution to where it is needed on the farm;
- Create low impact fencing. Fence off the source of water using chain-link to control movement to and from the water source;
- Plant indigenous shrubs and trees and ensure minimal area of water is exposed;
- Soil bunding (mounding) will divert contaminated runoff that may make its way to your water body. Also, frequently monitor water quality and levels.
3. Recharging groundwater
This happens when it rains and to a smaller extent through surface water (rivers and lakes) and by planting trees to increase water saturation into groundwater and reduce water runoff.
You can also artificially recharge your ground water by redirecting water across land surface, through canals, swales, infiltration basins or ponds, adding irrigation furrows or using sprinkler systems.
These methods reduce surface water flow allowing it to sink into the ground.
Groundwater recharge replenishes ground water levels, keeping your land moist long after the rains have subsided. It also reduces its salinity by removing excess salts accumulated in the root zone to deeper soil layers.
4. Re-use water from your household (grey water)
Grey water is water from our baths, sinks and laundry. One of the ways to make water last longer is by recycling and re-using grey water.
Grey water is not toxic immediately after discharge. However, if it is collected in a tank, it will consume oxygen very quickly and become anaerobic. Once it reaches the septic state, it forms sludge that either sinks or floats, depending on its gas content and density.
Septic grey water smells bad and contains anaerobic bacteria, some of which could include human pathogens.
Consequently, the key to successful grey water treatment is immediate processing and reuse before reaching the anaerobic state. The simplest, most appropriate treatment consists of directly introducing freshly generated grey water.
Reasons why grey water may need to be treated:
1. To remove substances that may be harmful to human health;
2. To remove substances that may be harmful to plants and soil;
3. To remove substances that may be harmful to the environment;
4. To remove substances that may clog the irrigation system.
Methods used to clean and collect grey water, include filtering it using a manmade wetland.
Crops such as banana, lilies or reeds feed on the waste and pass it through sand, gravel, pebbles and stones as a natural sieve.
It is advised to avoid black water, which is water that may contain effluent, faecal matter or other damaging elements. It includes water from the toilet/sewerage or wastewater from a factory.