Improving quality of sugarcane-growing soils by organic amendments under subtropical climatic conditions of India

A field trial was conducted on an inceptisol to assess the effect of different bio-manures on sugarcane yield, cane quality, and changes in soil physico-chemical and microbial properties in plant–ratoon system. Seven treatments, viz. control, vermicompost, farmyard manure (FYM), biogas slurry, sulphitation pressmud cake (SPMC), green manuring with intercropped Sesbania, and recommended dose of NPK (150:60:60 kg ha⁻¹), were randomized within a block and replicated three times. Improvement in bulk density and infiltration rates was recorded after the addition of various bio-manures. The highest organic C was recorded in the vermicompost (0.54%) and pressmud (0.50%) treatments. The highest increase in soil microbial biomass C (185.5%) and soil microbial biomass N (220.2%) over its initial value was recorded with the addition of FYM. Dry matter production in plant, as well as ratoon crop, was significantly higher by bio-manure application over the control. Plant N uptake was highest in the pressmud treatment (227.7 kg ha⁻¹), whereas P and K uptake were highest (41.4 and 226.50 kg ha⁻¹) in vermicompost treatment. The highest number of millable canes (95.6 and 101.0 thousand ha⁻¹) in plant and ratoon crop were obtained with the addition of pressmud. The highest yield (76.7 t ha⁻¹) was recorded in planted cane with vermicompost application, whereas ratoon yield was highest (78.16 t ha⁻¹) with pressmud application. In both planted and ratoon crop, organic amendments produced yields statistically similar to those with recommended NPK (76.1 and 78.1 t ha⁻¹ for plant and ratoon cane).