Hi Vivian, I am not sure where "here" is. What climate zone do you live in? You mentioned alkaline soil and nematodes so I suspect you do not live in my area of Western Washington. I can be a better help if I know where you are gardening. There are some areas where you may not be able to grow tomatoes but that does not mean you cannot garden or grow delicious edible crops.   Keep growing, Marianne Binetti