A free email agroforestry journal for practitioners, extension agents, researchers, professionals, students, and enthusiasts. One edition is sent each month focusing on a concept related to designing, developing, and learning more about trees and agroforestry systems. Focuses on trees and their roles in agriculture, natural ecosystems, human culture and economy.

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Overstory #261 - Alley Cropping

IMG 0120Crop of turmeric growing between rows of fruit trees in Kona, Hawaii.

Alley cropping is broadly defined as the planting of two or more sets of single or multiple rows of trees or shrubs at wide spacings, creating alleys within which agricultural, horticultural, or forage crops are cultivated. The trees or shrubs may include valuable hardwood species, such as nut trees, or trees desirable for wood products. Shrubs can provide nuts, fruit or other products. This approach is sometimes called intercropping and multi-cropping. Currently most of the emphasis and research focuses on pecan, chestnut and eastern black walnut alley cropping applications. However, there are numerous other potential tree, shrub and crop combinations.

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Overstory #260 - Living Fences

IMG 0766Living fence of gliricidia cuttings planted along field crop boundary in Chanthaburi, Thailand.

Purpose of a Fence

There are several reasons for establishing fences on the small farm.

  1. To mark boundary lines between farms or next to roads.
  2. To separate adjacent fields used for distinct purposes
  3. To protect and keep animals from straying
  4. To protect crops from animal damage

A fence represents a major investment on the small farm. Although it carries a cost, it also provides something of benefit, namely protection. It is often a challenge to small farmers to increase farm production, such as crop yield, and the use of fences can facilitate such improvements. Whereas a fence may facilitate yield increase on the farm, a living fence can improve the efficiency of the production as well.

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Overstory #259 - Quesungual agroforestry

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


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).

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Overstory #258 - The benefits of agroforestry systems for food and nutritional security

DSC00689CElevitchAs well as directly providing edible products, agroforestry trees support food production by a range of other means, including by providing shade and support for crops that need it, supporting animal production and improving soil fertility.


Agroforestry – the integration of trees with annual crop cultivation, livestock production and other farm activities – is a series of land management approaches practised by more than 1.2 billion people worldwide. Integration increases farm productivity when the various components occupy complementary niches and their associations are managed effectively (Steffan-Dewenter et al. 2007). Agroforestry systems may range from open parkland assemblages, to dense imitations of tropical rainforests such as home gardens, to planted mixtures of only a few species, to trees planted in hedges or on boundaries of fields and farms, with differing levels of human management of the various components. Agroforestry systems provide a variety of products and services that are important locally, nationally and globally (Garrity 2004); but their role is not always fully acknowledged in development policies and practices, reflecting the difficult-to-measure, diverse pathways by which trees affect people’s lives. Women who are unable to afford high-cost technologies due to severe cash and credit constraints often favour relatively low-input agroforestry options (Kiptot and Franzel 2012).

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Overstory #257 - Biological Soil Fertility Management for Tropical Tree-Crop Agroforestry

IMG 1324CElevitchTree-crop based systems are better able than some other production systems to regenerate soil conditions, such as soil organic matter levels and soil structure.


Tree crop-based agroforestry systems, which function as multistrata systems, are an ecologically and economically important group of land-use systems in the humid and subhumid tropics. They are also found in dry climates in regions with high water availability; however, this aspect is not focused on here. Multistrata systems are widespread in lowland and mountainous areas, often surrounding homesteads and thus referred to as homegardens or forming a transitional zone between cultivated land into forests (Murniati et al., 2001; Schroth et al., 2004a).

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Overstory #256 - Biochar

IMG 3188CElevitchBiochar is the carbon-rich product of heating organic biomass under certain controlled conditions. This piece of biochar was produced from the wood of Grevillea robusta, and clearly shows this species' characteristic intricate wood grain "lattice."

What is biochar?

Simply put, biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heated in a closed container with little or no available air. In more technical terms, biochar is produced by so-called thermal decomposition of organic material under limited supply of oxygen (O2), and at relatively low temperatures (<700°C). This process often mirrors the production of charcoal, which is one of the most ancient industrial technologies developed by mankind – if not the oldest (Harris, 1999). However, it distinguishes itself from charcoal and similar materials that are discussed below by the fact that biochar is produced with the intent to be applied to soil as a means of improving soil productivity, carbon (C) storage, or filtration of percolating soil water. The production process, together with the intended use, typically forms the basis for its classification and naming convention.

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