A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 2005

In Vietnam, the farmers in the subsistent agricultural systems rely more on animal manure, but rather reluctant to use green manure, which is believed to be less effective in terms of nutrient supply to crops compared to animal manures. This hinders the use of green manure in the local farming areas in the midlands and highlands of Vietnam. This study was conducted to assess the potential of both animal and green manures for improving the soil fertility and for improving the production of crops, as this helps to uplift the livelihood of subsistent farmers in the midlands of Vietnam. Nine different treatments composed of fresh pig manure, fresh buffalo manure, and fresh green manure and combinations of fresh pig manure, fresh buffalo manure, and fresh green manure at the ratios 1:1:1 and 1:1:2, fresh pig manure and fresh green manure, fresh buffalo manure and fresh green manure and fresh pig manure and fresh buffalo manure at the ratio 1:1 were evaluated together with two control treatments: without both manure and fertilizer and without manure but with recommended inorganic fertilizer were tested for leaf mustard (Brassica Juncea L.) in a randomized complete bock design with three replications during two consecutive dry and wet seasons from March to August 2005. Within the two seasons, addition of raw green material and composting technique was effective in the improvement of the quality of fresh organic material, yield of leaf mustard and soil fertility. The compost manures significantly increased soil fertility in terms of pH, electricity conductivity, organic matter, total nitrogen, total and available phosphorus and potassium contents in soil compared to fresh forms and control treatments. The average leaf mustard yields given by compost manure were superior to that of two control and fresh manure treatments. Heat compost prepared using pig dung, buffalo dung and green manure at a ratio of 1:1:2 gave the highest leaf mustard yield of 24.4 t/ha in the dry season and 24.5 tlha in the wet season. The second highest yield of 18.4 t/ha in the dry season and 22.56 t/ha in the wet season was found in the heat compost prepared using pig dung, buffalo dung and green manure at a ratio of 1:1:1. In addition, composting enhanced the hygienic condition of the yield as it destroyed both E. coli and egg of Ascaris worms that were detected in large numbers in plants harvested from plots provided with of the noncomposted form of manures