Crop establishment, which often receives insufficient attention, is one of the major rice production operations that should be considered when promoting sustainable rice production practices. There are available options for crop establishment, but a major research gap is quantitative data on the best approach in terms of sustainability. This study compared four crop establishment options: manual broadcasting , blower seeding, drum seeding, and mechanized transplanting.
Rice production faces many serious challenges, such as climate change, labor shortage, water shortages and loss of crop lands because of increased urbanization and industrialization. Flooded rice production has a substantial environmental footprint, such as contributing 1.5% to global greenhouse gases (GHG).
These challenges and problems of rice production are applicable in Vietnam, which is one of the top rice-exporting countries. Vietnam produces 6% of the global rice supply. In addition, there are concerns about the effects of intensification of cereal cropping on biodiversity. The current overuse of chemical inputs in rice production in Vietnam, such as fertilizers and pesticides, has adverse effects on biodiversity, the environment and human health.
In Southeast Asian countries, most rice fields are fragmented with small plot sizes of about 0.1–2 hectares (ha), causing low energy efficiency and productivity. In response to these challenges and problems, sustainable practices and programs are being promoted, such as Global G.A.P, VietGAP, and the Sustainable Rice Platform (SRP) standards.
In the Mekong River Delta (MRD) of Vietnam, rice farmers have been adopting a set of best management practices named “1 Must Do, 5 Reductions” (1M5R), which promotes six core principles: 1 Must Do = Use certified seed; 5 Reductions = Reduce seed rate, fertilizer use, pesticide use, water use and postharvest losses.
In addition, a model, “Small Farmers, Large Field,” has been introduced to improve land use efficiency and productivity of rice production in the MRD and elsewhere in Asia. The 1M5R approach applied in Vietnam increases nitrogen, water and pesticide use efficiency without compromising productivity and profitability. A water-saving technology called “Alternate Wetting and Drying” has been also applied on a large scale in the MRD. Such intermittent irrigation can reduce GHGEs by 40–50% compared to a continuously flooded rice production system.
Crop establishment, which often receives insufficient attention, is one of the major rice production operations that should be considered when promoting sustainable rice production practices. Direct seeding or DSR (e.g., broadcasting, drum-seeding, blower seeding), manual transplanting and mechanized transplanting are currently the common practices used in irrigated rice production.
DSR integrated with water-saving management has been reported as an advanced practice in terms of productivity, labor saving and water-use efficiency. Mechanized transplanting has demonstrated advantages for irrigated lowland rice with yields reported to be 7% higher compared to manual transplanting, as well as having lower production costs29,30. Mechanized transplanting is currently at an early stage of adoption in the MRD.
There are available options for crop establishment, but a major research gap is quantitative data on the best approach in terms of sustainability. This study compared four crop establishment options: manual broadcasting, blower seeding, drum seeding, and mechanized transplanting. The performance of these options was quantified for irrigated rice based on performance indicators for sustainable production. These indicators include grain yield, energy efficiency, GHG emissions, labor input, and net profit. Manual broadcasting is currently the common practice in the Mekong delta.
We hypothesize that mechanized transplanting, although requiring a high upfront cost, will perform as well or better than BroadC and the other practices when assessed against performance indicators for sustainable rice production.
The research provided field-trial evidence from studies within smallholder farmers’ fields of the benefits of mechanized transplanted rice compared to direct seeded rice in the MRD. Across the four treatments, the rice yield ranged from 7.3 to 7.5 and 6.2 to 6.8 Mg/ha in the winter-spring and summer-autumn seasons, respectively.
In comparison with direct seeding methods, the mechanized transplanting practice decreased the seed rate by 40% and reduced pesticide applications by 30–40% in the main crop season (winter-spring) of Vietnam. Despite mechanized transplanting required higher inputs for machine production (depreciation) and fuel consumption, its net energy balance, net income and GHGEs were at a similar level as the other non-mechanized planting practices. Thus, mechanized transplanting in combination with 1M5R is a technology package that should be promoted to improve the economic and environmental sustainability of rice cultivation in the MRD.
Read the study:
Nguyen, VH., Stuart, A.M., Nguyen, TMP. et al. (2022) An assessment of irrigated rice cultivation with different crop establishment practices in Vietnam. Sci Rep 12, 401.
