H—3

It is sufficient to say that it showed that there is a grave danger that the successful cultivation of hyacinths might cause serious trouble by the blocking of drains and waterways, and by the difficulty of preventing its spreading. These dangers have been recognized by the Department of Agriculture for several years, and the Department has obtained information about the trouble that water-hyacinths have caused in other countries. Their introduction into New Zealand was therefore prohibited by the Introduction of Plants Act, 1927, and action is being taken by the appropriate authorities to prevent their propagation in New Zealand by the application to them of the provisions of the Noxious Weeds Act, 1908. The plants have caused trouble in the Whakatane district, where they are infesting and blocking canals and streams, and the efforts made to eradicate them have proved to be very difficult. (7) We are satisfied from all the evidence that it would be most unwise to take the risks that would be involved in conducting experiments in their cultivation for composting purposes, and on this ground alone this proposal cannot be recommended. We should add that the evidence on this matter was so strong that Mr. Dyson in his final address was compelled to admit its weight, an admission which in our opinion was properly made. Composting of Municipal Garbage and Wastes 45. (1) It is an essential part of the Drainage League's proposals that the garbage collected by the Auckland City Council and other local authorities should be conveyed to a central depot where, after removing the inorganic matter, it would be used with wet sewage sludge to make compost. (2) The possibilities of utilizing city garbage and other wastes have in recent years attracted considerable interest and various municipalities have instituted schemes for composting these wastes. For example, in England the Boroughs of Leatherhead and Maidenhead, having populations of 26,000 and 28,000 respectively, have composted municipal wastes for several years, and in New Zealand the Borough of Dannevirke has embarked on an undertaking for the same purpose. Further, as has been mentioned, this subject was considered by the inter-departmental Committee which studied the utilization of organic wastes and which made the following recommendations : (а) One or more municipalities should be encouraged to install " pilot " plants for composting organic wastes. (б) Arrangements should be made for the processes of these " pilot " plants to be studied experimentally. (c) Arrangements should also be made for the large-scale agricultural and horticultural trial of the composts produced. The Auckland City Council is willing to conduct the experiments and the Government has granted a subsidy for the purpose. The construction of the necessary plant has not yet been completed. The results of these experiments and of other similar undertakings will, of course, be of national importance, and it is clear that many municipal authorities are showing great interest in the matter. (3) For the purposes of this inquiry the issue appears to be a comparatively simple one. Should the Drainage Board's schemes for the sewerage of the district and for the treatment and disposal of sewage be dependent on the results of the experiments ? (4) In considering this issue it must be pointed out that under the Drainage Board's scheme provision could be made if required for the production of an air-dried digested sludge which could be used as an activator in composting, and the production of this would not seriously affect the amount of sludge available for conversion to powdered fertilizer. The Drainage League, however, contends that the composting of municipal garbage and wastes should be carried out by the Drainage Board and that all the sludge available should be used in a composting scheme, which would be on a scale which has never previously been attempted and which would include novel features.

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