Green manure and cover crops for Philippine rice
Kudzu Seeds Trading supplies tropical legume green-manure seed to Philippine rice growers in Cagayan Valley, Central Luzon, Western Visayas, Ilocos and Bicol. A legume green-manure rotation before transplanted rice contributes nitrogen to the following crop; adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
At a glance
- PH role: Rice is the staple food crop of the Philippines, with planted area concentrated in Central Luzon, Cagayan Valley, Western Visayas and Ilocos.
- Institutions: The Philippine Rice Research Institute (PhilRice) leads PH rice research; the National Irrigation Administration (NIA) manages major irrigation systems.
- Green-manure benefit: Legume green manures grown in the fallow before rice contribute biologically fixed nitrogen to the next rice crop; the amount depends on species, biomass and incorporation method.
- Rotation context: Green-manure cover fits between the dry-season harvest and the wet-season transplant window (April to June) on irrigated land, or in the post-wet-season fallow on rainfed land.
- Primary species: Mucuna bracteata (MB), Pueraria javanica (PJ), Calopogonium mucunoides (CM).
Why green-manure cover crops matter for rice in the Philippines
The Philippines imports a large share of its synthetic nitrogen fertiliser as urea. Across the fallow window between dry-season and wet-season rice, or between rice and the next planting on rainfed bunds, a tropical legume green manure contributes nitrogen to the following crop, and how much depends on species, biomass and incorporation method. Adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
PhilRice and the wider irrigated-rice research community have long documented the agronomic value of legume green manure in Philippine lowland rice, mainly with species such as Sesbania, Aeschynomene and mungbean (PhilRice; Diekmann, Ottow and De Datta 1996). Tropical climbing legumes such as Mucuna bracteata, Pueraria javanica and Calopogonium mucunoides extend that toolkit, especially in rainfed and upland-rice systems where ground cover and erosion protection also matter.
The second value driver is soil structure. Legume root systems and biomass turnover add organic matter to continuously cropped lowland rice soils, and periodic green-manure rotations can help counter long-term soil organic matter decline in intensified Philippine rice systems.
Recommended species for Philippine rice rotation
Mucuna bracteata (MB)
Green-manure option for rotations on irrigated or rainfed bunds. Raised as nursery seedlings and transplanted, not broadcast (in oil palm, MPOB TT No. 501 used about 320 seedlings per hectare raised from about 500 seeds, 75 g). Measured at 67 to 84 percent of nitrogen taken from the air under three-year-old oil palm on Jawa Series soil in Malaysia (15N isotope dilution; Cheah et al. 2010); in a rice rotation, incorporation returns a share of the standing biomass to the next crop.
Green manure / transplanted, not broadcast
Pueraria javanica (PJ)
Sown alone, the published rate is about 4 kg per hectare (Tropical Forages). Fast-establishing tropical climber for rainfed rice fallows and rice-upland transitions. Good ground cover with moderate biomass return.
Rotation crop / broadcast
Calopogonium mucunoides (CM)
Broadcast; the seeding rate is confirmed on the quotation. Pioneer for acidic and degraded rice land, including the upland fringes of Cagayan Valley and Bicol where Ultisols are common.
Pioneer / broadcast
Centrosema pubescens (CP)
Broadcast, the published rate is 3 to 5 kg per hectare (Tropical Forages). Persistent legume for paddy bunds, headlands and irrigation canal banks. Adds organic matter on edges the rice crop does not reach.
Bunds and edges / broadcast
Calopogonium caeruleum (CC)
The published rate is 1 to 1.5 kg per hectare sown with 5 to 7.5 kg per hectare of PJ (Tropical Forages). Climbing legume for sloped upland-rice systems and rainfed margins, and a species that can persist as shade increases.
Upland margins / sown with PJ
SoilBoost EA
Leonardite-derived humic acid soil conditioner with 0.45 percent sulphur and pH 3.84. Broadcast 50 to 100 kg/ha at land preparation, or drench 10 to 15 kg/ha. A soil conditioner, not a fertiliser and not a substitute for one. Manufactured exclusively for Chemiseed Sdn. Bhd. and Kudzu Seeds Trading.
Amendment / not a fertiliser
PH-specific establishment timing
Philippine rice runs two main calendars: irrigated double-cropping across dry and wet seasons, and rainfed single-cropping in the wet season only. Green-manure timing follows the available fallow window.
- Irrigated Central Luzon and Cagayan Valley: after the dry-season harvest in April to May, broadcast PJ or CM, or transplant MB seedlings, into the fallow. Incorporate at land preparation in late June or early July before wet-season transplanting.
- Rainfed Western Visayas and Ilocos: after the wet-season harvest in November to December the fallow window is short and dry. PJ and CM established on residual moisture can carry through to the next wet-season transplant; CP and CC make better bund-edge perennials.
- Upland rice (Cordillera, parts of Bicol, Mindanao): establish CM or PJ ahead of the rice crop as a true rotation, ploughing it in before sowing.
Central Luzon and Cagayan Valley sit in the Type I climate with a pronounced dry season, which suits a short, fast green-manure rotation. Bicol, eastern Visayas and parts of the Cordillera carry rain through more of the year and need timing that avoids saturated incorporation.
Common challenges in Philippine rice
- Imported urea cost. Biological nitrogen fixation from a green-manure rotation contributes nitrogen to the next rice crop; adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
- Soil organic matter decline under intensified double-cropping. Periodic legume green manure adds organic matter between rice crops.
- Weed pressure in fallow paddies. A dense legume cover can help suppress Echinochloa and other weeds compared with a bare fallow.
- Acidic upland and rainfed soils. CM is used as a pioneer on the most degraded rainfed and upland-rice plots.
- Typhoon and flood exposure. Established legume cover on rice bunds and rainfed margins holds topsoil during high-rainfall events better than bare ground.
Frequently asked questions
How much nitrogen does a green-manure rotation supply to Philippine rice?
A tropical legume green-manure rotation contributes biologically fixed nitrogen to the following rice crop, and the amount depends on species, biomass and incorporation method. We do not publish a per-hectare figure for these species in Philippine rice rotations. Adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
Which species fit best between dry-season and wet-season rice?
For the April to June fallow on irrigated land in Central Luzon and Cagayan Valley, Pueraria javanica establishes quickly (published rate sown alone about 4 kg/ha, Tropical Forages). Calopogonium mucunoides works on more acidic blocks; its seeding rate is confirmed on the quotation. On longer fallows, Mucuna bracteata can be transplanted as nursery seedlings.
How much Mucuna bracteata seed do I need?
Mucuna bracteata is raised as nursery seedlings and transplanted. In MPOB TT No. 501 (oil palm on peat), about 320 seedlings per hectare, two per palm point, were raised from about 500 seeds (75 g); the quantity for a rice rotation is confirmed on the quotation. Mucuna bracteata is not broadcast in commercial practice, so kilogram-per-hectare rates quoted for other species do not apply to it.
Can I use legume cover crops on rainfed rice?
Yes. Rainfed systems in Western Visayas, Ilocos and parts of Mindanao benefit particularly, because the off-season fallow is long enough to produce real biomass before the next crop. CM and PJ established on residual moisture in the closing rains carry through to the next planting cycle.
How do I incorporate the green manure before transplanting rice?
Plough or rotary-till the legume cover into wet soil during land preparation, before transplanting. Green manure mineralises quickly after incorporation in flooded paddy soil (PhilRice), so time incorporation with land preparation and confirm the interval for your field with PhilRice or your agronomist. Older, woodier biomass such as mature Mucuna breaks down more slowly.
Can you deliver to Central Luzon, Cagayan Valley and other rice regions?
Yes, by arrangement. Orders are Ex Works (EXW) Tigatto, Davao City, unless the quotation states FOB or CIF for export. Delivery to Central Luzon, Cagayan Valley or any other rice region can be arranged on request and at your cost: you may collect from our premises in Tigatto, send your own trucker or forwarder, or ask us to book a carrier, in which case the quotation states the delivery address and the delivery cost. Export shipments carry a phytosanitary certificate issued by the Bureau of Plant Industry (BPI); documents for inter-island shipments are confirmed on the quotation. Quotations are available for cooperatives, irrigators' associations and government extension programmes.
Related pages
Request a Philippine rice green-manure quotation
Send a quotation request with your crop, area and delivery point, or WhatsApp us for pricing, lot availability and delivery options for your site. We reply within one business day (Philippine time).
Request a quotation WhatsApp Kudzu Seeds TradingAll Philippine plantation guides
Browse by region or by crop. Each guide covers Philippine-specific species and establishment notes, with published seeding rates where a source exists.
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Kudzu Seeds Trading is the Philippines-based sister company of Chemiseed Sdn. Bhd. in Malaysia (chemiseed.com). SoilBoost EA is manufactured exclusively for Chemiseed Sdn. Bhd. and Kudzu Seeds Trading.
Sources for the seeding and nitrogen figures: Tropical Forages, CIAT and ILRI (2020), tropicalforages.info; MPOB TT No. 501 (Hasnol Othman, Farawahida Mohamad Darus and Zulkifli Hashim, 2012); Cheah, Zaharah and Aminuddin (2010), Oil Palm Bulletin 60: 22-27, MPOB (PDF); Diekmann, Ottow and De Datta (1996), Biology and Fertility of Soils 21: 103-108, doi:10.1007/BF00336000; PhilRice (2022), Organic-based Nutrient Management for Rice Production.
Last reviewed 10 October 2026.