In a way this should have beenobvious. There is simply too muchsunlight for many crops in the tropics and this with heavy rains leads directlyto soil deteriation. What nature cannotdo well is to establish a planned distribution of trees able to support ahealthy nutrient base for cropping annuals. Yet we can.
Thus we see the onset of smallholder agroforestry were the operator uses a lot of trees to provide partial shade,absorb surplus water for respiration, provide fertilizer by lifting deeplylocated nutrients and shedding leaves and also possibly give a cash crop. These are early days, so the cash crop partis still sorting itself out, but that today is almost the easiest problem tosolve.
The method is not so promising intemperate climes, but again it is all about spacing and shade friendly crops. If trees are well spaced then the effectiveshade will be quite low and may even be beneficial to a lot of crops.
I recall how well some grassesperformed in shaded areas of the barn. The quick take home from that is that all permanent pasture land needscarefully spaced shade trees to increase productivity. Non dwarf apples would be a fine start.
Yet oak and the like will providefine timber in due time.
The other quick take home is thatthe woodlot is badly mismanaged and wasted land on most farms. Cleaning them out – fire is wonderful - and developing a working seed bed is a goodstart on a good pasture.
The fact is that we are spoiledby heavy machinery that wants a thousand acre field. Real productivity needs human inputs andskilled management with working trees. Somehow a fifty acre field producing a dense crop of natural grasses,densified because of occasional shade that supports at least one hay crop andsupports a herd after that while producing hundreds of tons of apples at theend of the season is surely an improvement over a sundried pasture inmidsummer.
Today we have the hardware tomake all this practical. This wouldinclude wood chippers, chainsaws and a disc plow.
Putting Trees On Farms Fundamental To Future Agricultural Development
by Staff Writers
Trees growing on farms will be essential to future development. As the numberof trees in forests is declining every year, the number of trees on farms isincreasing. Marking the launch of the International Year ofForest bythe United Nations Forum on Forests (UNFF9) in New York on 29 January, DennisGarrity, the Director General of the World Agroforestry Centre, highlighted theimportance of mixing trees with agriculture, the practice known asagroforestry.
"Over a billion hectares of agricultural land, almost half of theworld's farmland, have more than 10 percent of their area occupied bytrees," said Garrity, "and 160 million hectares have more than 50percent tree cover."
Growing trees on farms can provide farmers withfood, income, fodder and medicines, as well as enriching the soil andconserving water. As natural vegetation and forests are cleared for agricultureand other types of development, the benefits that trees provide are bestsustained by integrating them into agriculturally productive landscapes.
Speaking at the High Level Dialogue of UNFF9 on 3 February 2011,Garrity said, "Agroforestry is a crucial bridge betweenforestry andagriculture. Essentially, agroforestry is about the role of working trees inagricultural landscapes, particularly on, but not limited to, small-scalefarms."
Over the next two decades, the world's population is expected to growon average by more than 100 million people a year. More than 95 percent of thatincrease will occur in the developing countries, where pressure on land andwater is already intense.
A key challenge facing the international community is, therefore, toensure food security for present and future generations, while protecting thenatural resource base on which we all depend. Trees on farms will be animportant element in meeting those challenges. In some regions, such asSoutheast Asia and in
Central America, treecover on agricultural lands now exceeds 30%.
"The transformation of agriculture intoagroforestry is well under way across the globe," said Garrity. "Andthere are drivers, including climate change, that ensure that thistransformation will accelerate in the coming years, since agricultural systemsincorporating trees increase overall productivity and incomes in the face ofmore frequent droughts, and agroforestry systems provide much greater carbon offset opportunitiesthan any other climate mitigation practice in agriculture."
In many countries, it is now quite clear that the future of forestry ison farms. In countries such as
India, ,and many others, the majority of the nation's wood is derived from farm-growntimber. Kenya
Practiced by farmers for millennia, agroforestry focuses on the widerange of working trees grown on farms and in rural landscapes. Among these arefertilizer trees for land regeneration, soil health and food security; fruittrees for nutrition; fodder trees that improve smallholder livestock production;timber and fuelwood trees for shelter and energy; medicinal trees to combatdisease; and trees that produce gums, resins or latex products.
Evergreen Agriculture is a form of agroforestry that integrates trees withannual crops. "We see Evergreen Agriculture as nothing less than theradical, but entirely practical, pathway to a reinvention of agriculture,"said Garrity. "It is a vision of a future in which much of our food cropswill be grown under a full canopy of trees."
Combining fertilizer trees with conservation farming techniques isdoubling and tripling cereal crop yields in many parts of the Africancontinent. The nitrogen-fixing tree Faidherbia or Acacia albida, is increasingunfertilized maize yields in
Malawi, Zambia, Tanzania, , and in numerous othercountries. Ethiopia
They are now being grown on millions of hectares of crop landthroughout
,at densities of up to 200 trees per hectare, and show a tripling of yield inthe crops growing beneath them. Producing food crops like maize, sorghum, andmillets under these agroforests dramatically increases their drought resiliencein dry years, because of positive soil moisture regimes, and a bettermicroclimate. Niger
This development is not happening only in
Africa.The South Asia Network of EvergreenAgriculture has been launched to advance an evergreen revolution throughout thesubcontinent.
Feeding the hungry
Planting trees that provide natural fertilizers on farms with poor soils helpsfarmers restore fertility and increase yields. Gliricidia bushes fix nitrogenin their roots and act as natural green fertilizer factories, tripling yieldsof maize on farms in
The prunings are fed to the animals. The bushes also reduce the risk ofcrop failure during droughts and prevent waterlogging when it rains too much.The nitrogen-fixing tree Faidherbia increased unfertilized maize yield fourtimes in
.The trees are being grown on over 5 million hectares of crop land in Zambia . Niger
Domesticating wild fruit trees in the
Trees grown on homestead farms, in woodlots and on communal lands arean important source of wood and other products. In humid-zone West Africancountries,
Burundi, Rwanda and in particular, trees grownin home gardens meet most household needs for fuelwood and timber. Uganda
In many cash-crop systems, trees are grown for shade and eventuallyprovide wood - an example is Grevillea robusta in tea plantations in
.In the Kenya Sudan, Acacia ,the source of gum arabic, is largely grown in agroforestry systems. senegal
Investments in agroforestry over the next 50 years could remove 50 billiontonnes of additional carbon dioxide from the atmosphere. Most of thedeforestation in Africa, and in parts of
Agroforestry activities curb emissions of greenhouse gases by slowingthe conversion of forest to farm land and holding carbon in the trees on thefarms. Developing smallholder agroforestry on land that is not classified asforest could capture 30-40 percent of the emissions related to land-use change.Encouraging farmers to plant trees has the potential to increase farmers'income, sequester more carbon and benefit biodiversity.
"The International Year of Forests is a momentous opportunity tomore fully recognize the tremendous importance of agroforestry and evergreenagriculture in building a better world," noted Garrity.
"Agroforestry is one of mankind's best hopes to create a climatesmart agriculture, increase food security, alleviate rural poverty, and achievetruly sustainable development. And, thereby, better ensure that our world'sforests can indeed be conserved far into the future."
The World Agroforestry Centre, based in
is the world's leading research institution on the diverse role trees play inagricultural landscapes and rural livelihoods. As part of its work to bringtree-based solutions to bear on poverty and environmental problems, centreresearchers-working in close collaboration with national partners-havedeveloped new technologies, tools and policy recommendations for increased foodsecurity and ecosystem health. Nairobi, Kenya