Production Potential and Soil Fertility Status of Ratoon Sugarcane (Saccharum officinarum L.) as Influenced by Time and Level of Earthing Up and Nitrogen Levels in North-Eastern Uttar Pradesh, India

A field experiment was carried out during the spring seasons of 2008-09 and 2009-10 at Varanasi, Uttar Pradesh to find out exact time of earthing up with level of earthing up and optimum doses of nitrogen for getting higher productivity, monetary returns, and changes in the fertility status of soils after harvest of ratoon sugarcane (Saccharum officinarum L.). Twentieth fifth April earthed crop produced significantly more height of tillers, leaf area index at maximum tillering stage, grand growth stage and at harvest, dry matter/tiller at maximum tillering stage at grand growth stage and at harvest, cane length, cane diameter of top, middle and bottom, weight of cane, cane yield, monetary returns, B/C ratio, N, P and K uptake except number of tillers/ha, number of millable cane/ha and net available soil nutrient after the harvest of ratoon crops as compared to 25th May and 25th June respectively. Twentieth cm height of earthing up from the ridge also significantly increased all the above parameters such as height of tillers, LAI of maximum tillering stage, grand growth stage and harvest, dry matter/tiller at maximum tillering stage, grand growth stage and at harvest, cane length, weight of cane and cane yield than that of 10 cm earthed crop in both the ratoon crops. Application of 210 kg N/ha linearly and significantly increased number of tillers/ha at 60 and 120 days after ratooning, height of tillers at 120 days after ratooning, LAI at maximum tillering stage, grand growth stage, and at harvest, dry matter/tiller at maximum tillering stage, grand growth stage and at harvest, number of millable cane, cane length, cane weight, cane yield, monetary returns, B/C ratio and N, P, K uptake followed by 180 kg N/ha. Ratoon crop showed that there was a build up of nitrogen and phosphorous but depletion in potassium content of the soil. 210 kg N/ha with earlier earthed at 25th April to a level of 20 cm was found optimum for obtaining higher yields and monetary returns.