How Many Straw Bales Do I Have to Mulch My Backyard? – Deep Inexperienced Permaculture


straw bales stacked on palette

Straw mulches corresponding to hay, lucerne, pea straw and sugar cane mulch are in style to be used in vegetable gardens as a result of they’re simple to use, and so they work properly to preserve water and successfully suppress weeds.

These non-woody mulches breaks down in a short time, in round six months, including carbon to the soil in a short time. They’re labeled as labile soil carbon supplies, the carbon they comprise enters the soil shortly, however leaves the soil comparatively shortly again to the ambiance. They do create an exquisite humus to complement the soil after they break down, nevertheless it’s not a really steady type of humus. This isn’t an issue because the mulch is replenished at the start of the nice and cozy and funky seasons in vegetable gardens.

The way to Calculate the Quantity of Mulch Wanted to Cowl a Backyard Mattress

When making use of any mulch to a backyard mattress, there are two issues we have to know to find out the whole quantity of supplies required.

  1. The realm of the backyard mattress
  2. The thickness of the mulch required

To calculate the realm of an oblong or sq. backyard mattress, we merely multiply the size by the width. If we measure the size and width in metres, our last space calculation will likely be in sq. metres.

When making use of mulches, the minimal thickness is often round 5cm (2”), with round 7.5cm (3”) being preferable. For heavy mulching, a mulch layer as much as 10cm (4”) can be utilized, however at that thickness, much more mulching materials is required.

Mulches are bought by quantity, both in luggage by the litre, or in bulk by the cubic metre, so as soon as we all know the realm we’re mulching and the thickness of mulch we need to apply, we will calculate the quantity of mulch required.

diagram calculating volume of mulch required
To calculating the quantity of mulch required, we want the scale of the backyard mattress and the thickness of mulch wanted
  1. First convert all dimensions to centimetres. There are 100cm in1m, so multiply any measurements in metres by 100 to transform them to centimetres.
  2. Multiply size x width x top, then divide by 1000 to transform the outcome from cubic cm to cubic litres.
  3. If we have to convert the outcome from cubic litres to cubic metres, divide by 1000.

For instance, if we had a 10m lengthy by 1m extensive backyard mattress, and wished to mulch it very closely with a 10cm thick layer of mulch:

The realm of the backyard mattress (in sq. metres) is just size (in metres) x width (in metres) = 10m x 1m = 10 sq. metres (10m2)

  • Size = 10m x100 (to transform to cm) = 1000cm
  • Width = 1m x 100 (to transform to cm) = 100cm
  • Peak = 10cm

Quantity of mulch = size x width x top /1000 = 1000 x 100 x 10 /1000 = 1,000,000 / 1000 = 1000 cubic litres

To covert cubic litres to cubic metres, divide by 1000, so 1000L / 1000 = 1 cubic metre (1m3).

Due to this fact, 1 cubic metre of mulch will likely be required to cowl 10 sq. metres of backyard mattress with a ten cm layer of mulch.

This formulation works nice for uncompressed mulches, as a result of their quantity doesn’t change, however what about compressed mulches?

How A lot Straw is in a Bale? The way to Calculate Straw Bale Will Protection

Straw bales are compressed, so their true quantity is way higher than their compressed quantity.

How can we work the mulch protection {that a} straw bale will present? Now we have to calculate is uncompressed quantity.

The issue right here is that the baling machines could be set to extend the bale compression. At most compression, a bale can comprise one third extra straw. To have the ability to work out the common compression ratio of assorted forms of straw bales,

I checked out a variety of labelled plastic wrapped bale merchandise worldwide, and calculated the compression primarily based on the scale of the bales and their specified protection.

A regular bale has fastened top of 35cm (14”) x width of 45cm (18”) however can fluctuate in size, relying on the setting of the baler machine, however is often round 90cm (36”), 100cm (40”) or 120cm (48”).

Bales are usually compressed round 3 to 4 instances their unique quantity*, so if we calculate the quantity of a compressed bale, and multiply it by 3 or 4, we’d have an approximate quantity of uncompressed mulch materials that it’s going to present.

To calculate the quantity of a compressed bale:

  1. Measure the size, width and top in centimetres.
  2. Multiply size x width x top, then divide by 1000 to transform the outcome from cubic cm to cubic litres.

To calculate the uncompressed quantity of bale:

  1. Multiply the compressed quantity by 3 for a conservative estimate of the uncompressed bale quantity, in litres.
  2. Convert the outcome from cubic litres to cubic metres, divide by 1000.

To calculate bale protection:

Decide the mulch thickness (in centimetres) and divide by 100 to transform it to metres.

Divide the uncompressed bale quantity (in cubic metres) by the mulch thickness (in metres) to present the sq. metre protection.

A Sensible Instance of Straw Bale Protection Calculation

Utilizing a 35x45x90cm (14x18x36”) bale, and a mulch thickness of 5cm (2”) lets do the calculations:

Step 1 – To calculate the quantity of a compressed bale, we multiply the size x width x top, then divide by 1000 to transform the outcome from cubic cm to cubic litres.

  • 35x45x90cm / 1000 = ‭141,750‬ / 1000 = 141.75 L

Step 2 – To calculate the uncompressed quantity of bale, we multiply the compressed quantity by 3, then divide by 1000 to transform from cubic litres to cubic metres.

  • 141.75 L x 3 / 1000 = 425.25‬ L/ 1000 = 0.425 cubic metres, a bit lower than half a cubic metre of uncompressed straw mulch.‬

Step 3 – Divide the uncompressed bale quantity (in cubic metres) by the mulch thickness (in metres) to present the sq. metre protection.

  • mulch thickness of 5cm = 5/100 = 0.05m
  • uncompressed straw mulch quantity = 0.425 cubic metres
  • 0.425 / 0.05 = 8.5 sq. metres of protection at 5cm mulch thickness
  • Divide space by 0.09290304 to covert to sq. ft.
  • 8.5 / 0.09290304 = 91.5 sq. ft at 2” mulch thickness

Understanding our true quantity of uncompressed mulch, and deciding what mulch thickness we would like, we will calculate how a lot protection we’ll get throughout a backyard mattress.

Estimating the precise compression ratio of baled straw merchandise is difficult as a result of coarser mulches will ‘fluff up’ and decompress higher than finely reduce straw mulches, and the kind of straw mulch will decide how excessive it sits when in an uncompressed state and laid out on the soil floor.

Most packaged mulches will often specify an estimated protection of sq. ft or sq. metres for a selected thickness of mulch in inches or centimetres.

Utilizing this methodology, we will calculate approximate estimates of uncompressed quantity for normal, string-bound, unwrapped bales.

*Extra Info – Calculating Straw Bale Compression

For anybody desirous about how I calculated the compression ratio of a straw bale, I’ve included the data under, however that is simply further data and probably not crucial:

If we have a look at a bale from Lowes within the US, the producer specifies the protection of 1 bale as 80 sq. ft. at 3-in depth.

The bale dimensions are 36” x 18” x 14” and the compressed quantity for the bail is listed as 20 cubic ft.

Changing the imperial dimensions to metric for a world viewers…

protection space (conversion: 1 sq. ft = 0.09290304 sq. m)

  • 80 sq ft = 7.4322432 sq m

mulch depth (conversion: 1” = 2.54cm)

bale dimensions (conversion: 1” = 2.54cm)

  • 36” = 91.44cm
  • 18” = 45.72cm
  • 14” = 35.56cm

compressed bale quantity (conversion: 1 cubic foot = 28.31685 litres)

uncompressed bale quantity (conversion: 1 cubic foot = 28.31685 litres)

The Quantity Compression Ratio = uncompressed bale quantity / compressed bale quantity = 566.34 / 148.66 = 3.81


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