Ryzobium inoculant as a natural top dressing fertilizer

The Soil Productivity Research Laboratory at Zimbabwe's Grasslands Research Station has intensified a commercial production awareness campaign on the use of rhyzobium as a substitute for top dressing following last year’s fertilizer shortage.

The inoculant factory at Grasslands has been producing rhyzobium since 1962 and was started by Dr H.D.L Corby and microbiologist Mr W.P.L Sandman.

Rhyzobium or inoculant is extracted from nodules of legumes and preserved in a tissue culture form before it is used.

According to the principal research technician at the research laboratory, Mr Godfrey Kaunye, rhyzobium is cheaper and easier to use than ammonium nitrate fertilizer. He revealed that only 100 grammes of inoculant could be used as top dressing for 50kg seed soyabeans or groundnuts.

"This is equivalent to one hectare and is a lot cheaper, as six bags of ammonium nitrate are required to top dress the same one size," said Mr Kaunye. He added that the same amount of rhyzobium can top dress 25kg cowpeas seed, 25kg sugar beans seed, 10kg clover seed and 20kg roundnuts seed. It can also be used as top dressing for other pasture legumes like lucerne, stylo, acacia and velvet beans, among others.

Rhyzobium is not affected by leeching like fertilizer and it does not burn crops as ammonium nitrate does during times of drought.

Between 1996 and 1999, the International Atomic Energy Agency sponsored projects by the research laboratory trying to popularise the use of Nitrogen 15 isotope with effective monitoring of its useful and harmless effects.

Funding for the research laboratory, which operates under the Chemistry and Soil Research Institute under Agritex, is now a drop in the ocean as production costs have escalated over the years.

Commercial production of rhyzobium comes as a relief following closure of three major fertilizer-producing companies who cited persistent power cuts and the unavailability of raw materials.

Response from nearby farmers has been overwhelming, Mr Kaunye said, but the lab is facing challenges of resources and equipment like autoclaves, incubators as well as chemicals with power cuts being detrimental to production.

"At the moment, we are operating below capacity as we are capable of producing only 60 000 inoculant units per year instead of 200 000 units. We are also seeking funding for the construction of a new laboratory to increase our capacity," said Mr Kaunye.

The technology was previously a preserve for white commercial farmers aimed at achieving low input costs but high yields.

The Soil Productivity Research Laboratory has a staff complement of 32 who include the chief research technician, Mr Joram Tapfuma, and is headed by Mr Michael Nyika.

The Herald