A Thesis submitted in partial fulfillment of the requirements of the Degree of Master of Science, School of Environment, Resources & Development

Thesis (M.Sc) - Asian Institute of Technology, 1994

In a field trial on an acid sulphate soil, green manures gliricidia and leucaena, animal manures fresh goat manure and composted goat manure, and urea were applied as an N source for maize (Zea mays L. KTX 3501) at the rates of 25 and 50 kg N ha-1 {u2022} Growth of maize was determined largely by elevation of the plot. Elevation determined the degree of water-logging after irrigation. Crop growth and yield was strongly correlated with elevation. None of the N materials applied at 25 kg N ha- 1 supplied enough N to the crop to influence yield. Gliricidia and fresh goat manures at 50 kg N ha·1 resulted in growth and yield responses in maize similar to the response to added urea. Gliricidia applied at 50 kg N ha-1 increased plant height, dry matter accumulation, dry matter yield and N yield of maize compared with no N application. There were no significant affects of any material at either rate of application on net N mineralization, apparent N recovery or soil total N at harvest. Chemical constituents of manures such as concentration of N, lignin, polyphenol, and ratio of C:N, lignin:N, polyphenol:N, and lignin+polyphenol:N neither correlated with total dry matter yield nor with net N mineralization and apparent N recovery. The practice of using green manure as an alternative source of N fertilizer for maize is possible on acid sulphate soils in Thailand.