Pakistans population has reached 180 million, which need a huge requirement of forest products. With the passage of time it is becoming difficult to satisfy the basic necessities of life of the growing population. Being a nation, we are not giving proper attention to forest development. The existing forest area of Pakistan is 4.7 per cent, which is being depleted incessantly, due to cutting, felling of forest trees and commercial over-exploitation. Therefore, the need of tree plantation arises day by day. It is a fact that tree plantation needs land, but being an agricultural country, it is difficult to spare land for trees. So there should be an arrangement whereby forestry and agricultural practices are carried out at the same time and the same piece of land in a scientific manner. Agro forestry is an integrated approach to getting interactive benefits from combining trees with crops. It is a combine system of agriculture and forestry technologies. It is more productive, diverse, healthy, profitable and sustainable land-use systems. Agro forestry has received escalating importance because in addition to food production agro forestry has a high potential to yield timber, fuel wood and fodder. Moreover, agro forestry plays a fundamental function in the development of waste land.
The main purpose of agro forestry in addition to helping the farmer with increasing productivity on a sustainable basis is to provide basic necessities of life like food, fiber, and shelter. Agro forestry also contributes in food security by maintaining the soil fertility, by breaking the impermeable layer in certain soils, promoting nitrogen fixation process and green manure, etc. It is an important for controlling erosion and conserving natural resources like soil and water which are being depleted every second of time. Agro forestry provides a barrier by tree species for decreasing wind velocity and cover approach by grass species for controlling runoff. Therefore, integrating trees with grasses, conserve the soil and water by reducing erosion. While deep rooted tree species help in controlling water logging and reclamation of alkalinization. Agro forestry also provides solution for global crisis of energy by providing fuel wood as an alternate sources of energy. Some common classes and types of agro forestry are discussed below:
Agri-silviculture: In this system food crops and fodder crops are cultivated in between the trees. Acacia Nilotica has high tolerance to water logging when it is raised on the bunds of rice fields. It grows rapidly by using irrigation and fertilizer given to the rice crop. While the wood yield of eucalyptus increased quickly when it is intercropped with cassava and groundnut.
Silvia-pasture: In this system, pasture species are combined with tree species on the same unit of land. Grass species should be palatable, tolerate shade and high yielding. This is the best management practice for wasteland or marginal land which has low soil fertility. This system increases the rate of infiltration of rain water in the soil and also decrease the surface runoff which ultimately reduced the soil erosion.
Agri-silvipasture: It is the arrangement of agri silviculture and the Silvi pastoral system. In the dry area usually farmer grown crops and trees together, but in later after a particular stage, the grasses are replaced with the field crops.
Agri-horti-Silvivulture: This system is a combination of fruit trees, crops and multipurpose tree species.
Agri-horti system: In this system field crops and fruit trees are grown in the same unit of land. Normally for getting regular income the fruit trees are managed for the period of 30-35 years. Fruit trees such as guava, apple, and pomegranate are found promising under dryland situation. In semi-arid tropics oil seed crops, pulses and millets can inter crop under fruit trees.
Inter Cropping Systems: In inter cropping both annual and perennial plants are grown on the same land at the same time. The wood yield of eucalyptus increased rapidly when it is intercropped with cassava+groundnut. Mono cropping of cassava in association with Eucalyptus and Leucaena was found to enhance the fertility status of the soil by increasing phosphorus and potassium content of soil.
Wind Breaks and Shelter Belts: Any barrier which slow down the speed and effect of wind is known as a wind break. While a belt of trees or shrubs which shelter from sunshine, high speed wind or snow drill is called a shelter belt. The wind breaks should be planted in right angle to the direction of wind so that soil and moisture can be conserved in sheltered areas. Windbreak should be continuous and any passage, road or track through wind breaks should be avoided. While in case of 5% sloppy area, wind breaks would be planted along the contours.
For agro forestry, fast growing species should be selected which have high economic value. Because farmer cannot wait for long maturity periods, they are interested in early income from their piece of land. For this purpose disease free, short duration and economically sound hybrid poplars should be used. The major hurdle in the agro forestry development in Pakistan is the negative thinking of our farmer about it. Most of farmer thought that tree plantation on border of agriculture land would compete for water, nutrient and light from the share of agriculture crops. But scientific research revealed that this perception is totally wrong. The modern research says that the trees on the borders of agriculture fields consume only 6 to 9 percent of the total water, whereas these trees also save the field crops from desiccated wind.
Moreover, agro forestry plays an important role in reducing the poverty through increased production of wood and other tree products for sale and home consumption. Thats why agroforestry is an important practice that will lead us to food, fiber and shelter.
The writer is associated with the Department of Agronomy, University of Agriculture, Faisalabad, Pakistan.