Conservation Agriculture in Maize-Legume Cropping Systems
Source: Flickr, CIMMYT

A new study from the International Maize and Wheat Improvement Center (CIMMYT) finds that the use of maize-based cropping systems, combined with climate-smart soil and water management practices, could provide an important channel through which to improve agricultural productivity and reduce environmental degradation and water loss in northwest India.

According to the study, the rice-wheat cropping system traditionally used in northwest India has caused significant soil degradation and water depletion in the region. In addition, conventional crop management practices bring with them high production costs and often involve inefficient use of agricultural inputs like irrigation and fertilizer.  Maize, on the other hand, can be more environmentally sustainable when it is intercropped with legumes. There has thus been interest in recent years in the use of maize cropping systems to address environmental challenges – and to meet India’s growing domestic demand for maize for both food and feed.

CIMMYT researchers looked specifically at the potential benefits of conservation agriculture (CA) in irrigated maize cropping systems integrated with legumes. The authors hypothesized that the use of CA tillage practices, specifically zero tillage and permanent bed planting, in a maize-legume cropping system can improve crop and water productivity, soil health, and economic profit. The study spanned six years (2008-2013) and utilized data collected from four irrigated maize cropping systems (combining maize with a mixture of legume crops) at the research farm of the Indian Council of Agricultural Research (ICAR)-Indian Institute of Maize Research (IIMR). This data was used to evaluate the comparative performance – in crop and water productivity and in net returns – of these four systems using different CA tillage and crop establishment techniques.

Understanding how CA techniques can impact environmental degradation and water usage is particularly important in northwest India, according to the report. The region falls into what is known as the Indo-Gangetic Plains (IGP), a fertile area covering over 2.5 million square kilometers across Bangladesh, India, Nepal, and Pakistan. The IGP is an important food-producing region, and it also comprises 25 percent of global groundwater withdrawals. According to CIMMYT, aquifers in the region are being depleted faster than they can be refilled, threatening agricultural production and food security for more than 500 million people.

The study examined four maize-legume intercropping systems: maize-wheat-mungbean (MWMb), maize-mustard-mungbean (MMuMb), maize-maize-Sesbania (MMS), and maize-chickpea-Sesbania (MCS). Across the board, all of these crops showed increased yields over time with the adoption of improved tillage and crop establishment techniques like zero tillage and permanent bed planting, as well as with efforts to retain crop residue. The authors argue that the increased yields can be due to a number of factors, including additional nutrients in the soil, fewer weeds, improved soil physical health, improved nutrient-use efficiency, and lower water evaporation loss.

In terms of water productivity, both zero tillage and permanent bed planting techniques reduced the need for irrigation water by up to 65 and 98 hectares per millimeter, respectively, compared to conventional tillage systems. These techniques boosted all of the maize cropping systems’ water productivity by nearly 20 percent.

These positive effects – increased yields and lower irrigation requirements – brought economic as well as environmental benefits. For the use of maize cropping systems, these benefits varied somewhat. For the MMuMB (maize-mustard-mungbean) and MWMB (maize-wheat-mungbean) systems, production costs were lower and net returns were higher compared to traditional rice-wheat cropping systems; however, under the MCS (maize-chickpea-Sesbania) and MMS (maize-maize-Sesbania) systems, net returns were lower than under rice-wheat systems. The adoption of CA practices, on the other hand, brought economic benefits across the board. Using zero tillage and permanent bed planting increased returns by US$ 300-400 per ha per year compared to the use of conventional tillage techniques – an increase of more than 30 percent.

The CIMMYT study shows that both CA techniques and maize cropping systems can, on their own, provide important economic, environmental, and food security benefits. However, combining the two brings even more powerful change, improving crop and water productivity, soil health, and incomes.

Photo credit:Flickr, CIMMYT