Indian Agricultural Research Institute scientist Raman Jeet Singhab and I.
P. S. Ahlawat conducted a study to evaluate and quantify the residual effect
of two tiered intercropping of Bt cotton and groundnut with substitution of
25-50 percent recommended dose of nitrogen (RDN) for cotton by farm yard
manure (FYM), on productivity and soil fertility in Bt cotton-wheat system.
The study took place in New Delhi, India from 2006 to 2008.

Results showed that wheat following groundnut intercropped Bt cotton
receiving 50percent RDN substitution through FYM had significantly 5 percent
higher grain yield than that after sole cotton. Residual soil fertility was
improved under cotton and groundnut-wheat system with substitution of 50
percent RDN for cotton by FYM. Apparent nitrogen balance in the wheat
harvest was negative in most of the treatments, with greater loss recorded
under pure stand of cotton-wheat system with 100 percent RDN for cotton
through urea.

Based on the results, it was concluded that including a legume and organic
manure in Bt-cotton-wheat system is a sustainable practice to address the
increasing prices of N-fertilizers with environmental effects.

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