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Abstract: Excessive pumping of groundwater over the years to meet the high water requirement of flooded rice crop and intensive tillage have threatened the sustainability of irrigated rice–wheat system (RWS) in the Indo-Gangetic plains (IGP) of South Asia. Replacement of rice with less water requiring crops such as maize in the RWS and identification of effective strategies for alternate tillage systems will promote sustainable cropping systems in the IGP. To this effect a 3-year field experiment was established with annual maize–wheat rotation in the north-western IGP of India to evaluate the effect of 3 tillage systems (conventional flat, CTF; no-till flat, NTF; permanent raised beds, NTB) on crop production, water use efficiency, economic profitability and soil physical quality. Grain yield of maize was highest (8.2–73.4%) under NTB followed by NTF and CTF across the years. Wheat yield was significantly higher under NTF during the 1st year while tillage practices had non-significant effect in the succeeding two years. On average, maize planted on NTB recorded about 11% lower water use and 16% higher water use efficiency compared to CT. The NTB and NTF required 24.7% and 10.8% less irrigation water than CTF system, respectively with 11.5% higher system productivity and demonstrated higher water productivity. The NTB and NTF systems provided similar net returns (averaged over 3 years) in maize–wheat system (MWS), which were US$ 281ha−1 higher compared to CTF system. The CTF system had higher bulk density and penetration resistance in 10–15 and 15–20cm soil layers due to compaction caused by the repeated tillage. The steady-state infiltration rate and soil aggregation (>0.25mm) were higher under NTB and NTF and lower in the CTF system. Similarly, mean weight diameter (MWD) of aggregates was higher under NTF and NTB compared to CTF. The study reveals that NTB and NTF systems could be more viable options for MWS in order to save input costs and enhance profitability; however, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies. [Copyright &y& Elsevier]

Serious water deficits, diminishing profitability and deteriorating natural resources are threatening agricultural sustainability in many regions of South Asia. High water input and low water productivity of conventional irrigated rice–wheat (RW) systems has led to the depletion of surface water and ground waters in northwest India. Conservation agriculture (CA) practices with precision irrigation management and replacing rice with low water requiring maize crop may help to achieve sustainable crop production in the western Indo-Gangetic Plains (IGP) of India. A three-year field experiment was conducted to evaluate the effect of CA-based management (tillage, crop establishment, residue management mungbean integration), precision water management on crop and water productivity, and economic profitability in RW and maize-wheat (MW) systems. The treatments for RW systems included: i) conventional till rice-wheat with irrigation scheduling at critical growth stages (CTRW); ii) CTRW + mungbean (CTRW + MB); iii) Zero-till RW with residue retention (+R) scheduling precise irrigation (PI) based on soil matric potential approach (ZTRW + R + PI); and iv) ZTRW + MB + R + PI. A similar set of treatments was evaluated for MW systems, except the crops were established on raised fresh beds (FB) and permanent beds (PB). Treatment PBMW + MB + R + PI recorded 38% higher system productivity, saved 1660 mm of irrigation water, increased irrigation + rainfall water productivity (WP I+R ,) by 270% and increased net returns by 84% compared to CTRW. ZTRW + MB + R + PI recorded 24, 41 and 37% (3 yrs’ mean) higher system productivity, WP I+R and net returns, respectively, compared to CTRW. System productivity was increased by 19 and 33%, WP I+R by 223 and 29% and net returns by 84 and 57% with ZTRW and PBMW compared to CTRW, respectively irrespective of MB integration and residue management. On average, inclusion of MB in cereal systems (RW/MW) contributed an 18% increase in system productivity and a 15% increase in net returns. CA based sustainable intensification of MW systems (PBMW + MB + R + PI) is a better alternative to RW system (ZTRW + MB + R + PI) as it provides opportunities for saving 79% of precious water, enhancing crop and water productivity by 12 and 145%, respectively along with high (34%) economic benefits thereby helping to arrest decline in ground water table in the North-West IGP of India. [ABSTRACT FROM AUTHOR]

Intensive tillage-based conventional cotton-wheat system (CWS) entails high production costs and has low crop and water productivity thereby threatening its sustainability in the north-western India. Conservation agriculture (CA) based management practices such as conservation tillage, permanent raised beds and relay planting have the potential to improve sustainability, profitability, and water use efficiency in CWS. A two-year (2013–2015) field experiment was conducted to evaluate CA based management practices such as zero tillage (ZT), permanent beds, relay seeding (RS) of wheat, seeding configuration, and integration of mungbean (MB) in terms of crop productivity, input use efficiency (water and energy) and profitability in the CWS system. Treatments included; permanent narrow (67.5 cm, PNB) and broad (102 cm, PBB) raised beds with cotton planted in the centre of beds, ZT narrow flats (67.5 cm, ZTNF) and broad flats (102 cm, ZTBF), and PBB with cotton planted on one side of bed and intercropped with MB (PBBc + MB) or no MB (PBBc). In the above treatments, wheat was relay seeded in standing cotton after second picking. In addition, conventional till (CT) CWS on flats was included as control treatment. PBBc + MB produced 37% and 10% higher system productivity (2 yrs’ mean) over CT and PBB, respectively. Relay seeded wheat on PBB produced 50% higher yield and required 40% less irrigation water compared to CT wheat in both the years. Mean system irrigation water productivity (WP I ) was 131% higher with PBBc + MB compared with CT. The energy input was 61% higher in CT compared to PBB but energy output was 21% higher with PBB than with CT. PBB and PBBc + MB recorded 52–54% higher energy productivity and 64–69% higher net returns compared to CT. In conclusion, PBB and PBBc + MB were the best options for sustainable CWS under similar soil and climatic conditions in India. [ABSTRACT FROM AUTHOR]

In north-western India, maize-based systems are being advocated as an alternative to rice-based systems to address the issues of resource degradation, particularly declining water tables and climate-change-induced variability in rainfall and temperature. Conservation agriculture (CA) based best-bet crop management practices may increase crop and water productivity, while conserving and sustaining natural resources. In a 6-year study of conservation agriculture experiment established in 2008, we have evaluated the performance of CA-based management practices [permanent bed (PB) and zero tillage (ZT)] and conventional till (CT) for four intensified irrigated maize systems [maize-wheat-mungbean (MWMb), maize-chickpea- Sesbania green manure (MCS), maize-mustard-mungbean (MMuMb) and maize-maize- Sesbania (MMS)]. Significant (P < 0.05) tillage and cropping system interactions were observed for system productivity. Agronomic performance (yield attributes) of all the crops (except wheat) grown in sequence with maize was maximum with ZT, however wheat outperformed on PB over ZT and CT. In the initial two years, higher system productivity (maize equivalent yield) was recorded in PB (8.2–8.5 Mg ha −1 ), while from third year onwards ZT registered maximum productivity (11.3–12.9 Mg ha −1 ).The system glucose equivalent yield increased by 0.6 Mg ha −1 under ZT and PB compared to CT. Economic profits from maize-based rotations were invariably higher either in MMuMb or MWMb systems, while in terms of glucose equivalent yield, MMS and MWMb rotation were highest. Synergistic effects of summer legumes (mungbean and Sesbania ) after winter legume/oilseed/cereal were observed on yield of individual crop vis-a - vis system productivity and irrigation water use. ZT and PB practices reduced the irrigation water requirement by 40–65 ha-mm and 60–98 ha-mm, respectively compared to CT system, resulted enhanced system water productivity by 19.4% equally under both ZT and PB. Net profit from the maize-based systems under ZT was up to 31% higher with 72$ ha −1 lower production cost compared to CT. Results from our study showed that adoption of CA based tillage practices in MMuMb and MWMb system for sustainable increase of crop and water productivity in north-western region of India. [ABSTRACT FROM AUTHOR]

In intensive rice–wheat systems of north-west (NW) India, surface retention of rice residues in wheat has been recommended instead of burning. Optimum nitrogen (N) management for zero till (ZT) wheat sown into rice residues may to differ from that of conventional practice ( in-situ burning of residues followed by intensive tillage prior to sowing). Therefore, we conducted several on-farm and on-station field experiments in 2007–2008 to 2012–2013 to evaluate N management practices for ZT wheat sown into rice residues using the Happy Seeder. The optimum N rate for wheat planted into rice residues in fields with no or only a short history of rice residue retention was 120 kg N ha −1 , the current recommendation for conventional practice. Short-term (up to 20 d) soil N mineralization was lower in undisturbed soil than disturbed soil, while the total amount of N mineralization was similar after 40 d, suggesting that over the crop season, total soil N mineralization may be similar in tilled and non-tilled soil. Ammonia volatilization loss from urea broadcast over the residue covered surface, followed by irrigation, was low (<2 kg ha −1 ) regardless of time of urea application. Band placement of 20% of the fertilizer N as diammonium phosphate at seeding, and topdressing of the remaining 80% as urea in two equal doses before first and second irrigations produced higher grain yield and N use efficiency than other treatments. However, surface residue retention reduces the rate of soil drying and in some situations this delays the time of the second irrigation and thus N fertilizer application beyond the optimum time. Therefore, the effect of banding various proportions of the urea N between the rows at sowing was investigated. The results showed that, on a loam soil, up to 75% of the recommended N fertilizer can be applied at sowing, 24 kg N ha −1 as DAP with the seed and 66 kg N ha −1 as urea drilled between every second wheat row, without loss of yield. In conclusion, a better applied N management strategy for ZT wheat than currently practiced is drilling of 24 kg N ha −1 as diammonimum phosphate into the soil at seeding followed by two top-dressings of 48 kg N ha −1 each just prior to first and second irrigations. [ABSTRACT FROM AUTHOR]