Intercropping Canavalia ensiformis in replanted oil palm plantation as an alternative local protein feed source

Tazkiyah Annisa Utari¹, Nahrowi^2,5, Luki Abdullah^2,5, Hariyadi³, Sudradjat³, Suria Darma Tarigan³ and Maja Slingerland⁴

¹ Post Graduate Student Program of Nutrition and Feed Science, Faculty of Animal Science, IPB University, 16680, Bogor, Indonesia
kiya_tazkiyah@apps.ipb.ac.id
² Departement of Nutrition and Feed Technology Faculty of Animal Science, IPB University, 16680, Bogor, Indonesia
³ Departement of Agronomy and Horticulture Faculty of Agriculture, IPB University, 16680, Bogor, Indonesia
⁴ Plant Production System Group, Wageningen University and Research, 6700AK, Wageningen, Netherlands
⁵ Center for Tropical Animal Studies CENTRAS, IPB University Baranangsiang, 16129, Tegallega, Bogor, Indonesia

Abstract

Indonesia is the world's largest importer of soybean meal, reflecting the inadequacy of domestically available protein-rich feedstuffs to meet national demand. Therefore, addressing this gap by exploring and improving local alternatives is crucial. Canavalia ensiformis, a legume with high productivity, adaptability and a good nutritional profile, has strong potential as a substitute for soybean meal in Indonesia. This study evaluated intercropping of C. ensiformis in a replanted oil palm plantation as a sustainable strategy to increase locally sourced protein-rich feed resources. A completely randomized design (CRD) was employed to evaluate the impact of five fertilizer treatments on plant morphology, bean yield and nutrient composition. Data were analysed using SAS software, with each treatment replicated four times for productivity parameters and three times for nutrient analysis. At 150 days after planting, fertilizer notably affected (p<0.05) pod number, bean width, bean weight and nutrient content. The highest protein concentration (38%) was recorded in treatment T3 (4 tons of dolomite + 5 tons of manure applied/ha). These findings indicate that C. ensiformis can be successfully cultivated in oil palm replanting areas, producing high yields with a dense nutrient profile under marginal land conditions. To maximize this potential, site-specific fertilization strategies and precision management are recommended. Further research should focus on the morphological traits, antinutrient and nutrient digestibility of C. ensiformis for ruminant and poultry feed applications.

Keywords: biomass, crop, legume, nutrient, regenerative agriculture

Introduction

Currently, Indonesia is the world’s largest importer of soybean meal, with its conclusion as a protein source feed formulations reaching 20-25%. This reliance heavily drives ups feed costs. According to USDA (2024), the national soybean meal consumption amounts to 5.2 MMT annually, equivalent to IDR 31 trillion. A major challenge for sustaining livestock productivity and feed availability is the shortage of agricultural land (Abera et al 2021). Data from Ministry of Agrarian Affairs and Spatial Planning (2022), supported by Mulyani et al (2023) and the Indonesian Central Statistics Agency (2020), show a sharp decline in agricultural land area from 36.8 million ha in 2019 to 27.7 million ha in 2023, representing a 24.7% reduction.

In this context of limited land resources, boosting local feed production requires optimizing underutilized land and applying intercropping systems. Such a strategy not only increases overall output but also strengthens long-term feed security. Oil palm plantation, with their vast area, provide potential for integrating feed crops. Traditionally managed as monocultures, oil palm system can gain ecological, economic and social benefits trough intercropping (Yang et al 2016). Replanting is generally conducted when palms exceed 25 years of age or when palm fresh fruit bunch yields fall below 10 tons/ha/year. During this phase, young palm with lower canopy density allows more sunlight penetration, creating favourable conditions for intercrops (Sahari et al 2023).

The choice of intercrop species is crucial to avoid ecological competition and ensure sustainability. Legumes are particularly valuable because they offer multiple agroecological benefits, ground cover, nitrogen fixation, improved soil fertility, erosion control, weed suppression and enhanced nutrient cycling (Hansen et al 2021; Fu et al 2023).

Among them, jack bean (Canavalia ensiformis) shows strong compatibility with oil palm. It adapts well to diverse soil and climates, germinates rapidly and provides robust yields (Quiñones et al 2023). Seed production can reach 6-8 tons/ha under optimized conditions with organic fertilization such as goat manure (Soedarjo 2021). Nutritionally, C. ensiformis offers a promising local alternative to soybean meal. Unprocessed beans contain 31.6% crude protein, 3.01% crude fat and 9.13% crude fiber (Madani et al 2024). Processing methods such as soaking and peeling further improved its quality, raising protein to 34% and reducing fiber content 1.8% (Mutia et al 2024).

Despite these advantages, most oil palm intercropping studies have focused on food legume as soybean and mucuna (Yuliani et al 2021; Sapalina et al 2022), leaving the potential of jack bean as a protein-rich feed intercrop largely unexplored. Therefore, this study aimed to evaluate the intercropping of C. ensiformis in oil palm replanting areas as sustainable approach to enhance the supply of locally sourced, protein-rich feed ingredients.

Materials and methods

The study was carried out in replanting oil palm plantation located in Batu Ampar District, Tanah Laut Regency, South Kalimantan, Indonesia (3⁰57’13’’ S, 114^o50’41’’ E; Figure 1). The area has a humid tropical climate, with mean daily temperature ranging from 30-32°C during study period (June-December 2024). The highest temperatures were recorded in September-October (up to 34°C) and minimum temperatures around 23-24°C. Climate data were obtained from multiple sources, including The Meteorology, Climatology and Geophysical Agency (BMKG) of South Kalimantan, as well as datasets from the National Oceanic and Atmosphere Administration (NOAA) accessed via Microsoft News The Weather Channel. The intercropping system was implemented from July to December 2024 on experimental plots covering 1000 m². The plantation consisted of oil palm (Elais guineensis Jacq.) planted 9.2 m x 8 m spacing, intercropped with Canavalia ensiformis 0.7 m x 0.4 m spacing (Figure 2).

Figure 1. Map of study area

Figure 2. Spacing of Elais guineensis Jacq intercropped with Canavalia ensiformis

Before planting, composite soil samples (n=9 per treatment) were collected at a depth of 20 cm. Approximately 200 g of soil sample was analyzed for pH (H₂O), organic carbon, total nitrogen, potential phosphate, exchangeable potassium, exchangeable calcium and magnesium (Table 1). All analyses were conducted following standardized protocols of the Soil Research Institute (Balai Penelitian Tanah 2009). Soil amendments were applied sequentially. Dolomite was uniformly applied at 2-4 tons/ha two weeks before planting, by incorporation of layer manure into planting holes at a rate of 5-10 tons/ha.

Determination of biomass, pod, seed yield and nutrient quality

Pod and seed yields were measured at 150 days after planting (DAP). For each treatment, fresh pods and seeds were harvested and assessed for fresh weight, dried weight, seed morphological traits (length, width, thickness). Samples were oven-dried at 60 °C until a constant weight was reached. Subsample were then further dried at 105 °C, ground to uniform powder and analyzed for nutrient composition in triplicate, following AOAC (2005) procedures.

Photo 1. Intercropping Canavalia ensiformis in replanted area oil palm Elais guineensis Jacq

Experimental treatments and data analysis

The study applied five fertilizer treatments are T0 (control; unfertilized), T1 (2 tons dolomite + 5 tons layer manure/ha), T2 (2 tons dolomite + 10 tons layer manure/ha), T3 (4 tons dolomite + 5 tons layer manure/ha), T4 (4 tons dolomite + 10 tons layer manure/ha). The experiment followed a completely randomized design (CRD), with four replications for productivity parameters and three replications for nutrient parameters. Measured variables included total pod number, bean weight, bean size and nutrient composition, such as dry matter, crude protein, ether extract, crude fiber, ash, carbohydrate and gross energy. Data were analyzed using Analysis of Variance (ANOVA) and treatments were compared with Duncan’s test at a 5% significance level (α = 0.05), performed with SAS on Demand for Academics Edition.

Results and discussion

Pod yields and bean’s morphology of Canavalia ensiformis

The ANOVA results demonstrated a statistically detectable effect (p<0.05) of dolomite and layer manure combinations on key productivity parameters of C. ensiformis, including fresh and dry biomass, pod yield, bean weight, pod count, bean width and pod surface area (Table 2). These findings underline the crop’s adaptive capacity to nutrient availability and its responsiveness to integrated soil amendment strategies that balance pH regulation (dolomite) and organic nutrient supply (layer manure).

The unfertilized (T0) consistently showed the lowest performance, producing only 4.18 tons/ha of fresh biomass and 1.88 tons/ha of dry biomass. In contrast, treatment T3 (4 tons dolomite + 5 tons layer manure/ha) yielded 34.6 tons/ha of fresh biomass and 20.6 tons/ha of dry biomass. This represents an 8.3-fold increase over the control, demonstrating the pivotal role of optimized fertilization in boosting C. ensiformis productivity. Furthermore, the observed conversion efficiency of 68% from fresh to dry biomass suggests that improved nutrient management not only enhanced overall biomass quantity but also increased tissue density and quality. Such improvements may be attributed to better nutrient uptake and enhanced photosynthetic efficiency, leading to greater accumulation of structural and storage compounds in plant tissues. Nitrogen availability, supplied through layer manure, likely played a central role in stimulating vigorous vegetative growth. Increased leaf area and chlorophyll content enhance light interception, resulting in higher assimilate production and subsequent biomass accumulation.

This interpretation aligns with the observation of Prasojo et al (2025), who reported stage-specific increases in C. ensiformis biomass from 19 tons/ha at the vegetative stage, 34 tons/ha at flowering and up to 43 tons/ha at pod filling. Fertilization effects were also evident in pod and seed development. Pod counts ranged between 9–15 per plant across fertilized treatments, compared to only 4 pods per plant in unfertilized controls (Prasojo et al 2025). Notably, treatment T4 (4 tons dolomite + 10 tons layer manure/ha) recorded the highest pod weight proportion (64.4%), suggesting improved assimilate partitioning into reproductive sinks under nutrient-rich conditions. Enhanced bean size observed in fertilized treatments further indicates increased carbohydrate and protein deposition during seed filling, consistent with the well-established role of balanced nutrients in regulating photosynthate allocation to reproductive structures (Cho et al 2025). Although the intercropping system yielded beans ranging from 0.14 to 1.59 tons/ha lower than reported monoculture yields of 2.9–6.0 tons/ha (Rizal et al 2024) its broader ecological and economic benefits are noteworthy. Intercropping C. ensiformis in oil palm plantations not only contributes to local protein feed sources but also enhances agroecosystem sustainability. Benefits include biological nitrogen fixation, improvement of soil organic matter, suppression of weed growth and provision of an additional income stream for farmers (Yu et al 2025). This makes C. ensiformis an attractive multipurpose crop within oil palm replanting systems implemented the regenerative agriculture, where soil rehabilitation and economic diversification are critical.

Overall, the results highlight that combining dolomite and organic amendments can markedly improve the productivity and seed quality of C. ensiformis. While yields under intercropping conditions are modest compared to monoculture, the multifunctional ecosystem services provided by this practice strengthen its relevance as a sustainable agroecological strategy in oil palm-based farming systems.

Fertilization had a marked influence on the nutrient quality of C. ensiformis seeds, as reflected in variations of ash, crude protein, crude fat, crude fiber, carbohydrate and gross energy. The changes observed across treatments suggest that nutrient supply and soil amendments not only affect overall seed yield but also shape the biochemical composition of the seeds, thereby influencing their nutritional value for feed applications. This highlights the importance of appropriate fertilization strategies in optimizing both productivity and quality in legume crops.

The mineral fraction, represented by ash content, ranged between 3.5 and 3.7%, with the highest value recorded in T3 (3.75%). This modest increase can be attributed to enhanced mineral deposition under balanced fertilization, where the combined input of dolomite as a source of calcium and magnesium and organic manure provided a synergistic effect. Such a pattern indicates that proper nutrient management improves mineral assimilation in seeds. Comparable findings were reported by Madani et al (2024), who documented ash levels of approximately 3.5% in C. ensiformis, supporting the view that fertilization maintains mineral content within an optimal range.

Among all proximate components, crude protein exhibited the greatest response to fertilization, with values differing markedly across treatments (p<0.05). Protein concentration peaked under T3 (38%) and reached its lowest level in T2 (32.7%). The superior protein content under T3 is indicative of balanced nitrogen supply that favors both soil mineral N uptake and effective biological nitrogen fixation via root nodules. In contrast, excessive nitrogen input may suppress symbiotic fixation, thereby reducing protein accumulation. This outcome aligns with the findings of Lancheros et al (2024), who emphasized the role of moderate N inputs in stimulating symbiotic activity. Notably, the protein content recorded in this study surpasses the typical range reported for C. ensiformis (17–30%; Mutia et al 2024; Aryzegovina et al 2023), suggesting that the crop could serve as a viable alternative protein source with competitiveness to soybean meal.

Crude fat levels were relatively modest, ranging from 3.4 to 4.9%, which is in agreement with earlier findings of approximately 3.3% reported by Arise et al (2022). A slight decline in fat concentration under higher dolomite application suggests a possible calcium-related inhibition of lipid biosynthesis, as calcium has been known to influence lipid metabolic pathways. Fiber content, on the other hand, varied between 6.5 and 8.1%, with the highest value observed in the control treatment (T0). This may be linked to the development of thicker seed coats under nutrient stress, a physiological adaptation to unfavorable soil conditions as noted by Rahman (2022). Fertilization generally reduced fiber levels, an outcome beneficial for improving seed digestibility. Further reductions can be achieved through post-harvest processing methods such as soaking or dehulling, which have been shown to decrease crude fiber to as low as 1.8% (Mutia et al 2024).

Carbohydrate levels accounted for the largest proportion of the seed composition, ranging between 53% and 57%. The highest value was noted in T4 (57.8%), which corresponded fertilization also enhanced gross energy value of up to 4433-4511 kcal/kg. This represents a notable increase compared to previously reported 4340 cal/g (Fikriandi et al 2024). The improvement in carbohydrate and energy values under fertilization underscores the dual benefit of the crop, offering both protein and energy in a single feed ingredient. Such a profile not only strengthens its role as a protein source but also enhances its value as an energy-dense feed, thereby reinforcing the potential of C. ensiformis in diversified livestock feeding strategies.

Conclusion

The combination of 4 tons dolomite and 5 tons layer manure per hectare improved biomass, yield and nutrient quality of Canavalia ensiformis, with crude protein reaching up to 38% and energy at 4499 cal/g. Although seed yield was lower than in monoculture, intercropping remained beneficial for nitrogen fixation, organic matter enrichment, weed suppression and as a local high-protein feed source.

Acknowledgments

The authors gratefully acknowledge Wageningen University for sponsoring this research through the Sustain Palm Program and PT Citra Putra Kebun Asri for providing access to their replanting area for this study.

References

Abera M, Tolera A, Nurfeta A and Geleti D 2021 Production, utilization and constraints of Desho grass (Pennisetum glacifolium) as livestock feed in Ethiopia. Online Journal of Animal and Feed Research, 11, 196-205. DOI: https://dx.doi.org/10.51227/ojafr.2021.29

AOAC 2005 Association of Official Analytical Chemists Inc. Official Methods of Analysis, 18th Edition, Gaithersburg, Marylan USA. ISBN 0-935584-77-3. DOI: https://www.researchgate.net/publication/292783651_AOAC_2005

Arise A K, Malomo S A, Cynthia C I, Aliyu N A and Arise R O 2022 Influence of processing methods on the antinutrients, morphology and in-vitro protein digestibility of jack bean. Food Chemistry Advances, 1. DOI: https://doi.org/10.1016/j.focha.2022.100078

Aryzegovina R, Aisyah S, Desmiati I, Merina G, Roza Y and Karina I 2023 Organoleptic test and proximate test of feed for Panulirus Homarus using Canavalia Ensiformis as a substitute of soy flour. International Journal of Progressive Science and Technologies, 37, 181-187. DOI: 10.52155/ijpsat.v37.2.5150

Balai Penelitian Tanah 2009 Instructions for Chemical Analysis Techniques of Soil, Crops, Water and Fertilizers. 2nd Ed. Balai Penelitian Tanah.

Cho H, Choi I, Shahzad Z, Brandizzi F and Rouached H 2025 Nutrient cues control flowering time in plants. Trends in Plant Science. 2841, 12. DOI: https://doi.org/10.1016/j.tplants.2025.05.010

Fikriandi S, Sumiati and Mutia R 2024 Utilization of Jack bean (Canavalia ensiformis) meal as a substitute for soybean meal in diet of laying hens. Livestock Research for Rural Development, 36, http://www.lrrd.org/lrrd36/1/3605bedd.html

Fu Z, Chen P, Zhang X, Du Q, Zheng B, Yang H, Luo K, Lin P, Li P, Pu T, Yushan W, Wang X, Yang F, Liu W, Song C, Yang W and Yong T 2023 Maize-legume intercropping achieves yield advantages by improving leaf functions and dry matter partition. BMC Plant Bology, 23, 438. https://doi.org/10.1186/s12870-023-04408-3

Hansen V. Eriksen LS. Jensen K, Thorupkristensen and Magid J 2021 Towards integrated cover crop management: N, P and S release from aboveground and belowground residues. Agriculture, Ecosystems and Environment: 313, 107392

Lancheros A, Suquila F A C, Guedes C L B, Brito O and Guimarães M F 2024 Exploring the potential of Canavalia ensiformis for phytoremediation of B10 biodiesel-contaminated soil: insights on aromatic compound degradation and soil fertility. International Journal of Phytoremediation, 26, 1-9. DOI: http://dx.doi.org/10.1080/15226514.2024.2357646

Madani A M A, Muhlisin, Kuniawati A, Baskara A P and Anas M A 2024 Dietary jack bean (Canavalia ensiformis L.) supplementation enhanced intestinal health by modulating intestinal integrity and immune responses of broiler chickens. Heliyon, 10, e34389. DOI: 10.1016/j.heliyon.2024.e34389

Ministry of Agrarian Affairs and Spatial Planning (Kementerian Agraria dan Tata Ruang Badan Pertanahan Nasional Tahun) 2022 https://www.atrbpn.go.id/

Mulyani A, Mulyanto B, Barus B, Panuju DR and Hunain 2023 Potential land for agriculture in Indonesia: sustainability and legal aspect supporting food sufficiency, 12, 970. Journal Land. DOI: https://doi.org/10.3390/land12050970

Mutia R, Ridla M, Nahrowi and Maharani FA 2024 The impact of enzyme addition on the metabolizable energy and protein digestibility of peeled Jack bean meal ( Canavalia ensiformis L.). BIO Web Conference 123, 01019. DOI: http://dx.doi.org/10.1051/bioconf/202412301019

Prasojo Y S, Prasetyo B and Suwignyo B 2025 Morphology characteristic and biomass production of jack bean (Canavalia ensiformis) at different growth stages in Blora, Central Java, Indonesia. Australian Journal of Crop Science, 19, 84-88. https://doi.org/10.21475/ajcs.25.19.01.p218

Quiñones R P, Martínez A T P, Marrero D F, Gómez G P, Montero M E M, Muñoz D M Z, Solis N and Velez CIB 2023 Procedure for obtaining flour from Canavalia ensiformis (L) seeds. Revista Bionatura, 8, 1-10. DOI: http://dx.doi.org/10.21931/RB/2023.08.03.62

Rahman F A 2022 Buku Ajar Anatomi Tumbuhan. Alfa Press. Lombok Barat, 1-146. BUKU AJAR ANATOMI TUMBUHAN.pdf

Rizal S, Kustyawati ME, Sartika D, Sariany R, Hidayat R and Suyantohadi 2024 Innovation of tempeh from jack bean (Canavalia ensiformis) fermented with Mosaccha inoculum. Food https://doi.org/10.1016/j.fbio.2024.105564

Sahari B, Hendarjanti H, Yusran A, Ibrahim M I M, Ramadhan G F and Prabowo R 2023 Weed diversity in oil palm plantation: benefit from the unexpected ground cover community. IOP Conference Series : Earth and Environmental Science, 1220. DOI: 10.1088/1755-1315/1220/1/012011

Sapalina F, Farrasati R, Wiratmoko D, Rahutomo S, Santoso H, Ginting EN, Pradiko I and Hidayat F 2022 Oil palm intercropping system: A potential nature-based solution to improve soil biology activities in North Sumatra plantation, Indonesia. Malaysian Journal of Microbiology, 18, 235-241. DOI: http://dx.doi.org/10.21161/mjm.211275

Soedarjo M 2021 Teknologi produksi tanaman koro pedang Canavalia ensiformis (L.). Jurnal Keteknikan Pertanian Tropis, 9, 216-226. DOI: 10.21776/ub.jkptb.2021.009.03.03

USDA 2024 Department of Agriculture. Indonesia: Oilseeds and products update. Report Number: ID2024-0048. https://www.fas.usda.gov/data/indonesia-oilseeds-and-products-update-30

Yang H, Zhang F, Chen Y, Xu T, Cheng Z and Liang J 2016 Assesment of reclamatioan treatments of abandoned farmland in an arid region of China. Sustainability, 8, 1183. DOI: 10.3390/su8111183

Yu R P, Dresbøll D B, Finckh M R, Justes E, van der Werf W Fletcher A, Carlsson G and Li L 2025 Intercropping: ecosystem functioning and sustainable agriculture. Plant Soil, 506, 1-6. DOI: https://doi.org/10.1007/s11104-024-07111-w

Yuliani S, Sabur A and Napisah K 2021 Soybean as ground cover plant and intercrop in immature oil palm plantation. E3S Web of Conferences 306, 05011. DOI: https://doi.org/10.1051/e3sconf/202130605011