Improving water holding capacity on urban lots

Hi Toby, could you address how we can increase the water holding capacity of our city soils, in light of increasing climate change, i.e., our lengthening summer droughts in W. Washington, for example? (It's Oct, and after the drought-induced quiesence, many plants are blooming again twith the rains.) And also in your home area of Calif? And other places.

I'm thinking of incorporation of biomass, biochar, bentonite clay, post hole digger 'subsoil' enrichment leading roots deeper, etc. Vermiculture? What else? (The clim. ch. flooding in some areas may require swales, etc., but I'm interested here in the creeping dryness.) Mulch, mulch, mulch... with everything, and the attendant problems... er, challenges :) Thanks ;)

Oh, and thing #2, is it more space-efficient to produce the diet-essential carbohydrates (i.e., sugars, calories) from fruits? As in trees, berries, etc., rather than relying on the typical starchy root vegs? I understand that producing calories may be the limiting factor in home food production, rather than the protein requirement... ?

Nancy, you're on the right track for retaining more water in your yard. Build organic matter in the soil; that's really the key. And build up the natural worm population (earthworms and native worms so they w ill aerate the soil and allow deeper water penetration (red wigglers can't survive in soil). Do that with deep mulches of soft OM like straw and leaves, and tons of good compost. I like to top a straw mulch with a woody mulch, as the worms love the straw and the wood chips help build up soil fungi, which are primary sequesterers of carbon. Activated biochar will help, too.

I'm not sure why you want bentonite. That's usually used to seal soils to prevent water from penetrating. I know that clay does help with moisture retention--though nowhere near as well as organic matter, but I'd be worried about oversupplying bentonite and sealing the soil or creating a clayey hardpan.

On question #2, I'm not a nutritionist, but fruits mostly provide fast-burning sugars, not slow-calorie releasing starches and other carbs. And grains, tubers, and nuts have protein as well. I would not rely on fruit as a major carb source. I'd go with nut trees, tubers, and annuals like corn and beans. But it's hard to get a lot of calories from a small yard. My strategy is to grow nutrient-dense veggies, as they are expensive to buy compared to carbs and you can get constant yields in a mild climate like W. WA. Calorie crops are inexpensive, comparatively, so I buy these if there isn't a quarter acre or so to grow them (and enough time to be a subsistence farmer).

Thanks, Toby ;) I mention the clay because Elliot Coleman recommended it as a soil amendment, based on (cited) tests that were done in Germany, with beneficial results. I think the best proportion of sand, clay and silt requires some clay... and mine has very little :) This would not seem be in the amounts likely to create any seal (where it is valuable in making drilling thingies .pipes? tubes?.. waterproof) or a clay layer, and well incorporated into the organic matter, where it readily emulsifies. I remember the significant amount of primitive pottery shards found mixed withe biochar layers in the terra preta sites in So Am..... although, of course, are not tropical up here :) I also think of the zillion-but-tiny city lots that may not be able to liberally use hoses in the future...

I've put decades' worth of off-site collected grass clippings, plus many dumped mountains of wood chips, on my soil, and it seems to have been 'eaten up'. Plus I'm getting older and don't have a pickup anymore, so I'm looking for ways to make my soil's water-retention capacity last for future decades, with organic replenishment from on-site grown material. It's a strategy, anyway ;) Plus, of course, I'm deep burying a lot of hugel wood... I don't need to increase my already-too-excellent drainage with hugel mounds ;) (plus my lot is flat... swales aren't needed)