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• Conservation agriculture reduced sub-surface soil strength. • Total and microporosity improved, and therefore water retention under CA. • The impact was visible on the wheat root growth and development. • Soil aggregation improved, but marginal impact on soil organic carbon. The study compared conservation agriculture (CA) practice (no-tillage, crop residue cover on the surface and relay mung bean) with conventional intensive tillage system, in order to evaluate their effects on soil strength and water content, total porosity and pore-size distribution, roots and above-ground plant growth in wheat under a rice-wheat rotation. The experiment was started in the kharif season of the year 2010 in the research farm of the Indian Agricultural Research Institute, New Delhi, India. Observations were taken during 6th, 7th and 8th year of the rotation. The CA practice primarily reduced the sub-surface (15–30 and 30–45 cm) soil strength by 20–25% owing to 14% higher water content at this layer, and increased the total porosity (17%) and retention pores (22%). Soil aggregation and organic C improved primarily in the surface layer (0–15 cm). The modified soil physical properties led to better root growth, plant leaf area index and solar radiation interception, and higher grain and straw yields. The CA practice significantly contributed to improving the soil physical condition, especially in reducing the sub-surface compaction and improvement on root growth in wheat. This is significant in our quest to increase and sustain the rice-wheat production system in the Indian subcontinent. [ABSTRACT FROM AUTHOR]