The sites were all out in the open, all had the same amount of rain but such different outcomes. So why would that soil still be dry?
In sandy soils the water may drain through the soil profile so quickly that it could be dry after a very short time but sandy soils are not normal around this neck of the woods and for this reason I know it was not a case of the water draining away but rather one where the water didn’t sink in in the first place.
There are several reasons why water may not sink into soil. If the rain is very heavy it may simply run off before it has time to sink in. But our rain last week was gentle and steady so there has to be another reason. In my paddock there are two other reasons. The first is that in places there has been vehicle traffic and/or horse traffic. Any sort of repeated traffic over an area can compact soil very quickly. The previous owners of my property had a horse and the horse quite clearly had very specific routes he took round the paddock. After five years without a horse in residence those pathways are still as clear as day and that is because the ground has been compacted leaving no air spaces between the soil particles making it hard for water to sink in and therefore hard for plants to grow. The second reason I don’t get water running into the soil is that in places the soil in the paddock is dusty and hydrophobic. Hydrophobic soil (soil which repels rather than soaks up water) is caused by excessive hot dry weather of which we had plenty over summer and/or the coating of soil particles with waxy organic compounds from the breakdown of waxy leaves such as Eucalyptus leaves. There is a very clear and informative article in the ABC Organic Gardener magazine if you are needing some help to fix a problem like mine.
Finally another problem you may have which stops moisture entering the soil in your garden is the compaction of mulch which you will have added to the soil surface in good faith to help retain moisture. Again this can happen for two reasons. Frequent foot traffic over a garden bed will compact your mulch regardless of its particle size but a mulch with a fine particle size will compact easily no matter how careful you are not to tramp over it. A good chunky mulch (mulch made up of particles over 5 mm in size) with no more than 5% fine material is vital to help prevent compaction issues. Chunky mulches allow water to freely flow through to the ground below and at the same time reduces evaporation form the soil to the air. Mulches with fine particles (particles of less than 5 mm in size) capture water before it gets to the soil so the soil remains dry and they also then allow that water to evaporate into the air.
So if your plants continue not to grow despite a wonderful four days of rain I suggest you pop out and have a little dig around your plants and check if the water has actually soaked in.