C: N Ratio and Biological Yield under Rainfed Organic Cotton Production

Rhizosphere study for C: N ratio and biological yield in vertisol under organic cotton was studied at Cotton research station, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola in kharif 2011–12. Fym, vermicompost, castor cake and in-situ green manured with sunhemp were the organic sources of nutrients for rainfed cotton variety AKA-8. Significantly higher content of carbon and nitrogendue to addition of FYM @ 10 t ha⁻¹ reflected on significantly lowest C: N ratio of soil i.e. 10: 40 at flowering stage and 10: 50 at boll bursting stage of cotton. Significantly highest productivity of cotton i.e. 18.38 q ha⁻¹ seed cotton and 84.33 q ha⁻¹ dry matter was observed under the treatment of castor cake @ 500 kg ha⁻¹ and which was statistically equal to the seed cotton yield recorded FYM @ 10 t ha⁻¹. Thus, it can be concluded that, application of FYM @ 10 t ha⁻¹ as an organic source of plant nutrients for cotton cultivation improves the C: N ratio in Vertisols that resulted in improvement in yields of rainfed deshi cotton.