Wednesday, December 5, 2018

Impact of intensive vegetable production on the organic matter, nitrogen, and phosphorus levels of a volcanic soil (Andisol)

by Niezel Jane D. Estrellanes

Volcanic soils such as Andisols have many unique properties not usually found in soils derived from other parent materials (http:/ They are often very young and acidic depending on which type of volcanic materials they come from. They also largely consist of non-crystalline minerals such as allophane and imogolite (Nanzyo et al., 2002) which form strong bonds with organic matter thereby protecting it from decomposition. Andisols are usually light textured and are easy to till. However, they form strong complexes with phosphorus, rendering this element unavailable to plants.

One of the sampling sites in the central volcanic highlands of Ormoc, Philippines
This thesis research, a component of the Australian Center for International Agricultural Research (ACIAR) Soil Project based at the Visayas State University, evaluated the impact of intensive vegetable production on the nitrogen and phosphorus levels of volcanic soils in the central highlands of Leyte specifically in Cabintan, Ormoc City, Philippines. Twelve sampling sites (vegetable farms) including a reference site were chosen for this study. The objective was to find out if the continuous and heavy application of fertilizers for intensive vegetable production have caused the accumulation of nitrogen and phosphorous in Andisols.

Location of the sampling sites in Cabintan, Ormoc City
Soil samples were taken from the following soil depths 0-20, 20-40, 40-60, 60-80 and 80-100 cm using a soil auger. They were air-dried and passed through 2-mm sieve and analyzed for selected physical and chemical parameters such as pH (H2O, KCl and NaF), available phosphorus and particle size distribution. Enough 2-mm samples were also ground further and allowed to pass through 0.425-mm for organic matter content and total N analysis. 
Soil OM contents of the sampling sites. Sites 2, 4, 6 and 7 have much 
higher values than the reference site 12.
Soil N contents of the sampling sites. Most of the sites have much higher 
N levels than the reference site 12
Soil available P contents of the sampling sites. Reference site (12) has 
much lower P levels compared to all other sites.
Results revealed that majority of the vegetable farms sampled showed higher amounts of organic matter (OM), nitrogen (N), and available phosphorus (P) than the reference site (secondary growth forest). This clearly indicates the impact of the high and continuous application of chemical and organic fertilizers (chicken manure). The very high nitrogen contents of the soils point out to nitrogen pollution which could have serious negative impact on the groundwater quality. The high available phosphorus contents of the soils suggest improvement of the supply of this nutrient to the crops considering the fact that it is the major limiting nutrient to crop production in Andisols.

Based on the results it can be concluded that:

a. The intensive vegetable production has increased the nutrient status of the Andisol; 

b. The frequent and high rates of fertilizer application for the intensive vegetable production have greatly increased the nitrogen and phosphorus contents of the Andisol soil.

c. Nitrate and phosphate pollution of the ground water and the nearby rivers may result from the intensive vegetable production. 

Thursday, September 6, 2018

What does it take to be an agronomist?

By Dr. Jose L. Bacusmo, Past President, Visayas State University

What does it take to be an agronomist and what lies ahead of him or her?

Here are important figures for us to consider:

·       a) In 2017, the total paddy rice output of the Philippines met 93% of the country's annual requirement. The population consumed 11.7 million tons of rice. (usual shortage of 10% and brown rice/rice bran solution).

·       b) In 2016, for every 17 births per 1000 population there were 6 deaths per 1000 population. Every minute, 2.8 Filipinos are born. Every 10 or 11 minutes, we need one new classroom and down the road each of these kids will consume 120 kg of rice per year. (why is Philippine presidency such a contested and contentious position?)

(“ang ginoo pito ra kaadlaw nagbuhat ug yuta pero ang tawo walay hunong himo ug bata”-Gov. RE Lerias)

·       c) All of the scenarios of future climate change (CC) point to increase the estimates of the number of people at risk from hunger. (ascribing everything to climate change)

This country is therefore in dire need of professionals who study plants and work for increasing their production in an economical and environmentally sustainable fashion. Mind you, it is not only this country, but the whole world. Who are these professionals?

Used to be in the 1970’s and earlier, there was not much specialization. When it was plant, agronomists took care of it. Thus, an agronomist takes care of management: soil, pest and other growth and production issues in the field. I remember that there were only agronomy, animal science, agricultural education and home science as major fields in this campus. (lots of field work/learning by working, Agric was looked down).

Later, when Visayas Agricultural College (VAC) became a state college (ViSCA), other specializations were introduced such as arts and letters, ag. engineering, ag. economics, ag. chemistry, plant protection, plant breeding, forestry, vet. medicine grew out of animal science, ag. extension and dev. communication grew out of ag. education, food tech grew out of home science, and horticulture grew out of agronomy and, soil science was added to the agronomy department. Specializations are important for us to grow.

In the latter years of my term as president of this university, we had to “handle with care” a formal divorce of agronomy and soil science.  (jurisdiction and property distribution were quite tricky and sensitive to handle but they can’t go back living together again). 
VSU agronomists conducting a field experiment

All these specializations somehow delimit the scope of work agronomists are expected to deliver professionally. However, specialization did not and will not limit farmers’ expectations from an agronomist and other agriculture-related graduates from this university. In our national context where an agronomist most likely find himself/herself engaging with farmers alone in the field, an agronomist is also expected to be a good soil scientist, farm economist, horticulturist, plant breeder, communicator and even good in animal production, aquaculture and forestry or NRM to name some. To farmers, an agronomist is an “agriculturist”- an embodiment of expert. (McCoy and Ormoc rice farmers, Roy and cassava growers)

What does this tell you?

Do not limit yourself to knowing only field crops and cultural management practices. Endeavor to know and master beyond crop science. I recently analyzed the CHED Memorandum Order (CMO) that governs offering of agriculture and observed that the prescribed curriculum provides graduates the sciences needed for one to become a good agriculturist (but good is not enough). However, the CMO doesn’t preclude us from adding additional fundamental and major courses especially that now, some of the general education courses have been downloaded to senior high.

I will not interfere in the plans of this department, but I personally still subscribe to a 4-year BSA major in Agronomy curriculum rather than the 12+3. With the growing demand for climate SMART and precision agriculture, agriculturists need more mapping techniques, advance soil study techniques and even more understanding in biotechnology and IT. (possible from cross enrolment in the fourth year)

Furthermore, the CMO does not preclude our agronomy professors to deliver the course in a more advanced and exciting manner that student will endeavor to learn as much as possible in the course and not endeavor to end their suffering as soon as possible from taking their courses. This can only happen if professors in this department will engage in research/driven by discovery, extension work and actual farming. (farming lessons on seeds and weeding)

Specialization is usually overcome by collaboration or partnership but, it will be hard for anyone to collaborate/partner with someone who doesn’t have anything (absolute provision). If you don’t have anything other disciplines can offer, without your partners/collaborators, you will be paralyzed/inutile and unable. A person is appreciated and recognized usually when he can deliver more than what is expected of him. (basketball experience)

So, to faculty members and students, make BSA major in agronomy broad and exciting by learning beyond your coursework and collaborating with other specialists. For example, it will not be bad if some of you do research involving drones and high spectral cameras for field observation and management delivery. It will be exciting to see our agronomy students study how to use GPS and make or handle GIS maps as tractors are now equipped with GPS, and future tractors will be dominated with robotics. It will be great to see our agronomy students use plant or crop physiology study sensors, do genetic modification in their thesis or deal with soil problems as it affects field crops. Clearly for this to happen, there is a need for different specializations to relax, weaken and render more permeable the boundaries of various specializations of agriculture in this university and allow greater collaboration.

So, what’s the future of agronomists?

Let me say that the future of this country and this world depends on the agronomists. Agriculture is the backbone of this country and we need to feed and clothe an ever growing population. Agronomists are simply crucial to pulling off the job.

However, they should not be agronomists as usual. There is a saying that “a solution should measure up to the problem”. The problem of food and resources in this country has become more difficult and complex that the new breed of agronomists should be armed with complex knowledge and skills. With appropriate knowledge and skills, an agronomist will be potent and can go “places”. Short of this, an agronomist is doomed to be unexciting and lame.
Excerpt of the speech delivered during the acquaintance program, Department of Agronomy, VIsayas State University, on 31 August 2018.

Friday, August 3, 2018

Cebu Highlands: some notes on the agricultural practices and beautiful landscape

By Dr. Luz Geneston Asio
Department of Agronomy, Visayas State University

The highlands in the middle of Cebu which extends from the city in the east to Balamban/Asturias in the west, presents a beautiful mixture of protected landscapes with good secondary forest cover, and crop production systems consisting of orchard particularly mango, annual crops, vegetables and cut flowers. 

Beautiful views of the Cebu Highlands

The very beautiful scenery reminds visitors of Baguio City or some foreign places like Indonesia or Taiwan. Clearly observable even on distant undulating slopes are the mango trees which are adapted to the agroclimatic conditions of Cebu. 

Mango trees are abundant in certain parts of the landscape
Cebuanos are widely known to be corn eaters. This explains why corn is the most widely grown grain crop in the highlands. On red acidic soils from igneous rocks as well as on dark calcareous soils from limestone, nutrient deficiency symptoms (N, P) are clearly observable. But the crop is still able to produce a relatively good yield.

Large and small corn plantations are common in the highlands

On degraded limestone slopes on the western side close to Balamban, coconut plantations can be seen which are also showing nutrient deficiency symptoms most probably nitrogen and iron as indicated by the yellowing of leaves (plant analysis data from comparable lands in southern Leyte indeed revealed both nitrogen and iron deficiencies). 
Coconut plantations in the western side
But the most impressive crop production venture by the people in the highlands is the one which consists of cut flowers (e.g. Chrysanthemum) and vegetables (lettuce, cabbage, chayote, etc). The cut flowers are delivered to the city while the vegetables are sold in the city and in local stores along the highway. 

Stores selling the farm products are found along the highway

It must, however, be mentioned that although contour farming can be seen on some steep slopes, unsustainable cultivation practices can be clearly observed. The most obvious is the plowing or planting of crops along the slope (top to bottom orientation). This practice promotes soil erosion and loss of nutrients from the soil. This should be taken seriously as this could lead to severe soil erosion on the slopes accompanied by siltation of the streams below. It could have long-term impact on the water quality and quantity in the streams.

(Report was based on the field work we conducted from July 31 to August 2, 2018. I thank Dr. Vic Asio for his ideas and Julian Cumad (MSc Soil Science student) for organizing our visit. All photos are owned by the author.  

Tuesday, July 31, 2018

Rice production in Eastern Samar: is there a bright future?

By Luz Geneston Asio, PhD
Department of Agronomy, VSU, Baybay City, Leyte

Eastern Samar has been consistently ranked as one of the poorest provinces in the country ( A major reason for this is the low agricultural productivity due to several reasons: frequent typhoons, lack of government support, lack of political will, old farming methods, and many others.

During our one-week field work in the province this July, we travelled to interior barangays, observed crop production practices and technologies, interviewed farmers and technicians to get a picture of the real reasons for the low rice productivity of the province.
A poor rice farmer in San Jose village in Borongan City

Very striking across most of Eastern Samar is the widespread occurrence of uncultivated or only partly cultivated alluvial lands particularly near river systems. Such lands generally have great potential for intensive and highly productive rice production due to their generally flat topography. But most areas are idle and covered with Cyperus sedge and other grasses due to the lack of any irrigation system to supply the fields with sufficient water. Our field observations indicate that enough water lies beneath the land surface but nothing is done to tap it (e.g. deep wells) to support rice production.

An idle former rice land in Dolores, Eastern Samar

Only partly cultivated alluvial plain in San Julian, Eastern Samar

In many areas, we observed that farmers are planting modern rice varieties but are managed in the traditional way. For example, the modern rice varieties need proper spacing to grow well but most farmers are still practicing the random planting without proper spacing. Farmers also complained that they received seeds and small amount of fertilizers from the Department of Agriculture only once. It did not help them improve their production.

Modern rice variety planted at random (without proper spacing)

Shortly after planting, the soil dries up due to the absence of an irrigation system

Modern rice varieties are high yielding. Meaning, they are capable of producing high grain yields but they need high amounts of nutrients from the soil for them to attain their yield potential. Unfortunately, most farmers do not apply fertilizers or apply only insufficient amounts of fertilizers. The explanation by some agricultural technicians that the modern varieties need less fertilizers than the traditional varieties is simply not correct.

A farmer in Sulat harvesting his rice (he uses coconut leaves to protect him from the sun)

Quinapundan in the south is the only municipality where rice production appears to be very productive. The municipality possesses a large alluvial plain which is used for intensive rice production. The major reason is the availability of a functional irrigation system which allows farmers to plant two or more croppings of rice a year. We wonder why the local government in this municipality has been very successful in its rice production program but not Borongan, San Julian, Sulat, Taft, Can-avid, Dolores and the other municipalities which have wide areas of alluvial plains which are generally suitable for lowland rice production.

Intensive rice cultivation in Quinapundan, Eastern Samar

The prediction of one high ranking government official who was interviewed on local TV that Eastern Samar will attain rice self sufficiency in the next five years is not attainable. Not unless of course the politicians will do something drastic to solve the real causes of low rice productivity in the province. 

Just imagine how many tons of rice will be produced once these large idle lands throughout the province will be made productive through functional irrigation system, proper fertilization, high yielding varieties and other modern farming methods. Unfortunately, for Eastehanons this is not the priority of the politicians. Thus, we can safely assume that Eastern Samar will continue to be one of the poorest provinces. The future of rice production in the province may not be bright at all.
All photos were taken and are owned by the author.

Sunday, February 18, 2018

Nutrient addition as a forest restoration management strategy for Yakal yamban seedling establishment in ophiolitic soils

by Johannes R. G. Asio
Institute of Tropical Ecology and Environmental Management (ITEEM),VSU, Baybay City, Leyte, Philippines
Dipterocarp trees (Dipterocarpaceae) have crucial ecological roles such as in the prevention of landslides, sequestration of atmospheric carbon, and biodiversity. They are also economically important in terms of timber production. These native trees are also adapted to a variety of climatic conditions and geographic locations (e.g. areas prone to heavy typhoons, marginal lands). However, the sustainable management of dipterocarp forests is still poorly understood due to the limited studies conducted on the subjet. This is particularly so in terms of the ability of these forest trees to thrive in marginal lands like those naturally contaminated with heavy metals and those soils with very low nutrient status such as ophiolitic and serpentinite areas (Corlett&Primack, 2006; DENR, 2012; Appanah, 1998; Walpole, 2010).
Ophiolite rocks are widespread in Leyte, Samar, Cebu and Palawan.These rocks generally underlain marginal lands. A typical ophiolite complex is a stratified igneous rock complex that consists of different rock layers: an upper basalt member, a middle gabbro member, and a lower peridotite member (Ishiwatari, 2016). The fertility of Ophiolite rocks in the Philippines has not yet been studied in detail, however, according to some literatures, it is generally moderately acidic to neutral, low soil organic matter, low nitrogen (N), phosphorus (P), and potassium (K), which are the major nutrients needed for plant growth, and it contains high amounts of heavy metals, such as chromium, nickel, iron, and cobalt among others (Dimalanta et al., 2006; Ocba, 2016).
Mineral fertilizers have been used in agriculture and forestry to improve crop yield, enhance the soil fertility, and soil health. Thus, this study hypothesized that the addition of N, P, and K to an ophiolite soil could enhance the growth of Yakalyamban (Shorea falciferoides Foxw.) in problematic areas. This dipterocarp species was chosen for this research as it has been known to thrive in the ophiolitic and serpentinite areas of Samar and it is critically endangered, thus the need to preserve this dipterocarp to prevent it from becoming extinct (Fernando et al., 2009, 2008).

This study aimed to test whether the addition of nutrients enhanced the seedling growth of yakal yamban grown in an ophiolitic soils, determine the optimum nutrient combination level for yakalyamban seedling quality; and assess and evaluate whether fertilization could very well be adopted as a nutrient management practice in using yakal yamban as a rainforestation species for forest restoration in problematic soils.
The potting medium was selected based on the soil data obtained by the VSU-OXFAM Project (2015). Detailed soil analysis done by the project showed that the soils in Barangay Padang, Hernani, Eastern Samar developed from ophiolitic rocks and have low levels of N,P,K, and Mg, but high levels of Ca. Twenty sacks of topsoil (0-30cm depth) were collected and transported to the Terrestrial Ecosystems Division of the Institute of Tropical Ecology and Environmental Management for this screenhouse experiment. The bulk soil samples were mixed, air-dried thoroughly, pulverized and sieved using a 4-mm mesh sieve. About 1.5 kg of the air-dried soil was weighed; 0.75 kg sieved soil (from the 4-mm sieve) and 0.75 kg unsieved soil to avoid soil compaction.

This one-year study was conducted using a 5 x 3 Randomized Complete Block Design (RCBD) with five treatments and three replicates, wherein each treatment per replication consisted of 10 seedlings. The treatment are as follows: T1- No fertilizer application, T2- Application of 3.65 g of Urea, 9.33 g of Solophos, & 2.8 g of Muriate of Potash, T3- Application of 3.65 g of Urea, 9.33 g of Solophos, T4- Application 9.33 g of Solophos& 2.8 g of Muriate of Potash, T5- Application of 3.65 g of Urea & 2.8 g of Muriate of Potash. Placement application was done wherein the exact amount of fertilizer for each seedling was applied a few centimeters below the soil surface. Tap water was used. About 400 mL was added as required.
Three (3) randomly selected seedlings in each replication were harvested after 3 months and 6 months from fertilizer application. The selected seedlings were photographed before and after harvest, documenting each plant part and making notable observations. Thereafter, each individual seedling was cut; each leaf was photographed in preparation for leaf area analysis. Then, each plant part (roots, stem, and leaves) was separated and placed into the corresponding paper bags ready for oven drying. The soil samples in each replication were mixed and placed into labelled plastic bags ready for air-drying and analysis.
Major Findings
Results revealed highly significant differences in leaf area, percent biomass allocation, and root-shoot ratio between treatments 6 months after sampling. In terms of leaf area, treatment 4 showed the highest leaf area value. All treatments added with phosphorus (treatments 2,3 and 4) had leaf area values that were statistically the same. This indicates that P is the most critical nutrient in the soil and that this tree species is sensitive to the P levels in the soil.

There were also significant differences in terms of the percent biomass allocation between treatments in the root, stem, and leaves, with treatment 5 showing the highest allocation in the roots; plants in P-deficient environments enhance root growth as it is their adaptive mechanism that enables them to thrive in these conditions. The result also coincides with the root-shoot ratio as study plants in treatment 5 had the highest root-shoot value.

Soil nutrient analysis was done to determine the nutrient status of each treatment. The analyses concur with the fact that ophiolitic soils are deficient with N, P, & K, thus the high values of the nutrients were due to the fertilizers added prior to destructive harvesting. It was also observed that the fertilizer treatments have not yet fully dissolved even after 6 months of application.
Plant nutrient concentration was also done to determine the nutrient content of each plant part. In terms of nitrogen (N), there were high values of N in the leaves as it is needed for photosynthetic activity. However, it was below the optimum concentration needed for plant growth (Marschner, 1995). With regards to P, there were high values of the nutrient in treatments not added with P. It may be due to the mycorrhizae present in the roots of the study plants after 6 months of application. For K, solubility played a factor since there was an inhibition of nutrients to be taken up especially between N and K.

The presence of ectomycorrhizae (EcM) was also observed in the roots of the study plants of the control (T1) and NK (T5). Various studies have proven that mycorrhiza aids in the growth of a plant as it enhances the absorption of nutrients and water (Marschner, 1995; Read, 1991). The result also coincides with the study of Turner et al., 1992 as EcM infection may serve as a purpose when dipterocarps are grown in nutrient-poor conditions.
Nutrient addition could very well be adapted as a nutrient management strategy for the seedling establishment of Yakal yamban in ophioitic soils; Treatment 5 enhanced the root-shoot ratio of the study plants, thus these seedlings are of good quality. This implies that during establishment of the seedlings in an open area, they are most likely to survive due to its adaptive mechanism (e.g. enhance root growth in p-deficient environments) and the potential fungus-root association in the soil.
The above article is a summary of the BSEM thesis by the author which won as 2017 Phi Delta Outstanding Thesis in Applied Biological Sciences at VSU, Baybay City, Leyte. More information can be obtained from the author. Email: