Reduced tillage and crop diversification can improve productivity and profitability of rice-based rotations of the Eastern Gangetic Plains

Intensive rice (Oryza sativa)-based cropping systems in south Asia provide much of the calorie and protein requirements of low to middle-income rural and urban populations. Intensive tillage practices demand more resources, damage soil quality, and reduce crop yields and profit margins. Crop diversification along with conservation agriculture (CA)-based management practices may reduce external input use, improve resource-use efficiency, and increase the productivity and profitability of intensive cropping systems. A field study was conducted on loamy soil in a sub-tropical climate in northern Bangladesh to evaluate the effects of three tillage options and six rice-based cropping sequences on grain, calorie, and protein yields and gross margins (GM) for different crops and cropping sequences. The three tillage options were: (1) conservation agriculture (CA) with all crops in sequences untilled, (2) alternating tillage (AT) with the monsoon season rice crop tilled but winter season crops untilled, and (3) conventional tillage (CT) with all crops in sequences tilled. The six cropping sequences were: rice-rice (R-R), rice-mung bean (Vigna radiata) (R-MB), rice-wheat (Triticum aestivum) (R-W), rice-maize (Zea mays) (R-M), rice-wheat-mung bean (R-W-MB), and rice-maize-mung bean (R-M-MB). Over three years of experimentation, the average monsoon rice yield was 8% lower for CA than CT, but the average winter crops yield was 13% higher for CA than CT. Systems rice equivalent yield (SREY) and systems calorie and protein yields were about 5%, 3% and 6%, respectively, higher under CA than CT; additionally, AT added approximately 1% more to these benefits. The systems productivity gain under CA and AT resulted in higher GM by 16% while reducing the labor and total production cost under CA than CT. The R-M rotation had higher SREY, calorie, protein yields, and GM by 24%, 26%, 66%, and 148%, respectively, than the predominantly practiced R-R rotation. The R-W-MB rotation had the highest SREY (30%) and second highest (118%) GM. Considering the combined effect of tillage and cropping system, CA with R-M rotation showed superior performance in terms of SREY, protein yield, and GM. The distribution of labor use and GM across rotations was grouped into four categories: R-W in low-low (low labor use and low GM), R-M in low-high (low labor use and high GM), R-W-MB and R-M-MB in high-high (high labor use and high GM) and R-R and R-MB in high-low (high labor use and low GM). In conclusion, CA performed better than CT in different winter crops and cropping systems but not in monsoon rice. Our results demonstrate the multiple benefits of partial and full CA-based tillage practices employed with appropriate crop diversification to achieve sustainable food security with greater calorie and protein intake while maximizing farm profitability of intensive rice-based rotational systems

How we used APSIM to simulate conservation agriculture practices in the rice-wheat system of the Eastern Gangetic Plains

Examples of how to simulate performance of conservation agriculture (CA) and conventional tillage (CT) practices using cropping systems models are rare in the literature, and from the Eastern Gangetic Plains (EGP). Here we report a comprehensive evaluation of the capacity of APSIM for simulating the performance of CA and CT cropping practices under a diverse range of tillage (CT vs zero tillage (ZT)), crop establishment options (puddled transplanted rice vs unpuddled transplanted rice), residue, N rates, and irrigation practices from two sites in the EGP that differed in soil type, water table dynamics, and agro-climatic conditions. We followed a robust procedure of model parameterisation, calibration, and validation, then undertook statistical analyses to evaluate model performance. We have demonstrated that when different values for key model input parameters are employed (i.e. change in soil properties (Ks, BD)), crop rooting parameters (xf- root hospitality, kl- root extraction efficiency) and soil microorganism activity (Fbiom- fraction of soil organic matter present as microbial biomass and Finert- the inert fraction of soil organic matter), the model performed well in simulating the different performances of CA and CT management practices across the environments in the EGP. Model performance was markedly better in the full-N than in zero-N, but both are still considered acceptable. In addition to well-watered and fertilised treatments, the model was able to capture an observed crop failure in rainfed unpuddled transplanted rice accurately, illustrating an ability to capture crop response under a wide range of water stress environments. As demonstrated by robust statistical criteria, APSIM was able to capture the effect of cropping system, irrigation, tillage, residue, and N-application rate within the bounds of experimental uncertainty, hence is now deemed a suitable tool for scenario analyses around the relevant practices

Performance of a hermetic device and neem (Azadirachta indica) in storing wheat seed: Evidence from participatory household trials in central Bangladesh

Smallholder farmers in Bangladesh often use low-density polyethylene (LDPE) bags contained within woven polypropylene bags to store wheat seed during the summer monsoon that precedes winter season planting. High humidity and temperature during this period can encourage increased seed moisture and pests, thereby lowering seed quality. Following a farm household survey conducted to inform trial design, eighty farmers were engaged in an action research process in which they participated in designing and conducting trials comparing traditional and alternative seed storage methods over 30 weeks. Factorial treatments included comparison of hermetic SuperGrainbags® (Premium RZ) against LDPE bags, both with and without the addition of dried neem tree leaves (Azadirachta indica). SuperGrainbags® were more effective in maintaining seed moisture at acceptable levels close to pre-storage conditions than LDPE bags. Both seed germination and seedling coleoptile length were significantly greater in hermetic than LDPE bags. Neem had no effect on seed moisture, germination, or coleoptile length. SuperGrainbags® were also more effective in abating seed damage during storage, although inclusion of neem within LDPE bags also had significant damage. Quantification of seed predating insects and diseases suggested that SuperGrainbags® also suppressed Coleopteran pests and blackspot, the latter indicative of Fusarium graminearum. Conversely, where farmers used LDPE bags, neem also had an additional though limited pest suppressive effect. Post-storage treatment scoring by farmers revealed a strong preference for SuperGrainbags® and no preference differences for or against neem. This study demonstrates a process by which farmers can be involved in the participatory co-design and testing of alternative wheat storage options, and stresses the need to develop SuperGrainbag® supply chains so hermetic storage can be made widely available

Efficacy of pre- and post-emergence herbicide combinations on weed control in no-till mechanically transplanted rice

No-till mechanized-transplanted rice was evaluated for different combinations of pre- and post-emergence herbicides to determine feasible, economically viable weed management options to control complex weed flora in rice fields. All pre-emergence herbicides significantly reduced the population of grassy weeds; of these, pendimethalin resulted in the greatest reductions (83%) at 15 days after transplanting (DAT). Among five post-emergence herbicide treatments, the combination of bispyribac-sodium (10%SP) + pyrazosulfuron (10%WP) was found to be the most effective in controlling all weed flora at both 35 and 55 DAT. The sequential application of pendimethalin (pre-emergence) followed bispyribac-sodium + pyrazosulfuron (post-emergence) resulted in significantly higher rice grain yield (4.4 t-ha−1) and relative gross-margin (417 USD-ha−1) than all other treatments. A strong negative correlation was observed between rice grain yield and weed biomass, and a strong positive correlation between rice grain yield and weed control efficiency. Our findings demonstrate the potential to combine pre- and post-emergence herbicides in no-till mechanized-transplanted rice; these findings have applications globally in regions where rice is established by no-till or mechanized transplanting

Adapted conservation agriculture practices can increase energy productivity and lower yield-scaled greenhouse gas emissions in coastal Bangladesh

While numerous studies have documented the benefits of conservation agriculture (CA) in South Asia, most focus on favorable environments where farmers have reliable access to energy supporting irrigation and inputs. The performance of CA in South Asia’s under-developed coastal environments is comparatively understudied. In these environments, farmers are increasingly interested in growing a second crop to meet food security and income generation objectives in rotation following the predominant monsoon season rice crop, though labor, energy costs, and investment constraints limit their ability to do so. We hypothesized that rotating rice (Oryza sativa) with maize (Zea mays) using conservation agriculture, or CA (i.e., strip-tilled maize followed by unpuddled transplanted rice), or seasonally alternating tillage (SAT, i.e., strip-tilled maize followed by fully-tilled, puddled rice with residues retained across rotations) would reduce costs and energy use, increase energy-use efficiency, and reduce yield-scaled CO2-eq emissions (YSE) and total global warming potential (GWP), compared to farmers’ own practices (FP) and conventional full-tillage (CT) under the same rotation in Bangladesh’s coastal region. Starting with winter maize followed by summer rice, we evaluated four tillage and crop establishment treatments in farmer-managed experiments in partially irrigated and rainfed environments over three years in 35 farmer’s fields across Bangladesh’s coastal districts. Treatments included FP, CT, complete CA, and SAT under a rice-maize rotation. Across years, the full suite of CA practices and SAT were significantly more energy-efficient and energy-productive than FP or CT. The order of YSE in rice was CA< CT or FP < SAT while in maize, it was CA or SAT < FP < CT. Across environments, CA and SAT resulted in 15-18% higher yield at the cropping systems level (maize and rice yields combined) and 26-40% less manual labor than CT or FP. CA and SAT also reduced by 1-12% and 33-35% total production costs respective to CT and FP. This was associated with 13-17% greater grain energy output in CA and SAT, and 2-18% lower YSE, compared to CT or FP. While our data suggest that both CA and SAT can result in a range of positive agronomic, economic, and environmental outcomes compared to FP or CT, post-trial surveys and discussions with farmers revealed a strong practical aversion to use of the full suite of CA practices and preference for adapted practices due to logistical constraints in negotiating the hire of laborers for unpuddled manual transplanting

Potassium Supplying Capacity of Diverse Soils and K-Use Efficiency of Maize in South Asia

Increased nutrient withdrawal by rapidly expanding intensive cropping systems, in combination with imbalanced fertilization, is leading to potassium (K) depletion from agricultural soils in Asia. There is an urgent need to better understand the soil K-supplying capacity and K-use efficiency of crops to address this issue. Maize is increasingly being grown in rice-based systems in South Asia, particularly in Bangladesh and North East India. The high nutrient extraction, especially K, however, causes concerns for the sustainability of maize production systems in the region. The present study was designed to estimate, through a plant-based method, the magnitude, and variation in K-supplying capacity of a range of soils from the maize-growing areas and the K-use efficiency of maize in Bangladesh. Eighteen diverse soils were collected from several upazillas (or sub-districts) under 11 agro-ecological zones to examine their K-supplying capacity from the soil reserves and from K fertilization (100 mg K kg&minus;1 soil) for successive seven maize crops grown up to V10&ndash;V12 in pots inside a net house. A validation field experiment was conducted with five levels of K (0, 40, 80, 120 and 160 kg ha&minus;1) and two fertilizer recommendations based on &ldquo;Nutrient Expert for Maize-NEM&rdquo; and &ldquo;Maize Crop Manager-MCM&rdquo; decision support tools (DSSs) in 12 farmers&rsquo; fields in Rangpur, Rajshahi and Comilla districts in Bangladesh. Grain yield and yield attributes of maize responded significantly (p &lt; 0.001) to K fertilizer, with grain yield increase from 18 to 79% over control in all locations. Total K uptake by plants not receiving K fertilizer, considered as potential K-supplying capacity of the soil in the pot experiment, followed the order: Modhukhali &gt; Mithapukur &gt; Rangpur Sadar &gt; Dinajpur Sadar &gt; Jhinaidah Sadar &gt; Gangachara &gt; Binerpota &gt; Tarash &gt; Gopalpur &gt; Daudkandi &gt; Paba &gt; Modhupur &gt; Nawabganj Sadar &gt; Shibganj &gt; Birganj &gt; Godagari &gt; Barura &gt; Durgapur. Likewise, in the validation field experiment, the K-supplying capacity of soils was 83.5, 60.5 and 57.2 kg ha&minus;1 in Rangpur, Rajshahi, and Comilla, respectively. Further, the order of K-supplying capacity for three sites was similar to the results from pot study confirming the applicability of results to other soils and maize-growing areas in Bangladesh and similar soils and areas across South Asia. Based on the results from pot and field experiments, we conclude that the site-specific K management using the fertilizer DSSs can be the better and more efficient K management strategy for maize

Potassium supplying capacity and contribution of non-exchangeable potassium in wetland rice soils in Bangladesh

Information on soil potassium (K) supplying capacity, K-depletion, and contribution of exchangeable and non-exchangeable K in wetland rice ecology is limited. Understanding of K dynamics of different soil types can be a guideline for better K-fertilizer management and sustainable soil K use to achieve sustainable rice yields. To understand this soil K-supplying capacity to rice plants, a pot study with two K levels (K0 and K100 mg K kg-1 soil) was conducted with seven successive rice crops grown up to the panicle initiation stage using 18 different soils collected from across Bangladesh. The cumulative soil K-supplying capacity (242–758 mg K kg-1 soil) varied significantly (P ≤.001) among soils, showing a strong positive relationship (R2 = 0.78) with NH4OAc K. The potential K-supplying capacity of these soils was the highest (758 mg K kg-1 soil) in Mithapukur (AEZ 3-Tista Meander Floodplain) and the lowest (242 mg K kg-1 soil) in Barura (AEZ 19-Old Meghna Estuarine Floodplain). In K0 soils, the successive cycles of rice resulted in continuous depletion of both non-exchangeable and exchangeable K pools. The concentration of both exchangeable and non-exchangeable K was maintained and almost balanced in K100 soils compared to K0 with successive rice cropping. Non-exchangeable K contribution to K nutrition of rice plants during the seventh cropping ranged, respectively, from 83% to 93% and 26% to 55% in K0 and K100 soils. Results reveal the importance of a non-exchangeable K pool in K-supplying to plants in wetland rice production systems with different soil types

Sustainable intensification in eastern gangetic plains of South Asia via conservation agriculture for energy, water and food security under climate smart management system

Rice cultivation in the South Asian region of Eastern Gangetic Plains (EGP) is running out of water, labour, low productivity and profitability. In addition, this system of crop production often ignores CO2-equivalent greenhouse-gas emissions, which are often rather significant. Although a dominant food-producing region in Asia is becoming poor in crop production, crop management approaches based on conservation agriculture-based sustainable intensification (CASI) increase the crop yields and improve profitability while lowering the water, energy and labour requirements, as well as greenhouse-gas emissions. The use of CASI approaches in EGP region villages and districts enhances crop diversification and intensifies their production. It also facilitates employment opportunities and micro entrepreneurship in rural areas. In on-farm experiments traditional and improved approaches in rice-based cropping systems were compared. We discovered that CASI management approaches increased the crop yields by 10%, reduced labour demand by 50% and increased water and energy productivity by 19% and 26% respectively. Overall, these findings showed that using CASI lowered crop production costs by up to 22% and raised gross margins by 12–32% compared with traditional methods. CASI management also resulted in CO2-equivalent emissions that were between 10% and 17% lower than those with traditional management. Initially, this principal research was collaborated on with farmer support groups for further extension. To encourage CASI adoption and out-scaling on a scale outside of research domains, an actively supporting policy environment was required

Conservation Agriculture in South Asia

South Asia, a home of 1.7 billion people houses the most poor and malnourished people globally. The region need to double its food production by 2050. Current scenario puts South Asian agriculture in a dilema facing triple challenges: to increase production to meet the food demand of growing human population with a lower environmental footprint, preserve natural resources and mitigate or adapt to the changing climatic scenarios. Conservation Agriculture offers a number of benefits such as arresting and reversing the resource degradation, decreasing cultivation costs, making agriculture more resource – use-efficient, competitive and sustainable whilst increasing resilience to climatic variability and improving livelihood incomes in South Asia. The CA approach for managing agro-ecosystems is of paramount significance in improving soil health, sustained productivity and maintaining natural biodiversity. However, there is still a large knowledge gap in understanding of nutrient and water management in CA systems

Achieving the win–win: targeted agronomy can increase both productivity and sustainability of the rice–wheat system

Maximizing productivity of the rice–wheat (RW) system is a major challenge for achieving food security in the Eastern Gangetic Plains (EGP) of South Asia. Ideally, productivity should increase along with increasing farm profits while sustaining or enhancing the natural resource base. However, research focused on increasing the productivity and profitability of the RW system while considering long-term system sustainability is lacking from the EGP. Here, we show that using the process-based cropping system model Agricultural Production Systems sIMulator (APSIM) (earlier robustly validated in these environments), maximization of target variables (e.g. production, farm profit, water productivity) can be achieved by modifying the agronomic management currently recommended for RW farmers in the region. Our analysis demonstrates conservation agriculture-based intensification, through the addition of mungbean with modified irrigation and increased nitrogen fertilization, increases not only the system production (34%), farm profit (39%), and water productivity (54%), but also the soil organic carbon (31%) and total soil nitrogen (52%) in the 0–15 cm soil layer. In contrast, conventional tillage-based intensification increases system productivity but not sustainability. We found the ideal agronomic management varied across different environments for maximizing target variables. Our analysis illustrates the power of validated modeling tools like APSIM and has broader application for farmers globally whose production and sustainability are constrained by inefficient agronomic practices