Biophysical resources

The biophysical resources include land and other natural resources (e.g. trees, water sources, biodiversity) in it. Land quality such as soil traits and terrain contribute to farm productivity, or explain its limitations. These traits reflect how fit the farm land is to function within its environment, support plant productivity and human health.

The quality of the soil can be enhanced or degraded by natural processes (e.g.

erosion, weathering, decomposition) and human activities (e.g. cropping pattern, cultural management practices). The degradation of the soil could lead to both direct and indirect deterioration of surface and ground-water quality.

The conservation of the natural vegetation and forest helps to balance the ecosystem, which is critical in maintaining the diversity of plant-animal population in the area, the productivity of farming, and fishing (http://www/gcrio.org/geo/quality.html 8-3-2005).

Soil samples of farms of the case households were selected to represent the different agro-ecologies and land use in the villages. Table 6.3 summarizes

the results of the soil analyses, which can be referred to the sketch maps of the villages (Figs. 6.1 and 6.2, this chapter) in order to locate the field of specific agro-ecology and land use. Selected soil quality characteristics tested include soil texture, water holding capacity, pH, organic carbon (C), total nitrogen (N), available phosphorus (P), exchangeable potassium (K), exchangeable sodium (Na), cation exchange capacity (CEC), exchangeable calcium (Ca) and magnesium (Mg). The threshold levels of these soil properties based on the Booker Tropical Soils Manual (Landon, 1991) are shown in Table 6.2.

Table 6.2 Threshold levels of selected soil properties

Soil characteristic Very

Low Low Medium High Very

high

pH <5.5 5.5-7.0 7.0-8.5 >8.5

Organic carbon, C

(Walkley Black) <2.0 2.0-4.0 4.-10 10-20 >20 Total Nitrogen, N (%) <0.1 0.1-0.2 0.2-0.5 0.5-1.0 >1.0 Available Phosphorus, P

(Bray 2, ppm) <4 4-7 7-13 14-20 >20

Exchangeable potassium, K

(m.e./100g of soil) <0.2 0.2-0.4 0.4-0.8 >0.8 Exchangeable sodium, Na

(m.e./100 g soil) >1.0

Cation exchange capacity,

CEC (m.e./100 g of soil) <5 5-15 15-25 25-40 >40 Exchangeable Calcium, Ca

(m.e./100 g of soil) <4 4-10 >10

Exchangeable Magnesium. Mg

(m.e./100 g of soil) <0.5 0.5-4 >4

Soil quality

The soils of Alegre are generally classified as Umingan clay, and Palo clay loam, and mostly come from alluvial material, which were formed from sediments previously deposited by running water. The soils in Plaridel are formed from andesitic parent material of volcanic origin that are still undergoing weathering, creating new soil and releasing nutrients. This parent material comes from Mt. Sacripante (1000 masl), a dormant volcano located 6 km from the center of the village. On the mountain close to the volcano, the soils are andisols (black, deep soft soils). Their softness makes them vulnerable to erosion. In the hills, soils are mostly inceptisols, alfisols and ultisols (USDA classification system). Inceptisols at the early stage and alfisols in the middle stage are still relatively fertile soils, and are in the earlier stages of the process of transformation from the andesitic parent material. The later stage is the creation of ultisols, of Guimbalaon clay (mostly red, sometimes black), which are infertile and characterized by an increase of clay

in the subsoil (thus, little infiltration), by a high acidity, a low base saturation by a deficiency in phosphorus. In the lowlands, soils come from an alluvial material called Umingan clay loam (Table 6.3) (Barrera et al., 1954).

On average, crops grown in the area suffer from nutrient deficiency.

About 60 percent of the sample farms have low (4%) to high (56%) pH. Most crops prefer medium or slightly acidic soil (5.6<pH>6.8) since lower or higher pH values can cause plant nutrient deficiencies or elemental toxicities that have adverse effects on crop yield (Evanylo and McGuinn, 2000). The farms with medium or suitable pH include the rice terrace, the hill slopes of Malbago and Pikas, most of the mountain areas in Plaridel; and the rice paddies near Hindang creek and the alluvial farms in the central part of Alegre.

But while the pH level may be suitable, most of these farms are deficient in the macro nutrients nitrogen and phosphorus. All farms have very low to low organic carbon. Only the rice fields near the Talisay creek in Alegre and about 50% of the farms in the upper hill (coconut, corn, rootcrop, vegetables) and mountain farms (abaca) in Plaridel have moderate amounts of nitrogen (N). Where available phosphorus is moderate to high in some rice paddies in Alegre and Plaridel and in the central rainfed farms (coconut, banana, rootcrops) in Alegre, it could not be effectively used by these crops because these areas have low pH and with mixed sandy soil, which has a low buffering capacity. Phosphorus needs low soil moisture, a high pH and clayey soil in order to be effectively used. Since rice and rootcrops require high phosphorus, such soil conditions limit the crops’ growth (Dabin, 1980).

All irrigated rice paddies in Plaridel have low exchangeable potassium.

While all farms in Alegre and all non-lowland farms in Plaridel have medium to very high exchangeable potassium. But most of these farms have high pH, which reduces the effective availability of potassium. The low K in Plaridel rice fields could be because of the relatively high rainfall in the area, which causes leaching of nutrients into lower layers and the cropping intensity of 3 times a year leading to this nutrient’s loss. This low K content of rice paddies is similar to the findings in rice growing areas in Bangladesh, Cambodia, Sri Lanka and Thailand (Kemmler, 1980). For crops like rootcrops, vegetables, fruits and banana, K requirements are high.

Most farms, however, are less prone to the risk of the acidifying effects of nitrogen fertilizers (including organic N sources) because most soils have a relatively high base (e.g. Ca, Mg, K) status (Evanylo and McGuinn, 2000).

Except in the upper river bed farm in Alegre, the rest of the farms have medium to high cation exchange capacity.

From the community surveys and FGDs, the physical degradation of the soil mainly resulted from water erosion and land clearing since farmers do not use machineries. Chemical degradation mainly resulted from the depletion of soluble elements through rainwater leaching, and to a certain extent over cropping without the benefit of appropriate soil quality enhancement practices by farmers. In rice paddies, this could also arise from the accumulation of salts precipitated from irrigations schemes and other toxic contaminants. The intensive crop systems involving annuals lead almost inevitably to loss of soil fertility.

139 Chapter 6 Table 6.3 Soil analysis results of the sample farms of case households by location and land use

Farm location*

Tali-say River^1A Irrigated rice Silty clay

loam 48.2 5.2 Lowland: Coconut, mixed or rotation cropping M

Gabhok,

Understanding the Research Area Lowland, coastal/riverside: Coconut, banana/ rice M

Coastal Hill slope (lower): Coconut, banana, rootcrop, corn, few fruit trees

Malbago,

141 Chapter 6 Hill slope (upper): Coconut, banana, corm, sweetpotato, fruit trees M

Malbago, Mountain/slope: Abaca, rootcrop, vegetable

Bud dako,

* The letter superscript refers to the village: A for Alegre, P for Plaridel. The number superscript refers to the farm location on the sketch maps of the villages found in Figures 6.1 (Alegre) and 6.2 (Plaridel). ** This means that the soil analysis for this samples was not repeated as the results were good, as this soil attribute was not taken in the .first laboratory analysis. VL=very low; L= low; ML=medium low; M = medium; H = high; VH=very high based on the soil attribute threshold level

In the 1970s, the fertility of the soils, particularly in the hills and slopes and lowlands, began to decline. The abaca farms on the mountains, though, remain fertile until today.

Soil texture affects almost all other soil health indicators. It is changed by tillage and soil erosion. Soil-inverting tillage (mouldboard or disk ploughing) mixes subsoil with topsoil. This lead to an increase in clay content in the surface of soils that have a clayey subsoil. Soil erosion by water selectively removes fine sil-sized particles. Erosion by tillage moves topsoil downshope and is major reason for the formation of clay knobs.

Water-related concerns Alegre

With 90 percent of the area being relatively flat (0-3%), Alegre is severely hazardous to flooding or baha, as with the other barangays along the three river tributaries which run across the town. It has been singled out as very severely eroded especially along the river (Dulag, 1998). With baha, the water level rises and overflows through the fields or the village itself causing sediment deposits, called lahar. This is a locally adapted term referring to the volcanic ash popularised since the 1991 eruption of Mt. Pinatubo. Baha and lahar are threats all year round except during the dry months (February-May).

Floods occur several times a year especially in the lower Mombon area every time the water level rises caused by heavy rains or typhoons. The more serious floods with mudflows occur occasionally (1991 severe, 2001 less severe). This could flood the whole village a meter deep and leave muddy sediments. The 1991 flashflood, which was part of the tragic Ormoc flashflood⁵, left the Barilahay creek dry until today. The floods follow a progression: first affecting the lower river plains, then the paddies near the creeks, the upper river plains, and in serious cases, through the village. The village folks believed that these are due to slash and burn practice or kaingin, causing deforestation in the mountains of Burauen, and to indiscriminate sand and gravel-quarrying in Daguitan river. Some farmers refer to lahar as eroded mountain soil which for many is just soil or fine sand. Flooding also occurred through the irrigation canals when large volumes of water rushed through the fields during unwanted times, due to the disorganised irrigation system (Saint-Girons, 2003).

The instability of the rivers exposed farming to greater risks. The local people observed the widening of the river and some keen farmers attributed this to water erosion which caused the river bed to change. Located in the periphery of a wider watershed, these were referred to as resulting from upstream developments such as deforestation in the mountains (from slash and burn farming, indiscriminate logging) and along riverbanks, and sand and gravel quarrying in various villages along the river. Upstream river

5 The Ormoc flashflood in November 1991 caused a tragedy of about 8,000 lives. Ormoc is a city in the central western part of Leyte and is also a part of the Daguitan watershed.

degradation (e.g. bank erosion, river siltation) causes floods which in turn cause downstream river sedimentation and erosion of riverbank agricultural land. Soil quality decreases through the loss of topsoil during the floods but sometimes increases through deposition of fertile silt deposits or sediments.

However, sediments have low organic matter content and lose some of the nutrients in the process. Additionally, sediment quality is bound to decrease slowly (Saint-Girons, 2003). These phenomena affected agriculture through decreased fertility and crop productivity, or decreased production by washing out of crops or covering them up, or simply through loss of land.

Rice growing has been beset with water-related problems: too much water at unwanted times, and not enough when needed. The rains in December fill the rice fields and make them ready for the cropping season. Water would be drained during and after transplanting. When in excess and not drained at proper times (especially with the La Niña phenomenon), waterlogging destroys the rice crop. Though the rains that drain to the paddies benefit rice growing, the snail pests that may be carried by water are threats to the crop.

Also, the irrigation system set up by the National Irrigation Authority is another major constraint. Paddy rice growers could only grow the crop mostly once a year due to organization-management-related conflicts (Saint-Girons, 2003). Rainfed rice in the northern and central parts of the village were also exposed to the vagaries of the 8-10 year spells of serious drought (the El Niño phenomenon.

Plaridel

Soil erosion by water is evident in Plaridel as indicated by the following observations. BSWM reported that the erosion status is between slight erosion (sheet erosion and rills but less than 3 per meter) to severe erosion inland. The latter has been indicated by the presence of gullies and rills in many places, scores of areas with apparent rock or parent material from landslides, muddy river flows during rains, and huge run-offs after heavy rains and flooding flat areas. Water erosion causes the removal of the topsoil, reduces levels of soil organic matter (SOM), contributes to the breakdown of soil structure, and results to nutrient loss. This creates less favourable environment for plant growth. Deposits of eroded materials can obstruct roadways and fill drainage channels. Sediment can damage fish habitat and degrade water quality in streams, rivers, and lakes. The presence of small rills on the soil surface, soil deposits at the base of slopes, sediment in streams, lakes, and reservoirs, and pedestals of soil supporting pebbles and plant materials mark water erosion.

Long-term soil erosion creates large gullies, exposure of lighter coloured subsoil at the surface, and poorer plant growth. Water erosion is most obvious on steep, convex landscape position, but not always readily visible on crop land because farming operations may cover up its signs. (USDA, 2001; Saint-Girons, 2003).

Villagers distinguish between two common phenomena laka and banlas. The former refers to a condition of exposed rock found in many areas on the hillsides or mountainsides which were exposed to strong winds and

flow of water. Laka started with the very strong typhoon, “Oracan”, in 1929.

Other strong typhoons contributed to the presence of a number of severely eroded areas to the point that local folks have resigned themselves to the forces of nature. Farming has become a matter of luck.

Thus, laka is basically water-caused removal of soil through rains or flooding. While farmers acknowledged both human and natural causes, they could recognise only clearly the latest and more severe stages of erosion in their farms. The least severe stage recognised is a soil with most of the topsoil gone with visible stones. The more severe stages are landslides where only the parent material is left. At the farm level, banlas means that the soil cannot be productively farmed anymore due to erosion where the topsoil is removed and stones appear. This condition could be less evident when farmers plant some trees on their farms, or their farms are far from the river and, thus, not affected by heavy water flows. Many times, erosion symptoms are taken seriously only when it is already too late for a change in soil condition, or land use (Saint-Girons, 2003).

Biodiversity losses

The indigenous cultivars of upland rice, sweetpotato and other native crops have disappeared as they could not even be grown now in cogon areas. The garden vegetables like alugbati (Basilia rubra L. ), malunggay (Moringa oleifera), kangkong (Ipomoea aquatica), pako (Athyrium esculentum) are less grown now than before, except for a few industrious gardeners. The bag and mat making among women tended to shift part of the labour needed in field gardening and other non-farm activities. Yams used to be grown but these also diminished as these also needed intensive work when staking and care in the early stage of growth. Farmers then have shifted their labour to working in or growing coconut and/or abaca when these crops began to have important commercial value. Even native fruit trees such as the star apple (Chrysophyllum cainito), tisa or egg fruit (Poteria campechiana), and jackfruit (Artocarpus heterophyllus) diminished as they were not replaced when destroyed by strong typhoons. The destruction of some areas in the forest by small time loggers as well as its intensified use by deep-mountain-dwelling insurgents contributed to the disappearance of wild pigs, deer and monkeys which were hunted for food. A combination of degradation-induced destruction of the fish habitat and indiscriminate big-time fishing contributed to the loss of fish population. In addition currently, abaca and banana are facing the threat of diseases: locally known as alcojeres⁴ and “bugtok”⁴, respectively.

4 Both are types of the bunchy top disease (BTD) which is a serious viral disease infesting abaca and plantain. Infected plants have rosette appearance with narrow, upright and progressively shorter leaves, looking like a “bunchy top”. The leaf edges roll upwards, a marginal yellowing, with short dark green spots. The disease can be controlled only by eradicating the diseased plants and using clean planting materials; measures which are difficult among farmers in the hinterlands (Thomas et al., 1994)