BRE 211: Principles of Agriculture and Forestry LECTURE 10 AGRO-FORESTRY Definition Land-use systems and technologies in which woody perennials (trees, shrubs, palms, bamboos etc) are managed on the same land units as agricultural crops and/or animals. Is used to cover a variety of land uses that combine tree growing, pasture and crop production practices on the same piece of land for the purposes of increasing or improving the output of the soil. Definition Aims at increasing the overall productivity of the land by combining crops, animals and trees. Planting of trees and shrubs is purposely done in association with other farm enterprises. Implication of the Definition Agro-forestry: Involves two or more species of plants (or plants and animals) at least one of which is a woody perennial. Has two or more outputs Always has a cycle of more than one year. Implication of the Definition Has both ecological and economic interactions between the different components. Is more complex ecologically and economically than a mono-cropping system. Benefits of Agro-forestry In addition to enabling the farmer to grow trees for various uses, keep livestock and produce agricultural crops, this system of land use has an important role to play in Benefits of Agro-forestry A remedy to deforestation Source of Income Products from trees and shrubs can be sold for cash. Use of such products in the farm makes large cash savings. Increased Land Productivity Provides a sustainable source of firewood thus reducing deforestation. When properly planned and managed, agroforestry increases the overall farm productivity with little if any environmental damage. Labour Saving Availability of firewood on the farm releases the labour of women for other farm activities. Benefits of Agro-forestry Soil and water conservation. Trees Protect the soil from strong winds, rains and consequently reduce soil erosion. Improve water retention of the soils. Improve water catchment in an area Enhanced Soil Fertility Enrich soil through leaf litter and nitrogen fixation. Stabilise the soil mantle by binding soil particles. Aesthetic value All kinds of trees and shrubs help to beautify the environment and make a place more pleasant to live in. Choice of species of trees/shrubs Following factors should be considered Fast Growth ability Trees that produce products (firewood, fruits or timber) in a short time should be selected Deep-rootedness Deep-rooted ability ensure minimum competition for nutrients and moisture with crop plants They also resist drought Choice of species of trees/shrubs Nitrogen fixing ability Leguminous plants that are capable of fixing free nitrogen and converting it into a form that is utilisable by plants. Their foliage is also rich in proteins for animal feeding. Such plants are therefore good for soil enrichment and feeding farm animals. It is preferable that such plants should be palatable as fodder. Choice of species of trees/shrubs By-product The production species should be good in the production of timber, fruits, poles, honey etc. Such trees or shrubs should produce these by-products without harming or adversely affecting other crops in the farm. Agro-forestry systems Three basic types: Agro-silviculture (Crops and trees) Silvo-pastoral (Pasture/animals and trees) Agrosilvopastoral (crops Pasture/animals and trees) These systems give rise to different forms of agro-forestry including: Intercropping or Intensive Hedgerow Wide Row Planting Border Planting Woodlot Homestead Tree Planting Forms of Agro-forestry systems The form adopted largely depends on land size, type of crops grown, land topography in relation to soil conservation and climate. Intercropping/Intensive hedgerow Rows of trees or shrubs are planted between rows of crops. Preferrably leguminous shrubs (e.g.leucaena and calliandra) are intercropped with crops since they improve the soil. Intercropping can be done with maize, beans or nappier grass as they would benefit most . Spacing largely depends on the crop with which it is intercropped. Management Stages Management of intercropping includes: Establishment: Seedlings used for fast growth. The care of weeding, fertilizer application and protection from animals the seedlings get as the farmer tends to his crop plant enables the seedlings to grow fast. The first cutting of the shrubs should not be done until they are 3 to 4 metres high. Stages of Intercropping Coppicing: This is the cutting of the shrubs at the beginning of the cropping season in order to reduce competition for water, mineral nutrients and sunlight. The shrubs are cut down to 0.5 metres above the ground. During the growing season the shrubs are kept down by the removal of shoots during weeding operations. After the last weeding the bushes are allowed to grow since they will have little effect on the crop plants. Stages of Intercropping Growth When there are no crops in the field, especially during the dry season, the shrubs should be allowed to grow tall. This encourages the production of woodfuel and fodder and protects the soil. During this period, the green seed pods produced should be removed and fed to animals, as they are very rich in protein content. Wide Row Planting Trees and shrubs are planted in wide rows of between 8 and 10 metres from row to row and up to 4 metres between trees Aims at wood and tree products such as poles, timber and fruits unlike the intensive hedgerow form, which aims at fuelwood. This necessitates that the trees grow unchecked with only limited canopy management to reduce shade on crop plants. The trees grow tall due to unchecked growth making it necessary to space the trees widely to facilitate the growth of crop plants. Wide Row Planting The trees must always be planted in rows running from East to West to reduce the shading effect on the crop plants. Although trees in this form of agroforestry may not improve crop yields, the benefits gained from the sale of their products and by-products often outweigh the losses incurred. However, when it is practised with pasture, the pasture does well due to water retention and soil improvement effects of the trees. Wide Row Planting Species of trees used in this form of agro-forestry include: Fruit and nut trees such as coconut, cashew nut, mango, avocado and pear trees. Wood and timber production trees including Grevillea, whistling pine (casuarina equisetifolia) African Blackwood, Muhugu, Acacia, Fig etc. When animals graze under the trees they control weeds without damaging the fruits. Border Planting This is planting of trees, shrubs or hedges on the farm. Such trees, shrubs and hedges are used to: Protect the farm as a fence Mark boundaries Windbreakers to protect crops Provide wood and timber for fuel and building as well as for sale. Suitable trees for this system include Eucalyptus, Makhania, Jacaranda and Grevillea. Woodlots These are plots of land set aside for trees only, usually on the parts of the farm that are not productive or where other forms of agricultural production would encourage soil erosion. Trees for woodlots should be fast growing species such as Acacia and Eucalyptus. They produce large volumes of wood fuel, timber, poles and fodder. Homestead tree planting Generally trees around the house are planted for beauty and shade. However they can yield fruits, wood or timber for the farmer. They should, however, not be planted too close to the house to avoid their roots damaging the house, or in the event of a tree falling. Where the necessary care has been taken, many tree species, including fruit trees are suitable for homestead planting.