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Need Compost Advice for Sandy Soils


January 19, 2015

I live in Corrales and plan to put in a home vegetable garden in sandy soil this year. It took me about 3 years to increase the organic matter of a smaller garden plot (in similar soil) to 2% but this year I’ll be starting from scratch because I have to move the location. I’ve gotten lots of good advice on composting from attending several of your talks but feel unprepared on how to enrich a larger area in such a short period of time. The new space will be 30 x 30 feet and I’d like to begin planting in late March or April. Hence I would appreciate some pointers from you. I read your article on sheet-composting and cover crops but unfortunately I'll have to wait till the Fall to do this. In the past each spring I have added a truckload of compost from Soilutions and rototilled it, and supplemented it with home-made compost (plant-based). I can do this again, but how much would I need for a 30x30 ft garden? And should I water and cover it?  I also have at my disposal 7 bags of fairly fresh chicken manure. I haven't used manure before so what’s the best way to apply it: add to my compost bins and wait a month before adding to the garden or add it directly to the sandy soil or at the same time I add the truckload(s) of compost? Any advice you can offer is appreciated.


Answer by JZ: You will have a generous garden!  My sense is that you have amended and "innoculated" your new bed with compost so you have organic matter and soil microorganisms working for you already.  So now you may add compost just to the top of the bed. And/or you could poke holes throughout the bed with a fork spade, push it down to the hip, which would make 10" deep holes in the bed. Then spread your compost to a depth of 1-3", then rake the compost over the holes, then water the bed, then mulch it. 1 cubic foot of compost will cover 140 square feet to a depth of 1 inch - you could increase the calculation to meet your 30x30 bed size.  Bagged compost is often sold as 1 cubic foot.  Santa Ana garden center carries bagged compost from Soilutions. Then continue soil amending..... forever! Yes, I would water, then mulch the new bed to a depth of 3-4" with shredded leaves, paper and/or straw or any combination of them. When you are ready to plant just move the mulch aside, then put in plants/seeds.  The mulch, if it has moisture at the soil surface interface will gradually decompose and continue to amend your soil. The soil microorganisms need moisture to live & work for you. Any manure ideally could be put through a composting process, creating humus before being added to a garden bed.  Many gardeners add manures in the early fall, then allow it to decompose slowly over the winter months, as you know.  So, if you have the time you could set up a "hot" compost pile with the chicken manure.  Be sure to add coarse bulking material (12") to the bottom of the pile, then add more for every 5" of wet manure that you add as you build the pile.  Cover the finished pile with a tarp. Once the pile heats up, let it "cook" for 7 -14 days, then turn & churn it.  Continue that process til it is all humus.  Maintain moisture at 50% throughout the process.A well managed hot pile should produce humus by spring.

Response by Questioner: Thanks for the quick detailed response. I should clarify that I have NOT yet added any compost to the new garden. It's still mostly pure sand and I have added nothing to it yet.  So I assume I should start by adding lots of compost now, perhaps 3 inches deep rather than one? Then follow your instructions to incorporate the compost using a fork spade (rototiller OK?), then water and mulch?  I will follow your instructions for hot-composting the chicken manure -- that'll be a first for me.

Answer by JZ: Yes, you could cover the bed with 3" of compost.  Since it is your first amendment you could rototill it in - just this one time or use the fork method. Then water, then mulch.  Be sure that any irrigation system you might setup is under the mulch, so that water reaches the soil.  After you have watered & mulched you may cover the whole bed with card board sheets, old rugs, tarps - this really helps keep moisture in the bed, in my experience - your choice. I put rocks & boards on top of tarp to protect from wind.

This info may be helpful for hot composting:  Desert Composting.  I think that you will be thrilled with the hot method results ! It is worth the work. Let me know, if you have more questions.

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