"RAPID COMPOSTING TECHNOLOGY IN THE PHILIP PINES ITS ROLE IN PRODUCING GOOD QUALITY ORGANIC FERTILIZERS Virginia C Cuevas"
RAPID COMPOSTING TECHNOLOGY IN THE PHILIP- PINES: ITS ROLE IN PRODUCING GOOD-QUALITY ORGANIC FERTILIZERS Virginia C. Cuevas Institute of Biological Sciences (IBS), College of Arts and Sciences, University of the Philippines at Los Baños, College, Laguna, Philippines ABSTRACT Rapid composting technology involves inoculating the plant substrates used for composting with cultures of Trichoderma harziamum, a cellulose decomposer fungus. The fungus, grown in a medium of sawdust mixed with the leaves of ipil ipil, is called compost fungus acti- vator (CFA). There must be favorable conditions for the decay process, such as adequate mois- ture, an appropriate initial C:N ratio of substrates, and aeration. The composting period is shortened to just four weeks. The transfer of this technology to Filipino farmers through a National Program is de- scribed. Constraints in technology transfer, economic benefits from the use of compost processed through this technology, and other benefits attributed to the technology are explained. Soil fertility problems in the Philippines, and official fertilizer recommendations, are dis- cussed, together with how the use of compost processed through the rapid composting technology might address these fertility problems. FERTILIZER PRODUCTION AND UTILIZATION (PCARRD info sheet 1996). These figures may have IN THE PHILIPPINES increased by 1996, since a number of producers of compost who use the Rapid Composting Technol- The Philippines is basically an agricultural ogy have obtained licenses from the Fertilizer and country. Most of the population live in rural areas, Pesticide Authority (FPA). and agriculture employs about 50% of the total work force. A large amount of chemical fertilizers are MAJOR CONCERNS ABOUT SOIL FERTILITY used: 1.4 million mt in 1995. Of this, 37% was urea, STATUS IN THE PHILIPPINES, half of which was imported. In 1995, the Philippines AND FERTILIZER RECOMMENDATIONS exported around 700,000 mt of chemical fertilizer and imported about 1,237 thousand mt, about half of Some major problems regarding soil nutri- which was urea. More than half the chemical fertil- ents and soil productivity in the Philippines, and izer applied in the Philippines (52%) is used for rice fertilizer use by Filipino farmers, have been identified and corn. by the Bureau of Soils and Water Management Organic fertilizer production began in 1974, (BSWM) of the Philippine Department of Agricul- but in 1978 organic fertilizers were less than 1% of ture. total fertilizer sales, rising to 1.34% in 1992. As of Most soils in Central Luzon, a major rice 1993, there were 26 licensed manufacturers of or- producing area of the country, have been degraded. ganic fertilizers, and 15 processors of guano phos- They are suffering from soil acidity, low organic phate, phosphate rock, and soil conditioners matter, and a deficiency of zinc and sulfur. In most Key words: Composting, compost fungus activator, inorganic fertilizers, technology transfer 1 cases, the sulfur deficiency is because of the continu- inoculation with pure cultures of Trichoderma ous use of urea as the main nitrogen carrier. harzianum Rifai, a cellulolytic fungus. The fungus is Zinc deficiency is not confined to Central cultured in sterile sawdust mixed with leaves of ipil- Luzon, but is also found in other major rice-produc- ipil (Leucaena leucocephala, a leguminous tree). ing areas of the country. A number of zinc-deficient The whole package — a one-kilogram pack of areas have been identified where lack of zinc is a fungus medium in a plastic bag — is referred to as major limiting factor, and yields are low even with compost fungus activator (CFA). The activator is high fertilizer applications. The problem is thought broadcast over rice straw or other plant residues to arise because the soils are derived from limestone, when the substrate is made into a pile. It should be and because of intrusions of tidal sea water. applied at a rate of 1% (by fresh weight) of the There is an increasing consumption of fer- substrate. Adequate moisture and aeration should tilizer in the Philippines, but this increase has not be provided throughout the composting period. The been translated into a proportional increase in crop initial C:N ratio of the substrate should be kept low, yields. This is probably because of the lack of a good by combining animal manure with plant materials nutrient balance in fertilizer applications. Filipino with a high carbon content. The composting time, farmers use 4 - 7 kg nitrogen to every kilogram of using this procedure, ranges from 21 to 45 days, phosphorus fertilizer, while the desired ratio should depending on the plant substrates used (Cuevas be 3 - 4 kg N for every kilogram of P. 1988a, b). In most situations, small-scale farmers ap- The activator increases the population of ply much less fertilizer than has been recommended. microbial cellulose decomposers. If the compost This can be attributed to the high cost of chemical pile has an adequate moisture content, enough ni- fertilizers. trogenous materials and good aeration, these micro- Furthermore, most soils in the Philippines organisms multiply rapidly. The increase in the require a balanced supply of calcium and magne- population of microorganisms raises the tempera- sium, in addition to N, P, and K. ture inside the compost heap, which in turn hastens The Bureau has submitted a series of rec- the decomposition process. The composting period ommendations for fertilizer use. These include both is shortened to just four weeks. primary fertilizer recommendations to supply basic The technology basically consists of two soil nutrients, and secondary fertilizer recommenda- parts: the production of the compost fungus activa- tions that supply additional nutrient requirements tor, and the composting process. according to the need of the actual crop location. These nutrients can be supplied by both organic and TECHNOLOGY TRANSFER TO inorganic sources. Different grades for inorganic FILIPINO FARMERS fertilizers, or the amount of organic fertilizer needed for each soil type and climatic types in each province In 1990, the Philippine government, through and region, are available (BSMW, Dept. Agriculture the Philippine Council for Agriculture, Forestry and 1996). Natural Resources Research and Development The Fertilizer and Pesticide Authority (FPA) (PCARRD), began a national program which intro- is an agency under the Department of Agriculture duced to Filipino farmers the rapid composting tech- that regulates the importation, manufacture, distri- nology and the use of compost as fertilizer. The bution, and sale of fertilizer. It has formulated compost produced through this technology is now guidelines on good agricultural practices to optimize part of fertilization recommendations for rice and fertilizer use. These guidelines advocate an inte- other crops. grated plant nutrition system that involves the com- During the first three years, emphasis was bined use of organic and inorganic fertilizers. It is on the establishment of mass production centers for designed to promote sustainable productivity. the compost fungus activator throughout the Philip- pines. Government technicians were trained in the THE IBS RAPID COMPOSTING TECHNOLOGY production of the activator, and in the composting process using this activator. These trainees in turn This technology was developed by the au- conducted their own training courses in their home thor (Dr. V.C. Cuevas), and is named after the provinces. The target of the program then changed Institute of Biological Sciences (IBS) where the to farmers, encouraging them to produce their own author works. It is a development of the windrow compost using raw materials such as rice straw and type of composting, and the main innovation is animal manure available on their farms. 2 In this second phase of the program, farm- 3 parts rice straw - 1 part ipil-ipil ers’ cooperatives, private enterprises and non-gov- 4 parts rice straw - 1 part chicken manure ernment organizations were assisted to establish 4 parts grasses - 1 part legume materials + compost production units. Mechanization of some 1 part manure of the production steps was included in the program. 4 parts grasses - 1 part Chromolaena The compost produced was sold to farmers in 50 kg odorata* or bags. Assistance was given in terms of: Mikania cordata* + • Training in the production of the activa- 1 part animal manure tor; • Advise on how to use it in proper Note: It is important to use grasses and weeds composting procedures; which do not have any flowers or seeds. • Analysis of the nutrient content of the compost produced; Composting Procedure • Mechanization of the composting pro- cess; The substrates should be piled loosely in a • Help in obtaining credit from banks and compost pen to provide better aeration within the other institutions; heap. The material should not be too compact and no • Conduct of efficacy trials of the compost heavy weights should be put on top. Compost heaps produced; should be located in shady areas such as under big • Registration of the compost at the FPA; trees. The platform should be raised about 30 cm and from the ground, to provide adequate aeration at the • Securing a license as a compost manu- bottom. Alternatively, aeration can be provided by facturer from the FPA. placing perforated bamboo trunks horizontally and vertically at regular intervals, to carry air through the STEPS IN COMPOSTING compost heap. The compost activator, consisting of a cel- Preparation of Substrates lulolytic fungus, is broadcast onto the substrates during piling. The amount of activator used is Substrates such as rice straw, weeds and usually 1% of the total weight of the substrates (i.e. grasses should be chopped. Chopping helps speed about 1 kg compost activator per 100 kg substrate). up decomposition by increasing the surface area Decomposition is faster if the activator is mixed available for microbial action, and providing better thoroughly with the substrate. A greater amount of aeration. If large quantities of substrates are to be activator can be used if faster decomposition is used (i.e. several tons), a forage cutter/chopper is desired. needed. Chopping can be dispensed with if the The heap should be covered over com- compost is not needed in the near future. pletely. This maintains the heat of decomposition, and minimizes water evaporation and ammonia vola- Adjustment of Moisture Content tilization. White plastic sheets, or plastic sacks with their seams opened and sewn together, can serve as Substrates should be moistened with water. a cover. Plant substrates can be soaked overnight in a pond, The compost heap usually heats up in 24 - which cuts down on the need for water. If a large 48 hours. This heat is very important, especially if volume of substrates are to be composted, a sprin- manure is used, because it kills disease microorgan- kler is more convenient. isms. Some seeds of weeds are also rendered nonvi- able. Temperature readings should be taken at The Compost Mixture different parts of the pile at least three times a week. Heat should be maintained at 50°C or higher, Carbonaceous substrates should be mixed and the heap should be turned over every 5-7 days for with nitrogenous ones at a ratio of 4:1 or less, but the first two weeks, and thereafter once every two never lower than 1:1 (on a dry weight basis). Some weeks. Turning over the pile provides adequate possible combinations are: aeration, and evens up the rate of decomposition * Chromolaena odorata: A common broad-leaf weed Mikania cordata: Herbaceous climbing plant, a common weed in the Philippines. (Ed.). 3 throughout the pile. It also serves as a means of up big lumps of mature compost before checking the moisture content of the substrate. After drying. the first week, the volume of the pile should be • During rainy months, it is more eco- reduced by one-third. After two weeks, the volume nomical to dry compost mechanically of the pile should be reduced to one half the original. than try to sun dry it. Compost Maturity NUTRIENT CONTENT OF COMPOST The compost is ripe if: Table 1 presents the ripening period and • The temperature in all parts of the pile chemical composition (% C, N, P, K) and pH of the drops to 33-35°C, or approximately air mature compost produced through this rapid temperature, after the 2nd or 3rd turn- composting technology. The compost has a neutral ing. to alkaline pH. The length of time needed for the • The different materials in the substrate compost to mature was dependent on the type of are no longer recognizable. plant substrates used for composting. The more • The compost is dark brown to black, fibrous the plant materials, the longer the period and looks like soil. needed for composting. The composting period for • The ripe compost does not emit a foul rice straw, for example, was almost double that odor. needed for sugarcane bagasse. This difference can If the temperature of the heap drops to be traced to the initial C:N ratio of the substrates 30°C but the compost is not needed immediately, it used for composting. Usually, fibrous materials is best to let decomposition continue further. The have a low nitrogen content but are rich in carbon, mature compost should be removed from the pen, giving a high initial C:N ratio. The initial C:N ratio and dried in the sun for two days. It should then be of the substrates used for composting plays a major put into sacks and stored in a shaded area. Decom- role in determining the length of the composting position will continue until the substrate is finely period. If substrates have an initial C:N ratio of 25:1, fragmented, so that the finished product has a pow- the composting period can be shortened to only three dery texture. Then, once decomposition is com- weeks. plete, the compost should be sun-dried again until The mature compost has a low level of N, the moisture contest is at most 10-20%. P and K, compared to chemical fertilizer. On the If mature compost is needed at once, it other hand, compost also contains a wide range of should be sun-dried for one day, as soon as its the plant nutrients that are essential for crop growth. temperature drops to 30°C. Drying removes excess Table 2 shows that compost contains C, Ca, Mg, Zn, moisture, and makes the compost much easier to and B, and probably contains a number of other handle. Although the compost still retain some micronutrients which were not included in the analy- fibers, it can be applied immediately as fertilizer. sis. These micronutrients are not present in the In a tropical country like the Philippines, ordinary formulations of inorganic fertilizer sold on compost can be made throughout the whole year. the market. The presence of large quantities of Mature compost can be stored for at least six months organic carbon in compost also helps improve the without any appreciable change in nutrient content, physical and chemical properties of soils. Common especially if the stored compost has a very low changes which follow continuous compost applica- moisture content (10-20%). tion are: improved water holding capacity, increased soil aeration and increased soil pH. Commercial Compost Production FERTILIZER RECOMMENDATIONS In the large-scale commercial production USING COMPOST of compost, it is recommended that the following steps be mechanized. Compost Produced by Individual • Chopping of substrates. Farmers • Mixing/Turning. When there are several tons of substrate, a pay loader will Farmers are advised to utilize all available make mixing of substrates or turning of materials on the farm as substrates. All the compost heaps much easier. produced should be applied as a basal fertilizer just • A hammer mill should be used to break before the last harrowing, and before the transplant- 4 Table 1. Maturing period and composition of compost from different materials, using rapid composting technology Source: Cuevas and Agarado 1987 5 ing of rice seedlings. The compost should be applied N, P and K content than the compost produced by at a rate of at least 1 mt/ha. With regard to chemical most farmers. To compensate for the low nutrient fertilizer, half of the recommended rate should be content of compost produced on farms, larger quan- applied 30 - 45 days after transplanting, as a side- tities of the fertilizer are therefore recommended. dressing or top-dressing. CONSTRAINTS EXPERIENCED IN TECHNOL- Commercial Compost OGY TRANSFER When commercially-produced compost is One reason why large number of Filipino used, 500 - 750 kg/ha should be applied (10 - 15 farmers were not very enthusiastic in adopting the bags, 50 kgs each) as basal fertilizer. As with the rapid composting technology was the high labor farm compost, half of the recommended level of input involved in making the compost and applying chemical fertilizers should be applied 30 - 45 days it as fertilizer. The labor demand was about 6% after transplanting. higher than when chemical fertilizer alone was used. It can be seen that the recommended level The higher labor input involved: the gathering of of compost to be applied by farmers when they make substrates, piling substrates into heaps, and applying it themselves is higher than when commercial com- a large volume of compost to the field. Filipino post is used. Experience has shown that the compost farmers would prefer to buy commercial organic produced on farms has a very low N, P and K fertilizer (if this is available), rather than make their content, because only small amounts of nitrogenous own compost. substrates are used for composting. Table 1 shows Other major constraints in making compost that farmers’ compost contained only 1% of N, P on farms were the lack of animal manure as a source and K. Farmers have difficulty in obtaining large of nitrogen and phosphorus, and also of plants rich in amounts of animal manure. Filipino farmers do not nitrogen, and water shortage during dry months. In usually confine their draft animals in feedlots, but many parts of the Philippines, there is a dry season graze them in the open field, which makes it difficult which lasts 2 - 4 months. to collect the livestock manure. These three major factors — increased Commercially produced compost is regu- labor demand, inadequate nitrogenous materials and lated by the FPA. For a product to be registered as lack of water for composting — made transfer of the a commercial organic fertilizer, it must contain a technology difficult in the first three years of the total of at least 7% of the three main elements, N, P program. The emphasis at that stage was on con- and K, and at least 10% carbon. The National vincing farmers to produce their own compost. Program requires that of this 7%, the N content is not Mass production centers for the activator were es- lower than 1.5%, while P and K make up the remain- tablished in almost every province, so the activator der. Thus, commercial compost has a much higher Table 2. Composition of compost made from rice straw + weeds (grasses, broadleaved weeds), chicken manure and inoculant (Trichoderma harzianum) Source: W.M.J. Bandara (1991) 6 would be easily available to farmers. Although, the main emphasis in gathering data was Despite these drawbacks, a sizeable num- on rice, increases in yields were also noted in sugar- ber of farmers adopted the technology, and followed cane and vegetables where compost was applied as the recommendations for using the compost as fertil- a basal fertilizer and chemical fertilizers were applied izer. In addition, there were a number of farmers’ as a side or top-dressing. cooperatives, NGOs, and small enterpreneurs who picked up the idea of commercially producing com- Improvement in Physical and Chemical post, using the technology. The National Program Properties of Soil shifted its emphasis, and over the last three years (1993 - 1996), has been assisting interested organi- Other benefits were also mentioned by the zations to establish compost production units. farmers. These perceived benefits, and the relative The two biggest problems encountered in importance given to them by farmers, are presented doing this was firstly, the registration of the compost in Table 6. Improvement of soil tilth and texture, product as organic fertilizer by the Fertilizer and increase in soil fertility and reduced fertilizer costs Pesticide Authority (FPA), and secondly, securing a were the most important benefits that farmers got license for the compost producers from FPA to allow from using compost in rice production. The de- them to produce compost commercially. The rules crease in nitrogen fertilizer requirements was esti- and regulations regarding efficacy trials for their mated to be about 19 kg N/ha. compost were not immediately clear to the compost The yield increases in rice and other crops producers. This lack of proper information posed can be traced to the capability of the compost to great problems in marketing, and was a constraint to supply nutrients needed for crop growth. The Bu- further expansion of commercial compost produc- reau of Soils and Water Management of the Philip- tion. pines has identified an imbalance of nutrients sup- Important lessons noted were the impor- plied by chemical fertilizers alone, and a deficiency of tance of extension staff and demonstration farms in Ca, Mg and Zinc in soils in different parts of the technology adoption. country. These elements, lack of which may limit crop growth and productivity, are present in com- POSITIVE IMPACT OF THE COMPOST post fertilizer. Fertilizer applications which included TECHNOLOGY compost have a better chance of meeting all the crop’s nutrient requirements. The technology there- Crop Yields and Economic Benefits fore has great potential in helping Philippine agricul- ture attain sustainability, not only in terms of crop Pilot testing of the technology in different yields, but also in terms of protecting and conserving parts of the Philippines have shown clearly the soil fertility. benefits farmers can get if they follow the program. Table 3 presents the cost/benefit analysis of rapid Compost Production as a Viable composting during pilot tests in two regions of the Business Enterprise country in 1989-90. At that time, the increase in farmers’ income ranged from US$78-100 per crop- As farmers became aware of these benefits, ping season (4 months). In terms of crop yields, a demand for commercial compost arose. The combined use of compost + 50% inorganic fertilizers number of compost production units using the rapid resulted in increases in crop yields which were 13% composting technology increased. At present, there - 16% higher than in fields where chemical fertilizers are 48 Mass Production Centers for the fungus alone were used. activator, and 23 Mass-Production Compost units in A socio-economic analysis was conducted different parts of the Philippines. Most of these are in 1996 on the impact of the rapid composting in the large islands of Luzon (northern Philippines) technology. This study confirmed the increased and Mindanao (southern Philippines), with relatively incomes of 68 farmers (from three different prov- few in the Visayas. Most of the Mass Production inces) who had adopted the technology. These Centers have been established by national or local results are presented in Tables 4 Table 5. Yield government agencies, and serve individual farmers increases were up to 15% higher compared to those who want to produce their own compost. of farmers who did not use the technology, but used Table 7 presents the production and sales of only chemical fertilizers. In monetary terms, the the compost produced by commercial plants using increase in income per season was up to US$169. the activator. Compared to the production and sales 7 Table 3. CostBenefit analysis of rapid composting using rice straw (198990 data) Source: Cuevas 1991 of the organic fertilizers from 1988 - 1992, the values, it is estimated that the government’s invest- performance of these plants was better. Their sales ment of US$2.36 million into technology gave a were higher, reaching about 50% of their produc- benefit of US$18.1 million (Librero and Tidon tion, whereas sales of organic fertilizer before the 1997). rapid composting technology (1992) reached only 35% of production. Rola, et al. (1996), in their Employment Generated by the Produc- socio-economic evaluation of the technology, noted tion Units the positive growth rate of the compost plants, which suggests that farmers are increasingly buying com- The cost benefit ratio of 7.7 mentioned post rather than producing it themselves. above was based only on the contribution made by the compost to rice production. Rola et al. (1996) High Cost-Benefit Ratio mentioned the employment generation that the es- tablishment of compost production units brings to A cost-benefit analysis of the government local communities as an additional benefit derived investment into the National Program was carried from the rapid composting technology. Each out, using socio-economic data collected by Rola et. composting unit employs 2 - 23 laborers. Although al. 1996. The techno-logy transfer of rapid employment is often intermittent, these composting composting to farmers was accompanied by an in- units are located in rural areas where employment is crease in total rice production in the Philippines of very scarce. 0.11%. The data are presented in Table 8. An incremental value of US$13.3 million was estimated Environmental Impact of the for this increase in rice production for the period Technology 1992 - 1996. The computed cost-benefit ratio for the technology was 7.7 (Table 9). Using 1996 monetary Another benefit from the technology is 8 Table 4. Comparative Analysis1) of Rice Yields, Fertilizer Use and Labor, Among users and nonusers of Rapid Composting Technology, 1993 and 1995 wet season Source: Rola et al. 1996 Table 5. Comparative analysis of cost and returns1) per hectare among users and nonusers of Rapid Composting Technology, 1993 and 1995 wet seasons *Source: Rola et al. 1996 the efficient recycling of agricultural wastes. farms and sold to compost producers. In this A number of compost production units utilize process, environmental pollution due to these mud-press, a waste product of sugarcane wastes is slowly being reduced. processing, as a substrate. Others use corn cobs, while one farmers’ cooperative utilizes PRESENT STATUS OF THE banana peels, and still others use market NATIONAL PROGRAM wastes. Animal wastes such as chicken and hog manure are now being collected from Additional funds from the Philippine Gov- 9 Table 6. Farmers’ perceived benefits from using the Rapid Composting Technology1), wet season 1995. Source: Rola et al. 1996 Table 7. Compost production and distribution using Rapid Composting Technology Source: Librero and Tidon 1997 ernment are being requested for continuation of the M.Sc. Thesis, University of the Philippines program for another three years, which will consti- at Los Baños, College, Laguna, Philip- tute its last phase. The emphasis during this last pines. phase will be on completing the technical assistance Bureau of Soils and Water Management, De- to the CPUs and to all other organic fertilizer pro- partment of Agriculture. Philippines. ducers. The main goal is to offer to farmers in the 1996. A Primer on Reformulating Fertil- Philippines good-quality organic fertilizers at a rea- izer Recommendations. sonable price, to the benefit both of farm incomes Cuevas, V.C., S.N. Samulde and P.G. Pajaro. and Philippine agriculture. 1988a. Trichoderma harzianum Riifai as an activator for rapid composting of agri- cultural wastes. The Philippine Agricul- REFERENCES turist 71,4: 461-469. Cuevas, V.C. 1988b. Make Your Own Com- Bandara, W.M.J. 1991. Effects of Lime and post. TLRC-UPLB Techguide Series No. Organic Matter on Soil Acidity, Alumi- 11. National Book Store, Inc., Manila, num, Phosphorus and Growth of Corn Philippines. and Mungbean on Two Acidic Soils. 10 Table 8. Estimated incremental rice production from Rapid Composting Technology (RCT) 19921996 Source: Librero and Tidon 1997 Table 9. Estimates of economic benefit and cost from rapid composting (US$ million at 1996 prices) Cuevas, V.C. and M.T. Agarrado. 1987. Rapid Composting held at Marina de Bay, Technology: Make Composting Easy with Puerto Princesa City, Palawan, April 16- Trichoderma. Philippine Council for Agri- 17, 1997. (Unpublished mimeograph). culture, Forestry and Natural Resources Maglinao, A.R. 1997. The National Program Research and Development, Los Baños, on Rapid Composting and Use of Com- Laguna, Philippines. post as Fertilizer: Accomplishments and Cuevas, V.C. 1991. Rapid Composting for Direction. Paper presented during the 5th Intensive Riceland Use. Innovations for Annual Reional Coordinators Meeting of Rural Development 1,1: 5-10. SEAMEO- the National Program on Rapid SEARCA. Composting held at Marina de Bay, Fertilizer and Pesticide Authority (FPA), De- Puerto Princesa City, Palawan, April 16- partment of Agriculture, Philippines. 18, 1997. (Unpublished mimeograph). 1996. Fertilizer Statistics from CY 1990 Philippine Council for Agriculture, Forestry to January - June 1996. and Natural Resources Research and De- Fertilizer and Pesticide Authority (FPA). velopment (PCARRD). 1996. Informa- 1993. Report. Department of Agri- tion Sheet: The Fertilizer Industry. May culture, Philippines. 1996. Fertilizer and Pesticide Authority (FPA). Rola, A.C., A.R. Chupungco, M.G. Umali 1997. Guidelines on Good Agricultural and S.D.E. Callet. 1996. Socio-Eco- Practices. Department of Agriculture, nomic Evaluation and Policy Analysis of Diliman, Q.C., Philippines. the Commercialization of the Rapid Librero, A.I. and A.G. Tidon. 1997. Socio- Composting Technology-Phase II. Termi- Economic Evaluation of the Commercial- nal Report. University of the Philippines ization of Rapid Composting Technology. at Los Baños and the Philippine Council Paper presented during the 5th Annual for Agriculture, Forestry and Natural Re- Meeting of the National Program on sources Research and Development, Col- 11 lege, Laguna, Philippines. (Unpublished mimeograph). DISCUSSION Dr. Cuevas was asked about the origin of the fungal inoculant for compost production. She explained that she had isolated it in soil from Mount Makiling, near the University of the Philippines at Los Baños. This had been part of a survey of fungal flora, particularly of Trichoderma which is a common fungus in the Philippines. The identification had been confirmed by Kew Gardens, United Kingdom. The fungus produces a cellulase and can be cultured very easily in a simple medium such as coconut water. It is a common contaminant of mushroom culture, and Trichoderma culture should not be carried out near mushroom production houses. It was noted that bags of compost sold in the Philippines must carry a label with the N, P and K content. One participant asked how often the company checks on the nutrients in the compost. Dr. Cuevas explained that the FPA requires the producer to submit an analysis of the nutrient content of the compost before it is registered, and before the producer is granted a license to make commercial compost. She did not know whether the NPK levels are regularly monitored, but thought that levels would probably be variable, since the materials used for compost are variable. Another participant asked whether the compost is tested, and Dr. Cuevas explained that commercial compost must pass an efficacy test in the field, carried out by an approved research institute. Another participant asked about the cost of compost compared to chemical fertilizer, on a nutrient basis. Dr. Cuevas replied that a 1 kg bag of urea costs about US$20, and contains 23% N. In comparison, a 1 kg bag of compost costs US$5, and contains about 4% N. Chemical fertilizers are therefore much cheaper, on a nutrient basis. It is recommended that farmers use a combination of chemical and organic fertilizers, rather than compost alone. Because of excessive nitrogen use in the past, many soils have an imbalance of nutrients, and show a good response to compost. The question was asked what the term “maturing period” meant, in Table 1. Dr. Cuevas explained that this refers to the length of time it took the compost to reach maturity. There are several criteria of compost maturity, one being color — mature compost is black. Temperature is also a good indication of maturity. If after some time, the temperature of the compost falls to a stable lower level of around 28-30oC, the compost is probably mature. The main indicator of compost maturity is the C:N ratio, but this is not suitable for use by farmers, who must rely on temperature changes and the appearance of the compost. 12