"Save and Grow in practice" highlights importance of pulses in crop rotations and intercropping

FAO recently released “Save and Grow in practice: maize, rice, wheat”, a new book that looks at the application of sustainable intensification (“Save and Grow”) practices and technologies to the production of the world’s key food security crops – maize, rice and wheat. In Save and Grow farming systems, cereals are regarded not as monocultures but as components of mixed farming systems. When farming cereals like maize and wheat, farmers have improved yields and soil fertility by incorporating pulses into crop rotations (rotating different crops on the same land) or intercropping (growing two or more crops among each other). Read on for details and success stories of smallholder farmers around the world using pulses (also referred to as grain legumes) in cereal production.

Pulses and wheat

When planted with wheat, legumes such as pulses are especially beneficial because of their ability to fix nitrogen from the atmosphere into the soil. Although the residual nitrogen levels vary greatly, they can cover between 20 and 40 percent of wheat’s nitrogen needs, with some legume varieties fixing as much as 300 kg of nitrogen per ha. As a result, wheat grown after pulses produces higher grain yields, with higher protein content. In addition, some pulses like chickpeas and pigeon peas secrete compounds that make phosphorus more readily available to the wheat’s roots, and a gas that improves the plant’s overall development.

In North Africa and Western Asia, rotation of wheat with pulses – including chickpeas, lentils and faba beans – is practised increasingly in rainfed wheat production areas, especially in soils with low levels of nitrogen. Legumes diversify production, enrich the soil through biological nitrogen fixation, enhance water-use efficiency, and disrupt the life cycle of weeds, pests and disease agents.

In the highlands of Ethiopia, pulses are grown in rotation with cereals, or as intercrops, to spread the risks of drought and to improve soil fertility. In the Bale region, wheat after field peas significantly out-yields wheat-wheat and wheat-barley rotations. A faba bean-wheat rotation system resulted in wheat yield increases of up to 77 percent while reducing the need for nitrogen fertilizer

In the Islamic Republic of Iran, cereal-legume intercropping has been shown to be more productive and profitable than wheat monocropping.

Pulses and maize

Rotation, intercropping and relay cropping of pulses with maize lead to higher land productivity, making maize-legume systems especially suitable for smallholders. Legume rotation can increase maize yields by 25 percent. Maize intercropped with legumes under conservation agriculture produces 33 percent more grain than monocropping.

Maize-bean intercropping is a traditional practice among smallholder farmers in Latin America, especially in the land-scarce highlands. In Peru, practically all beans, and in Ecuador about 80 percent, are planted along with maize. In areas of Central America where land is limited and rainfall low, maize is often intercropped with field beans.

In recent years, many smallholder farmers in southern Africa have revived the traditional practice of growing legumes, including pigeon peas, along with maize. Often, the legumes are valued more as sources of food and income than for their contribution to soil fertility.

In Mexico, smallholder farmers have developed a system that grows velvet beans in the maize ‘off-season’, and leads to significantly higher levels of soil pH, organic matter and nitrogen. That, in turn, contributes to a 25 percent increase in the yield of the subsequent maize crop.

In northern Ghana, planting fields with cowpeas, from three to six weeks before maize, yields a nutritious food at a time when other crops are not yet mature and, with the retention of residues, provides nitrogen to the soil.

For more examples of farmers using pulses in sustainable farming, see FAO’s new practical guide to sustainable cereal production, “Save and Grow in practice: maize, rice, wheat”.