Overstory #259 - Quesungual agroforestry

Quesungual agroforestry is the production of annual staple crops (maize, beans, and sorghum) in the understory of dispersed trees.

Introduction

Over 10 million families in Mesoamerica (Mexico, Guatemala, El Salvador, Honduras and Nicaragua) are subsistence hillside farmers who grow their own food, primarily maize and beans: They face serious challenges to be able to produce enough to feed their families; most own 0.5-4 hectares of highly degraded hillsides (80% of the soils are degraded) (1), which is farmed using traditional farming techniques of slash and burn or more recently slash and chemicals. They are food insecure, having high levels of chronic malnutrition. It is estimated that farmers make a loss two years out five from maize production and studies show that rural families have incomes less than expenditures (2). It is no accident that this is a region of high levels of food insecurity (3) the rural population face an even more serious threat and that is climate variability. This region is one of the world’s most susceptible to growing climate instability (4) and studies indicate that yields are threatened to decline by 30% over the next thirty years (5).

A consensus is now emerging for a new model of grain production that responds to the farmers’ needs in the new environmental reality; an agroforestry system that is now rapidly being adopted throughout this region that began in the community of Quesungual, Lempira, Honduras, hence the name of the system. Quesungual is the result of collaboration between small hillside farmers and agronomists.

Description of Quesungual agroforestry

Quesungual agroforestry is the production of annual staple crops (maize, beans, and sorghum) in the understory of dispersed trees. It is part of a move to agroecological  production with an emphasis on farm nutrient and energy recycling, species diversification, increasing total productivity of the farming system, as well as the marriage of local and scientific knowledge. For farmers heavily dependent on external inputs, it offers a gradual easing into a new way of farming. This reflects the reality that farmers will only adopt alternatives that not only greatly lower risks from climate instability, but also reduce input costs and labour.

The Quesungual system has been developed in response to the needs of dryland hillside subsistence farmers whose major staple food crop is maize. The region has 15-35 degree slopes from 100 to 1600 meters above sea level. Rainfall is highly irregular ranging between 500 mm to 1600mm over a 5-6 month season with a dry intermediate period called the “canicula” for which local maize varieties have been developed so as to be able to withstand up to 6 weeks without rainfall. Maize cultivation developed in this region and there are many local maize varieties perfectly adapted to these climatic conditions.

The Quesungual system consists of three layers of vegetative cover. First, the ground is always covered by mulch and stubble (the soil is never left uncovered). Second, there are the annual crops. The third is composed of leguminous trees/shrubs, fruit and timber trees. In the fields over 40 tree species, all naturally present in the ecosystem, have been utilized. The trees used are predominantly leguminous species that can be heavily pollarded (especially Gliricidia sepium and Leucaena, including the variety lempirana) and hardwoods such as laurel (Cordia alliodora), mahogany (Swietenia sp.), etc., that are good for timber.

Key elements to the success of the system include:

• crop production based on soil conservation techniques
• volunteer, well adapted, dispersed trees and bushes
• maintaining soil cover at all times.

Key system elements include:

• the elimination of burning
• zero tillage
• direct planting
• contouring
• retention and even spreading of crop residue
• natural regeneration
• management of mulch and the by-products of regular pollarding
• dispersed trees
• crops that guarantee soil cover (legumes)
• Integrated Pest Management
• live barriers (pineapples are common)
• developing the right density balance between trees and crops, and
• cultivating trees that provide multiple services including fruit (6).

Research on the hillsides of Central America has shown that the mulch and stubble are critical in reducing and eliminating runoff from heavy rainfall. Substantial mulch cover ensures that even extremely heavy rainfall is absorbed into the soil and total soil erosion is reduced to less than that of the native forests. The presence of trees with their deep root systems also helps to prevent landslides during heavy storms (a major problem in the region). In regions of large scale adoption landsides are now only associated with poor road building techniques, not agriculture.

For many the priority remains ensuring a yearly harvest of maize and beans despite weather fluctuations. One hectare of land can now produce the needs of a family of seven with a surplus stored in household silos.

Steps to the Establishment of Quesungual (7)

What follows is a generic process description. In practice, each farmer develops their own method of transition. It requires three crop cycles to achieve a decreasing need for external inputs, as the biomass in the field reaches levels of degradation that releases enough nutrients to ensure yearly yields of 4 tons per hectare. Increasing yields above this level requires further increases in fertilizer usage. There are now examples of fields with over 15 years of sustained production. For farmers with little land, fallow cycles of up to 6 years is an unaffordable luxury and starting the system on fields already in use means a drop in yields in the first two cycles as biomass decomposition competes for nutrients with the crops. After the third year this problem dissipates. For subsistence farmers the transition is risky and so it is recommended that this period be subsidised.

Ideally the farmer should start with a field that has been fallowed for at least 6 years with tree stems of 10 cm or more. A 6-year fallow is customarily thought to restore fertility sufficiently for production. Before weeding and clearing the field and pruning the trees, bean and sorghum seeds are broadcast. These seeds will take advantage of the mulch that is created by pruning the trees back. The trees arepruned and some are removed, leaving 24 to 30 trees per hectare. Hardwood trees such as mahogany, laurel, paradise tree (Simaruba glauca) and Diphysa robinioides are favoured. Bushes such as gliricidia, leucaena, guava (Psidium guajava), Lonchocarpus sp., and others are cut back to a height of 1.5-3 meters. This generally allows for the harvesting of 30 to 40 cargas (8) of firewood, with the remaining biomass left on the ground.

The organic matter pruned from the tree is spread evenly over the whole of the field and left to decompose during the rest of the rainy season and into the dry season. The bean and sorghum seeds sprout through this mulch and are managed in the traditional way. The beans are harvested at the beginning of November, with the residue spread over the field. In January the sorghum is harvested primarily for animal feed – people only eat sorghum when maize becomes scarce – with residue left again as mulch.

In May the following year, just at the beginning of the rainy season, all growth is cut back with firewood removed and the rest of the organic matter applied as mulch. Once the land is prepared, the farmers plant 2 to 3 seeds of maize directly in contoured rows with half metre spacing. Herbicide is applied immediately after planting to control any emerging weeds at the rate of 1.5 litres per hectare, half the conventional rate used in tilled cultivation.

In the first year, 250 kg of commercial fertilizer (20-20-0 and 12-24-12) per hectare is applied 8-15 days after planting. Urea is applied in the same way 30 days after planting. This is necessary in the first year as the biomass is still in the process of decomposition, by the third year the biomass is sufficiently mineralized for the amount of fertilizer to be halved. Good farmers obtain a yield of 7 t/ha with this system, but even in extreme weather yields rarely fall below 4 t/ha.

Depending on the scale of the weed infestation a second round of herbicide is applied just before the urea application in the same quantity as in the initial application. As the vegetation cover stabilizes with legume cover, the need for herbicides declines. The beans are harvested the first half of November. The maize is harvested the second half of November when the grain has reached less than 15% moisture content. The maize ears are then stripped off the cob and the grain stored in metal silos that can hold 1,800 kg each. This ensures maize availability all year and the possibility of selling any surplus when prices rise 6 months later.

How the system works [see also photos]

There is an important biological process that takes place in the changeover from the traditional system to agroforestry. The organic matter takes up to 3 years to reach a level of degradation that releases its minerals. Thus yields suffer in the first 2 years without a judicious program of fertilization. Once up and running, fertilizer inputs drop while yields remain stable. There are also problems of weeds and insects at the beginning associated with the introduction of the system to damaged environments. As the soils recover their macro-faunal balance, these problems begin to fade and integrated pest management (IPM) practices greatly reduce the need for insecticides and fungicides (9). As the farmer stabilises the field incorporating legume cover the need for herbicides is also greatly reduced. Weaning off of external inputs in association with the ability to stabilize yields means a recovery of profitability for basic grain agriculture.

There are many forecasts of future loss of productivity, particularly maize yields, in this region associated with climate change. More recent studies recognise the importance of the macro-fauna in the soil and how Quesungual agroforestry not only helps it recover but also ensures soil temperature stability despite rising external temperatures. The most recent study by CRS recognises that such agroforestry systems minimise the threat of climate change induced temperature rise (10). The trees provide not just temperature control but many fix nitrogen and others draw nutrients such as phosphorus from deeper down at the rock level and hillsides are stabilised with deep anchoring roots. This has proved itself in various tropical storms and hurricanes where in the land of Quesungual landslides are a thing of the past. This core area has a population of over 6,000 smallholder farmers and covers 60,000 hectares of secondary forest staying green even during the height of the dry season.

Comparison with other farmer-driven systems (Taungya, SALT)

Taungya is a method of raising forest trees in combination with (seasonal) agricultural crops, used in the early stages of establishing a forest plantation. Unlike taungya, Quesungual agroforestry allows cultivation of maize year after year in the same fields with trees at a density of 30-40 per hectare.

Another similar system is Sloping Agricultural Land Technology (SALT), which cultivates annual crops between contour hedgerows of nitrogen fixing trees. Rather than using contour hedgerows, Quesungual employs trees and shrubs that are dispersed throughout the fields. These trees are not planted, they regenerate naturally, the farmer eliminates those that do not serve thus selecting and managing each species  according to its potential role in the system and contribution to the family economy. The many nitrogen fixing species most adapted to the region are compatible with maize and sorghum growing as they then can be severely pruned at the start of the rainy season and still thrive. Hillside agriculture implies varied soil and climate and farmers are continually adjusting the system to their local needs. Some now have an orchard model growing maize and sorghum in fruit orchards, others are allowing grain production to take second place to maturing trees with more lucrative yields.

New livestock systems of intensive and semi-intensive cattle ranching are being developed where livestock feed is transported from the field to the animals. Leguminous species are being promoted for cattle fodder together with grass species that also can thrive under the dry forest conditions. In Quesungual, the organic material is left in the field, returning nutrients to the soil  and reducing erosion through building up organic mulch. Whereas cattle were traditionally allowed in the field after harvest, soil impact especially on steep slopes is very negative. Therefore, the system is now being accompanied with a strategy of semi-stabling cattle – the aim being bringing the food to the cattle.

Conclusions

CIAT has been a leader in investigating various aspects of the Quesungual system and have found that it can readily be adapted to farming systems in other regions, particularly in Africa and Asia.

The primary transferable characteristics of the system include:

• It is best suited to tropical ecosystems with distinct rainy seasons with 400-1500 mm of annual rainfall.
• It has developed in response to the needs of subsistence production of maize and beans.
• In Mesoamerica it is most attractive to hillside farmers of 0.5-5 hectares of land who must grow their yearly supply of basic grains on under a hectare of land on hillsides of 10-40 degrees of slope.
• These crops are grown amongst trees and shrubs that have regenerated naturally and that are managed by the farmer according to their utility and complementarity to the desired crops.
• Legumes, whether trees, shrubs or vines, are an integral part of the system. Priority is always given to native species.
• Critical to the successful maintenance of crop yields in the same field is the ability to maintain stable soil temperatures, which is accomplished by maximising soil coverage with mulch, as well as dispersed canopy cover by trees and shrubs. This starts with the elimination of burning and tilling together with judicious management of natural plant regeneration.
• External inputs such as chemical fertilizer are applied, but in reduced quantities compared with conventional systems, resulting in significant savings for the farmer.
• The management of the system and its ability to adapt to current weather conditions is only sustainable if farmer led. Local knowledge and needs are critical for success.
• The system is still evolving and is sufficiently flexible to be open to adaptations to different ecosystems and cropping needs.

Small farmers who have received support in changing to Quesungual agroforestry, have had little problem in adopting the new system. Problems of change at scale are to be found elsewhere, in government policies and development aid strategies by the donors. A new concerted push for adequate policies in support of mass adoption of agroforestry is currently being undertaken in the region. CIAT is leading research and validation of the system and FAO has been leading the development of the methodologies and instruments for its adoption and expansion. Many NGOs have begun to promote these practices and more recently governments in the region have begun to recognise their importance and are developing policies for stimulating expansion.