The arsenic contamination in rice

Arsenic (As) is a heavy metal that is well-known as a poison and a carcinogen. Its average concentration in the soil ranges from 5 to 6 mg/kg which is generally related to rock type and industrial activity.

Arsenic contamination of paddy soils is widespread and elevated arsenic levels in rice grains is now a hot issue in many parts of the world. Martha Rose Shulman wrote in the New York Times (15 April 2013) that “it is clear that the levels of inorganic arsenic in rice and rice products are high, and that we and especially children, babies and pregnant women should limit our intake of rice and rice products.”

According to Bogdan and Schenk (2012) in their recent study published in the highly respected Journal of Plant Nutrition and Soil Science (Wiley-VCH Verlag GmbH), flooded rice may contain high arsenic concentration compared to other grain crops. In fact, aside from arsenic-contaminated drinking water, rice is the largest food dietary source of inorganic arsenic. This is because the reducing environment in flooded rice fields causes the dissolution of arsenic and thus increases its availability to the rice plant. Meharg (2004) added that under paddy field conditions, inorganic arsenic introduced into the soil is inter-converted between the reduced inorganic species arsenite (the dominant type) and the oxidized species arsenate. Moreover, arsenite is taken up into the root by the highly efficient Si pathway and arsenate can be taken up via the phosphate transport system.

Bogdan and Schenk (2012) observed among other things that continuous arsenic supply in the soil resulted in doubling of arsenic concentration in rice shoot and grains. They also found that arsenic was mobilized from the root and shoot to the rice grains where it accumulated.

References
Bogdan K. and M.K. Schenk. 2012. Arsenic mobilization in rice (Oryza sativa) and its accumulation in the grains. J. Plant Nutr. Soil Sci. 175: 135-141.
Meharg A.A. 2004. Arsenic in rice-understanding a new disaster for Aouth-East Asia. Trends in Plant Science 9: 415-417.

Invitation to the 2013 National Conference on Marginal Uplands

The Visayas State University (VSU), through the Philippine Higher Education Research Network (PHERNet) of the Commission on Higher Education (CHED), is spearheading a research project on enhancing farm productivity and environmental quality in climate change vulnerable marginal uplands in Eastern Visayas. As part of the project activities, the university will organize a National Conference on Development Initiatives in the Philippine Philippine Marginal Uplands, with the theme, "Enhancing farm productivity and environmental quality of Philippine marginal uplands: A scan of the past and a look into the future." The conference will be held on 22-24 October 2013 at VSU, Baybay City, Leyte.

Marginal uplands: current research initiatives at VSU

Marginal uplands are hilly or mountainous lands having very low crop productivity due to poor soil quality (degraded soil), limited water availability, and unfavorable socio-economic conditions. They are widespread in Southeast Asia and other parts of the humid tropics (e.g., Agustin and Garrity 1995; Asio et al., 2009). Resource poor-farmers (~ 1.4 billion people) in the developing world are located on these risk-prone marginal environments (Altieri 2002). 

Marginal uplands in Inopacan and Hindang, Leyte

In the Philippines, the poorest households, who are also the most vulnerable and most food insecure, are living and farming on these marginal lands (Roa 2007). The agro-ecological conditions in these areas are typically not suited to intensive production systems due to low-quality soils, hilly slopes, limited access to inputs or markets and extremely diverse and site specific conditions (Asio et al., 2009; Tyler 2004). Crops that can be grown on these marginal lands are often restricted to root crops such as sweet potatoes, beans and other legumes, thereby limiting food supply and diversity in hilly lands.  In addition, farmers often seek seasonal off-farm employment to survive.  Thus, research efforts are urgently needed to enhance food security and alleviate the difficult and risk-prone living conditions of these poor farming households. 

A daughter of a poor farmer living in the marginal upland of Inopacan, Leyte

Two on-going research projects on marginal uplands at VSU are the CHED-funded Philippine Higher Education Research Network (PHERNET) Program on “Enhancing food production and environmental quality in climate change vulnerable marginal uplands of Eastern Visayas” and the NRCP-funded project “Characteristics and nutrient status of degraded upland soils in Samar Island”.

Poor soil quality and low biodiversity characterize marginal uplands

References
Agustin PC and Garrity DP (1995). Historical land use evolution in a tropical acid upland agroecosystem. Agriculture, Ecosystems and Environment 53:83-95.
Altieri MA (2002). Agroecological principles for sustainable agriculture.  In: Agroecological Innovations (N. Uphoff, ed.). Earthscan, London, pp: 40-46.
Asio VB, Jahn R, Perez FO, Navarette IA, and Abit SM Jr (2009). A review of soil degradation in the Philippines. Annals Tropical Research, 31:61-94.
Roa JR (2007). Food security in fragile lands. PhD Dissertation, Wageningen University, Netherlands.
Tyler S (2004). Participatory research for community-based natural resource management in Asia. JIRCAS International Symposium Series 12: 165-169.

Happy World Soil Day

The Department of Agronomy and Soil Science at Visayas State University in Leyte, Philippines joins the global community of more than 60,000 soil scientists in celebrating the World Soil Day today, December 5.

Our soil science program at VSU is now more than 30 years old. It produced the first batch of BSA (Soil Science) graduates in 1980. It is now among the top soil science programs in the Philippines. 

Many of our BS alumni have become very successful professionals/scientists in various academic and research institutions in the Philippines and other parts of the world. 

We are very proud to name a few:

Dr. Leticia S. Sonon, University of Georgia, USA
Dr. Marife Corre, University of Goettingen, Germany
Dr. Nilda R. Burgos, University of Arkansas, USA
Dr. Sergio Abit Jr., Oklahoma State University, USA
Dr. Joel Bandibas, National Institute of Advanced Industrial Science & Technology (AIST), Japan
Dr. Constancio Asis, Jr., Philippine Rice Research Institute
Dr. Ian Navarrete, University of Goettingen, Germany

Response of Abaca (Musa textilis Née) to shade, irrigation and fertilization

Abaca plants

Abaca (Musa textilis Née), a relative of the edible banana (Musa acuminata and Musa balbisiana), is a native to the Philippines. It is grown primarily for its fibers which are utilized by the pulp, cordage and fiber craft industries. Studies have shown that the specific tensile strength of abaca fiber is comparable to or even higher than that of fiberglass (Bledzki et al., 2007;Sinon, 2008).

Dr. Marlito Bande and co-workers, in a paper to be published in the international journal Industrial Crops and Products 42:70– 77, reported on the optimum light, nutrient and water requirements of abaca to attain optimum yield. They also discussed how these parameters affect fiber recovery and fiber quality under field conditions. 

They showed that abaca planted under 50% shade had significantly (p < 0.01) higher fiber yield than those planted under the other shade/light treatments (30% and 40% of full sunlight using polypropylene shade nets) since the plants pseudostem under such treatment were longer, bigger and heavier.They revealed that the combination of irrigation and fertilization further enhanced fiber yield to as much as 41% but this was not enough to offset the effects of shade on the performance of the plant which significantly (p < 0.01) increased fiber yield to as much as 165%. Shade and irrigation–fertilizer application had no significant effect on fiber fineness and tensile strength. 

They concluded that 50% shade is the optimum requirement of abaca to achieve an optimum machine stripped fiber yield of 135.04± 4.31 g/plant without affecting fiber quality for industrial purposes.

The study which was conducted in Ormoc, Leyte, Philippines was funded by the German Research Foundation (DFG).

References

Bande MM, J Grenz, VB Asio, and J Sauerborn. 2013. Fiber yield and quality of abaca (Musa textilis var. Laylay) grown under different shade conditions, water and nutrient management. Industrial Crops and Products 42:70–77.

Bledzki AK, AA Mamun, O Faruk. 2007. Abaca fibre reinforced PP composites and expansion with jute and flax fibre PP composites. eXPRESS Polymer Letters 1 (11), 755–762.

Sinon FG. 2008. Optimization of stripping technologies for the production of high quality abaca fiber. Dissertation, Universität Hohenheim, Stuttgart, Germany

Environmental pollution: the case of Xenobiotics

Xenobiotics are chemical substances that are foreign to the biological system. They include naturally occurring compounds, drugs, and environmental agents (Mondofacto online medical dictionary at www.mondofacto.com).The classes of xenobiotics include: pesticides, polyaromatic hydrocarbons (PAHs), polychlorinated aromatics, solvents, hydrocarbons, and others (surfactants, silicones, and plastics).

Xenobiotics levels in soils are generally low (less than 100 ppm) unless they are concentrated by application as in the case of pesticides, by spills or by waste disposal. They can occur in soils in solid, dissolved and gaseous phases and all undergo microbial and abiotic (chemical) transformations (Logan, 2000).

Photo source: www.cleanwaterfund.com

Pesticides are the most important xenobiotic pollutants because of their widespread use in agriculture. In many developing countries, unregulated use of pesticides by poor farmers contributes not only to environmental pollution but to health problems as well.

In the soil, pesticides can be temporarily fixed through adsorption by soil particles. The persistence or decomposition of pesticides in the soil is influenced by soil moisture, organic matter content, redox potential, soil acidity, soil temperature, texture, adsorption potential and clay minerals (Schactschabel et al., 1998; Sonon and Schwab, 2004).

References

Logan, T.J. 2000. Soils and environmental quality. In: Handbook of Soil Science (M.E. Sumner, ed.). CRC Press, Boca Raton, pp: G155-G169.

Schactschabel P., H.P. Blume, G. Brümmer, K.H. Hartge and U. Schwertmann. 1998. Lehrbuch der Bodenkunde (14th ed.). Ferdinand Enke Verlag, Stuttgart.

Sonon, L.S. and P.A. Scwab. 2004. Transport and persistence of nitrate, atrazine and alachlor in large intact soil columns under two levels of moisture contents. Soil Science 169: 541-553.

N.L. Galvez: The Dean of Filipino Soil Scientists

Dr. Nicolas L. Galvez (1903-1991) laid down the groundwork for the different fields of soil science in the Philippines and he trained many Filipino soil scientists as a professor at the University of the Philippines College of Agriculture (UPCA) for 42 years. He was the head of the Soils Department at UPCA from 1948 to 1961, a difficult but crucial post-war period that had long-term impact on the development of soil science as an academic field in the country. Upon his retirement in 1970, Dr. N.L. Galvez was honored by being appointed as a University of the Philippines Los Banos (UPLB) Emeritus Professor. 

Dr. N.L. Galvez (Source: SAED, UPLB-CA)

Dr. N.L. Galvez was an internationally recognized scientist having published numerous relevant scientific papers on soil chemistry, soil mineralogy, and other aspects of soil science. For his pioneering and great contributions to the development of soil science in the Philippines, Dr. Galvez is widely considered, and deserves to be called, as the “Dean of Filipino Soil Scientists”.

Dr. N.L. Galvez finished his Bachelor of Chemistry at the University of Minnesota, USA, in 1925 and his PhD degree in Soil Science in 1934 from the Institute of Agricultural Chemistry and Soil Science,University of Göttingen, Germany, under the supervision of Prof. E. Blanck (1877-1953), one of the leading soil scientists during the first half of the 20th century who edited the monumental 10-volume Handbuch der Bodenlehre (Handbook of Soil Science) published from 1929 to1932. Dr. Galvez wrote a dissertation entitled “Über Bodenpresssäfte und wurzellösliche Pflanzennärstoffe” (On the pressed soil extract and root-soluble plant nutrients) which was published in the Journal für Landwirtschaft (Journal of Agriculture) Vol. 89, No. 4, pages 257-320 (1934), a prominent peer-reviewed scientific journal at the time.

The University of Göttingen is a world renowned university associated with such scientific giants as Gauss, Wiechert, Correns, Eigen, Fermi, Debye, Nernst, Langmuir, Heisenberg, Born, Teller, Oppenheimer and many more including nearly 50 Nobel Prize winners. Interestingly, when the great theoretical physicist Werner Heisenberg in Göttingen won the Nobel Physics Prize in 1932, N.L. Galvez was a student there. It is easy to speculate that he must have brushed shoulders with some of the world’s leading scientists (who were teaching or doing research in that small university town of Göttingen) which could have inspired him to excel in his own field of science.  

In recognition of his outstanding scientific achievements, N.L. Galvez was awarded a Guggenheim Fellowship for postdoctoral research at the University of Wisconsin from January 1955 to August 1956 where he worked with M.L. Jackson (1914-2002), one of the most influential American soil scientists and author of the world famous textbook “Methods of Soil Analysis”.  This postdoctoral experience in Wisconsin which focused on the colloidal minerals of important agricultural soils of the Philippines, must have enhanced further his international standing as a scientist.

In 2008, a museum (N.L. Galvez Hall) was established in his honor at the Soil and Agro-ecosystem Division of the College of Agriculture at UPLB under the able leadership of its former head, Dr. Pearl B. Sanchez, a professor of soil chemistry. It was funded by the US-based family of Dr. Galvez.

(Note: Many of the facts cited were taken from materials available at the above-mentioned N.L. Galvez Hall.)