About 14.82 million hectares or 49.4% of the country’s total land area have slopes of 8-50%.  These uplands/hilly lands are further classified into the following slope classes: 8-18% (4.69 M), 18-30% (5.15 M), and 30-50% (4.97 M).  About 4.3 M hectares of the country’s hilly lands are being cultivated (BSWM, 1994).  The major concern in the hilly lands and upland areas is controlling soil erosion.  This soil degradation process had been recognized. Plot and farm level studies have been conducted and the following erosion control measures have been developed

  1.  Vegetative or biological control measures  

• Hedgerow farming or contour strip farming, cover cropping, intercropping/multiple cropping, multi-storey cropping, crop rotation, strip cropping/buffer strip cropping, contour, agro forestry
• Other biological methods are brush cover or matting, bench brush layer, wattling, fascine, sodding and mulching
• The improved version or adaptation of the hedgerow method is the alley cropping system which is also known as the sloping agricultural land technology.  Several studies have been conducted to identify suitable hedgerow species.   Some of the species tested as hedgerow species include N-fixing trees or shrub legumes (Leucaena leucocephala, Gliricidia sepium, Acacia villosa, Flemingia congesta, Tephrosia candida);  forage grasses (napier, king grass, vetiver, sugarcane);  and fruit trees (banana, jackfruit, sapodilla, citrus, coffee, papaya, mulberry, cashew).
• Specific cropping schemes have been found successful in hilly areas with such main crops as corn, coffee, peanut and sweet potato.  Some effective cover crops have been identified also for selected locations.

2.  Engineering structures or mechanical control measures:  

• Terracing, rip rapping,/retaining walls, log cribs, gabions, check dams, zero tillage, contour tillage, water impounding, grassed waterways

 Acid soils  

     Acid soils are those which have a pH of less than 5.2 in the major part of the rooting zone.   About 16 million hectares of the country are constrained by various degrees of soil acidity.  To improve the productivity of acid soils grown to corn, pasture grasses and legumes, the studies conducted and technologies developed for some locations include:

• Rates and time of lime application and fertilization, particularly of phosphorus.
• Studies on the use of rock phosphate and peat to determine their effect on the yield of crops grown in acid soils.
• Screening/selection of acid tolerant varieties of corn, mungbean, peanut, soybean, sorghum, upland Agricultural Ecosystems and sugarcane.
• Studies are being done to improve strains of rhizobia for acid soils.

Ash and lahar-laden areas  

 The studies conducted and technologies developed for ash and lahar-laden areas include the following:  

• Documentation of extent of damage by volcanic deposits of Mt. Pinatubo
• Characterization of ash and lahar laden areas
• Micronutrient release in ash-soil mixture
• Physico-chemical and mineralogical dynamics in ash-soil mixture
• Studies on the performance of various crops in lahar affected areas
• Soil management and crop production techno guides for the following crops:  cabbage, corn, cowpea, eggplant, okra, onion, peanut, radish, Agricultural Ecosystems, sesame, sorghum, soybean, squash, sunflower, sweet potato, tomato.
• Performance of multi-purpose tree species in ash and lahar-laden areas.
• Controlled release fertilizers for lahar areas are being developed.
• Studies have shown that bagasse, mudpress, sesbania green manuring, and application of organic fertilizers improve the soil characteristics of volcanic ash-laden soils.