Doubled Up Legumes

Description:

doubled up legumes figure 1 jpegIntercropping, a common practice in sub-Saharan Africa (SSA), is when different crops are cultivated at the same time and in the same space. Smallholder farmers intercrop to diversify income sources, reduce risks from crop failure, and sustainably intensify their operations on limited land resources. Additionally, some crops are considered too minor to occupy land on their own and therefore grown in crop mixtures. Most of the intercrop systems in SSA involve maize as the main crop and a grain legume such as groundnut as the companion crop. A relatively new approach is intercropping two legumes that have different but compatible growth habits. An example is that of a pigeonpea and groundnut intercrop (Figure 1). The approach is known as the doubled-up legume technology, an approach that takes advantage of beneficial interactions between the two legume crops. The main goal of the doubled-up legume technology is to ‘double’ the farmer’s crops and the soil fertility benefits of cropping legumes.[read more=”Read more” less=”Read less”]

Successful doubled-up legume intercropping systems mostly involve pigeonpea, a semi-perennial legume. Pigeonpea is mainly grown in mixed cropping systems such as intercrops (Nene et al., 1990). The success of the doubled-up technology is hinged on the initial slow growth of one of the legumes facilitating growth of companion crops as if sole cropped (Snapp et al., 2003; Snapp, 1998). Pigeonpea grows very slowly for the first two months after planting, and can therefore be intercropped with other legumes such as groundnuts or soyabeans with limited competition for water, nutrients, and sunlight. Pigeonpea only starts rapid growth when the companion crop is approaching maturity. After harvesting the companion crop, pigeonpea continues to grow as a sole crop until harvest. Research in Malawi has shown that pigeonpea productivity in the pigeonpea/groundnut intercrop is comparable to sole cropped pigeonpea (Gwenambira, 2015).

Thousands of legume species exist and in most developing countries legumes are the primary source of protein in human diets (Broughton, 2002). There are other benefits that come with adopting the doubled-up legume technology (see Multipurpose Legumes for Soil Rehabilitation). Biological nitrogen fixation and high quality residues from the two legumes can help to improve soil fertility in a degrading soil base.

Legumes are vital in agriculture as they ‘fix-nitrogen’ (Broughton et al, 2002). They are the main source of nitrogen through BNF in developing countries where fertilizers are expensive and inaccessible to many (Giller and Cadisch, 1995). This can help to minimize fertilizer requirements for farmers (see N-It’s What’s for Dinner). Diversifying the farm through doubled-up legumes provides security from crop failure for farmers, especially in the face of climate change. In a good season with favorable climate, farmers have the potential to get surplus grain from the two different grain legumes they cultivate. Additionally, the legumes can provide an important protein source both at the household level and potentially for livestock as well. [/read]

Principles:

  • Sustainable intensification with legumes
  • Increasing agrobiodiversity to cope with climate change
  • Incorporating crop residues in the soil to prevent soil erosion [read more=”Read more” less=”Read less”]
    • Retaining high quality biomass from both legumes in the field
    • Intercropping two compatible grain legumes for successful doubled-up systems
    • Rehabilitation of soils through biological nitrogen fixation
    • Offers high protein source of household nutrition

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Debates:

Innovative Pigeonpea and Lablab intercrop in Tanzania

Innovative Pigeonpea and Lablab intercrop in Tanzania

  • Possibility of increased labor requirements
  • Willingness of farmers to ‘sacrifice’ land on two legumes
  • Uncontrolled livestock grazing after maize harvest reduces pigeonpea grain
  • Questions about the sustainability of the approach with regards to expensive legume seed

Links:

FAO profile of our research on legumes and land productivity in Malawi (pdf)

Learning lab resources:

Gwenambira, C. (2015). Below- and Aboveground Pigeonpea Productivity in on-Farm Sole and Intercrop Systems in Central Malawi. Michigan State University. Ann Arbor: ProQuest. Web.

Snapp, S. S. (1998). Soil nutrient status of smallholder farms in Malawi 1.Communications in Soil Science & Plant Analysis, 29(17-18), 2571-2588.

Snapp, S. S., Jones, R. B., Minja, E. M., Rusike, J., & Silim, S. N. (2003). Pigeonpea for Africa: a versatile vegetable—and more. HortScience, 38(6), 1073-1079.

Bibliography:

Broughton, W. J., Hernandez, G., Blair, M., Beebe, S., Gepts, P., & Vanderleyden, J. (2003). Beans (Phaseolus spp.)–model food legumes. Plant and soil, 252(1), 55-128.

Giller, K. E., & Cadisch, G. (1995). Future benefits from biological N fixation: an ecological approach to agriculture. In Management of Biological N Fixation for the Development of More Productive and Sustainable Agricultural Systems (pp. 255-277). Springer Netherlands.

Nene, Y. L., Hall, S. D., & Sheila, V. K. (1990). The pigeonpea. CAB International.

Challenges Addressed: Smallholder Demographics (land scarcity); Soil Quality, Soil Fertility, and Low Productivity; Climate change; Poor Access to Inorganic and Organic Inputs; Poverty & Food Insecurity.

Tags: Agrobiodiversity, Agronomy, Soil Science, Crop Science, Sustainable Intensification.