Gaitano Ayieko of Real IPM points to 100 population bag for balcony and rooftop farming. Mixing equal rations of soil and manure boosts water penetration. PHOTO BY LABAN ROBERT.

Rooftop and balcony bag farmers can avoid hardening or compacting of soil and drying of the crops by balancing the ratio of the soil and that of manure.

Hardening of soil particles leads to drying of the crops because water cannot penetrate to every end of the bag a few weeks after installation.

“Hardening is common especially in bags of 100 or more crops due to the higher number of soil particles than organic matter. There must be a balance in the mix ratio of the two. One wheelbarrow of the soil must be mixed with an equivalent amount of manure,” Isaac Guda, an environmental specialist and agronomist at Real IPM, Thika.

Manure allows for drainage by loosely binding the soil particles. Water can easily and evenly seep through from the top to the bottom.

Growing crops in bags is one of the vertical farming methods gaining popularity with urbanites, who place the portable containers on balconies, rooftops or outside their homes with the hope of generating income from vegetables besides meeting domestic needs.

For instance, a bag with a mix of 100 spinaches, kales, black night shade and spider flower requires about 16 wheelbarrows. Guda said manure and soil should be eight wheelbarrows each.

When planting, the farmer must make the holes and press the sides with a stick before inserting the seedlings straight.

In ensuring the crops establish quickly, the farmer needs to add at least three kilos of DAP to the 16 wheelbarrows capacity bag. The fertiliser is to offer the immediate nutrients required for stabilisation.

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Another three kilos of lime are required to counter the acidity of the contents that is likely to be caused by the manure.

If one were to harvest at least one leaf from 50 spinaches and 50 kales twice a week, they can make about Sh170 from one sack per week. That is if the leaves are bound into bunches of six, which will be sold at Sh5.

Other farmers deal with the problem of water shortage by placing a pipe at the centre of the bag while filling it. Instead of soil, maize-grain sized sand particles are filled in the pipe, which will be removed.

The Real Integrated Pests Management company, which is based in Thika sells the bags of various sizes besides offering training to farmers on organic farming.