Fallbrook California. Market Garden

Greetings fellow permaculture people. I have the opportunity of farming a few plots of land in Fallbrook California on a 17 acre property. It would be for market gardening to make some money. For my growing area, one plot is about 0.80 acres, another plot (not sure if I can use it) is 0.20 acres, and one or two other plots are about 2000 sq ft. each. I want to hear all of your helpful opinions, suggestions, ideas, etc. on what to do. (Mediterranean climate farmers especially welcome)

Climate
Mediterranean. Generally frost-free. Average 10 inches of rainfall per year.

Land
The soil is rocky sandy loam and highly compacted. USGS Soil Survey describes it as "Cieneba very rocky coarse sandy loam", and "Cieneba-Fallbrook rocky sandy loam eroded". Elevation about 500-600 ft. Most of the property is sloped. Decompaction will be required but I don't know if I can use a hardpan broadfork or if I need to go big and rip a single shank subsoiler with the owner's low hp Kubota tractor.

The .8 acres is sloped and eastward facing. Just from the hit and miss Google Earth measurements, it may be 14%-18% slope gradient. (To find the percent grade I'm pretty sure I just take the difference of elevation from top to bottom divided by the total length of the path from top to bottom and multiply by 100. Is that correct?) This sloped 4/5 of an acre is giving me the most confusion of all the other plots, yet it's the majority of the amount of land I have to work with. I have no skill whatsoever in terracing, swale construction, surveying for contour lines, etc. I don't know if I should just plant vetiver grass hedges (Chrysopogon zizanioides) on contour, let sediment slowly build behind the hedges and eventually get naturally formed terraces that way. I could maybe plant drought tolerant edible grass like White Sonoran Wheat between the contour hedges. The problem with these natural formed terraces is that it would take a long time to form, and I want to get to farming.

Water Supply
Irrigation is available, but I don't want to have to depend on municipal water because of cost and the problems of irrigation in arid regions. For the flat smaller plots, I want to set up a system of fast growing crops to start bring in some revenue. If I need to get "traditional" and just irrigate tomatoes, peppers, cucumbers to make some good money at first I'm fine with that.

Trees
Was an avocado and citrus farm with fruit trees dotted along the slopes. It seems most trees haven't been watered in some time and aren't in the best of shape. I would have access to whatever fruit is produced from these trees however.

I want to quickly bring fertility back to this land. I'm willing to devote space to high biomass plants to grow my own mulch. What are some exceptionally good biomass plants for my climate? Would the vetiver grass I mentioned be a good fit for this? I've got a thousand questions by I'd like to hear your initial thoughts. Thanks guys.

Congratulations on your opportunity! I am not an expert either, but have been working on my 1/2 acre in NW CA (Redwood country) for the past 3 years and have access to a similar sized plot to yours (16acres) with friendly owners who encourage permaculture and gleaning on the property. I imagine you have a major water shortage as your limiting factor more than I do, but more light and heat to work with. After basing my approach on experience as a ranger in the NW old growth forests, I am having the most success with hugel beds (basically nurse logs you build yourself). These reduce irrigation needs and rebuild soil fertility and texture on a large scale. The wood can hold water for months longer than sandy soil and slowly disperses excess water and nutrients absorbed from floods over a long period into surrounding soil along with a rich fungal inoculation, helped with deep mulch of bird enriched woodchips and weed/straw. This is what nature has done throughout the western US for eons. I would imagine you have oak/pine/doug fir aound there? I have been working with mostly Doug fir and Sitka spruce wood as that is the most plentiful other than redwood (better for frames as it will decompose little in our lifetime) around here. Geoff Lawton has some great videos breaking down concepts for building soil fertility while minimizing inputs of time and resources. The basic concepts seem to be swales/hugels along contour to slow and direct water flow along with ponds that form from this directed waterflow and store water and nutrients from flood waters and ducks or fish. I would also encourage you to find some grape clones to plant and do so as soon as possible, as they can produce a lot of food with no irrigation as well as value added products like wine to subsidize less profitable endeavors.

Thanks Ben. Yeah, I had considered hugelculture but I was alittle hesitant about its applicability to arid regions. There are piles of chopped avocado wood throughout the property though. I was thinking about giving it a go but I worry that avocado wood could be allelopathic. Grapes are a good idea. The owner has a small vineyard he's set up and I'm sure I could take some cuttings. Do you know if there are any special varieties that have a good fruit set within the first year? As for swales and ponds, I think they would be very helpful but I'm a bit nervous about actually getting it done. I just feel like there's always some sort of hydrological engineering procedure that I'll overlook or something. Do you have an experience digging swales or ponds on your market garden?