Email: vuky124@gmail.com

Our research results indicated that the mixed intercropping system of coffee and durian (Coffee & Durian) exhibits the highest total greenhouse gas emissions. This specific configuration is identified as the most resource-intensive model among all surveyed systems in Dak Lak, resulting in a total carbon footprint of 9,407.9 kg CO₂e/ha/year.

The two key drivers of high emissions in this system:

(i) Massive Agrochemical Inputs This system recorded the highest emissions specifically from agrochemical use, totaling 8,194.3 kg CO₂e/ha. The presence of durian, a high-value crop, drives farmers to invest heavily in inputs to maximize yield, often disregarding optimal efficiency.

– Nitrogen Fertilizer: The “Coffee & Durian” system had the highest emissions from nitrogen fertilizer application alone, reaching 4,338.6 kg CO₂e/ha.

– Phosphorus and Potassium: It also led to emissions from phosphorus (P₂O₅) and potassium (K₂O) fertilizers, contributing 1,479.2 kg and 1,629.2 kg CO₂e/ha, respectively.

(ii) Intensive Plant Protection and Energy Use: Beyond fertilizers, this system also required significant non-fertilizer emissions.

– Pesticides and Fungicides: It required the highest volume of fungicides (37.4 liters/ha) and electricity for spraying (238.5 kWh/ha), resulting in plant protection emissions of 615.9 kg CO₂e/ha.

– Transportation: It involved the longest total transportation distance (101.5 km) for moving inputs and harvests, further adding to the fuel-based footprint.

Comparison with Other Systems: To visualize the scale of these emissions, it is useful to compare this high-intensity system with the lowest-emitting model:

Highest (Coffee & Durian): 9,407.9 kg CO₂e/ha (Driven by intensive input management for durian).

Lowest (Coffee & Avocado): 5,089.8 kg CO₂e/ha (Benefiting from lower inputs, as avocado is often considered a shade tree with minimal fertilization).

In short:  While the “Coffee & Durian” system sequesters a significant amount of carbon due to the biomass of the trees (4,620.7 kg CO₂/ha), the dominant volume of emissions from fertilizers and energy means it still has the highest net emissions at 4,787.2 kg CO₂e/ha. This classifies it as a substantial carbon source rather than a sink.

References: N. V. Ky (2025). Assessment of Greenhouse Gas Emissions from the Intercropping Systems in Robusta Coffee Farms in Dak Lak, Vietnam. Graduate School of Science and Technology, University of Tsukuba

Email: vuky124@gmail.com

Our study results on greenhouse gas (GHG) emissions from intercropping systems in Robusta coffee farms in Dak Lak province showed that synthetic fertilizer played the role of the absolute dominant driver of GHG emissions, specifically acting as the central “emission hotspot” that overshadows all other farm inputs.

1. The Dominant Source of Emissions: Synthetic nitrogen fertilizer was identified as the single largest contributor to the carbon footprint of coffee farming. Across all farm types surveyed, the use of inorganic fertilizers accounted for approximately 71% of total emissions. When analyzed specifically within intercropping systems, this figure ranged between 75.8% and 81.8% of total emissions, rendering all other sources, such as irrigation, lime, and fossil fuels, minor in comparison[1].

To contextualize its dominance, emissions from synthetic nitrogen fertilizer (2,300 to 4,340 kg CO₂e/ha) were significantly higher than those from urea, phosphorus, and potassium fertilizers. It also outweighed emissions from irrigation (~8%), lime (~6%), and plant protection products (~4.8%)

2. The Mechanism of Emissions: The “hotspot” status of synthetic nitrogen is driven by the biological and chemical processes that convert applied nitrogen into nitrous oxide (N₂​O), a gas with a Global Warming Potential 273 times that of CO₂[2]. Of which:

Direct Emissions: When synthetic nitrogen fertilizers are added to the soil, they increase the available nitrogen for microbial processes. This enhances nitrification of the oxidation of ammonium to nitrate) and denitrification (the reduction of nitrate to nitrogen gas), both of which are released directly as by-products from the soil[3].

Indirect Emissions: Synthetic nitrogen also drives emissions off-site through two pathways:

• Volatilization: a fraction of the applied nitrogen vaporizes as ammonia (NH₃) and nitrogen oxides (NO_x), which deposit elsewhere and convert to N₂​O.
• Leaching and Runoff: Nitrogen that is not taken up by plants (mainly as nitrate NO₃-) leaches into groundwater or runs off into surface waters, where it undergoes transformation into rivers and estuaries. The default factor for the fraction of nitrogen lost to leaching in wet climates is 0.24 (24% of applied N)

3. Drivers of High Emissions: the role of nitrogen as a hotspot is exacerbated by specific farming behaviors and environmental factors.

Overuse: farmers in the Central Highlands frequently apply significantly more nitrogen than recommended, up to 300% more in some cases, believing that high inputs guarantee high outputs.

Intercropping Demands: The integration of high-value crops like durian and black pepper has led farmers to increase agrochemical inputs further. Systems including durian were noted as the most input-intensive, often disregarding the actual nutrient demands of the mixed crops in favor of maximizing yield.

Habit over Science: The application of fertilizers is often driven by habit rather than scientific assessment of soil or crop needs.

4. Comparison with other activities: Understanding the scale of the nitrogen “hotspot,” it is helpful to compare it to other farming activities:

Nitrogen Fertilizer: ~71% of total emissions.

Irrigation (Energy use): ~8% (the second-largest source).

Lime: ~6%.

Pesticides/Plant Protection: ~4.8%.

5. Implications for Mitigation: Because synthetic nitrogen is the primary hotspot, it also represents the greatest opportunity for decarbonization. The study concludes that reducing inorganic fertilizer use and substituting it with organic alternatives (such as animal manure or compost) is the most impactful strategy for lowering the carbon footprint of these farms. Systems that relied less on intensive fertilization, such as coffee intercropped with avocado, demonstrated significantly lower overall emissions

[1] N. V. Ky (2025). Assessment of Greenhouse Gas Emissions from the Intercropping Systems in Robusta Coffee Farms in Dak Lak, Vietnam. Graduate School of Science and Technology, University of Tsukuba

[2] IPCC (2021). Climate Change 2021 – The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. https://doi.org/10.1017/9781009157896

[3] IPCC (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. https://www.ipcc-nggip.iges.or.jp/public/2019rf/vol4.html.

#WASI #SOFRI #consultation #Capacity #Cadmium #AuramineO #Durian

Nguyen Van Long, Pepper Research and Development Center, Western Highland Agriculture and Forestry Science Institute.

Black pepper is one of Vietnam’s key export crops, largely concentrated in the Central Highlands. In recent years, however, productivity and sustainability of black pepper production systems have been increasingly threatened by soil degradation and rising pressure from soilborne pests and diseases.

A study conducted by the Pepper Research and Development Center, Western Highlands Agriculture and Forestry Science Institute (WASI) in 2023, surveyed 150 intensive black pepper plantations across Dak Lak, Dak Nong, and Gia Lai provinces to assess soil acidification and nutrient balance under long-term intensive cultivation. The results identified three major constraints to sustainable production: (i) strong to very strong soil acidity (pH 3.55–6.40), (ii) low cation exchange capacity (CEC), and (iii) pronounced nutrient imbalances.

More than 80% of soil samples showed excessive phosphorus accumulation (>96 mg P/kg soil), while potassium deficiency was widespread, particularly in Dak Lak (57.6%) and Gia Lai (48%). Calcium (365-978 mg Ca/kg soil) and magnesium (108-161 mg Ca/kg soil) levels varied considerably across provinces, resulting in imbalanced nutrient ratios in many plantations. Correlation and principal component analyses highlighted soil pH and organic matter as the key factors regulating nutrient availability and retention. Spatially, Dak Lak exhibited the most severe soil acidification and CEC depletion; Dak Nong showed relatively stable soil fertility; and Gia Lai soils had higher nutrient levels but greater variability among farms.

These constraints not only reduce fertilizer-use efficiency but also weaken root systems and create favorable conditions for soilborne diseases such as Phytophthora, Fusarium, and plant-parasitic nematodes. The study recommends prioritizing correction of soil acidity, improving soil buffering capacity, and adopting balanced, soil-test–based nutrient management to restore soil health and ensure the long-term sustainability of black pepper production in the Central Highlands.

Author: Nguyễn Văn Long     Phone: 0935 493 127    Mail: vanlongpleiku@gmail.com

Download: https://smujo.id/aja/article/view/23725

PhD. Nguyen Van Long

Determining the harvest stage is one of important factors that directly affect the yield and quality of black pepper. The experiment investigated the effect of harvesting ripe levels of pepper fruits on quality in Gia Lai and Dak Lak provinces, including 5 treatments: CT1 (the number of ripe fruits/spike > 75%), CT2 (the number of ripe fruits/spike > 50%), CT3 (the number of ripe fruits/spike > 25%), CT4 (the number of ripe fruits/spike > 5%), CT5 (the number of ripe fruits/spike < 5%). The results showed that the levels of ripe fruits affect both the physical (percentage of firmness, ratio of fresh fruits to peppercorn and weight of 1,000 peppercorns) and chemical characteristics (piperine, volatile oil and ete) of peppercorns. The physical parameters increased gradually as ripeness levels increased and there was a statistically significant difference between the treatments (P < 0.05); however, the chemical compositions of peppercorns decreased. To achieve the highest chemical contents of peppercorn, harvesting should be done when the ripe fruits/spikes are less than 5%. On the other hand, harvesting should be done when ripe fruits/spike is over 75% to achieve the best physical parameters, fitness, and appearance of peppercorns. The study has provided scientific evidence related to changes in peppercorn’s physical and chemical properties caused by different ripeness levels, helping producers choose appropriate harvest stages to meet various product quality and yield requirements.

Contact author: Nguyen Van Long, Mail: vanlongpleiku@gmail.com

Article download address:

http://tapchikhoahoc.nnmt.net.vn/vjae/article/view/942

Abstract

Monoculture and intensive fertiliser use in the cultivation of Robusta coffee (Coffea canephora var. Robusta) and black pepper (Piper nigrum L.) have led to soil degradation and increased disease pressure in Vietnam’s Central Highlands. To identify key factors driving soilborne diseases and threatening sustainable production, a soil and root survey was conducted across three provinces: Gia Lai, Dak Lak, and Dak Nong. Soils were characterised by high clay content (51.2–62.0 %), moderate silt (35.5–46.0 %), and low sand (2.5–2.8 %), with a notably low cation exchange capacity (7.72–8.04 cmol_c kg⁻¹). The soils were strongly acidic, with average pH values of 4.51 in coffee farms and 5.45 in pepper farms. Despite sufficient levels of nitrogen (N), phosphorus (P), and potassium (K), soilborne pathogens were widespread. Fusarium spp. were detected in all samples, Phytophthora spp. in 64–76 % of black pepper farms, and plant-parasitic nematodes in 67–84 % of farms, with Meloidogyne spp. predominant. Fusarium density increased with soil acidity in coffee plantations. In coffee, nematode density was positively correlated with N input, while in black pepper, N was negatively correlated with Phytophthora. Organic matter and available K were negatively associated with Fusarium in coffee but positively with Phytophthora in black pepper. These findings underscore the need for integrated management of nutrients and pathogens to sustain perennial crop production in the region.

The consultation council consisted of 15 members, with participation from experts, managers, and enterprises representing various organizations such as the Department of Agriculture and Rural Development, the Department of Science and Technology of Dak Lak Province, Tay Nguyen University, the Institute of Agricultural Chemistry and Soils, and several durian cooperatives. Dr. Nguyen Viet Tru presented the research proposal, which received numerous constructive comments. Experts highly appreciated the project’s urgency, feasibility, and practical significance. Several suggestions focused on optimizing survey and sampling methods as well as improving the research methods to reduce costs. The consultation achieved strong consensus, providing a scientific basis for finalizing and implementing the next phases of the project.

Pepper Research and Development Center, 322 Truong Chinh, Hoi Phu Gia Lai.

^*Email: vanlongpleiku@gmail.com ; ĐT: 0935 493 127

ABSTRACT

Pinto peanut (Arachis pintoi) is a versatile legume that helps protect soil, improve its physicochemical properties, and, significantly, fix nitrogen. The study aimed to identify the biomass, nutrient content, and the effects of Arachis pintoi mulch on soil fertility and the yield of Black pepper (Piper nigrum L. cv. Vinh Linh). The experimental design consisted of two blocks without replication across two locations on productive Black pepper plantations in Gia Lai and Dak Lak. The trial consisted of two treatments: A+ (Arachis pintoi planted in inter-rows of Black pepper and A- (the unplanted control). After two years, depending on intercropped areas, Arachis pintoi produced an average of 5.31 MT of fresh biomass/ha/year (equivalent to 1.48 tonnes of dry biomass/ha/year). Arachis pintoi contributed an average of 32.7 kg N + 4.2 kg P and 17.9 kg K/ha/year through this bio-mulching practice. Moreover, Arachis pintoi mulching significantly improved soil pH, organic carbon, nitrogen, phosphorus, and potassium concentration when compared to the control by 1.87 – 6.59%, 7.36 – 13.58%, 9.52 – 11.75%, 7.95 – 11.87%, and 3.57 – 4.96%, respectively. However, the study did not find differences in crop yield between treatment and control, regardless of location. Arachis pintoi should be recommended for sustainable Black pepper production in Vietnam. These findings provide evidence that cover cropping with Arachis pintoi could reduce overall nitrogen fertilizer applications, reduce soil erosion, maintain soil moisture, and contribute to the sustainable development of the pepper industry.

Keywords: Black pepper, Arachis pintoi, intercropping, and soil health improvement.