P.S. RAO, K. PARIMALA, M. RAJASRI AND M. SUDHA RANI. “Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore - 641 003”. The Journal of Research ANGRAU, vol. 43, no. 1 & 2, June 2015, pp. 44-48, https://epubs.icar.org.in/index.php/TJRA/article/view/133278.