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Case Study: Food Security & Nutrition, Market Access

Leaf Colour Charts Help Asian Farmers Manage Nitrogen Fertilizers

Farming First Farming First

Leaf colour charts are an effective, low cost tool to assist farmers in improving their nitrogen fertilizer management. These standardised guidelines developed by IRRI for efficient fertilizer use are based on the colour of the plant’s leaves. Using LCCs for rice in Asia has helped Asian farmers estimate plant nitrogen demand, to produce high rice yields.

The general idea is that a critical leaf colour has to be maintained for optimal growth, and the LCC provides guidance when to apply nitrogen fertilizer to avoid nitrogen deficiency. The critical leaf colour depends on the varietal group (inbred, hybrid, new plant type) and crop establishment method. The LCC is used at critical growth stages to decide whether the recommended standard nitrogen rate needs to be adjusted up or down based on the leaf colour.

The LCCs must be specific to the crops in the region: LCCs developed at the University of California, using Californian rice varieties, produced a spectrum of colours that did not match the rice leaves found in Asia. The Asian LCC can be used for all modern, high yielding rice varieties in Asia, but guidelines on the use of the chart have to be adjusted to local conditions.  Local guidelines on the LCC use have now been developed for the major irrigated rice domains in Asia.

The results of research show that for many farmers in Asia, sub-optimal nitrogen management is a key constraint to increasing yield. Consequently, improving nitrogen management can help produce greater yields. It was also found that yield responses to phosphorus and potassium fertilizers often occurred only after nitrogen management was improved.

Improved nitrogen and fertilizer management are key components of the site-specific nutrient management (SSNM) approach developed by the International Rice Research Institute (IRRI). Field studies using the LCC method in major irrigated rice areas have shown significant yield and profit increases with SSNM over farmers’ typical use of fertilizers.

Since 2003, more than 250,000 LCCs have been distributed to Asian rice farmers in Bangladesh, China, India, Indonesia, Burma, the Philippines, Thailand and Vietnam. Efforts are now underway to promote the technology at wider scale among Asian rice farmers.

The full case study, provided by the International Plant Nutrition Institute (IPNI) can be found here.

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