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.

The effects of conservation agriculture (CA) practices on soil properties along with crop yields of rice-based triple cropping systems have not been adequately assessed in Bangladesh. An experiment was conducted at Bangladesh Agricultural Research Institute, Gazipur, Bangladesh from 2009 to 2012 to assess the effects of tillage practices and crop residue retention on soil physical properties, soil organic carbon (SOC) and crop yields in a wheat-mungbeanrice system. Treatments consisted of three tillage practices (MT: minimum tillage; CT: conventional tillage and DT: deep tillage) and eight levels of crop residue management (S 0 -no residues retention, S r -retention of 30 cm rice straw, S m -whole mungbean stover retention, S W -30 cm wheat straw retention, S mr -whole mungbean stover & 30 cm rice straw retention, S rw -30 cm rice & wheat straw retention, S mw -whole mungbean stover & 30 cm wheat straw retention and S wrm -30 cm wheat and rice straw along with whole mungbean stover retention) were applied in split plot design with three replications. Bulk density (BD) and porosity responded positively to MT and increased residue retention of all crops (p > 0.05). Minimum tillage and S wrm also significantly accumulated SOC (p < 0.05; 0.38% higher than DT with no residue retention) and retained soil moisture (p < 0.05). Minimum tillage practice performed better in upland crops (p < 0.05; wheat & mungbean yields) and CT outperformed MT in wetland rice crop (p < 0.05). The grain and straw yields of wheat and rice were also influenced by previous crop residue retentions (p < 0.05). The results, therefore, suggested that increased residue 2 retention with minimum tillage practices improved soil properties and yield of upland crops but with deeper tillage practices consistently maintained wetland rice production.

Cropping systems of Bangladesh are highly diverse and cultivation costs of puddled transplanted rice (PTR) are high. Therefore, an improved system is needed to address the issues, a field experiment was conducted during 2011-2013 to evaluate system intensification with varying degrees of cropping systems and residue retention. Four cropping systems (CSE) namely CSE1: T. boro rice-T. aman rice (control), CSE2: wheat-mungbean-T. aman rice (wheat and mungbean sown using a power tiller-operated seeder (PTOS) with full tillage in a single pass; puddled transplanted aman), CSE3: wheat-mungbean-dry seeded DS aman rice (DSR), and CSE4: wheat-mungbean-DS aman rice (all sown by PTOS with strip tillage) were compared. Two levels of aman rice residue retention (removed; partial retention i.e. 40 cm of standing stubble) were compared in sub plots. Grain yield was significantly higher (by 11%) when wheat was grown after DSR than PTR. Similarly, PTR and DSR (aman rice) produced statistically similar crop yields. Rice residue retention resulted a significantly higher (by 10%) wheat yield and a slightly increased (by 6%) mungbean yield than that of residues removed. The system productivity of CSE4 was significantly higher (by 10%) than CSE1 when averaged of the two years data. Partial aman residue retention gave significantly higher system yield than residue removal (by 0.6 t ha-1). After two years, no effect of CSE or partial aman residue retention was found on soil physical property (bulk density) of the top soil. Therefore, CSE4 along with residue retention would be more effective for sustainable crop production. The Agriculturists 2019; 17(1-2) 14-30

Co-composting is an effective approach to biowaste management. The co-composting potential of banana pseudostem (BPS) and mushroom media waste (MMW) with chicken manure (CM) has not been explored, let alone their suitable ratios of co-composting being determined. Meanwhile, the imbalance ratios of the feedstocks used in the process severely restrict the physicochemical properties and quality of the finished product. For this reason, six different ratios of BPS, MMW, and CM, viz. 1:1:1, 1:2:1, 1:3:1, 2:1:1, 2:2:1, and 2:3:1, respectively (T1–T6), were composted together in aerobic conditions to identify the suitable ratio by evaluating the changes in the physicochemical properties in the composting process. According to the ratio of treatments, the feedstocks were mixed on fresh weight basis. The turning process of co-composting piles was repeated at seven-day intervals to maintain the uniform aeration throughout the composting period. The piles having BPS, MMW, and CM at ratios of 1:2:1, 1:3:1, and 2:3:1, respectively, demonstrated a longer thermophilic phase, indicating more complete decomposition and earlier maturity compared to piles with higher amount of BPS. Of the ratios, BPS:MMW:CM at 1:2:1 ratio (T2) resulted in the highest total nitrogen (1.53%), lowest C:N ratio (12.4), organic matter loss (54.5%), and increased CEC (41.3 cmol/kg). The highest germination index (129%) was also recorded in the T2 compost, indicating that it was toxic-free and safe for seed germination. The nutrient-rich compost with high alkaline pH (≥10) can effectively ameliorate soils of an acidic nature, for example, the acidity of Ultisols and Oxisols.

Medium-term changes in the labile nutrient pool of microbial biomass carbon (MBC) and nitrogen (MBN) resulting from organic manure application in rice (Oryza sativa L.)-based triple cropping systems have been poorly studied.Therefore, the effects of organic materials on the soil physico-chemical properties and microbial biomass in rice fields were investigated at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh, from April 2010 to December 2012. Five treatments (control, cow dung, poultry manure, rice straw, and chemical fertilizer) were laid out in a randomized complete block design with four replications. The organic residues (2 t C ha −1 ) were applied 7 days before transplanting and were combined with inorganic fertilizers, following integrated plant nutrition systems. This paper presents the results from the last of the five consecutive rice growing seasons. All of the organic residues increased the pH, and organic C, N, P, and K contents of the soil. However, poultry manure was more efficient in increasing soil fertility than cow dung and rice straw, resulting in a significant increase in P from 22 mg·kg −1 to 63 mg·kg −1 at crop harvest. All of the organic residues also increased the soil water holding capacity and decreased bulk density. Furthermore, poultry manure resulted in significantly higher microbial biomass C (432 mg·kg −1 ; P < 0.05) and N (31.60 mg·kg −1 ; P < 0.05) levels in the soil at crop harvest, followed by cow dung and rice straw. These findings indicate that the regular application of organic residues and manures will help to enhance soil fertility and production sustainability.

Phytochemicals in plant extracts help plants to grow, develop and survive. This study aimed to identify the phytochemicals and quantify soluble nutrients present in banana (Musa acuminata Colla)-pseudostem sap, and to observe the subsequent effect on seedling growth of sweet corn (Zea mays L. var. saccharata (Sturtev.) L.H. Bailey). The collected banana pseudostem sap was extracted with methanol followed by a liquid-liquid extraction procedure. The extracted fractions were analyzed by liquid chromatography mass spectrometry (LC-MS). Seven concentrations of fresh banana pseudostem sap, i.e., 5%, 10%, 15%, 25%, 50% aqueous, and 100% raw sap with control (distilled water) were replicated three times following a completely randomized design. The LC-MS analysis identified 86 various phytocompounds, while inductively coupled plasma (ICP) quantified different essential plant nutrients in the fresh sap, confirming the benefits of phytocompounds and mineral nutrients on sweet corn. The sap showed 44 beneficial plant compounds such as 1-amino-1-carboxycyclopropane, 4-aminobenzoic acid, glutamic acid, 1,4-benzoquinone, proline betaine, butanoic acid, hydroxysouric acid, 2,4-dihydroxybenzoic acid and aluminium acetate. These are vital for plant growth and development. The results confirmed that a high number of beneficial secondary metabolites and mineral nutrients in aqueous banana pseudostem sap, especially in lower concentrations (5%-15%), significantly influenced seedling growth over higher concentration and control. However, compared to control, 10% aqueous banana pseudostem sap resulted in 21.2% larger root length, 19.6% shoot length, 32.0% dry biomass, and 17.4% chlorophyll content, respectively. It is concluded that a 10% aqueous solution of fresh banana pseudostem sap will be more effective for crop production.

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