The A to Z of catfish farming, using ash as fertiliser

What to do to have healthy catfish

Please take me through the rearing of catfish in a pond, from acquiring fingerlings – or hatchings – to harvesting. I have realised the market for this species in counties like Homa Bay, Migori, Kakamega, Busia, Siaya, Kisii and Nyamira is growing fast. What feeds do I require? Explain to me the dos and don’ts in catfish rearing too.

John Okinyi
Budalang’i

When starting a fish farm, the technical requirements for production should be satisfied to run it efficiently and economically.

This begins from designs and construction of ponds, which underscores the need to involve technical experts, the closest being a county fisheries extension officer. Pond construction site/fish production site should be close to a water source both in quality and quantity and suitable topography to allow cost-effective setting up.

When stocking, consider sourcing for quality fingerlings. For instance, improved strain of catfish with a higher survival rate; higher final table body weight and better feed conversion ratio.

You can find out from the Kenya Marine and Fisheries Research Institute.

Other important aspects are water quality management/environmental requirements such as optimal temperature, dissolved oxygen, salinity and pH. For best experiential learning, it is best to learn from established farms and possibly obtain quality fingerlings.

Proposed farms in your locality include Jafi fish in Kakamega, Chwele Fish and Jolwa Fish farms in Bungoma.

Felix Akatch Opinya, Livestock Production adviser.

Inoculating and dressing seeds: The difference
Some extension officers recently advised farmers to dress and inoculate their beans. I must confess that I didn’t really get the difference between the two. Could you explain this in a plain and simple language? The extension officers appeared young and many of us at the meeting came to a conclusion that they were just showing off by using complicated language and terms.

Hussein Twaha, Kwale

Seed dressing is the coating of seeds with a fungicide or insecticide or a combination of the two chemicals. It is mainly practised in cereals and legumes. It is done to protect seedlings from soil-borne pests and diseases.

Certified seeds sold by seed merchants in Kenya are already dressed with these chemicals.

However, farmers can also buy the chemicals and dress their own seeds.
Seed inoculation is coating of legume seeds with a nitrogen fixing bacteria (Rhizobium or Bradyrhizobium) before planting.

The bacteria penetrate the root, resulting in the formation of nodules that fix nitrogen from the air and make nitrogen readily available to the plant.

Seed inoculation is carried out in legumes such as beans, soybean, clovers, groundnuts and peas.

Every legume crop has its own rhizobium species. The legumes and the bacteria are in a symbiotic relationship and thus, both benefit.

Seed inoculation is important because Rhizobium bacteria in the soil are not effective or are not enough to stimulate biological nitrogen fixation and increase a farmer’s harvests.

Inoculated seeds should not come into contact with chemicals. This means the inoculated seeds should not be dressed with chemicals because this will kill the useful bacterium.

Lastly, inoculated seeds should be planted when the soil is moist to avoid dehydration, which kills the bacterium.

The following are some of the Rhizobium species for some legumes.

Legume Rhizobium species

Bean-Rhizobium phaseoli

Chick pea- radyrhizobium japonicum

Pea-Rhizobium leguminosarum

Soyabean-Rhizobium japonicum

Lupin-Rhizobium lupini

Lucerne-Rhizobium melioti

Clover Rhizobium trifoli

Carol Mutua
Crop Production Specialist

Caution as you use ash as fertiliser

Is it true that ash can be used as a fertiliser? On what crops can it be used and what quantity?

What nutrients does it add to soil? Does the kind of plant burnt determine the nutrients in the ash?

John Oloo, Migori.

Thank you John for your question.

It is true that ash can be used as a fertiliser.

Ash is a good source of phosphorous, calcium, magnesium, potassium and some trace elements like boron, copper, molybdenum, zinc.

Ash also increases pH in acidic soils.

Generally, soils in areas that receive high rainfall tend to be more acidic compared to soils in dry regions.

Ash can be applied on crops like onion, garlic, carrot, beet, turnip, collard, lettuce, spinach, broccoli, cauliflower, cabbage, Brussel sprouts, sage and basil.

Wood ash should not be applied on apples, peach, pears, potatoes, sweet corn, pepper, eggplant, rhubarb, parsley, raspberries and blueberries.

In potatoes, wood ash can lead to potato scab.

Wood ash is also effective in controlling pests like snails, slugs, beetles and borers.

It is also true that the plant from which the wood ash was obtained from will determine the nutrients present in the ash.

For instance, hardwoods like oak contain more nutrients than softwoods like pine or fir.

Do not use wood ash produced by burning treated wood or trees grown in industrial areas or soils contaminated by toxins as they may contain toxins and or heavy metals.

The quantity of wood ash to be applied will depend on the recommendations from a soil test.

It is also based on the amount of nutrients required by the crop you intend to plant.

Application of excess wood ash may result to nutrient toxicity and or nutrient deficiency in many crops.

Carol Mutua
Crop Production Specialist