Optimizing Peanut Intercropping Density in Young Coconut Plantations: A Case Study from Phu Quoc, An Giang, Vietnam

Coconut (Cocos nucifera L.) and peanut (Arachis hypogaea L.) are widely cultivated in tropical and subtropical regions. Intercropping peanuts in young coconut gardens can enhance soil fertility through biological nitrogen fixation while supporting local food production. This study evaluated the optimal intercropping density of VD 01–1 peanut in Dua Dua coconut gardens (an aromatic variety) during the establishment phase in Phu Quoc, An Giang Province, Vietnam.

A field experiment was conducted in Phu Quoc, An Giang Province (10°14'40.7"N; 104°01'22.4"E) from 2024 to 2025 to compare three intercropping densities (15, 20, 25 peanut rows) with a non-intercropped control. The study assessed VD 01–1 peanut growth, yield and pod quality, as well as changes in soil properties and nutrient availability.

VD 01–1 peanut grew well under Phu Quoc conditions. Intercropping 20 rows in Dua Dua gardens resulted in higher yield and better pod quality than 15- or 25-row treatments, without affecting coconut growth. This density also enhanced soil fertility and nitrogen-fixing microbial activity, with the most favorable soil and microbial conditions observed at 20 rows. Nutrient availability supported coconut growth, with highest nitrogen and phosphorus at 20 rows and potassium at 25 rows. Overall, intercropping 20 rows (covering 60% of the intercroppable area) is optimal, improving productivity, soil health and economic returns while maintaining coconut development.