Restoration of Agriculture in Pinatudo Laser Areas

1991年，Mt.菲律宾皮纳图博火山爆发，大量火山灰沉积在赞巴莱山区。火山灰的存款在雨季被侵蚀成拉哈尔，一直延伸到吕宋岛中部平原的农业区。约有90，000公顷的农业和居民区受到拉哈尔沉积物的影响，1995年雨季的危害仍在继续。在塔拉克省的班班山谷对受拉哈尔影响地区的拉哈尔沉积物和先锋植物进行了调查。拉哈尔沉积物几乎由纯火山灰组成。火山灰的岩石类型为英安岩至安山岩。主要矿物成分为无色火山玻璃和长石。石英、角闪石、磁铁矿和黑云母被列为次要矿物。由于Truog法测得的有效磷含量高达50-60 mgP_2O_5/100 g，因此认为火山灰中含有磷灰石，粒度分布为粗砂-粉砂。虽然粉质材料含有10 - 15%的粘土，但粘土部分中的主要矿物是火山玻璃。非常少量的蒙皂石、蛭石和埃洛石也包括在粘土级分中。埃洛石的含量变化很大，主要的先锋植物是野生甘蔗，豆科植物较少。这些先驱植物的人口是高的，在远离主要的拉哈尔流的地方，并在主要的流沉积和侵蚀是重复frequent.Rice，玉米，花生种植进行了研究，控制有效性肥料（CAFs）在混凝土地块充满了拉哈尔存款。CAF对贫瘠和粗糙结构的拉哈尔沉积物中的玉米植株有效。在水稻小区中，由于缺铁，即使在CAFs小区中，植物生长也不是那么好。

In 1991, Mt. Pinatubo, Phillipines erupted and a large amount of volcanic ash deposited in the Zambales Mountain Area. The deposit of volcanic ash is eroded down to the agricultural area of the Central Plain of Luzon as lahar in the rainy season. About 90,000 ha of agricultural and residential areas were affected by the lahar deposits and the hazard was still continuing in the rainy season of 1995.Survey of the lahar deposits and pioneer plants in the lahar-affected area was carried out in Bamban valley, Tarlac Province. The lahar deposits consist of almost pure volcanic ash. The rock type of the volcanic ash is dacitic to andesitic. The major mineral components are non-colored volcanic glass and feldspar. Qualtz, hornblend, magnetite, and biotite was included as minor minerals. Since the content of available phosphorus by Truog's method was as high as 50-60 mgP_2O_5/100g, apatite was considered to be included in the volcanic ash.Particle size distribution was coarse-sandy to silty. Although the silty materials contained 10 to 15% of clay, the major minerals in the clay fraction was volcanic glass. Very small amount of smectite, vermiculite and halloysite was also included in the clay fraction. The content of halloysite was highly variable.Major pioneer plant was wild sugarcane with lesser population of leguminous plants. Population of these pioneer plants was high in the far places from the major lahar stream and was low in the major stream where deposition and erosion is repeated frequently.Rice, corn, and peanut cultivation was examined using controlled-availability fertilizers (CAFs) in the concrete plots filled with lahar deposits. CAFs were effective for corn plants in the infertile and coarse-textured lahar deposits. In the rice plots, plant growth was not so good even in the CAFs plot due to iron deficiency.