Improving farmyard manure (FYM) by covering it with black plastic sheeting to provide a favourable environment for microbialactivities, and to conserve available nutrients and moisture
Applying compost or farmyard manure (FYM) is an excellent way of maintaining and building soil fertility. Considerable nutrient losses often occur through the inappropriate handling or storage of compost and FYM. Drying out causes losses through volatilisation and rainfall whilst runoff causes leaching and the washing out of nutrients. To reduce nutrient losses, farmyard manure needs to be protected from direct sunlight, rainfall, run-on, and runoff. A number of improved composting methods have been tested and demonstrated with farmers in the Jhikhu Khola watershed. The Sustainable Soil Management Project (SSMP) has recommended black plastic-covered farmyard manure as one of the most promising methods. Farmyard manure is covered with a piece of black plastic to prevent nutrients from leaching out, to decrease evaporation losses, and to provide a more favourable environment for the growth of microbes due to the increased temperature and moisture content. This method is especially suitable for areas with low temperatures.
In this method, raw organic materials that are used for animal bedding – crop residues, leaves, grass, weeds and other organic materials – are piled up or put into a pit in layers together with animal urine and dung. The pile is then completely covered with black plastic sheeting. This method is based on the passive aeration approach, the plastic sheet is removed from the heap each day to add more bedding materials. It is then covered again immediately. Maintenance is easy although care is needed to avoid damaging the sheet. The black plastic should be handled carefully while taking it off and returning it to the pile as the composting material may contain sharp-edged plant stems.
The method was found to be easy to apply and took little time and labour. In the Jhikhu Khola area, women are mainly responsible for preparing manure and carrying it to the fields. This technology reduces their burden as a smaller amount of black plastic FYM is needed to meet soil nutrient requirements compared to traditional FYM, which is normally applied in a poorly decomposed form and in large quantities. The method was tested in the middle mountains of Nepal in the Jhikhu Khola watershed, located at 800-2200 masl and with 1200-1600 mm annual rainfall, about 70-80% in the monsoon months (June to September). The temperature ranges from 3-400C in the lower parts of the watershed and about 30C less at the higher elevations.
The investment costs are paid back within the first year leading to positive results due to higher production due to more nutrient-rich compost.