Paddy lodging (padi rebah): why it happens and how to prevent it

Lodging is when rice stems bend or break and the crop falls flat, usually during flowering and grain filling when the panicles are heavy. Farmers call it padi rebah.

Lodging limits both grain yield and quality by breaking or bending the stems. Fallen plants also make harvesting slower and harder.^[6]

Wind and heavy rain are what push the crop over, but whether it falls depends on how strong the stems and roots are. That is mostly decided by how the crop was managed in the weeks before.

• Too much nitrogen. Excess nitrogen gives lush growth that reduces stem strength, leading to lodging during flowering and grain filling. Over-fertilised fields may be lodged at maturity — especially direct-seeded rice — and have thin stems that are prone to disease and insects.^[1]
• Seeding too thickly. When plants are too close together the stems are often weak, which can result in lodging and yield loss during heading. Direct-seeded fields tend to lodge more, especially when the seed is sown on the surface.^[2]
• Potassium shortage. Potassium-deficient rice has short, thin stems and a greater incidence of lodging.^[3]
• Silicon shortage. Silicon-deficient plants are particularly susceptible to lodging. The deficiency is more common in old and degraded paddy soils than in most irrigated fields.^[4]
• Stem rot and insect damage. Stem rot decays the leaf sheaths and causes lodging and poor grain filling. Infection is higher on plants wounded by lodging or insect attack.^[5]
• Tall varieties. Plant breeders reduced lodging risk by introducing semi-dwarf traits to produce shorter varieties.^[6]

• Match nitrogen to the crop, not more. Apply enough nitrogen to meet the plants' needs and take into account how much is already coming from the soil and other sources. Excessive nitrogen harms the environment and lowers farm profits.^[1]
• Use a sensible seed rate. Avoid overly dense stands, and in direct-seeded fields make sure seed is not left lying on the surface.^[2]
• Keep potassium up. Replace the potassium removed with each harvest using potassium fertiliser, farmyard manure, compost or rice husk ash, and incorporate the straw.^[3]
• Return straw and husk to the field. Leaving straw in the field and recycling rice straw and husks helps prevent silicon deficiency. Avoid excessive nitrogen at the same time.^[4]
• Choose a variety that stands. Where lodging is a recurring problem, choose a shorter, lodging-tolerant variety recommended for your area.^[6]
• Manage water. Keep water levels appropriate to crop height, then drain the field before harvest as recommended for your variety.^[7]
• Watch for stem rot and stem borer. Check stems for rotting sheaths and insect damage and act early.^[5]

NEXGROW is a bio-organic, phosphate-solubilising fertiliser. For paddy, the product booklet describes it as supporting strong root systems for efficient water and nutrient uptake, anchoring the plant and helping prevent lodging, and contributing to grain filling.

It is not a substitute for getting nitrogen, potassium and seed rate right — those are the main causes above. The booklet sets paddy rates by soil cation exchange capacity (CEC), so you need a soil test to know which row applies to your field. Rates below are taken directly from the booklet.

Test the soil if lodging keeps recurring in the same fields, if yields have been falling on old paddy land, or before you change your fertiliser plan. A test shows whether potassium is low and what your soil CEC is, and helps you set nitrogen at what the crop needs instead of topping up by habit.^{[1, 3]}