Zinc and sulphur nutrition in sugarcane (Sachharum officinarum) and potato (Solanum tuberosum) intercropping system affecting soil microbial biomass carbon, respiration and crop growth in subtropical India

A field experiment was conducted during 2 cropping seasons of 2015-2017 at experimental field Lucknow, Uttar Pradesh to evaluate the sulphur- and zinc-containing complex fertilizers in sugarcane (Sachharum officinarum L.)-potato (Solanum tuberosum L.)-based cropping systems. The experiment was laid out in a splitplot design under 3 replications. The treatments of cropping system (CS) and nutrient management (NM) were kept in main and subplots, respectively. Results revealed that soil organic carbon did not differ significantly with the cropping systems. Higher values of soil organic carbon, soil respiration and soil microbial biomass nitrogen (SMBN) were obtained after harvesting of potato as compared to sugarcane crop in both the cropping systems. Balanced application of NPSZn compound fertilizer improved the SMBC, soil organic carbon (SOC), soil respiration and SMBN. The extent of increase in SMBC and SMBN owing to application of NPSZn was higher at harvesting of potato (component crop) compared to sugarcane. Application of farmyard manure (FYM) with recommended fertilizer (NPK) significantly increased SOC (0.92%) after harvesting of potato. After harvesting of sugarcane, SOC declined and reached the level of 0.76%. Recommended dose of NPK and FYM significantly left the highest status of residual level of nutrients (199.45 kg N, 23. 81 kg P2O5 and 348.15 kg K2O/ha) after harvesting of sugarcane crop in both the systems. The statistically at par yield (32.98 t/ha) of potato was harvested in potato- sugarcane system as compared to potato + sugarcane (31.48 t/ha) system. Recommended NPK (T2)/ recommended NPKS (T3) were found superior to the absolute control (T1) and produced significantly higher yield of potato (30.67 to 31.33 t/ha). The highest individual cane weight (1,015 g) was recorded with application of recommended NPK + FYM. Commercial cane sugar was influenced greatly by different levels of nutrients. The highest sugar yield (11.60 t/ha) was obtained with application of recommended dose of NPK along with S and Zn application equivalent to compound fertilizer (NPSZn).