EFFECT OF ORGANIC MANURES ON SOIL FERTILITY AND PRODUCTIVITY OF SUGARCANE IN NORTH COASTAL ZONE OF ANDHRA PRADESH.

The experiment was conducted on a clay loam soil in sugarcane plant-ratoon system at Regional Agricultural Research Station, Anakapalle with a variety 93 A 145 during 2007-08 and 2008-09 to study the comparative performance of effect of different organic manures on soil health and yield of sugarcane. Results revealed that the addition of different organic manures in addition to recommended dose of fertilizers (RDF) resulted in the higher organic carbon content and available nutrient status of the soil compared to chemical fertilizers alone. The plots which received FYM @ 25 t/ha +RDF recorded highest organic carbon (0.55 %) and available N (226 kg/ha). However maximum available P2O5 and K2O (38.89 & 254 kg/ha) was observed in plots which received press mud cake @ 12t/ha +RDF as press mud cake is a rich source of phosphorus (2.76 %). Decrease in pH in manured plots was attributed to increase in partial pressure of CO2 and organic acids due to organic matter decomposition. Slight increase in soil organic carbon content and available nutrient status was observed in ratoon crop than plant crop is due to residual and cumulative effects of added organic manures in ratoon crop. The highest N uptake (301 kg/ha) was recorded with the treatment which received RDF + vermicompost. However maximum phosphorus uptake of 54.11 and 58.96 kg/ha (plant and ratoon crop respectively) was recorded in the treatment which received press mud cake + RDF is due to maximum P availability when compared to other sources. Better juice quality was observed in manure treated plots than RDF alone. Maximum juice sucrose (19.75 %) and % CCS (13.72) was observed in FYM + RDF of plant crop. Farm Yard Manure+ RDF registered higher cane yield (94.18 t/ha) and sugar yield (12.92 t/ha) than application of entire 'N' through RDF alone (cane yield: 87.42 t/ha and sugar yield : 11.06 t/ha) but was found at par with vermicompost + RDF (cane yield 93.88 t/ha; sugar yield : 12.59 t/ha). The study showed that integrated use of organic manures and inorganic fertilizers produced higher and sustainable cane yields and maintained the soil fertility (Organic manures, soil fertility, productivity and sugarcane). [ABSTRACT FROM AUTHOR]