Sugarcane Yield Using Minimum Tillage Technology Through Subsoiling: Beneficial Impact on Soil Compaction, Carbon Conservation and Activity of Soil Enzymes

Abstract

Adverse effect of intensive tillage practices on soil chemical and biological properties is already known. Soil organic carbon maintains porosity, releases nutrients for crop growth and also provides shelters to microbes. However, maintaining soil organic carbon at higher level and increasing crop productivity have become two faces of a single coin. Without addressing both issues simultaneously, the sustainability of production system will be far away. Strategic tillage intervention in no-tillage plots for sustaining long-term productivity is gaining importance. Strategic tillage through subsoiling/ripping of soil up to 45 cm depth at about 1 m spacing before sugarcane planting is feasible in sugarcane-based system. Thus, keeping the above points in view, the experiment was conducted during 2015–2017 with hypotheses of (i) whether the minimum tillage (once subsoiling) could maintain soil physical, chemical and biological parameters to sustain sugarcane productivity for longer period and (ii) how the mouldboard ploughing and/or conventional tillage practice affects these parameters and crop yields. The experiment was laid out in four preplant tillage treatments, i.e., one subsoiling (SS) and two harrowings, minimum tillage through subsoiling and direct planting of sugarcane through IISR Cutter Planter (SS), one ploughing through mouldboard plough and two harrowings (MBP + H) and conventional practice (CP—two ploughings through cultivator and one through rotavator) with six replications in randomized block design. The effect of these treatments was recorded on various soil physical, chemical and biological parameters vis-a-vis infiltration rate, cumulative infiltration and optimizing sugarcane yield in subtropical India. The results concluded that minimum tillage and direct planting of sugarcane through Sugarcane Cutter Planter could break hard impervious layer and improve soil physical, chemical and biological parameters besides improving sugarcane and sugar yields. Minimum tillage favoured build-up of soil organic carbon (SOC) and also release of nutrients for crop growth, which optimized rhizospheric environment as compared to conventional practice. Minimum tillage through subsoiling had shown major effect in reducing soil compaction in subsurface layers (bulk density—1.52 Mg m−3 (SS) vs 1.61 Mg m−3 through MBP + H). During tillering period, basic infiltration rate could reach the level of 7.5 mm/hr in SS plots compared to 5.5 mm/hr in conventional practice (CP). Minimum tillage recorded the highest SOC at all the crop growth stages. The highest mean SOC was recorded during grand growth phase (13.51 Mg ha−1). Minimum tillage altered lower amount of soil and showed the highest population of soil bacteria (log10 6.90x 105). Thus, the minimum tillage through subsoiling significantly improved sugarcane (96.32 t ha−1) and sugar yields (12.14 t ha−1) as compared to conventional tillage/mouldboard ploughing.