To,Hi
Please contact Dr Amaresh Kumar Nayak, Senior Scientist, Soil Science Division, ICAR Research Centre, Modipuram, Meerut, U.P. He is working on effect of phosphogypsum in rice-wheat cropping system since last 3-4 years in colaboration with BARC. Presently he is working perhaps with PDCSR or CPRIC. You can get references or any thesis on your desired topic from him.
Please contact..
Best regards
Ubaid Khan
Lucknow