Action: Use alley cropping
A controlled, randomized, replicated study from Canada found that intercropping with trees resulted in a higher diversity of arbuscular mycorrhizal fungi.
SOIL TYPES COVERED: sandy-loam.
This agroforestry intervention grows crops between hedgerows or tree lines planted at regular intervals across crop fields or along slope contours. Hedges may be pruned and the foliage used as mulch or green manure on the adjacent crop alleys. The technique may control weeds and insect pests in a number of ways, for example by modifying the field’s climate, disrupting pest movement and weed growth, increasing crop vigour, providing habitat for natural enemies and using the insecticidal properties of hedgerow foliage. Studies that plant/allow trees around the edges of fields are included in 'Plant new hedges'. Arbuscular mycorrhizal fungi are a group of fungi that live around the roots of plants. By living together, the fungi and host plant benefit each other: the fungi can live in a habitat without having to compete for resources and receive a supply of carbon from the plant, while they give an enhanced supply of nutrients back to the plant, improving plant growth, the ability to reproduce and tolerance to drought. Arbuscular mycorrhizal fungi colonise a wide variety of host plants, including grasses, herbs, agricultural crops and legumes (Bardgett 2005). A phylotype is a way of classifying an organism by its phylogenetic (or evolutionary) relationship to other organisms.
Bardgett R. (2005) The Biology of Soil: A Community and Ecosystem Approach. Oxford University Press, Oxford.
Supporting evidence from individual studies
A randomized, controlled, replicated study in 2008 on sandy-loam soil in Ontario, Canada (Bainard et al. 2012) found a greater diversity of arbuscular mycorrhizal fungi (AMF) under tree-based intercropping (6 phylotypes) compared with conventional cropping (4.7 phylotypes). Colonization of corn Zea mays roots was greater than 50% in both intercropped and conventional treatments, and AMF richness was similar in both treatments. Different tree species supported distinctive AMF communities. Trees were intercropped annually with corn, soybean Glycine max, winter wheat Triticum aestivum or barley Hordeum vulgare using no-till cultivation. The tree rows accounted for 16% of the crop area and were spaced 12.5-15 m apart. Tree species included silver maple Acer saccharinum , white ash Fraxinum americana , hazelnut Corylus avellana , black walnut Juglans nigra , Norway spruce Picea abies, hybrid poplar Populus deltoides, red oak Quercus rubra, black locust Robinia pseudoacacia, willow Salix discolor and white cedar Thuja occidentalis.