Envío Digital
Central American University - UCA  
  Number 166 | Mayo 1995



Faith, Hope and Mung Beans

Experiments are beginning in Nicaragua with the green mung bean, and the results are excellent: the mung destroys weeds, fertilizes and rescues the soil, and feed both humans and animals. Nicaragua welcomes this small but powerful ally.

Raquel Fernández

The mung bean is small and round, with a striking green color, like hope. And, like everything having to do with hope, it hides within its small size incalculable energy and an enormous capacity to grow and survive where nothing else will. It needs almost no water and its colorful plant provides a multitude of different products: animal feed, protein and vitamin rich food for human beings and fertilizer for organic agriculture. The most important product obtained from the mung bean, however, is unquestionably the hope it generates among the peasants of Nicaragua's most depressed and forgotten lands.

Stubborn, Resistant, Fast and Easy

The mung bean (Vigna radiata) originally comes from Southeast Asia and India. From there, it moved out to the rest of Asia, particularly the Philippines, Pakistan, Indonesia and Thailand. Later, it was cultivated in different countries of Africa and the Americas. Today, it is cultivated and its various products are used in a number of countries of Latin America.

In Central America, Nicaragua is the only country that grows mung beans. It all began here with a university experimental plot in Posoltega, where Albéniz Miranda found it. Miranda is a technician at the Center for the Research and Promotion of Rural Social Development (CIPRES), a nongovernmental organization which, among its goals, offers sustainable development alternatives to the country's poor peasants.

The most attractive feature of this legume which differs in appearance from red or black beans, the most commonly used on Latin American tables is its rapid growth. Less than three months pass between planting and harvest. And in that same short space of time, the mung provides its other products as well.

Sowing the bean is also attractive, since little soil preparation is necessary; it's enough just to turn the fresh stubble back into the soil. Learning to plant this way, peasants are little by little abandoning the tradition of burning off the land, which ruins soil by destroying its important organic layer on top. If sowing is done with an animal drawn plow, it is helpful to till the land two weeks before to help the stubble mix with the rest of the soil.

Once the mung bean germinates, it demonstrates a stubborn determination to keep on growing right up to harvest and beyond. In reality, all it needs is contact with the land. A little bit of water three or four good rains when the bean is beginning is enough. The hope for life hidden in the little green balls of the mung bean is so great that any balls that fall to the ground will sprout with the slightest bit of rain. That happened in Somotillo, one of Nicaragua's driest and most impoverished zones. "After the first harvest, we'll have another small harvest at the strangest time," declares Francisco Vargas, CIPRES technician in Somotillo.

The mung bean's obstinacy to stay alive is noteworthy. The first time this bean was planted in the rural areas of Somotillo, a plague of insects devastated the tiny seedlings. But once the voracious insects had gone, the little plants began to sprout again. And they produced an abundant harvest as if nothing at all had happened.

Efficient Fertilizer and Herbicide

The mung seeds germinate three to four days after planting. The plants blossom with yellow flowers some 30 or 35 days later. In that first month of life, the plants also carry out other important tasks. Like all legumes, the mung has the capacity to capture nitrogen from the air and fix it in the soil. Once fixed, the nitrogen fertilizes the land for other crops, which can feasibly be planted after the mung harvest, since its own cycle is so short. In addition, the vigorous mung successfully competes with weeds, destroying many of them without the need to apply chemical herbicides.

These two linked characteristics fertilizer and herbicide mean that planting mung beans in association with another crop can produce more abundant harvests of both. But you have to know how to do it. One peasant from Somotillo who began to plant the new green bean CIPRES calls these peasants "experimenters" was afraid it wouldn't produce anything so he also planted corn between the rows. The mung bean attacked the corn, resulting in a copious harvest of mung beans and not a single ear of corn.

The experience, however, was extremely useful. Inspired by this error, the other peasants imitated their colleague, but worked to perfect his system. They planted the corn first and, when the plants were well developed, planted mung beans between the rows. The corn plants thus benefited from the nitrogen but the still small beans were no real threat. That time around, there were two bountiful harvests one of mung beans and one of corn.

More Nutritious than Soy Beans

Whatever the initial process of planting is, the mung bean is ready to harvest 75 80 days after planting. It is not harvested like other beans, pulling up or cutting the plant. Rather, the pods are cut open. If the plant is uprooted, the roots take the nitrogen they have accumulated with them. Nor is it cut, to insure that its rich organic material is reincorporated into the soil. The beans thus produce no chaff. They produce fertilizer, along with yields of up to 34 hundredweight of beans per acre.

Reina Isabel Corrales, who lives near Somotillo, now knows how to prepare the mung beans for eating. It's easy. The secret is to let them soak in water for two or three hours, to get rid of the green skin, then cook them in just a little bit of water for only 15 minutes or so. "More than that, no, because this bean is very soft and, if you cook it too long, it falls apart and ends up like atol [a cornflour based pudding]," explains Reina. The fact that cooking takes only 15 minutes is a great advantage in a country like Nicaragua, where the majority of stoves use firewood, and deforestation is rapidly turning the country into a desert.

The cooked beans are great just sautéed in a little bit of oil; add a little onion, and they're even better. Their nutritional value is greater than any other bean, including soy.

To grow, the mung bean has to take on powerful enemies: domestic animals. Cows, pigs, chickens and other farm animals love the taste of the beans and will quickly strip plants bare. Only the bean's enormous capacity to resprout allows it to prosper and make it to harvest.

Mung beans are great feed for animals. José Angel ("Chango") Betanco, a peasant from the Los Limones rural community northeast of Somotillo, has observed that animals fed on mung beans are more productive hens lay more eggs, cows give more milk and pigs fatten up more quickly, and their meat is tastier.

Today, Somotillo's peasants grow mung beans mainly for animal feed. For their own food, they still prefer the red bean that can be planted in the largely desert dry Somotillo. Women and children like the mung beans, but the men always more rigid only eat them when absolutely nothing else is available. As is well known, eating habits are among the hardest things in the world to change.

An Act of Faith

When mung is planted for its beans, the plot is enriched by nitrogen and organic matter that helps subsequent plantings. But there is an even more direct way to fertilize with mung beans plant, but don't harvest.

This use of the mung bean as "green fertilizer" demands some calculations: it must be planted with enough lead time so it flowers on schedule and thus enriches the other crop. The moment the mung blossoms is when its roots have their highest nitrogen concentration. That's the optimum moment to trim back the plant, plow it all back into the soil and plant the other crop to be fertilized with the mung bean. In the Somotillo area, that other crop tends to be sesame.

It's not easy to convince a peasant of the efficacy of this "incomprehensible" operation. And it gets harder when they realize that only 85 to 100 pounds of seed per acre must be planted to harvest food, while between 150 and 170 pounds must be used if organic fertilizer is the goal.

Peasants plant to harvest, so many mental schemes must be broken before they'll take a machete to a promising plant that can provide food. It's even tougher in areas where people have gone through long spells of hunger. "This way of doing things really does benefit the land, but it was so hard for me to mistreat the plants that way," said one peasant.

At first it takes an "act of faith," before the peasants can appreciate the multiple advantages of mung based fertilizer. The first and most compelling short term advantage is the cost. At least 730 córdobas (about $100) must be invested in fertilizer to plant an acre with a marketable crop like sesame. The fertilizer must be bought from a commercial establishment with hard earned cash, often acquired on credit, which is hard to get and even harder to pay back, due to high interest rates.

The cost of mung based fertilizer is in addition to the seed itself about 200 córdobas (under $30), the cost of plowing under the acre. But since the peasants themselves do that work, it costs much less. Buying enough mung seed to fertilize an acre costs about 153 córdobas, but it's a one time cost; once the mung is being produced on the peasants' land, the fertilizer is free. In any case, even when money has to be paid out, the "green fertilizer" the mung bean provides ends up being much more inexpensive than conventional fertilizers.

And there's another advantage. The main crop in this case, sesame can be sold as "organic" when no chemical insecticides are used on it, which brings better and more stable market prices. That holds for any crop combined in this way with the mung bean.

The Miracles of "Green Fertilizer"

There is still no reliable data regarding yields or percentage increases since the use of mung beans as a "green fertilizer" still has a very short experimentation period in Nicaragua barely three years. But the peasants are convinced their lands are producing more, just based on what they can observe. While increased yield is an important achievement, even more important is giving eroded soil back its fertility and life.

Weeds are an ongoing headache for peasants, since they can really cripple crops. Until now, the only things effective against abundant and aggressive weeds were herbicides very harmful or using a harrow four or five times per plot. But a harrow is very heavy, and little by little it compacts the soil, reducing its usefulness for planting to a thin and increasingly impoverished layer, less able to absorb the moisture, nutrients and air that any crop needs.

Constantly going over land with agricultural machinery reduces even more the thin layer of fertile soil that hasn't already been eroded. Meanwhile, in the deeper reaches of the soil, the thick layer compacted by the machines becomes so tough that it is eventually almost impermeable. This makes it hard for rainwater to pass through to the water table, which causes crop loss due to flooding.

A "green fertilizer" like the mung bean deals with all these problems. According to data from the Ministry of Agriculture and Livestock's National Soil Fertility Program, when the mung bean is used exclusively as green fertilizer, it produces 535 hundredweight of organic material, 2.2 hundredweight of nitrogen and just over 5 hundredweight of urea per acre.

Cultivating mung beans or with them offers the Nicaraguan peasantry great possibilities, particularly in the country's most depressed lands. The mung bean's capacity to make leeched soils fertile again have made it extremely popular in the areas where CIPRES has introduced it so much so that its fame has spread and it is now being cultivated in many other parts of the country.

The Limitations of the Versatile Mung

When this experiment began, the 123 peasants who offered to serve as "experimenters" got six pounds of seed each. The objective was for their neighbors, observing the results, to get enthused and want to take part. The experimenters began as seed producers.

"But I didn't plant this green thing on my best lands," confesses Chango Betanco, whom life has taught many survival lessons. "I just stuck it in a little bit of land I have over there, next to the river, useless land that hadn't produced anything for eight years. I didn't even plant it, I just left it there."
Though unintentionally, Chango did just what CIPRES had hoped, as the idea was also to use the mung bean as organic fertilizer. After all the insecticides that had been dumped onto Chango's little plot by the river, the land had been finally exhausted by the powerful chemicals. The mung arrived in time to wake up the forces sleeping within the soil. It grew prodigiously. And, even though the plot was dangerously near some voracious hogs, there was no problem: they got fat and the mung beans were harvested. Last but not least, the plot became more fertile than ever and was ready to have new crops planted.

The mung based green fertilizer like everything related to bio sustainable agriculture attempts to offer a solution, but not to be the only answer. The mung bean itself presents some problems that need to be studied and resolved with other techniques.

One such problems is the mung bean's inability to grow on land with too much water or, worse, in swampy soil. This bean can withstand droughts without even losing its color, but dies or drowns in too much water. Another problem is that, although it is extremely aggressive against most weeds, it can do nothing against tall and rapidly growing ones the sorghum halapense and titonia sp.

Mung is not the only bean that farmers can use as green fertilizer. Nor is its cultivation the only way to recover eroded and wasted soils. Other varieties of beans offer different responses to other issues and solutions to the many problems that the failed "green revolution" left us with.

Many experiments are still to be done, and much is to be tested and proved to return to nature what a few short years of human arrogance and insanity stripped away. The humble mung is not out to be "Tarzan"; it would be quite content to see its small green beans simply contribute something to a task that will take many hands and many years.

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