While maize is the primary staple food crop in Zambia, its productivity on farmers’ fields reaches on average only about 20 percent of what it could achieve with good agronomic practices. Some reasons for this inefficiency are use of traditional varieties, low fertilizer use, and ineffective weed and pest control.
Closing the gap between potential and realized yields would have major benefits for farmers in Zambia, both in terms of income and food security at the household and national levels. One possibility to increase maize productivity is by increasing crop diversity through the inclusion of legumes in maize-based farming systems. This could be done through intercropping, growing legumes in the rows between maize plants, or crop rotations and alternating maize and legumes in the same field from season to season.
CIMMYT scientists, along with collaborators from the Zambia Agriculture Research Institute (ZARI) and the University of Zambia’s School of Agricultural Science, set out to determine which cropping systems might lead to increased productivity for maize farmers in Zambia and their results were published in the journal Field Crops Research.
“There is great potential in Zambia to increase yields to help ensure food security,” said Mulundu Mwila, PhD candidate and scientist at ZARI. “We wanted to determine the cropping systems that offered the most benefits.”
Setting up the study
For this research, ZARI and CIMMYT scientists established maize-based cropping systems trials, comprising maize monocropping, and maize-legume rotations and intercrops under both ‘conventional’ tillage, and Conservation Agriculture, across 40 farms in a variety of agroecological zones in Zambia. The team also conducted household surveys in the same communities hosting the on-farm trials to determine the share of households with enough cultivated land to benefit from the tested cropping systems.
Researchers found that the tested cropping systems produced more maize per hectare compared to non-trial host farms in the same region. The greatest positive effect uncovered was that maize-legume rotations in Zambia’s Eastern Province had the potential to increase maize yield by 1 to 2 tons per hectare, per growing season. “The Eastern Province trials showed better results because of stable and adequate rainfall amounts and distribution and because of using groundnut as a rotation crop,” said Mwila.
Researchers attributed the small effect of legumes on maize yield in the Southern Province to low levels of biomass production and nitrogen fixation, due to low and erratic rainfall, and to low residue incorporation because of livestock grazing. Conversely, the small effect of legumes on maize yield in the Northern Province might be attributed to the high rainfall amount in the region, leading to high rates of leaching of residual nitrogen during the growing season as well as the use of common beans as the preceding crop.
Finding the right amount of land
With evidence showing the potential benefits of maize-legume rotations, the availability of land is a constraint for small farms across sub-Saharan Africa, thus it is important to quantify the land area needed for farmers to implement maize-legume rotations.
“Our findings match prior research showing the benefits of maize-legume rotations in Eastern Zambia” said Silva. “However, implementing maize-legume rotations remains a challenge for many smallholders due to small farm sizes.”
Nearly 35, 50, and 70% of the surveyed farms in the Northern, Eastern, and Southern Provinces, respectively, had enough land to achieve the same level of maize production obtained on their farm with the yields of the maize-legume rotations tested in the on-farm trials. “With our findings showing increased maize yields, and our efforts to determine the amount of land needed for food and nutrition security at household level, the next steps can be to facilitate methods to disseminate this information to policy makers and to farmers that have enough land area to benefit from diversified cropping systems,” said Silva.
For farmers with not enough land to reap the benefits of maize-legume rotations, intercropping legumes within the maize has shown promising results. The researchers also call for further research to specify the contributing factors to small farms not seeing benefits from maize-legume rotations.
I am Grace Malaicha, a proud native of the Zidyana Extension Planning Areas in Central Malawi, where my journey with Conservation Agriculture (CA) began. In 2005, I observed neighboring farmers practicing CA techniques on their land. Intrigued and inspired, I decided to embark on this path myself, joining the CA program initiated by CIMMYT and Total LandCare in 2006. I started practicing it on my demonstration plot and observed that yields were getting higher from the second year onwards.
My dedication to CA has changed not only myself but also influenced other members of my farming community. As a mother trial host farmer under the CGIAR Initiative: Diversification for resilient agribusiness ecosystems in East and Southern Africa today, I have been implementing different treatments, which include maize doubled-up legume system and improved drought-tolerant maize varieties planted under CA on flat land and comparing it to the traditional ridge tillage system that involves substantial soil movement.
But what does CA mean to me? It is more than just a set of principles that I apply like minimum soil disturbance, mulching, and crop rotation. CA reduces drudgery, secures yields, and maintains productivity in times of climate change. CA has changed my approach to farming, transforming my once conventional maize monocrop into a diverse maize-legume system. By intercropping with two crops, I have spread the risk of unanticipated crop failure, while incorporating groundnut, cowpeas, and pigeon pea into the mix, which are more drought tolerant. I increased the land area under CA and tried it on many other crops including different legumes as rotation or intercrops, birds-eye chili, vegetables, and cassava.
Over the years, I have witnessed firsthand the harsh realities of a changing climate in central Malawi, from intense heat to prolonged droughts and erratic rainfall patterns. This year, 2024, has even been worse due to the prolonged dry spells between January and February, and the erratic rainfall during this time. Despite these challenges, our CA plots have continued to thrive, showcasing the resilience and adaptability of climate-smart farming practices.
Grace trains farmers on Conservation Agriculture. (Photo: Christian Thierfelder/CIMMYT)
Recognizing the power of knowledge sharing and from the encouragement by CIMMYT and Total LandCare, I started to train fellow farmers, both locally and across borders. At first, I worked with women groups around my homestead and trained about 100 female farmers on the principles of CA. I was fortunate to be given the opportunity to train other farmers in other districts of Malawi. Since 2008, I have also trained farmers in eastern Zambia and from Mozambique where all farmers speak my language Chichewa. Farmers believe other farmers more and are now realizing the benefits of implementing CA in their own fields.
I enrolled to be a local trainer in CA within my community in 2016. My passion for teaching and catalyzing change has led to the adoption of CA by numerous farmers. I embrace my commitment to ongoing learning through carefully implementing these CA trials and playing an active role during awareness meetings.
My life had changed so much. I was speaking on the radio and television. In 2012, the Minister of Agriculture visited my plot, and I was asked to speak in front of a Parliamentary Committee about my experiences as a smallholder woman farmer in Malawi. I spoke about what women can do in agriculture and what changes I made on my land. From representing my country at high level meetings, each step has shaped me into a resilient and empowered woman.
However, my journey has not been without obstacles, including hardships in my personal relationship. In 2012, I made the decision to join my husband in South Africa where I took up menial jobs to earn a living, abandoning my plot back home. But my true passion lay in farming, and I decided to make the bold decision to come back home, leaving my husband and continue with farming. Through perseverance and determination, I have overcome these challenges, and I am now much stronger.
Grace Malaicha stands in her field. (Photo: Christian Thierfelder/CIMMYT)
Today, I stand with pride in front of my CA plot, not only sustaining my family but also sending all my children to school. I now converted all my land to conservation agriculture, 3ha are under maize and 2ha under groundnuts. Beyond farming, I have investments in housing, claiming rentals in the nearby town of Salima to sustain my financial income and expand in farming.
I will continue on this path as I learned so much over the years and believe that CA may be the only climate-smart agriculture response in reach of smallholder farmers that everybody can apply, and I will continue to support others as a champion of CA.
For decades, women farmers like Maureen Bwalya from the Musa camp in Kasama district of northern Zambia, have upheld the tradition of cultivating cassava on ridges. These small piles of soil created by hand hoes, 30-50 cm tall and 50 cm wide are intended to reduce water logging and facilitate cassava growth. But forming row after row takes a significant amount of physical labor. Establishing ridges follows a traditional practice known as chitemene, a Bemba word which means “place where branches have been cut for a garden.”
Chitemene, a slash and burn technique once common in Zambia, involves cutting down standing trees in the Miombo woodlands, stacking the logs, and then burning them to create a thick layer of ash believed to enhance soil fertility. The ashen fields are initially cultivated with pearl millet and followed by crops like cassava. As years progressed, this method has been associated with adverse environmental impacts disrupting the ecosystem balance due to increasingly shortened fallow and recovery periods. However, with the ever-changing climate, Bwalya and other farmers recognize the need for sustainable practices that require less labor.
Alternatives to the traditional methods
Since childhood, Maureen Bwalya, a mother of seven from Musa Camp in the Kasama District of northern Zambia, has dedicated her life to cassava farming. Thriving under very low fertility and acidic soils, cassava has offered a lifeline amid the challenges of rural agriculture. When the Sustainable Intensification of Smallholder Farming Systems in Zambia (SIFAZ) project was introduced in the northern province, where cassava is a strategic crop, Bwalya saw a valuable opportunity for change to cultivate better practices that not only improve cassava yields but also replenish soil fertility in her fields.
“When I started these trials, it was a tough transition,” said Bwalya, reflecting on her journey. “Shifting from ridge planting to flat land cultivation posed its challenges as this practice was new to me. But with time, I have learned the advantages of intercropping: increased yields, less labor, and enhanced productivity, all of which enrich my farming practices.”
Maureen Bwalya gazes through her plot. (Photo: CIMMYT)
Implemented over the last five years by CIMMYT, in collaboration with FAO and the Ministry of Agriculture, SIFAZ aims to advance the intensification of farming practices and catalyze widespread adoption among farmers in Zambia. In the Musa camp, key partners took on the challenge of advancing better farming techniques with cassava. Their collective objective was clear: to identify methods that minimized labor intensity while maximizing yields. Through rigorous trials, including comparing flat land planting against traditional ridge systems and experimenting with intercropping cassava with common beans and groundnuts, promising results have been seen.
The outcomes yielded thus far have been nothing short of inspiring across farmers. It has become clear to farmers and researchers that cassava planted on flat land, particularly within a Conservation Agriculture (CA) framework, was not only feasible in high rainfall areas but also yielded significantly higher returns. Despite observing fewer root structures, the roots themselves proved to be robust and weighty, ultimately translating to increased productivity for smallholder farmers. Furthermore, farmers have confirmed that cassava from the CA plots tastes better than the one from the ridged portions.
“As a cassava trial implementer,” Bwalya said, “I undertook various trials exploring intercropping cassava with beans and groundnuts, across both flat and ridge systems.”
Thriving and innovating
Her six-hectare plot has become a hub of experimentation, with 0.3 hectares dedicated to the ongoing trials. Encouraged by the successes and promising yields witnessed on flat land, Maureen extended these sustainable practices to the remaining expanse, intercropping maize with cassava. Her results have been noticed, drawing the interest of over fifty neighboring farmers, inspired by her flourishing plot.
As the harvesting season approaches, Bwalya faces no shortage of opportunities to market her produce. From cassava cuttings to nutrient-rich leaves and tubers, she never runs short of eager buyers in local markets, ensuring a steady income for her family.
Navigating through the different trials across the Kasama district, pockets of adoption in some farmers’ fields are noticeable. Through collaborative partnerships and community engagement, SIFAZ strives to empower farmers with the knowledge and tools stemming from the trials to become more food secure in the face of evolving climatic challenges.
Farmer Eveline Musafari intercrops maize and a variety of legumes on her entire farm. She likes the ability to grow different food crops on the same space, providing her family with more food to eat and sell. (Photo: Matthew O’Leary/CIMMYT)
Honest Musafari, a fifty-year-old farmer from rural Zimbabwe, eagerly picks up a clump of soil from his recently harvested field to show how dark and fertile it is. A farmer all his life, Musafari explains the soil has not always been like this. For years, he and his neighbors had to deal with poor eroding soil that increasingly dampened maize yields.
“My soil was getting poorer each time I plowed my field, but since I stopped plowing, left the crop residues and planted maize together with legumes the soil is much healthier,” says Musafari. His 1.6-hectare maize-based farm, in the Murehwa district, supports his family of six.
For over two years, Musafari has been one of the ten farmers in this hot and dry area of Zimbabwe to trial intercropping legumes and green manure cover crops alongside their maize, to assess their impact on soil fertility.
The on-farm trials are part of efforts led by the International Maize and Wheat Improvement Center (CIMMYT) in collaboration with Catholic Relief Services (CRS) and government extension services to promote climate-resilient cropping systems in sub-Saharan Africa.
Increasing land degradation at the farm and landscape level is the major limitation to food security and livelihoods for smallholder farmers in sub-Saharan Africa, says CIMMYT senior cropping systems agronomist Christian Thierfelder.
“Over 65 percent of soils in Africa are degraded. They lack the nutrients needed for productive crops. This is a major part of the reason why the region’s maize yields are not increasing,” he explains. “The failure to address poor soil health will have a disastrous effect on feeding the region’s growing population.”
The area where Musafari lives was chosen to test intercropping, along with others in Malawi and Zambia, for their infamous poor soils.
Mixing it up
When legumes are intercropped with maize they act as a green manure adding nutrients to the soil through nitrogen fixation. Intercropping legumes and cereals along with the principles of conservation agriculture are considered away to sustainable intensify food production in Africa. (Photo: Christian Thierfelder/CIMMYT)
Planted in proximity to maize, legumes — like pigeon pea, lablab and jack beans — add nitrogen to the soil, acting as green manure as they grow, says Thierfelder. Essentially, they replace the nutrients being used by the cereal plant and are an accessible form of fertilizer for farmers who cannot afford mineral fertilizers to improve soil fertility.
“Our trials show legumes are a win for resource poor family farmers. Providing potentially 5 to 50 tons per hectare of extra organic matter besides ground cover and fodder,” he notes. “They leave 50 to 350 kg per hectare of residual nitrogen in the soil and do not need extra fertilizer to grow.”
Added to the principles of conservation agriculture — defined by minimal soil disturbance, crop residue retention and diversification through crop rotation and intercropping — farmers are well on their way to building a resilient farm system, says Geoffrey Heinrich, a senior technical advisor for agriculture with CRS working to promote farmer adoption of green manure cover crops.
For years Musafari, as many other smallholder farmers in Africa, tilled the land to prepare it for planting, using plows to mix weeds and crop residues back into the soil. However, this intensive digging has damaged soil structure, destroyed most of the organic matter, reduced its ability to hold moisture and caused wind and water erosion.
Letting the plants do the work
Growing legumes alongside maize provides immediate benefits, such as reduced weeding labor and legume cash crops farmers can sell for a quick income. The legumes also improve the nitrogen levels in the soil and can save farmers money, as maize needs less fertilizer. (Photo: Christian Thierfelder/CIMMYT)
Musafari says the high price of mineral fertilizer puts it out of reach for farmers in his community. They only buy little amounts when they have spare cash, which is never enough to get its full benefit.
He was at first skeptical green manure cover crops could improve the quality of his soil or maize yields, he explains. However, he thought it was worth a try, considering growing different crops on the same plot would provide his family with more food and the opportunity to make some extra cash.
“I’m glad I tried intercropping. Every legume I intercropped with my maize improved the soil structure, its ability to capture rain water and also improved the health of my maize,” he says.
Thierfelder describes how this happens. Nitrogen fixation, which is unique to leguminous crops, is a very important process for improving soil fertility. This process involves bacteria in the soil and nitrogen in the air. The bacteria form small growths on the plant roots, called nodules, and capture the atmospheric nitrogen as it enters the soil. The nodules change the nitrogen into ammonia, a form of nitrogen plants use to produce protein.
In addition, legumes grown as a cover crop keep soil protected from heavy rains and strong winds and their roots hold the soil in place, the agronomist explains. They conserve soil moisture, suppress weeds and provide fodder for animals and new sources of food for consumption or sale.
Farmers embrace intercropping
Extension worker Memory Chipinguzi explains the benefits of intercropping legumes with cereals to farmers at a field day in the Murehwa district, Zimbabwe. (Photo: Christian Thierfelder/CIMMYT)
Working with CIMMYT, Musafari and his wife divided a part of their farm into eight 20 by 10 meter plots. On each plot, they intercropped maize with a different legume: cowpea, jack bean, lablab, pigeon pea, sugar bean and velvet bean. They also tried intercropping with two legumes on one of the plots. Then they compared all those options to growing maize alone.
“Season by season the soil on each of the trial plots has got darker and my maize healthier,” describes Musafari. “Rains used to come and wash away the soil, but now we don’t plow or dig holes, so the soil is not being washed away; it holds the water.”
“I really like how the legumes have reduced the weeds. Before we had a major problem with witchweed, which is common in poor soils, but now it’s gone,” he adds.
Since the first season of the trial, Musafari’s maize yields have almost tripled. The first season his maize harvested 11 bags, or half a ton, and two seasons later it has increased to 32 bags, or 1.5 tons.
Musafari’s wife Eveline has also been convinced about the benefits of intercropping, expressing the family now wants to extend it to the whole farm. “Intercropping has more advantages than just growing maize. We get different types of food on the same space. We have more to eat and more to sell,” she says.
The family prefers intercropping with jack bean and lablab. Even though they were among the hardest legumes to sell, they improved the soil the most. They also mature at the same time as their maize, so they save labor as they only have to harvest once.
The benefits gained during intercropping have influenced farmers to adopt it as part of their farming practices at most of our trial sites across southern Africa, CRS’s Heinrich says.
“Immediate benefits, such as reduced weeding labor and legume cash crops that farmers can sell off quick, provide a good incentive for adoption,” he adds.
Honest and Eveline Musafari with extension worker, Memory Chipinguzi. Neighbors have noticed the intercropping trials on the Musafari’s farm and are beginning to adopt the practice to gain similar benefits. (Photo: Matthew O’Leary/CIMMYT)
The majority of African farmers are smallholders who cultivate less than 2 hectares, explains Thierfelder. If they are to meet the food demand of a population set to almost double by 2050, bringing it to over 2 billion people while overcoming multiple challenges, they need much more productive and climate-resilient cropping systems.
New research identifies that the defining principles of conservation agriculture alone are not enough to shield farmers from the impacts of climate change. Complementary practices are required to make climate-resilient farming systems more functional for smallholder farmers in the short and long term, he warns.
“Intercropping with legumes is one complementary practice which can help building healthy soils that stand up to erratic weather,” says Thierfelder. “CIMMYT promotes climate-resilient cropping systems that are tailored to farmers’ needs,” he emphasizes.
“To sustainably intensify farms, growers need to implement a variety of options including intercropping, using improved crop varieties resistant to heat and drought and efficient planting using mechanization along with the principles of conservation agriculture to obtain the best results.”
