Wednesday , 20 February 2019

Back to our roots

Miguel Braganza

Farmers in Goa have long discovered that growing alsando during the ‘vaingonn’ or Rabi season after the monsoon crop of rice increases the yield of rice in the next monsoon season. The alsanddo crop is also best suited for the Goan who is in a celebratory mood from Diwali through Christmas and New Year.

Pulses provide the proteins to build our body. Pulses are also legume plants that associate with a bacterium Rhizobium japonicum to fix nitrogen from the air and enrich the soil. They work as miniature fertiliser factories and produce enough nitrogen for the legumes as well as the next crop of rice.

The Don Bosco College of Agriculture (DBCA), at Sulcorna, Quepem, has isolated a strain of Rhizobium from the root nodules of the Yard Long Beans or ‘Irvil’, Vigna sesquipedalis. The species name literally means ‘one-and-half feet’ and that is about the length of the beans also known as ‘wal’ in Konkani and Marathi languages. The DBCA laboratory produces Rhizobium japonicum culture to help farmers who grow beans, peas and groundnut to completely avoid the use of urea and other nitrogen fertiliser. During the Rural Agricultural Work Experience Program (RAWEP) for a period of five months, six groups of six students each from the fourth year B. Sc (Agri) lived and worked with farmers from five target villages of Molcornem, Zambaulim, Rivona, Pirla and Neturlim, with Molcornem hosting two groups. They have done training demonstrations and laid out field demonstrations with each student focusing on a single host farmer.

The Rhizobium bacteria are multiplied as a pure culture in the laboratory and then mixed into coal dust for easy use by farmers. When the farmer wishes to use the bacterial culture, all he or she has to do is to activate the bacteria by giving it a sugar source like jaggery slurry or sugarcane juice. The activated slurry is poured on the seeds of peas, beans, gram or groundnut that are collectively known as legumes and mixed to give them a coating that appears like the coating of masala groundnut, except that here it is black instead of brown. The seeds are then dried in shade to prevent them from sticking to each other while sowing. They are not dried in sunlight because sunlight kills the bacteria.

Legume plants treated with Rhizobium will have darker green leaves than untreated seeds. In soils rich in organic carbon where crops are grown organically, the Rhizobium will remain in the soil for future crops, unless exposed to adverse conditions. Over a period of time, application of Rhizobium becomes unnecessary because the soil is already rich in it. It is now truly time for us to go back to our roots.

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