Agroforestry & How It Can Boost Water Use Efficiency.

Water scarcity is a hot topic these days (with Cape Town looking like it’s going to be the first city in the world to run out of water), so it’s important that we all try to conserve as much of this precious resource as we can.


The World Agroforestry Centre points out that agroforestry may be an excellent tool to have in our arsenal as we try to reduce water consumption – which is certainly necessary because the global population is still growing, so more food needs to be produced. Apparently, agricultural water consumption is likely to rise by 19 per cent come the year 2050 – so it’s clear that something must be done.


But exactly how is growing trees an effective measure for reducing our usage of water on a worldwide scale? As the Centre observes, planting the right kind of trees in the right kind of areas can actually help boost water use efficiency since annual crops can only use a certain amount of the water that’s available.


India was given as an example, where sorghum transpiration makes up 41 per cent of rainfall, with the remainder going to drainage, runoff and evaporation. But integrating certain types of trees means that more of the annual rainfall can be captured – with research showing that combining Grevillea trees with maize can use 70 per cent of annual rainfall.


Agroforestry can also help to boost crop productivity, by increasing soil water storage and infiltration, reducing leaching and soil erosion, and supporting nutrient supplies through nitrogen fixation.


It can also help with water retention, with some tree species in south-west Uganda that grow on the upper levels of terraced hillsides helping with soil water content and evaporation in cropping areas.


“Another role of trees on farms is in providing shade, helping to maintain soil moisture. This is proving especially important in the Great Green Wall, an initiative to revegetate a corridor extending from Senegal in the west of Africa to Djibouti in the east. Here, trees are providing shade and fertilizing the soil so that less water is lost and crops can be grown,” the Centre went on to state.


Further research from Penn State University has found that agroforestry could also have a pivotal role to play in mitigating the effects of climate change because it sequesters more atmospheric carbon in soil and plant parts than traditional farming methods.


This system, which brings trees with crops and livestock together in the same place, is particularly popular in developing countries since it allows smaller farmers who have less land to make the most of their resources.


Professor of forest resources Michael Jacobson explained that the study proves how effective agroforestry can be in global carbon sequestration, involved in the long-term storage of atmospheric carbon dioxide and carbon capture – a process that is vital to deferring or mitigating climate change.


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