Cluster sowing solution for high-quality, low-emission rice cultivation in the Mekong Delta

It is evident thatv stakeholders can maximize economic efficiency in rice production, particularly in sustainable rice cultivation, by implementing a comprehensive technical package. This solution combines multiple factors, including seed selection, mineral nutrition, plant protection, and cultivation techniques.

Notably, seed reduction is the most crucial aspect of this integrated technical package in the current state of rice production. Using only the minimum amount of seeds allows farmers to invest in high-quality varieties. More importantly, reducing seed use can lower fertilizer and pesticide consumption, reduce environmental pollution, improve rice yield and quality, and cut emissions.

The widespread impact of seed reduction is significant, as it creates a ripple effect—from the reduction itself as well as through its interaction with other factors within the integrated technical package, thereby enhancing the growth and development of rice fields.

In reality, the initiative to reduce seed rates has seen practical and extensive implementations for multiple years. Stakeholders have complemented the process by promoting mechanization in rice production, with a focus on the sowing process—currently the most underdeveloped aspect in achieving comprehensive mechanization in rice cultivation. Moreover, a mechanized sowing process possesses significant potential in further reducing seed usage.

The introduction of cluster sowing machines has fostered a revolution in seed usage reduction. Despite long-standing efforts by the agricultural sector and local authorities to encourage lower seed rates, tangible results have remained limited.

The success of this technology lies in its ability to operate with minimal seed input—at only 50 to 60 kilograms per hectare. In addition to reducing the amount of seed used, the machine’s specialized "seed dispensing system" ensures uniform seed distribution across the field, both in rows and clusters, similar to traditional transplanting. Unlike conventional row-seeding machines, which only distribute seeds in rows, cluster sowing aligns seeds both in rows and clusters. By maintaining the required sowing density, cluster sowing enables rice fields to maximize the advantages of the edge-row effect—both laterally and longitudinally—thereby enhancing crop growth and development in a way that other sowing methods cannot achieve.

In essence, cluster sowing incorporates all the technical advantages of rice transplanting while eliminating its limitations, such as high labor costs and poor adaptability to soft, muddy soils, which are common issues for transplanting machines.

Moreover, when combined with deep fertilizer application at the time of sowing, the benefits of cluster sowing are further enhanced:

• Fertilizer is placed deep within the soil, minimizing losses—particularly nitrogen loss due to evaporation or runoff when fields are flooded.
• Deep placement encourages root development, reducing the risk of lodging (plants falling over), which is particularly beneficial during the Summer-Autumn and Autumn-Winter crops. This practice also enhances the rice plants' resistance to drought, salinity, and water shortages at the end of the Winter-Spring season.
• Fertilizer is applied directly adjacent to the seed clusters, ensuring efficient nutrient uptake by the rice plants and reducing losses to surrounding weeds, unlike traditional surface broadcasting. Consequently, farmers can enhance their fertilizer use efficiency.
• Integrating fertilizer application with cluster sowing reduces labor costs by eliminating the need for multiple manual fertilizer applications.

Most importantly, deep fertilizer placement during the sowing process ensures that rice plants receive essential nutrients from the earliest growth stages. This timely nutrient supply enhances the strength of the seedling, promotes early and concentrated tillering, and maintains an optimal number of panicles per square meter—critical for maximizing yield in cluster-sown and sparse-planted rice fields.

By adopting cluster sowing with deep fertilizer application, farmers can reduce fertilizer use by 20–30% compared to traditional surface broadcasting practices.

Recognizing these advantages, the Department of Crop Production has incorporated cluster sowing and cluster sowing in combination with deep fertilizer application into its official rice production guidelines, including: the cost-reducing and efficiency-enhancing rice cultivation process (Decision No. 73/QD-TT-VPPN, dated April 23, 2022) and the integrated climate-adaptive rice cultivation process (Decision No. 102/QD-TT-VPPN, dated March 14, 2023).

Additionally, cluster sowing and cluster sowing in combination with deep fertilizer application has also been included in the national “One Million Hectares” Project according to Decision No. 1490/QD-TTg issued by the Prime Minister on November 27, 2023.

These achievements result from stakeholders' concerted efforts and continuous improvements since 2019. Accordingly, they have refined various types of machinery to match the unique physical and soil conditions of Vietnamese rice fields. Moreover, they conducted extensive trials to optimize supporting technical practices, thereby promoting the adaptability of the cluster sowing model to various ecological conditions.

The following pilot models have demonstrated the effectiveness of cluster sowing and cluster sowing in combination with deep fertilizer application:

1. During the 2023 Summer-Autumn crop, Saigon Kim Hong Trading & Services Co., Ltd., in collaboration with Binh Dien Fertilizer Joint Stock Company, implemented a smart rice cultivation model in Luong An Tra Commune, Tri Ton District, An Giang Province.

The parties conducted this trial on 3 hectares using OM18 rice variety and Dau Trau fertilizers (Dau Trau Tang Truong – DTTT and Dau Trau Chac Hat – DTCH) under three different treatment formulas:

• Formula 1 (broadcast sowing, surface fertilization): Farmers broadcasted rice seeds at a rate of 150 kilograms/hectare and applied fertilizer freely, using commercially available products (70 kilograms of phosphorus, 58 kilograms of DAP, 240 kilograms of NPK 16-16-8, 55 kilograms of urea, and 30 kilograms of potassium per hectare).

  Total fertilizer used: 77N, 66 P₂O₅, and 47 K₂O.

• Formula 2 (cluster sowing, surface fertilization): Farmers utilized the cluster sowing method at a rate of 60 kilograms/hectare, applied 300 kilograms/hectare of DTTT at two tillering stages, and added 100 kilograms/hectare of DTCH at the panicle initiation stage.

  Total fertilizer used: 73N, 42 P₂O₅, and 37 K₂O.

• Formula 3 (cluster sowing, incorporated fertilization): Farmers utilized the cluster sowing method at a rate of 60 kilograms/hectare, incorporated 210 kilograms/hectare of DTTT into the soil at the sowing stage (reducing the amount of fertilizer used by 30% compared to Method 2), and applied 100 kg/ha of ĐTCH at the panicle initiation stage.

  Total fertilizer used: 55.9N, 31.2 P₂O₅, and 31.6 K₂O.

Model results:

• Method 1 (broadcast sowing, surface fertilization): Farmers achieved a yield of 5.40 tons/hectare and earned a profit of 21.8 million VND/hectare.

• Method 2 (cluster sowing, surface fertilization): Farmers achieved a yield of 5.67 tons/hectare and earned a profit of 23.4 million VND/hectare.

• Method 3 (cluster sowing, incorporated fertilization): Farmers achieved a yield of 5.92 tons/hectare and earned a profit of 21.8 million VND/hectare.

Key findings

• Effectiveness of cluster sowing compared to broadcast sowing:

  • Formula 2 (cluster sowing, surface fertilization) achieved a yield of 5.67 tons/hectare, outperforming Formula 1 (broadcast sowing, surface fertilization) by 0.27 tons/hectare (+5%). Profit in Formula 2 reached 23.4 million VND/hectare, exceeding Formula 1 by 1.6 million VND/hectare (+7.3%).

• Effectiveness of deep fertilizer application compared to surface application:

  • Formula 3 (cluster sowing, deep fertilization) achieved a yield of 5.92 tons/hectare, outperforming Formula 2 (cluster sowing, surface fertilization) by 0.25 tons/hectare (+4.4%), despite using 30% less DTTT fertilizer.
  • Profit in Formula 3 reached 26.8 million VND/hectare, exceeding Formula 2 by 3.4 million VND/hectare (+14.5%).

• Overall impact of cluster sowing in combination with deep fertilization:

  • Formula 3 (cluster sowing, deep fertilization) achieved a yield of 5.92 tons/hectare, outperforming Formula 1 (broadcast sowing, surface fertilization) by 0.52 tons/hectare (+9.6%).
  • Profit in Formula 3 reached 26.8 million VND/hectare, exceeding Formula 1 by 5 million VND/hectare (+22.9%).

These results, along with findings from other production models, confirmed that:

• Cluster sowing is more effective than broadcast sowing.
• Combining cluster sowing with deep fertilizer application further enhances rice production efficiency.

These findings provide the foundation for integrating Saigon Kim Hong’s cluster sowing and deep fertilization techniques into the mechanized rice sowing solutions under the “One Million Hectares” Project.

2. Building on these results, the method for cluster sowing in combination with deep fertilizer application developed by Saigon Kim Hong was adopted for the pilot implementation under the "One Million Hectares" Project during the 2024 Summer-Autumn crop in Tra Vinh Province (Phuoc Hao Cooperative – Phuoc Hao Commune, Chau Thanh District). This model was subsequently expanded to Dong Thap Province (Thang Loi Cooperative – Lang Bien Commune, Thap Muoi District) and Kien Giang (Thanh Nien Phu Hoa Agricultural Service Cooperative – Tan Hoi Commune, Tan Hiep District) during the 2024 Autumn-Winter crop.

The models followed the technical guidelines for high-quality, low-emission rice production in the Mekong Delta. In addition, they strictly comply with the objectives of the "One Million Hectares" Project, as outlined in Decision No. 1490/QD-TTg, issued by the Prime Minister on November 27, 2023.

The Department of Crop Production, in coordination with relevant agencies under the Ministry of Agriculture and local authorities, thoroughly inspected, summarized, and evaluated the model sites in Tra Vinh, Dong Thap, and Kien Giang.

The evaluation results confirmed that the models produced remarkable achievements, particularly in technical aspects, exceeding the initiative’s criteria.

Key results

Specific Results

• Seed usage: Farmers applied seeding at rates ranging from 60 kilograms/hectare in Tra Vinh to 70 kilograms/hectare in Dong Thap and Kien Giang, achieving an average of 64.6 kilograms/hectare. This figure was 55.7% lower than the traditional broadcast seeding rate of 81 kilograms/hectare and met the target of the 2030 national plan, which aims to reduce seeding rates to below 70 kilograms/hectare.
• Nutrient fertilization (N, P₂O₅, K₂O): Due to the reduced sowing density, the rice fields required lower nutrient inputs. Farmers applied fertilizer at rates ranging from 144–147 kilograms/hectare (Tra Vinh, Kien Giang) to 177 kilograms/hectare (Dong Thap), achieving an average of 153 kilograms/hectare—38.9% less than the traditional application rate of 97.4 kilograms/hectare.
• Nitrogen fertilization: Farmers applied nitrogen at rates ranging from 66–67 kilograms/hectare (Kien Giang, Tra Vinh) to 80 kilograms/hectare (Dong Thap), achieving an average of 70.2 kilograms/hectare. This figure was 45.1% lower than the traditional nitrogen application of 57.6 kg/ha, which meets the 30% nitrogen reduction target set in the 2030 national plan.
• Pesticide applications: With reduced sowing density, improved sunlight penetration, and lower fertilizer usage—particularly nitrogen—pest pressure dropped significantly. Farmers applied pesticides between five times (Tra Vinh), six times (Kien Giang), and seven times (Dong Thap), achieving an average of 5.7 applications per crop cycle. This figure was 31.2% lower than the traditional rate of 2.6 additional applications per cycle, which meets the national goal of a 30% reduction in chemical pesticide use by 2030. As a result, Tra Vinh’s model fields received VietGAP certification, and rice grown under this system secured a higher selling price, at 350 VND/kilogram above market rates.
• Production costs: Farmers spent between 18,059,000–18,712,000 VND/hectare (Dong Thap, Kien Giang) and up to 22,380,000 VND/hectare (Tra Vinh), achieving an average of 20,521,746 VND/hectare. This figure was 13.1% lower than traditional production costs, resulting in a total saving of 3,097,486 VND/hectare—a crucial advantage as rising input prices.
• Rice yields: Despite unfavorable weather conditions in the late Summer-Autumn and throughout the Autumn-Winter crop—including prolonged heavy rains, storms, and strong winds that restricted crop management and harvesting efforts—yields remained relatively stable. Farmers harvested between 4.68 tons/hectare (Kien Giang), 5.88 tons/hectare (Dong Thap), and 6.6 tons/hectare (Tra Vinh), achieving an average yield of 6.1 tons/hectare. This figure was 5.3% higher than the traditional average, with an increase of 310 kg/hectare.
• Profitability and Return on Investment: With an average yield increase of 5.3% and a reduction of 13.1% in production costs, profits ranged from 20,732,000 VND/hectare (Kien Giang) to 32,852,554 VND/hectare (Dong Thap) and 45,570,000 VND/hectare (Tra Vinh), reaching an average of 37,368,255 VND/hectare. This figure was 20.9% higher than the traditional profit margin, exceeding external production profits by 6,455,920 VND/hectare. Additionally, the return on investment (ROI) reached 64.6%, exceeding the 50% target under the national plan.
• Production costs per kilogram of rice: Production costs ranged from 2,941 VND/kilogram (Dong Thap), 3,391 VND/kilogram (Tra Vinh), to 3,998 VND/kilogram (Kien Giang), reaching an average of 3,362 VND/kilogram. This figure was 17.5% lower than traditional production cost average, reducing expenses by 713 VND/kilogram.
• Greenhouse gas emissions reduction: Carbon emissions reached 5.36 tons CO₂-eq/hectare (Tra Vinh), 6.0 tons CO₂-eq/hectare (Kien Giang), and 6.41 tons CO₂-eq/hectare (Dong Thap), achieving an average of 5.76 tons CO₂-eq/hectare. This figure represented a reduction of 54.8% compared to the traditional emission level of 6.99 tons CO₂-eq/hectare—far exceeding the 10% reduction target under the national plan. Notably, all three pilot sites implemented three water drainage cycles during the season, but Tra Vinh Province achieved lower emissions due to its reduced fertilizer use.

The Ministry of Agriculture and Rural Development (now the Ministry of Agriculture and Environment), local authorities, and rice producers commended these results during review conferences. The pilot models in Tra Vinh, Dong Thap, and Kien Giang successfully met the technical criteria set under the “One Million Hectares” Project.

3. Another notable model under the National Agricultural Extension Project titled "Developing Low-Emission Rice Cultivation Models to Support the Sustainable Growth of Rice Export Production in the Mekong Delta" saw a successful implementation process.

The model was carried out during the 2024–2025 Winter-Spring crop in Vinh Quoi Commune, Nga Nam Town, Soc Trang Province, covering an area of 50 hectares.

Farmers used the ST25 rice variety, with a sowing density of 70 kilograms/hectare, and utilized the cluster sowing method in combination with deep fertilizer application.

Key Results

• The cluster sowing method in combination with deep fertilizer application achieved a rice yield of 6.87 tons/hectare. This figure represented an increase of 0.93 tons/hectare (15.7%) compared to traditional broadcast sowing method in combination with surface fertilizer application, which yielded only 5.94 tons/ha.
• The economic efficiency of the cluster sowing method in combination with deep fertilizer application reached 39.247 million VND/hectare. This figure represented an increase of 9.353 million VND/hectare (31.3%) compared to the traditional broadcast sowing model, which generated 29.894 million VND/hectare.

The results from these models confirmed that cluster sowing—particularly when combined with deep fertilizer application—is an effective mechanized solution for rice seeding. This method plays a crucial role in promoting a high-quality, low-emission rice cultivation process that complies with the green growth strategy for the Mekong Delta.

With its superior advantages in rice production, Saigon Kim Hong’s cluster sowing technology has gained widespread adoption among farmers across Vietnam, from the Mekong Delta to the Red River Delta. The company has also successfully exported its cluster sowing machines to Cambodia and India, with upcoming shipments planned for the Philippines.

 

Sai Gon Kim Hong currently distributes four main models of cluster seeding machines:

• Cluster Seeder Attachment for Rice Transplanter

  • Seeding width: 3.0 meters
  • Number of rows: 12, with 25 centimeters row spacing
  • Seeding capacity: 6–8 hectares per day

• Cluster Seeder Attachment for Large Tractor

  • Seeding width: 4.0–5.0 meters
  • Number of rows: 16–20, with 25 centimeters row spacing
  • Seeding capacity: 8–12 hectares per day

• Cluster Seeder Attachment for Small Tiller (Ten Hen)

  • Seeding width: 3.0 meters
  • Number of rows: 12, with 25 centimeters row spacing
  • Seeding capacity: 6–8 hectares per day

• Hand-Pushed Cluster Seeder

  • Seeding width: 2.0 meters
  • Number of rows: 8, with 25 centimeters row spacing
  • Seeding capacity: 3–4 hectares per day
  • Ideal for fields with weak soil foundations and small, fragmented plots

Additional Features

Multifunctional Integration: With the exception of the hand-pushed model, all cluster seeding machines can be upgraded with integrated fertilizer applicators and pre-emergence herbicide sprayers, transforming them into "2-in-1" or "3-in-1" machines.

Adjustable Seeding Patterns: These machines can switch between uniform cluster seeding (25 cm × 25 cm) and border-effect cluster seeding (35 cm × 15 cm or 38 cm × 12 cm, depending on rice variety and season).

Convertible Seeding Methods: The machines can switch from cluster seeding to row seeding by reducing the cluster spacing to 3–4 centimeters and decreasing the number of seeds per cluster to 2–3 seeds.