Hi
I have 3 raised beds. They need topping up after settling with about 3/4 of a ton of material. I'm not sure whether to just chuck in pure compost, or topsoil, or a mix. Does sterilised/sieved topsoil from garden centres have any nutrients in at all? Clearly compost has plenty but it doesn't last that long.
Any help much appreciated.
It depends on the quality of what you have and what you want to grow in the beds. The nutrient content of commercial topsoil is very variable, it can be anything from quite ordinary to excellent. Perhaps there is somebody local (garden club?) who can show you how to assess such things?
How do you know you need 3/4 of a ton? Bulk materials like this are usually sold by volume and the weight will vary according to content and moisture. Consider if it will be cheaper in the long run to buy a truck load and have some left over for other purposes than buy bags.
David
Assuming your talking about a pickup truck worth and dirt weighs that amount and topping up actually means filling up the raised bed completely.
Hmmm... 3/4 ton or 1500 pickup truck bed carries which would be about
6'x3'x2'= 36 cubic feet. 36 / 3 beds = 12 cubic feet per raised bed. So that would fill a bed that is 4' x 6' x .5' = 12 cubic feet for each of the three beds.So a loaded pickup SHOULD fill 3 beds that measure 4' x 6' x (1/2)' raised beds.
I would go for a fifty fifty mix. Topsoil is good for structure, compost for microbes and some nutrients. Could add some peat moss to lighten the mix if the Mix seems to heavy for the plants. Carrots love a light soil and I find tomatoes like it a tad bit heavier ( the can topple over and uproot if soil is too light ).
If going to landscape supplier or free local compost recycler, a typical small front loader is 27 cubic feet 3x3x3. If you go before a rainy day that soil will be much much heavier and harder on your truck. However, I usually get half loads with my Dakota, rated for 750 not 1500, full loads damaged the protective bumpers for the drive shaft that cost me fifty bucks to repair. So half loads for me.
Is that what your looking for?
Where did you get 36 cuft? My back-o-the-envelope says it would be much less, about 12.
See
The Myth of Soil Amendments, Part III ³Healthy soil has high organic content² The Myth One of the newer catch phrases making the rounds in print and on gardening websites is ³Building Healthy Soil.² The starting premise is that residential soil is inherently unhealthy and in need of amendment. Without fail these media sources recommend incorporation of large volumes of compost as a means of improving soil structure, adding nutrients, improving drainage and aeration, and increasing water holding capacity. Websites recommend adding anywhere from 1 to 4 inches of compost; one site suggests ³1 part compost to 2 parts dirt.² In general, the message is that unamended soil is unacceptable and the only way to make it healthy is by adding large quantities of compost. The Reality The dubious practice of amending soil areas destined for permanent landscape installations has been discussed in this column on other occasions. To summarize briefly, the problem with this practice is that within 10 years (conservatively) the organic amendment will have decomposed; one is then left with the original soil, which will have subsided and compacted during this time. You can see evidence of this practice by looking at older residential lawns; the lawns slope away from sidewalks and driveways and are inches below grade of surrounding surfaces. There is no way to incorporate additional amendment into permanent landscapes without damaging root systems. Instead, it is easier, cheaper, and more natural to add organic material by topdressing landscapes that are not planted and harvested on an annual basis. (My fondness for wood chip mulches has been expressed in this column before!) What about landscapes that are planted and harvested on an annual basis including vegetable gardens and flower beds? These landscapes are more logically managed by agricultural models adding organic matter (OM) to replace nutrients removed from the soil by flowers and vegetables. The annual incorporation of compost makes sense here. However, one needs to have an idea of what the soil already contains before more material is added. During home construction, topsoil is removed from the site and eventually replaced by ³designed soil.² It is almost impossible to purchase native topsoil in urban areas; it is too precious a commodity. Commercially available topsoil is usually a mixture of native topsoil and a variety of inorganic and organic materials including sand, perlite, compost, peat moss, bark, sawdust, and manure. These designed soils usually contain 15% OM by weight (equivalent to 30% compost by volume). By comparison, native topsoils contain about 5% OM by weight (or 10% OM by volume); this level of OM is considered to be optimal in terms of nutrient content. Obviously, new residential landscapes contain high levels of OM, well above what is considered ideal. If you don¹t know what your soil already contains in terms of nutrients, how can you possibly determine how much OM to add? It is simple and cheap to have your soil tested for OM content and nutrient levels and this should be done at least once to determine baseline values. This information can help you determine if you need to add more organic material, and which nutrients in particular are at minimal levels. It wastes resources, both financial and natural, to add excessive amounts of OM without these baseline values. Last fall we collected soil samples from a local organic demonstration garden and sent them out for nutrient analysis; this garden had recently experienced some soil and plant health problems. Every single one of the sites that was tested came back with nutrient readings off the scale. In large capital letters the report warned ³DO NOT FERTILIZE THIS SOIL.² The excessive addition of nutrient-rich compost to this landscape contributed not only to plant health problems but to nutrient loading of adjacent natural waters. The Bottom Line ? Ideal soils, from a fertility standpoint, are generally defined as containing no more than 5% OM by weight or 10% by volume ? Before you add organic amendments to your garden, have your soil tested to determine its OM content and nutrient levels ? Be conservative with organic amendments; add only what is necessary to correct deficiencies and maintain OM at ideal levels ? Do not incorporate organic amendments into landscapes destined for permanent installations; topdress with mulch instead ? Abnormally high levels of nutrients can have negative effects on plant and soil health ? Any nutrients not immediately utilized by microbes or plants contribute to non-point source pollution For more information, please visit Dr. Chalker-Scott¹s web page at
What number are you using? At 95 lbs/cft a pick-up would hold 15.8 cft at 1500 lbs. 15.8 cft on a surface of 24sq. ft. = a depth of 0.65789475 ft., or 7.894737 in. or you need 1.52 pick up loads/1500 lbs/load, depending on the type of soil that you buy.
Do I win anything?
Sounds about right, however, I subtract points for not rounding off calculations to two decimal points :) My My we love math around here :)
My assumption was at the beginning of topic was by volume not by weight. When the OP stated 3/4 Ton, the volume of a pickup bed was in my mind, not weight. I have a gut feeling that is what he meant. I could be wrong though, my friends (few) call this "taking the primrose path" of solving problems, sometimes it works sometimes it does not.
But my truck is beater truck on country roads, it is abused :)
Size of a pickup truck bed, six feet long, three feet wide and two feet high.
doesn't she billy?
Mine's a 1980 Datsun, also a "beater". It's a great truck for dependability, i.e. they're hard to kill. It's the 2nd one I've had. I sold the first one, and missed it immediately. I can't imagine gardening without a truck.
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