do you have something like a tool-lending library in your area? Most chippers I have seen/used do not make sawdust, but make chips which decompose differently and are more decorative than amendment...sorry to not help more with your quesiton but...

fyi about fresh sawdust amendment in the garden (sorry about the mishmash of good info here)
Sawdust is organic, an obvious by product of lumber processing. However, for the necessary breakdown process to occur, the sawdust requires nitrogen. Gardeners know that fresh or new sawdust can cause a shortage in available plant nutrients by using nitrogen from the ground, pulling it away from plants.

Sawdust is often readily available, but is the least desirable source of organic matter. Sawdust ties up nitrogen as it decomposes in the soil, causing plants to suffer or even die from nitrogen deficiency. The nitrogen deficiency from sawdust decomposition often lasts 2-4 years, requiring additional applications of nitrogen to supply plant needs. Mix slow-release forms of nitrogen, such as manure or composted biosolids, with sawdust because they will supply nitrogen for many months as the sawdust decomposes. Sawdust and biosolids or manure should be mixed in a roughly 2-3:1 (sawdust:nitrogen source) ratio. Additional nitrogen fertilizer is often needed in the second and even third year after sawdust addition to maintain plant growth. Watch plants for nitrogen deficiency (pale green leaves and slow growth) and add nitrogen in doses of 1 pound per 1000 square feet of garden as needed. Nitrogen deficiency is usually most apparent during the summer when sawdust decomposition is fastest and plant demand for nitrogen is greatest.

If you do wish to spread raw or undecomposed sawdust, add some extra nitrogen to help the break-down process, and be sure to wet the sawdust thoroughly. For every cubic yard of raw sawdust, add nitrogen. If you use organic fertilizers, you can add kelp meal or cottonseed meal to the sawdust, at about 20 pounds per 1 cubic yard. If you use processed nitrogen fertilizer, add it carefully and be certain not to place the sawdust where the nitrogen will leach into any body of water.

The amounts of processed fertilizer are: 1 cubic yard sawdust, plus 14 pounds of 21-0-0 (ammonium sulfate) or 9 pounds of 33-0-0. (ammonium nitrate.) The sawdust plus nitrogen can be tilled into garden soil for next spring's vegetable garden or into any place where the garden is empty and fallow. It will break down over winter into a useful soil amendment.

Adding grass clippings in quantity to a pile of fresh sawdust will also provide you with good springtime mulch after the materials break down. Or you can leave the sawdust plus nitrogen fertilizer in a pile to compost. (Wet it and cover the pile with a tarp during winter to prevent leaching of the nitrogen.)