Sustaining soil health and productivity of sugarcane (Saccharum species hybrid complex) plant-ratoon system through integrated use of organic and inorganic sources in clay loam soils of Rajasthan.

A field experiment was conducted during 2014–17 at Kota, Rajasthan to find out a suitable nutrient-manage-ment strategy for sustaining soil health and sugarcane production. The experiment consisted of 9 nutrient-management strategies, viz.T1, no organic + 50% recommended dose of fertilizer (RDF) in plant and trash 10 t/ha + 50% RDF in ratoon; T2, no organic +100% RDF in plant and trash 10 t/ha + 100% RDF in ratoon; T3, no organic + soil-test recommendation (STR) in plant and trash 10 t/ha + STR in ratoon; T4, FYM 20 t/ha + 50% RDF in plant and ratoon; T5, FYM 20 t/ha + 100% RDF in plant and ratoon; T6, FYM 20 t/ha + STR in plant and ratoon; T7, FYM 10 t/ha + Azotobacter + phosphate-solubilizing bacteria (PSB) + 50% RDF in plant and ratoon; T8, FYM 10 t/ha + Azotobacter + PSB + 100% RDF in plant and ratoon; T9, FYM 10 t/ha + Azotobacter + PSB + STR in plant and ratoon, laid out in randomized block design with 3 replications. Among the treatment combinations, application of 10 t FYM/ha + Azotobacter + PSB (12.5 + 12.5 kg/ha) + STR (150: 50: 30 kg N: P2O5: K2O/ha) had significant influence on germination at 45 days after planting (DAP) (51.0%), tillers at 150 DAP (183, 000/ha), number of millable canes (125, 800/ha), cane yield (88.2 t/ha), commercial cane sugar yield (10.8 t/ha), net return (110, 500 /ha) and benefit: cost (BC) ratio (2.00). Sugarcane-quality characteristics like brix (20.2%), sucrose (17.7%), commercial cane sugar (CCS, 12.2% and purity (87.4%) recorded were significantly superior with application of 20 t FYM/ha + STR (T6). Significant increase in soil organic carbon content (0.55%) and infiltration rate (4.69 mm/hr) were also noted under application of FYM 20 t/ha + STR over T1 and T2 treatments, while soil pH (8.12) and bulk density 1.34 Mg/m2) of soil reduced significantly. Available nitrogen (363.81 kg/ha), phosphorus (27.02 kg/ha) and potassium (331.13 kg/ha) in soil exhibited higher values under FYM 20 t/ha + 100% RDF, FYM 10 t/ha + Azotobacter + PSB + STR and FYM 20 t/ha + STR. Thus, the result showed that integrated application of FYM 10 t/ha + Azotobacter + PSB (12.5+12.5 kg/ha) + STR (150: 50: 30 kg N: P2O5: K2O/ha) may be recommended for obtaining higher cane yield, net returns and sustained soil health in plant-ratoon system in spring season on clay loam soils of Rajasthan.