Agro-forestry is a kind of land management in which the same pieces of land is used for different purposes such as pasture, agricultural crops and growing trees. The agricultural crops, the fodders and the trees are either grown sequentially or simultaneously. Though it needs more labour than the traditional way of agriculture, the products of the different components such as the crops, timber, fruits, fodder etc provides a source of income through-out the year. Apart from the economic significance, agro-forestry is also very important from the environmental point of view as the trees improve the quality of the environment to a great extent.

Characteristics of trees for agro-forestry:

Selecting a tree for agro forestry needs proper planning as it is a long term plan. The most important factor to be considered during the selection of the trees is the objective for planting the tree. If the main purpose of it is to act as a wind break, then any tall and sturdy trees with deep roots like eucalyptus species, neem trees, pines and cypress could serve the purpose. If the purpose is to act as a living fence to protect the land from wild animals and other intruders, then any fast growing varieties with thorns, spines or nettles would be preferable. If it is to just add additional incomes, any fruit tree can be grown. For increasing the soil fertility, species that could fix nitrogen while providing fuel and fodder would be preferable. Whatever purposes the trees serve, it is desirable to have the following characteristics in the trees selected:

• It should be a multipurpose tree.
• It should take less time to mature up.
• Trees that require less maintenance is preferable.
• The trees should be compatible with the crops grown and should not compete with them for the sunlight, nutrients or water.
• It should be deep rooted so that they can make nutrients uptake more efficient by utilizing the minerals and nutrients from the sub-soil and bring it on the top-soil.

Types of agro- forestry:

Based on the components, agro forestry can be of four different types:

1.Silvopasture Agro Forestry: In silvopasture agro-forestry, tree plantation and livestock rearing is practiced together. The foliages and the leaves of the trees are pruned regularly and fed to the grazing animals. The trees also provide shade to the animals during hot weather. Trees like neem tree, species of acacia, tamarind etc are usually planted.

2.Silvoarable agro forestry: When trees are planted along with the arable or horticultural crops, it is called silvoarable agro forestry. The trees planted should be compatible with the crops grown.

3.Forest Farming: in forest farming, crops are cultivated in certain parts of the forest. The canopies of the forest are pruned regularly so that the crops get suitable amount of sunlight. The crops cultivated include mushrooms, nuts; medicinal plants etc while the trees are generally of commercially important varieties. The fertile areas of the forest boost the production of the crops.

4.Forest Gardening: In forest gardening, different varieties of plants are planted together so as to resemble a natural forest. It includes different varieties of herbs, shrubs, trees etc.The plants are usually perennials. The plants act as companion plants. It means the presence of a particular species of plant has beneficial effects on the neighboring plants.

Some popular agro forestry practices:

Agro- forestry is practiced in many different ways all over the world. Some of the popular practices are:

Alley cropping: In alley cropping, trees or shrubs and crops are planted in alternate rows. The objective of alley cropping is to improve crop production by improving the soil fertility. So, the trees selected are usually the fast growing variety that could fix nitrogen. So, when the crops are growing, the trees are pruned regularly and the pruned parts are left on the ground as ‘green manure’. The twigs and branches of the pruned parts are utilized as fuels.

Improved fallows: It is practiced along with the shifting cultivation. In shifting cultivation a part of the forest is cleared for practicing agriculture and after the crop is harvested, it is left fallow for the lands to be rejuvenated under natural condition. At the end of the fallow period, the land is again utilized for cultivation. During this fallow period another piece of lands are used for cultivation. So, in improved fallows, instead of leaving it to rejuvenate naturally, trees are planted in these fallow lands. Such practices reduce the fallow period.

Contour buffers: rows of trees or shrubs are planted across the slope to prevent the soil erosion. Plantation of trees on the slopes also stabilizes the land while improving the soil fertility.

Windbreaks: in this system, rows of strong trees are planted along the edges of the fields. The trees reduce the speed of the wind and thus protect the growing crops. It also prevent the soil erosion and surface water run-off.

Role of trees in agro-forestry:

Apart from its economic value the presence of the trees benefits the crops and the environment as a whole. Some of the ways in which it benefits the environment are as follows:

1. The trees act as a wind break thus protecting the crops. It also reduces soil erosion and surface water run-off promoting water and nutrient percolation in the soil.
2. The nutrients which have leached below by the percolating rain are brought back into the cycle by the deep roots of the trees. When the trees shed off their leaves or die and decompose, the nutrients are made available to the crops.
3. Some of the tree species also increase the fertility of the soil by fixing nitrogen. Soil fertility can also be increases by growing ‘green manure’ the foliages and twigs of which are dropped or placed in between the crops. On decomposition, it provides the nutrients. It is particularly useful for the unproductive croplands and grasslands.
4. It improves the quality of the air by absorbing the particulate matter, odour, carbon-dioxide etc. Consequently, it can also indirectly help in mitigating the problem of global warming by absorbing the carbon-dioxide.