Sunday, March 14, 2010

Soil degradation in the Philippines

Soil degradation is a severe global problem of modern times. About six (6) million hectares of agricultural land worldwide become unproductive every year due to the various soil degradation processes. The problem is much more serious in tropical than in temperate areas since tropical soils are generally more prone to degradation because of the nature of their properties (e.g. they are more weathered) and the prevalent climatic conditions. Countries in Asia and Africa that depend upon agriculture as the engine of economic growth are believed to suffer the greatest impact of soil degradation. In the Philippines, soil degradation is one of the most serious ecological problems today. The National Action Plan (NAP) for 2004 to 2010 identified soil degradation as a major threat to food security in the country. NAP reported that about 5.2 million hectares are seriously degraded resulting to 30 to 50% reduction in soil productivity.

A degraded upland in Leyte

Soil degradation is defined as the process which lowers the current or future capacity of the soil to produce goods or services. It implies long-term decline in soil productivity and its environment-moderating capacity. The concept of soil degradation was first used by Kostychiev and Korchinski in 1888 to describe a natural soil change. Since natural degradation is slow, the present concept of soil degradation according to the Global Assessment of Soil Degradation (GLASOD) focuses on a human-induced process. Soil degradation occurs because of drastic changes or disruption in the normal processes of soil formation due to human activities.

A degraded upland covered with Imperata (cogon) grass in Samar
In a review paper on the problem of soil degradation in the Philippines published in the Annals of Tropical Research vol. 31, we (Asio et al. 2009) revealed that soil erosion is the most widespread process of soil degradation and is also the most studied in the country. Other important but less studied soil degradation processes include loss of nutrients and organic matter, salinization, acidification, pollution, compaction, and subsidence. 

A degraded upland in Bukidnon

Studies reviewed have shown that the widespread degraded upland soils possess chemical and physical constraints for crop growth like acidic or calcareous pH, low organic matter and nutrient contents, shallow solum, presence of toxic substances and compaction. The major factors that cause soil degradation include deforestation, overgrazing, agricultural practices, industrial activities, mining, and waste disposal. Deforestation is the main cause of soil degradation in Asia and south America while overgrazing is the main factor in the dryland areas of Australia, Africa, Europe and Asia.

The typical degraded land in Cagayan Valley due to deforestation & overgrazing 

There is a need for more data on the physical and socio-economic characteristics of degraded lands to aid in the formulation of appropriate soil management strategies to support biodiesel production in these unproductive lands which is now being promoted by the Philippine government. Also, there is the danger that the use of the degraded lands for intensive and long-term biodiesel production without the appropriate soil management would cause further soil deterioration and thus aggravate the ecological problems that are now occurring.


Asio VB, Jahn R, Perez FO, Navarrete IA, and Abit SM Jr. 2009. A review of soil degradation in the Philippines. Annals of Tropical Research 31: 69-94

Note: All photos are owned by the author.


RL Alvarez said...

Sir, do you have data on the extent of soil degradation in Luzon island? Thank you.

Victor B. Asio said...

Thanks for the question. The review article published in the Annals of Tropical Research Vol 31 2009 on which this blog post was based contains a lot of information about soil degradation in the Philippines.I will send you a pdf copy of it.

Ozzy Nicopior said...

Hi Sir Asio:

I am a grad student and currently taking an academic subject entitled "Forestation Techniques for Marginal and Degraded Lands". And I stumbled across your website.

I was tasked by my Prof to do some research about ACIDIC SOILS esp. (1) Occurrence & extent(national statistics maybe?) (2) Soil Productivity problem related to soil acidity (3) Some techniques for correcting acid soils, etc.

Would you mind sharing some relevant references?
I wouldn't miss citing you as one of my sources.

Thanks and more power!

bret said...

hi sir. i am 4th year high school student and one of the requirement is to make an SIP (Science Investigatory Project). since my study encompasses an introduction, i have copied some of your works. i'll just include the site in my bibliography. by the way, my study is all about mitigation of ACIDIC SOIL USING EGGSHELLS and oysters.
thank you!

Victor B. Asio said...

Thanks bret for leaving a note. Your study sounds interesting. Acidic soils are widespread in the Philippines and in other humid tropical (equatorial) countries. So they are a big problem for agriculture. I wish you good luck and I hope you would have a successful study.

jay jasmin said...

sir, do you know some information about soil remediation using fungi?

Efraim Roxas said...

Hello sir.

I am exploring Land Degradation as a topic for my graduate thesis. Can I have a copy of the paper referred here in your article for my reference. It will be properly cited.

Many thanks!

Victor B. Asio said...

Thanks for your comment. You can find a pdf copy of this article at the website of the Annals of Tropical Research at

aiza said...

sir good morning I would like seek help I am currently taking my MS thesis focused on soil degradation can I please ask a pdf copy of Annals of Tropical Research Vol 31 2009??? thank you God Bless

EM said...

Sir, I'm a 3rd year HS student and I have copied most of this article for our Science Investigatory Project. Rest assured, your work will be properly cited.

Victor B. Asio said...

Thanks EM for leaving a comment. I am glad that you can use this article for your HS science project. Please feel free to email me if you have questions or problems.

Leslie Ann said...

Good day Sir!

I am Leslie, a 2nd year law student, and we are having a term paper in Environmental Law. Can i ask for your e-mail address, sir? I would like to ask some advice with regard to soil problems in the Philippines. I would highly appreciate your reply. Thank you po. :)

djenz said...

Hi Dr. Asio,

I am interested in drawing a Physical Degradation Index and Chemical Degradation Index map for Abuyog, Leyte using GIS. May I kindly ask if you may recommend a degradation index formula (Physical & Chemical) that would suit Leyte and likewise share soil site data (GPS readings per soil site with pH,OM, N, P, CEC etc.) as mentioned in your soil degradation review paper for Philippines. Thank you very much.

Victor B. Asio said...

Thanks for leaving a note. a soil degradation index is interesting. There is no established degradation index but yes, it is possible to formulate one based on the established threshold values/critical values of soil properties. For example, for physical degradation, one property that can be included is soil bulk density. It is generally accepted that a value higher than 1.4 g/cm3 indicates a compact soil (would inhibit or greatly reduce root penetration into the soil). There are several other properties that may be used as well.

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