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Deep Tillage, Soil Moisture Regime, and Optimizing N Nutrition for Sustaining Soil Health and Sugarcane Yield in Subtropical India

Shukla, S. K., Yadav, R. L., Gupta, Rajendra, Singh, Akhilesh Kr, Awasthi, S. K., Gaur, Asha
Communications in soil science and plant analysis 2018 v.49 no.4 pp. 444-462
bulk density, carbon, crop yield, evaporation, field experimentation, harrowing, harrows, irrigation water, microbial biomass, nitrogen, nutrition, physicochemical properties, planting, plowing, plows, porosity, ratooning, soil microorganisms, soil quality, soil water regimes, subsoiling, subsurface soil layers, sugarcane, tillering, India
A field experiment was conducted at ICAR-Indian Institute of Sugarcane Research, Lucknow, with three tillage practices (T₁: Control- two times ploughing with harrow and cultivator, each followed by planking before sugarcane planting; T₂: Deep tillage with disc plough (depth 25–30 cm) before planting followed by harrowing, cultivator, and planking; and T₃: Subsoiling at 45–50 cm and deep tillage with disc plough/moldboard plough (depth 25–30 cm) followed by harrowing, cultivator, and planking before planting, two soil moisture regimes (M₁: 0.5 irrigation water (IW)/cumulative pan evaporation (​CPE) ratio and M₂: 0.75 IW/CPE ratio) at 7.5 cm depth of IW, and four N levels (N₁- 0, N₂- 75, N₃- 150, and N₄-225 kg N ha⁻¹) in sugarcane plant crop. Deep tillage and subsoiling increased porosity and reduced bulk density in surface/subsurface soil. Further, these physical changes also improved soil biological and chemical properties responsible for higher crop growth and yield. Deep tillage and subsoiling reduced the compaction by 6.12% in 0–15 cm depth in sugarcane plant crop at maximum tillering stage. The highest N uptake (158.5 kg ha⁻¹) was analyzed with deep tillage and subsoiling compared to all other tillage practices. Maintaining suboptimal moisture regime with deep tillage and subsoiling showed the highest IW use efficiency (157.16 kg cane kg⁻¹ N applied). Mean soil microbial biomass carbon (SMBC) in ratoon crop was higher compared to plant crop. During initial tillering stage, ratoon crop showed higher SMBC with application of deep tillage and subsoiling (1209 mg CO₂-C g⁻¹ soil day⁻¹) at 0–15 cm depth and 1082.9 mg CO₂-C g⁻¹ soil day⁻¹ at 15–30 cm depth. Thus, it could be concluded that besides improving sugarcane yield, soil health could be sustained by adopting subsoiling (45–50 cm depth) and deep tillage (20–25 cm depth), with soil moisture regime of 0.75 IW/CPE and application of 150 kg N ha⁻¹ in sugarcane (plant crop).