Trees as natural fertilizers

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New findings concerning nitrogen fertilizer use and alternatives in form of trees were announced at the opening of the 2nd World Congress of Agroforestry, which is being held in Nairobi, Kenya this week.

Nitrogen fertilizers are predominately used for maize production increase, which is the staple food of Africa. Nitrogen fertilizers are presently made using fossil fuels such as natural gas and coal, which are limited and increasingly expensive, putting further pressure on African farmers trying to achieve food security. Nitrogen fertilizer is often synthesized producing ammonia. The production of ammonia currently consumes about 5% of global natural gas consumption, which is somewhat fewer than 2% of world energy production. The cost of natural gas makes up about 90% of the cost of producing ammonia. The price increases in natural gas in the past decade, along with other factors such as increasing demand, have contributed to an continued increase in fertilizer price. Storage and application of some nitrogen fertilizers can cause emissions of the greenhouse gas nitrous oxide. Ammonia gas may be emitted following application of such fertilizers. Besides supplying nitrogen, ammonia can also increase soil acidity. Excessive nitrogen fertilizer applications can also lead to pest problems by increasing the overall fitness of certain pests, some of which are linked to the spread of diseases.

Now scientists have revealed through Satellite images that small_leave.gifaround 50% of farmland worldwide have at least 10% cover of trees, and linked these findings to increased crop production. These findings have lead to ‘tree plant solutions’ put forward at the 2nd World Congress of Agroforestry, suggesting it could be a long-term solution to food security as well as a step towards combating Climate Chance. It concludes that maize production could be increased 4- fold by using trees as organic fertilizers without increased labour or use of nitrogen fertilizer. Dennis Garrity, of The World Agroforestry Centre, said: “The problem is that policymakers and planners have been slow to recognize this phenomenon and take advantage of the beneficial effect of planting trees on farms. Trees are providing farmers with everything from carbon sequestration, to nuts and fruits, to windbreaks and erosion control, to fuel for heating and timber for housing. Unless such practices are brought to scale in farming communities worldwide, we will not benefit from the full value trees can bring to livelihoods and landscapes.”

The Faidherbia tree has been found to fulfil many requirements for widespread use in African farming, because it sheds leaves and goes dormant during early rainy season and grows during dry season. It does therefore not compete with food crop for light, water and nutrition. It takes nitrogen from the air, fixes it in its leaves and incorporates it into the soil.

It has been shown there’s a crop increase of up to 280% for fields under tree canopy. In Zambia, unfertilized fields benefiting from tree planting produced 4.1 t/ hectares compared to fields nearby only producing 1.3t/hectares.

Maize yields in Africa are only 1/10 of yields in America, which is being contributed to limited fertilizer use. Top users of nitrogen fertilizer are China and the US, with no African country in the top ten of users.

Prof. W. Maathai, who was awarded the 2004 Nobel Peace Prize for work that included planting more than 30 million trees to provide food, fuel, shelter and income for Africa’s rural poor, sees the planting of trees on farms as a natural fertilizer fix, much needed in order  to adapt to extreme weather conditions due to Climate Change. Trees also act as windbreaks and protect watersheds, and improve resiliency of farmers to provide food and income. When crop and livestock fail, trees can withstand the drought conditions and help farmers to hold over to the next season.

Farming has always been associated with deforestation, but it has been proved that farms and forests are by no means exclusive.  According to experts at the World Agroforestry Centre, farmers, particularly in developing countries, would adopt various agroforestry practices more rapidly if their trees were included in international climate change mitigation schemes now under development.

co2.gifThe data in this report illustrate that agroforestry will be critical to efforts aimed at making agriculture more productive and sustainable in order to contribute to the alleviation of climate change,” said Garrity. “It is estimated that further investments in agroforestry over the next 50 years could remove significant amounts of carbon dioxide from the atmosphere.”

This is yet another example that proves that energy efficiency and increased productivity do not contradict each other and could be a milestone for the developing world.

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