In the tropics deforestation can possibly lead to a quick degradation (laterization) of soils if we are not taking the proper measures. In this particular case what is the best and cheapest way to recover fertile soil?
The fertility of degraded tropical soils can be restored by plantations of suitable native tree species of different potential heights, and ground seeding with grasses and leguminous forbs. The grass and legume cover not only adds organic carbon and nitrogen to the soil, but also serves as a trap for windblown seeds and other material and as mulch.
Thank you very much Dr Singh for your answer . Is the high concentration of Fe and Al in laterized soils not going to cause a problem of toxicity for the plants?
All degraded soils initially are inhospitable for plant growth, but once after establishment, plants gradually neutralizes the effect of stressful conditions.
The soil can be restored sustainably with the application of biochar that can/could be produced on-site by the biomass (eg.: logs, tree stumps and other debris) already available. Biochar will increase the moisture retention ability of the soil, while promoting the colonization of microrganisms that will feed on its carbon-rich molecules. In this way the establishment of native trees (especially nitrogen-fixers) can be facilitated and speed up the soil recovery. An employment of grazing livestock (if available) will assist in this process rapidly, and successfully.
Dr Borsari, the idea of biochar is excellent especially if it can be produced in situ. Its probably the cheapest and the most effective way to start with. Do you know whether this procedure is being used in the tropics?
Dear Dr. Jost,
Check out the work on biochar that Dr. Hue and his team in Hawaii has been doing. Nguyen Hue I strongly recommend you connect directly with Dr. Hue.
Also, the attached review article may be of interest to you.
The work of Alan Savory may be of interest to you. Here below is the link of a TED Talk of his titled: How to fight desertification and reverse climate change. https://www.ted.com/talks allan_savory_how_to_green_the_world_s_deserts_and_reverse_climate_change
Dear Dr Borsari,
I take note of your new information and links about Dr Hue and Dr Savory. Thank you very much for your valuable cooperation
Best regards
jpj
Soil as per the founder father of soil science, V V Dokuchaev, is a system of life that originates, grows and mature with natural vegetation. Reclamation is the process to regain and maintain the life in natural soils so that they develop fertility and retain natural vegetation or crops, quite a sustainable manner.
In tropics, depending on the climate, the vegetation can be of different kinds from deserts to Savannah to different kinds of forests such as dry deciduous, moist deciduous to wet evergreen, which depends on the climate.
Therefore, reclamation depends on the climate and the degree of degradation. In general, reclamation (there is no need of the use bio-reclamation because no soil reclamation is possible without organic or bio-materials) starts with proper physical design for protection (creation of contour bunds or slope controlling designs to avoid soil erosion).
Afterwards organic material need to be added, for which natural vegetation or green manure of all kinds (resistant weeds or wasteland trees) would the best initial material.
The available vegetable matter in a degraded soil may be used to cover the degraded soil surface as a mulch.
Depending on the season (if little bit of rain or irrigation possibility is available) some pulses and millet may be sown to generate the green cover, which also after certain period may be cut or pluoughed back to soil to enrich the organic mulch.
Fresh Cow-dung need to be extremely diluted and sprayed on the mulch to improve the microbial community. After the initiation of soil life, cultivation of suitable crops may be begun with a focus on further improving the life and organic content of soils.
Any kind of soil can be reclaimed by a careful and dedicated approach, but the cost of reclamation and the time required depends on the type soil, climate, extent of degradation, availability of organic and labour resources and the like.
In the Sahel region of sub-Saharan Africa (Burkina Faso, Niger, Mali) the "ZAI" is an effective approach to soil restoration and reclamation. Shallow holes are excavated and filled with compost, or composted manure and here is where seeds are sown. These circular holes have a slope toward the center to retain water from rain precipitation, or simply moisture from the condensation of water vapor during the early morning hours.
Bruno this is a very interesting procedure, I think that about 50 years ago the same procedure was experimented in some area in Israel.
Concerning the problem deforestation / reforestation I consider that the policy that is currently carried out in Otronga reserve (Ecuador) is quite interestinf from both ecological ans sociological stand points. Please see
http://www.parks.it/world/EC/riserva.otonga/Epar.html
Thank you Mario for the link. This is an excellent example how it should be done!
regards
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