Rice-based Cropping Systems Research Articles

Soil Health as Influenced by Fertilizer Management in Rice Based Cropping System

Nutrient management influences soil health and crop productivity. Sustained crop production re-quires specific nutrient management options after a certain period. The objectives of this investigation were to examine the effects of inorganic and organic fertilization on yields and soil carbon budget under rice based cropping patterns in Bangladesh. The research data and informationhave been gen-erated based on previouslypublished, unpublished sources and own concept.Omission of K or im-balanced K are more influential for reduction in grain yield up to 47% in Boro (dry) season but N was most limiting up to 35% in T. Aman (wet) season. With existing fertilizer rates for growing rice, the balances of N and K are always negative. Balanced chemical fertilizer (NPKSZn) can be an option for improving crop productivity and maintain soil quality. Net ecosystem carbon (C) balances are posi-tive when 3 t ha-1 cow dung (CD), 2 t ha-1 poultry manure (PM) and 2 t ha-1 vermicompost (VC) are used in combination with chemical fertilizers. Soil amendments with organic nutrient sources (rice straw, CD, PM, VC, legume crops) and rice based cropping patterns such as T. Aman-Mustard-Boro, Boro-Fallow-Fallow, Jute-T. Aman-Fallow, Wheat-Mungbean-T. Aman, Grass pea- T. Aus-T. Aman and Potato-Boro-T. Aman can be beneficial in improving soil C budget, soil nutrient ratio, total crop production and maintenance of environmental health that will meet SDGs goal. Bangladesh Rice J. 24 (2): 119-131, 2021

Organic carbon storage potential of cropland topsoils in East China: Indispensable roles of cropping systems and soil managements

Soil organic carbon (SOC) is receiving increasing attention due to its large storage potential in global carbon cycles and its great importance to soil fertility, agricultural production, and ecosystem services. The increases of SOC storage and reliable estimation of its potential are essential for evaluating the soil sustainability and climate change adaptation under intensive cultivation. In this work, a data-driven approach combining mixture clustering and Random Forest models was proposed to estimate the SOC storage potential of cropland topsoil and its controlling factors in East China. The carbon landscapes systems (CLSs) were delineated using a mixture clustering model by combining the climatic condition, soil properties, cropping systems, and soil management practices. The SOC storage potentials with 95 % confidence intervals at 250 m spatial resolution were estimated as the difference between the current SOC stock and empirically maximum SOC stock at basic (75 %), intermediate (85 %), and ambitious (95 %) expectation objectives for each CLS. The SOC storage potential increased with the increasing of expectation objective settings, with the averaged levels of 13.1, 20.8, and 35.5 t C ha−1 at 75 %, 85 %, and 95 % percentile objectives, respectively. The variable importance from Random Forest indicated that the cropping systems and soil management practices were the unignorable factors controlling the SOC storage potential beyond the climatic conditions and soil properties. Moreover, the shifts of human-induced controlling factors, e.g., cropping systems, also indicated their capability of SOC sequestration potential for partly achieving the “4p1000” initiative (annual growth rate of 0.4 % carbon stocks in the first 30 cm of topsoil). The currently optimal soil management practices for achieving the SOC sequestration potential was the combination of rice-based cropping systems, straw return, and organic fertilizer applied. The data-driven approach coupling with CLSs improved our understanding of the controlling factors on SOC storage potential at regional level with homogenous conditions, enabling evidence-based decision making in promoting carbon sequestration by adopting locally feasible soil management practices.

Thirty years of agronomy research for development in irrigated rice-based cropping systems in the West African Sahel: Achievements and perspectives

Rice (Oryza spp.) is an important food crop and plays an essential role in food security in the Sahel region in West Africa. The Africa Rice Center (AfricaRice) Regional Station for the Sahel was established in 1976 to respond to the demand for increased domestic production through research for development (R4D). This paper aims to review 30 years of rice agronomy R4D in this region and provide perspectives for future research. Rice is mainly grown by smallholders in irrigated systems in the Sahel, where productivity is higher than in other African regions. However, there is still a large gap between potential yield and actual yield obtained by farmers, due to various factors including sub-optimal crop management (e.g. nutrient, weed, water management) and abiotic stresses (e.g. extreme temperatures, salt-affected soils). AfricaRice has developed crop simulation models, integrated crop management practices, water-saving technologies, agronomic interventions alongside salt-tolerant varieties, and decision-support tools for field-specific nutrient management (e.g. “RiceAdvice”). While evaluation of agronomic options is well covered in the literature, there is limited information on scaling and impact in terms of improved smallholder livelihoods. While results from long-term soil fertility trials show that double-cropping rice with appropriate fertilizer application can be sustainable, models that integrate climate change indicate a huge risk of yield reduction due to heat stress, especially in the dry season, unless adaptations such as change in sowing date and varietal improvement are applied. There has been limited research on farming systems beyond plot-level agronomy, and less focus on environmental and social sustainability than economic sustainability (i.e. yield and profit). Further R4D efforts are needed to scale out and scale-up agronomic options for enhancing the productivity and sustainability of irrigated rice-based cropping systems in the Sahel in the context of increasing competition for water, land, and labor under increasingly extreme weather conditions. Digital approaches such as the decision support tool “RiceAdvice” could play an important role in out-scaling of productive, profitable, and sustainable agronomic options.

MINIMUM TILLAGE NON-PUDDLED TRANSPLANTED RICE (ORYZA SATIVA L.): WEED CONTROL AND ECONOMICS UNDER CONSERVATION AGRICULTURE PRACTICE IN BANGLADESH

Crisis of agricultural laborers in South Asia’s rural zones is pushing to pursue a labor-saving conservation agriculture strategy for crop production and weed control. Non-puddled transplanting and mulching residues of the previous crop are being developed for rice-based cropping systems in Bangladesh to address this issue. Hence, the present study was undertaken to determine the effectiveness of strip tillage vs. conventional tillage combined with previous rice residues relative to herbicides and hand weeding on weed control and grain yield of winter rice during January-May in 2015 and 2016. Rice cv. BRRI dhan28 was transplanted with a combination of six treatments: puddled conventional tillage (CT)+3 hand weeding (HW) (Control); Preplant (PRE) herbicide (glyphosate)+non-puddled strip tillage (ST)+1HW; PRE+ST+pre-emergence (PE) herbicide (pendimethalin); PRE+ST+post-emergence (PO) herbicide (ethoxysulfuron-ethyl); PRE+ST+PE+PO; PRE+ST+weed-free (WF); and two levels of rice residues: no-residue (R0) vs. 50% standing residue (R50). The CT had done using a two-wheel tractor (2WT) by four ploughings and cross ploughings followed by levelling. A Versatile Multi-Crop Planter (VMP) was used for ST in a single pass operation. Over the two years, PRE+ST+PE+PO reduced weed density by 40% in the first year and 50% in the second year and weed biomass by 70% than CT+3HW in both years. Retention of 50% residue reduced weed density by 20% and biomass by 34%. The highest grain yield (12% higher than CT+3HW without residue) was obtained from PRE+ST+WF with 50% residue, while the highest BCR (47% higher over CT+3HW without residue) was obtained from PRE+ST+PE+PO with 50% residue.

Resource conservation technology for sustainable productivity of intensive rice-based cropping pattern in Bangladesh

Exhaustive conventional tillage and removing residues of previous crops in the rice-based cropping system are labor intensive, costly, soil destructive and non-ecofriendly. In recent years, increased concerns for healthier food production and environmental quality, and increased emphasis on sustaining the productive capacity of soils, have raised concern in the maintenance and improvement of soil organic matter through appropriate land use and management practices. Strip tillage with the application of herbicides and crop residue mulching are being developed to overcome this challenge. A two-year experiment of the summer rice-mustard-winter rice (R-M-R) system was conducted at the farmers’ field in the northern Bangladesh during 2014-2016. Summer rice (BRRI hybrid dhan6), mustard (BARI Mustard 14) and winter rice (BRRI dhan28) were grown under, T1: Conventional tillage (CT) + three hand weeding (Control) and T2: Pre-plant herbicide (PRE) + strip tillage (ST) + pre-emergence herbicide (PE) + post-emergence herbicide (PO) with two levels of crop residue mulching, M0: no-mulch and M50: 50% standing mulch. The CT consisted of two primary tillage operations by a two-wheel tractor, and ST had done by a Versatile Multi-crop Planter in a single-pass process. The PRE (glyphosate) and PE (pendimethalin) in all crops and the PO (ethoxysulfuron-ethyl in rice and isoproturon in mustard) were applied at recommended dose and time. The combination of applied PRE, ST, followed by PE and PO herbicide and the retention of 50% mulch fetched the highest yield and economic returns of individual crop and the productivity of the summer rice-mustard-winter rice system.

A Study on the Physical, Chemical, Biological, and Molecular Characteristics of Coastal Saline Soils under a Rice-Based Cropping System

Carbon (C) dynamics and soil biology are affected by the varying salinity present in coastal agro-ecosystems, which decreases from the coast in landward. The research's goal is to look at coastal saline soils through the lens of a rice-based cropping system from a physical, chemical, biological, and molecular standpoint.

Carbon sequestration potential of rice-based cropping systems under different tillage practices

Carbon sequestration potential of rice-based cropping systems under different tillage practices

Soil Organic Carbon Sequestration and Carbon Pools in Rice Based Cropping Systems in Indo-Gangetic Plains: An Overview

Carbon sequestration in the agricultural lands is possible through different soil management strategies and could be substantial with widespread implementation. Sequestration of historic carbon emissions is now essential as mitigation alone is not enough to stabilize our atmosphere. There are numerous management strategies for drawing carbon out of the atmosphere and holding it in the soil. Effectiveness of these strategies vary across different climates, soil types, and geographies. Still, it is a controversy about the durability of sequestration in soil and about the precise conditions that maximize drawdown of carbon emissions. Carbon sequestration in soil is the potential strategy which can reduce or mitigate the impacts of the global warming. The Asian countries are having more than 90% of rice fields, they are being blamed for their contribution in the methane emission and associated climate change. A major part of rice is grown under the continuous submergence condition that may influence the active and passive pools of soil carbon besides methane emission. In this paper we have reviewed the carbon sequestration potential of rice-based soils besides discussion on the mechanisms and strategies that promote accumulation of soil carbon while minimizing carbon emissions. The strategies viz. System of Rice Intensification, Integrated Nutrient Management, promoting mycorrhizal symbiosis in aerobic rice system besides enhancement of phytolith-occluded carbon are some of the key areas facilitating better carbon sequestration in rice ecosystem.

Temporal Variations of Soil Organic Carbon and pH at Landscape Scale and the Implications for Cropping Intensity in Rice-Based Cropping Systems

Landscape scale assessment of temporal variations in soil organic carbon (SOC) contents and soil pH and the implications for long-term agricultural sustainability was determined using legacy datasets collected over two periods separated by 20 years: the 1990s and 2010s. Soil data on SOC and pH were categorized according to the prevailing land types (based on inundation as highland (HL), medium highland (MHL), and medium lowland (MLL)), and physiographic types (i.e., Himalayan Piedmont plain, Tista Floodplain and Barind tract/Terrace) to determine which variable or combination of variables was more influential in spatial and temporal changes of these properties. SOC contents in the physiographic types were generally found to be low, varying between 8 to 12 g/kg. While, SOC contents were significantly higher in MHL and MLL compared with HL that experienced less inundation. The change in SOC contents over 20 years was significant with a 14.5% increase of SOC. There was a greater influence of land type compared with physiography on SOC contents over time. Inundation land types and associated cropping intensity were considered likely to influence SOC of soils under rice-based cropping systems. Furthermore, the levels of soil pH decreased by 0.5 units over 20 years with an approximately 50% increase in soils within a pH category of 4.6–5.5. The majority of soil pH results shift from slightly acidic to strongly acidic in the intervening 20-year period between samplings. Soil acidification is potentially a combination of inefficient and excess use of ammonium-based fertilizers with higher application rates and low input from residues. We conclude that acidification may continue with more intensive land use. However, trends in SOC contents over time under certain combinations of physiography and land type either increased slightly or showed a significant loss and in the latter, specifically, the role of land management is not clear. The legacy datasets would be useful for monitoring spatial and temporal soil quality trends at a regional scale, but has limited capacity to capture field level variations in soil properties as data on smallholder cropping practice and management were not collected. Therefore, future research examining the role of management in SOC and pH dynamics at the field-scale would guide the use of fertilizers, crop residue management, and amelioration of acidic soil, to improve the sustainability of rice-based cropping systems in Bangladesh.

Distinct nature of soil organic carbon pools and indices under nineteen years of rice based crop diversification switched over from uncultivated land in eastern plateau region of India

Crop diversification and their impact on soil C pools and C indices in Eastern plateau region of India is yet to be clearly understood. To explore this, a nineteen years field experiment was carried out to identify suitable diversified cropping system of this region with assessing the SOC pool, C and humification indices. Selected cropping systems were, uncultivated grassland (D-0), rice-fallow (D-1), rice-fallow/rice-okra/rice-maize (D-2), rice-fallow/rice-capsicum/rice-mungbean (D-3) and rice-fallow/rice-capsicum/rice-babycorn/rice-groundnut systems (D-4). Total organic carbon (TOC), various fractions of reactive and recalcitrant C pools, humification indices, dehydrogenase activity and carbon management index (CMI) were determined for 0−15, 15−30 and 30−45 cm soil layers. After 19 years of cultivation, SOC content (g kg−1) of the soil was improved by 22.9 % in D-1 system in 0−15 cm soil depth. Depth dynamics revealed decrement of SOC fractions and stocks with increasing soil depth, although minimum decrement has noticed in D-3 and D-4 systems. D-1 system had the highest very labile C (VLC), labile C (LC) stock, whileless labile C (LLC) and humus C (Hum-C) was found to be highest in D-0. In deeper soil layers (30−45 cm), D-4 system had the highest reactive C pool (RP) stock. Percent deviation of RP-C stock under D-4 system had also the lowest across the 45 cm soil profile. D-2, D-3 and D-4 systems had ∼34, 52 and 40 % higher C lability index (CLI) than D-0 in 0−15, 15−30 and 30−45 cm soil depths, respectively. Besides, D-1 system had similar and ∼ 63 % higher CMI value at 0−15 and 15−30 cm, while, ∼76 % higher CMI value was observed in D-4 system at 30−45 cm in respect to the reference. At lower depth, rate of humification and dehydrogenase activity were enriched in D-4 system. Thus D-4 can be considered as efficient agro-ecosystem to maintain temporal soil fertility and soil health. At regional scale, more diversified rice-based cropping system with legumesappears to be more promising cropping practice that sustains SOC with higher rate of humification and microbial activity.

Crop diversification in rice-based systems in the polders of Bangladesh: Yield stability, profitability, and associated risk

Diversifying and intensifying the rice-based cropping systems in the southern coastal zone of Bangladesh is a government priority to meet the food, feed, and fiber demand of an increasing population and changing climate. This study was conducted for three years (2016–2019) in Polder 30 located in southwest coastal zone of Bangladesh with five cropping systems [improved varieties of rice-maize (R-M); rice-mungbean (R-MB); rice-sunflower (R-S); traditional varieties of rice-mungbean (RTrad-MBTrad); and rice-fallow (RTrad-F)]. The objectives were to quantify yield gaps and spatiotemporal variability in rice production, evaluate various rice-based cropping systems for yield and profitability, and investigate individual crop and system-based stability and resilience in the coastal zone. Averaged over three years, results indicated an approximate 30% attainable yield gap on average within improved varieties and a 56% yield difference between traditional and improved rice varieties. Spatial autocorrelation analysis of both systems was positive and significant, suggesting crop yields in spatially closer locations were similar than those that were far apart. Lower spatial autocorrelation for the improved variety of rice compared to traditional varieties, indicates greater spatial dependence in addition to a narrow yield range for traditional rice. Overall, the improved rice-maize and rice-sunflower systems were the highest yielding and productive cropping systems, followed by the improved rice-mungbean. The traditional rice-fallow system was the least productive. In a high climate-risk year, however, rice was the only crop with positive net income, and the traditional systems had a relatively higher income than the improved systems. In an average opportune year, maize had the highest net income, and all improved rice-based cropping systems had a relatively higher income than traditional systems.

Improved management practices vis-à-vis farmers’ practices for rice-based cropping systems in Bangladesh: yield gaps and gross margins

ABSTRACT Rising global food demand attributable to ever-increasing population and income growth requires a substantial increase in food production, but there are limits to yield growth. Therefore, this study was carried out to assess potential yield, yield gap, and gross margins under improved management practices (IMP) and farmers’ practices (FP) in potato (Solanum tuberosum L.)-boro rice (Oryza sativa L.), and transplant aman rice-cropping patterns. The two representative subdistricts selected in Bangladesh were Mithapukur (Rangpur district) and Ulipur (Kurigram district), which are located in Tista Meander Floodplain Agroecological Zone. Fifteen farmers were selected from each location. Each farmer cultivated an area of 1,200 m2 and divided it into two plots – one received IMP, the other FP. Management practices included the use of modern varieties, fertilizers, pesticides, and irrigation. The study findings revealed that IMP provided higher yields than FP at both locations for all three crops. The yield gap between IMP and FP was 42–60% at Mithapukur and 45–51% at Ulipur for potato, 23–28% and 19–21% at Mithapukur and Ulipur, respectively, for boro rice, and 16–23% at Mithapukur and 20–26% at Ulipur for transplant aman rice. The findings showed that IMP provided substantially higher yields across crops and study locations. Gross margins of the crops under IMP were higher compared with FP at both locations. Therefore, greater yield can be obtained by following the IMP. To materialize this, regular and close collaboration between research and extension wings of the government and farmers is extremely essential.

Trade-off with tillage, irrigation schedules and novel rice establishment methods implications on soil properties and plant biomass nitrogen chemistry

Global food security depends on the continued success of rice production. Though rice production has shown a consistent increase, it faces major challenges: The increasing demand for rice versus declining growth in yield and harvested area; soil fertility and productivity decline of intensive rice-based cropping systems resulted from depletion and or limitations of natural resources (soil and water) for rice production. Therefore a field study was conducted for three seasons on a clay loam soil in karnataka, India during Kharif season (2015 & 2016), Rabi season (2015) to investigate the trade-off with tillage, irrigation schedules and novel rice establishment methods implications on soil properties and plant biomass chemistry. Tillage treatments were Dry (No puddling) and wet tillage (puddling), Establishment methods were Direct seeding (DSR, WSR) and Transplanting (NPTR, PTR), Irrigation treatments were based on soil water tension (SWT) ranging from continuous flooding/saturation (daily irrigation) to alternate wetting and drying (AWD) with irrigation thresholds of 10 and 40 kPa at 18-20cm soil depth. The study reveals that among different establishment methods DSR and NPTR under dry tillage (non puddle) condition recorded higher available N, P and K (kg/ha). Higher Organic carbon (g/kg), low bulk density, less textural disturbance compared to WSR and PTR under wet tillage (puddled) conditions.

Response of Conservation Agriculture on System Productivity and Carbon Sequestration in Rice-Based Cropping Systems

Low crop yields due to constant monocropping systems and deteriorating soil health in a smallholder farmers’ field of Indo-Gangetic plains of India have led to a quest for sustainable production practices with greater resource use efficiencies. The aim of the study was to elucidate the short term effects of conservation agricultural systems on productivity, soil health and carbon sequestration rate of soils in three different diversified cropping systems. The treatments consisted of two different tillage systems (conventional and reduced tillage), two mulch levels (no and straw mulch) and two levels of fertility (100 and 75% RDF) were compared in three rice-based cropping systems (rice-wheat; rice-vegetable pea-greengram; and rice-potato-maize sequences) for two years on an experimental field (clay loam) located at Norman E Borlaug Crop Research Center, Pantnagar, India. The resource conservation technologies (RCT) i.e. reduced tillage, mulch, and 100% RDF had recorded 2.5 and 3.0% higher system productivity and relative production efficiency in rice-vegetablepea-greengram and rice-potato-maize sequences, respectively in two consecutive years. Conservation tillage had sequestered three times higher carbon than conventional tillage while mulching acted four times higher than non-mulched condition in agricultural soils. Even though cropping system not significant significantly influenced on carbon sequestration, rice-vegetablepea-greengram sequence had recorded higher carbon sequestration rate and higher soil organic carbon stock noted in surface plough sole layer than any other cropping systems. Therefore, our results suggested that Indo-Gangetic farmers should consider adopting resource conservation practices together in indogangetic area because of benefits to soil health, carbon sequestration and system productivity.

Nutrient management options modulating soil physico-chemical and biological properties under direct-seeded rice-based cropping systems

ABSTRACT To achieve higher system productivity and better soil health under rice‒based cropping systems, this study was conducted to ascertain the best agricultural and nutrient management strategies. The study involved four cropping systems (CS) comprising direct seeded basmati rice (DSBR)‒wheat (CS1), DSBR‒wheat‒greengram (CS2), DSBR‒cabbage‒greengram (CS3) and DSBR‒cabbage‒onion (CS4) under different nutrient management strategies (NMS) comprising of control (NS0), 100% recommended dose of N, P and K fertilizers (RDF-NPK) (NS1), 50% RDF + 25% recommended dose of nitrogen (RDN) through leaf compost (LC) + biofertilizer (NS2), 50% RDF + 25% RDN through vermicompost (VC) + biofertilizer (NS3) and was carried out for two consecutive years. At the end of study, soil carbon fractions, bulk density and water stable aggregates were significantly (p < 0.05) higher under integrated NMS as compared to control and RDF alone. Soil biological parameters such as dehydrogenase, alkaline phosphatase and microbial biomass carbon increased significantly (p < 0.05) in all three seasons (rainy, winter and summer) under integrated NMS (NS2 and NS3) plots, as compared to NS0 and NS1. Inclusion of greengram in rice–based cropping systems and combined use of inorganic and organic nutrient sources resulted in positive influence on soil health parameters and sustaining system productivity.

Potential of conservation agriculture modules for energy conservation and sustainability of rice-based production systems of Indo-Gangetic Plain region

Rice-based cropping systems are the most energy-intensive production systems in South Asia. Sustainability of the rice-based cropping systems is nowadays questioned with declining natural resource base, soil degradation, environmental pollution, and declining factor productivity. As a consequence, the search for energy and resource conservation agro-techniques is increasing for sustainable and cleaner production. Conservation agriculture (CA) practices have been recommended for resource conservation, soil health restoration and sustaining crop productivity. The present study aimed to assess the different CA modules in rice-based cropping systems for energy conservation, energy productivity, and to define energy-economic relations. A field experiment consisted of four different tillage-based crop establishment practices (puddled-transplanted rice followed by (fb) conventional-till maize/wheat (CTTPR-CT), non-puddled transplanted rice fb zero-till maize/wheat (NPTPR-ZT), zero-till transplanted rice fb zero-till maize/wheat (ZTTPR-ZT), zero-till direct-seeded rice fb zero-till maize/wheat (ZTDSR-ZT)), with two residue management treatments (residue removal, residue retention) in rice–wheat and rice–maize rotations were evaluated for energy budgeting and energy-economic relations. Conservation-tillage treatments (NPTPR-ZT, ZTTPR-ZT, and ZTDSR-ZT) reduced the energy requirements over conventional tillage treatments, with the greater reduction in ZTTPR-ZT and ZTDSR-ZT treatments. Savings of energy in conservation-tillage treatments were attributed to reduced energy use in land preparation (69–100%) and irrigation (23–27%), which consumed a large amount of fuel energy. Conservation-tillage treatments increased grain and straw/stover yields of crops, eventually increased the output energy (6–16%), net energy (14–26%), energy ratio (25–33%), and energy productivity (23–34%) as compared with CTTPR-CT. For these energy parameters, the treatment order was ZTDSR-ZT ≥ ZTTPR-ZT > NPTPR-ZT > CTTPR-CT (p < 0.05). Crop residue retention reduced net energy, energy ratio, and energy productivity when compared with residue removal. Our results of energy-economic relations favored the “conservative hypothesis,” which envisages that energy and monetary investments are not essentially the determinants of crop productivity. Thus, zero tillage-based crop establishments (ZTTPR-ZT, ZTDSR-ZT) in rice-based production systems could be the sustainable alternative to conventional tillage-based agriculture (CTTPR-CT) as they conserved non-renewable energy sources, reduced water requirement, and increased crop productivity.

Soil Physical and Chemical Quality under Long-Term Rice-based Cropping System in Hot Humid Eastern Plateau of India

ABSTRACT Inclusion of a legume crop in a cropping system can improve soil physical and chemical properties, particularly in predominantly rice cultivating areas. Analysis of Variance (ANOVA) was performed between different soils and cropping systems to evaluate soil physical and chemical properties in Balod District of Chhattisgarh state of India. Among the soils, inVertisols, bulk density (BD) (p = .024), hydraulic conductivity (HC) (p < .005), available Fe (p < .005), available Mn (p < .005), available Zn (p < .005) and available B (p < .005) were found to be significantly lower than that of Inceptisols. However, significantly higher for porosity (p = .040), field capacity (FC) (p < .005), wilting point (WP) (p < .005), water holding capacity (WHC) (p < .005), mean weight diameter (MWD) (p < .005), soil pH (p < .005), electrical conductivity (EC) (p < .005), organic carbon (OC) (p < .005), available N (p < .005), available P (p < .005), available K (p < .005) and available S (p < .005). Tukey’s post-hoc test for multiple comparisons indicated that BD was found significantly higher for soils under rice-wheat (RW) cropping system, than that of soils under rice-chickpea (RC) (p < .005), rice-lathyrus (RL) (p < .005), and rice-fallow (RF) (p = .032). However, other soil properties i.e. porosity, FC, WP, WHC, HC, MWD, soil pH, OC, available N, available P, available K, available S, and available Zn were found significantly higher for soils under rice-legume cropping system (RC and RL), than that of soils under RW and RL. Thus, from the study, it is concluded that inclusion of legumes into cropping systems maintained better soil physical and chemical properties and helpful to work out the best management practices for sustaining intensive cultivation.

Multi-year weed community dynamics and rice yields as influenced by tillage, crop establishment, and weed control: Implications for rice-maize rotations in the eastern Gangetic plains

In South Asia's rice-based cropping systems, most farmers flood and repetitively till their fields before transplanting. This establishment method, commonly termed puddled transplanted rice (TPR), is costly. In addition, it is labor and energy intensive. To increase labor and energy efficiency in rice production, reduced or zero-tilled direct seeded rice (ZT-DSR) is commonly proposed as an alternative tillage and crop establishment (TCE) option. Effective management of weeds in ZT-DSR however remains a major challenge. We conducted a four-year experiment under a rice-maize rotation in Northwestern Bangladesh in the eastern Gangetic Plains to examine the performance of two TCE methods and three weed management regimes (WMR) on the diversity and competitiveness of weed communities in the rice phase of the rotation. The Shannon-Weiner Diversity Index, a measure of species diversity, was significantly greater under ZT-DSR than puddled TPR. It was also greater under no weed control (Weedy) and two manual weeding (MW) treatments compared to chemical herbicide with manual weeding (C + MW). In DSR Weedy plots, weed communities began shifting from grasses to sedges from the rotation's second year, while in the ZT-DSR and C + MW treatments, sedges were consistently predominant. In both puddled TPR Weedy and TPR C + MW treatments, broadleaves and grasses were dominant in the initial year, while sedges dominated in the final year. There were significant main effects of year (Y) and weed management regime (WMR), but not of TCE. Significant Y × TCE and TCE × WMR interaction effects on rice yield were also observed. Grain yields under ZT-DSR were similar to puddled TPR. ZT-DSR with one application of pre-emergence herbicide followed by one hand weeding at 28 days after establishment however resulted in significantly higher grain yield (5.34 t ha−1) compared the other weed management regimes. Future research should address methods to effectively manage weed community composition shifts in both ZT-DSR and TPR under rice-maize rotations utilizing integrated and low-cost strategies that can be readily applied by farmers in the eastern Gangetic Plains.

Crop residue and weed biomass incorporation with microbial inoculation improve the crop and soil productivity in the rice (Oryza sativa L.) -toria (Brassica rapa L.) cropping system

Agriculture residue can be converted as a nutrient resource to enhance the soil and crop productivity through their soil incorporation. The aim of the three years study was to know the response of crop residues and weed incorporation with the bio-inoculants in rice ( Oryza sativa L.)–toria ( Brassica rapa L. Var Toria) cropping system (RTCS). Experiment was imposed in split-plot, where main-plots have five residue management treatments viz; 50% weed biomass mixed (WBM) 2 ​t ​ha −1 , 50% crop residues of rice (CRR) 2 ​t ​ha −1 , 50% WBM 2 ​t ​ha −1 + 50% CRR 2 ​t ​ha −1 , 100% WBM 4 ​t ​ha −1 and 100% CRR 4 ​t ​ha −1 in toria, whereas in rice, each treatment received half of above biomass (WBM and CRR), while in the sub-plots two microbial decomposing agents, Trichoderma viridi (TV) 2 ​g ​kg −1 and Pleurotus sp. (PS) 20 ​g ​kg −1 as spawn seed. Results revealed that 50% WBM ​+ ​CRR considerably increase the rice grain yield (9.8–37.7%) and toria seed yield (15.3–31.5%) over the 100% CRR. Likewise, TV recorded higher yield of rice and toria. Incorporation of 100% CRR improves the bulk density and water content, while 100% WBM improved the soil pH (4.6–5.7%), available nitrogen (9.8–11.8%), available phosphorus (21.6–22.8%) and labile potassium to the extent of 7–11.3% than the 100% CRR. Contrarily, 100% CRR improved soil organic carbon by 7–8.6% over 50% WBM. The manuscript provides insight for improvement of crop productivity and improves the soil health indicator in existing rice-fallow cropping system. Crop reside and weed biomass convert as nutrient source, it will promote the soil and environmental sustainability indicators. This is a novel kind of study, such information is not available yet to policymakers and this will also help in modelling and simulation for sustainable production and diversification in the rice-based cropping systems.

Rice (Oryza sativa L.) Establishment Techniques and Their Implications for Soil Properties, Global Warming Potential Mitigation and Crop Yields

Rice-based intensive cropping systems require high input levels making them less profitable and vulnerable to the reduced availability of labor and water in Asia. With continuous conventional puddled rice transplanting, the situation is exacerbated by damaged soil structure, declining underground water and decreasing land and water productivity. To minimize these negative effects a range of new crop establishment practices have been developed (zero tillage, dry direct seeding, wet direct seeding, water seeding, strip planting, bed planting, non-puddled transplanting of rice, mechanical transplanting of rice crop and combinations thereof) with varying effects on soil health, crop productivity, resource saving and global warming mitigation potential. Some of these allow Conservation Agriculture (CA) to be practiced in the rice-based mono-, double- and triple cropping systems. Innovations in machinery especially for smallholder farms have supported the adoption of the new establishment techniques. Non-puddling establishment of rice together with increased crop residue retention increased soil organic carbon by 79% and total N (TN) in soil by 62% relative to conventional puddling practice. Rice establishment methods (direct seeding of rice, system of rice intensification and non-puddled transplanting of rice) improve soil health by improving the physical (reduced bulk density, increased porosity, available water content), chemical (increased phosphorus, potassium and sulphur in their available forms) and biological properties (microbiome structure, microbial biomass C and N) of the soil. Even in the first year of its practice, the non-puddled transplanting method of rice establishment and CA practices for other crops increase the productivity of the rice-based cropping systems. Estimates suggest global warming potential (GWP) (the overall net effect) can be reduced by a quarter by replacing conventional puddling of rice by direct-seeded rice in the Indo-Gangetic Plains for the rice-based cropping system. Moreover, non-puddled transplanting of rice saves 35% of the net life cycle greenhouse gases (GHGs) compared with the conventional practice by a combination of decreasing greenhouse gases emissions from soil and increasing soil organic carbon (SOC). Though the system of rice intensification decreases net GHG emission, the practice releases 1.5 times greater N2O due to the increased soil aeration. There is no single rice establishment technology that is superior to others in all circumstances, rather a range of effective technologies that can be applied to different agro-climates, demography and farm typologies.