Long term effect of conservation agriculture in maize rotations on total organic carbon, physical and biological properties of a sandy loam soil in north-western Indo-Gangetic Plains C.M. Parihar a, *, M.R. Yadav b , S.L. Jat a , A.K. Singh a , B. Kumar a , S. Pradhan b , D. Chakraborty b , M.L. Jat c , R.K. Jat d , Y.S. Saharawat e , O.P. Yadav a a ICAR-Indian Institute of Maize Research (IIMR), New Delhi 110 012, India b ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110 012, India c International Maize and Wheat Improvement Center (CIMMYT), NASC complex, New Delhi 110 012, India d Borlaug Institute for South Asia (BISA), Bihar, India e International Center for Agricultural Research in the Dry Areas (ICARDA), Kabul 11082010, Afghanistan A R T I C L E I N F O Article history: Received 2 September 2015 Received in revised form 10 March 2016 Accepted 2 April 2016 Keywords: Diversified crop rotations Enzymatic activity Indo-Gangetic Plains Organic carbon Soil physical properties Tillage practices A B S T R A C T Maize-based crop rotations are advocated as alternate to rice-based systems in South Asia due to better suitability for diverse ecologies, higher yields with less water use and more palatable maize fodder compared to rice, and increased demand of maize from piggery and poultry industries. Alternate tillage and crop establishment practices are important management strategies for tackling the issues of soil health deterioration and over exploitation of underground water resources, particularly in rice based intensive crop rotations. The conservation agriculture (CA) based tillage and crop establishment practices such as zero tillage (ZT) and permanent raised beds (PB) hold potential to enhance soil organic carbon (SOC), physical and biological properties for sustainability of soil health. Therefore, a long term study was conducted to evaluate the twelve combinations of tillage practices (03) and irrigated intensive maize based crop rotations (04) on organic carbon, physical properties and microbial biomass and enzymatic activities of a sandy loam (Typic Haplustept) soil in north-western India. The tillage practices consisted of ZT, PB and conventional tillage (CT) in main plots and four diversified intensive maize based crop rotations (MWMb: Maize-Wheat-Mungbean, MCS: Maize-Chickpea-Sesbaina, MMuMb: Maize-Mustard- Mungbean, MMS: Maize-Maize-Sesbania) in sub plots. In this study we analysed the SOC, physical and biological properties of soil at various depths after 7 years of continuous ZT, PB and CT in diversified maize rotations. Compared to CT plots, the soil physical properties like water stable aggregates (WSA) > 250 mm were 16.1-32.5% higher, and bulk density (BD) and penetration resistance (PR) showed significant (P < 0.05) decline (11.0–14.3 and 11.2–12.0%) in ZT and PB plots at 0–15 and 15–30 cm soil layers. The soil organic carbon (SOC) increased by 34.6-35.3% at 0–15 cm, and 23.6-26.5% at 15–30 cm soil depths with conservation agriculture (ZT and PB) based crop establishment techniques over CT. Similarly, the soil microbial biomass carbon (MBC) under CA based systems increased by 45–48.9% in 0–30 cm profile depth of a sandy loam (Typic Haplustept) soil. Significant (P < 0.05) improvement in soil enzymatic activities i.e., Fluorescein diacetate, dehydrogenase, b Glucosidase and Alkaline phosphatase was also recorded in the CA based treatments. Significant (P < 0.05) synergistic effects of summer legumes (mungbean and Sesbania) with winter legume/cereal in crop rotations were observed on SOC,WSA, BD, PR and K sat at 0–15 and 15–30 cm depths. Interaction between tillage and crop rotations were significant (P < 0.05) for soil organic carbon, physical properties and enzymatic activities. Thus our long-term study suggests that CA based crop management with selected diversified maize based rotations (MCS and MWMb) can be Abbreviations: ALP, alkaline phosphatase activity; BD, bulk density; BG, ß Glucosidase activity; CA, conservation agriculture; CT, conventional tillage; DHA, dehydrogenase activity; FDA, Fluorescein diacetate hydrolysis activity; GMD, geometric mean diameter; ICAR, Indian Council of Agricultural Research; IGP, Indo-Gangetic Plains; K sat , saturated hydraulic conductivity; MBC, microbial biomass carbon; MCS, maize (Zea mays L.)-chickpea (Cicer arietinum L.)-sesbaina (Sesbania acculata); MMuMb, maize (Zea mays L.)-mustard (Brassica juncea)-mungbean [Vigna radiata (L.) Wilczek]; MMS, maize (Zea mays L.)-maize (Zea mays L.)-sesbania (Sesbania acculata); MWMb, maize (Zea mays L.)-wheat (Triticum aestivum L.)-mungbean [Vigna radiata (L.) Wilczek]; MWD, mean weight diameter; PB, permanent raised bed; PR, soil penetration resistance; SCL, sandy clay loam; SOC, total soil organic carbon; SL, sandy loam (Typic Haplustept); WSA, water stable aggregates; ZT, zero tillage. * Corresponding author. E-mail addresses: pariharcm@gmail.com, cm.parihar@icar.gov.in (C.M. Parihar). http://dx.doi.org/10.1016/j.still.2016.04.001 0167-1987/ ã 2016 Elsevier B.V. All rights reserved. Soil & Tillage Research 161 (2016) 116–128 Contents lists available at ScienceDirect Soil & Tillage Research journal homepage: www.else vie r.com/locate /still