You'll probably never get 100% weed free straw. Depending upon where you get it though it might be very close. I generally get straw from craigslist. Not sure where in Colorado you are but there is a humongous pile of old straw for free up in Broomfield. It is aging straw and not all that easy to break up and load but it is free.

If you're going to continue being a mulcher then you'll generally need mulching supplies on hand. What I would do is use more straw on top of the weeds that have been sprouting up.

It depends on what the source of the straw is - straw is just the dried hollow stems of various cereal grains. And these grains will have varying nutrient content. When you are dealing with the green plant (not the seeds or grain itself and not dried) it is called hay. Leguminous hays tend have a higher nutrient content than grass hays and all hays will have a higher nutrient content when young plants as opposed to more developed, mature plants. But the bulk of the nutritional value information you will find will be associated with feeding livestock rather than the soil :-)

Straw is considered in agriculture as "carbohydrate fertilizer". It favour to symbiotic root-node nitrogen fixing bacteria on legumes. But in first year decomposition of straw in soil gives toxic substances which inhibit plant's growth. Some plants such as pea are tolerant to toxic compounds of straw decomposition and can be ferilized by the straw.

Straw is also good for Azotobacter.

Many people get really concerned because most all straw will have some of the seeds that the straw grew, wheat, oats, barley, rye, and these seeds germinate providing more of the same thing you put down. These are not "weeds" unless you want them to be and they can be allowed to grow to provide more stalks or even a green manure for that bed.

We often disc the sprouts as well as any weeds back into the land when the field is summer fallowed. It is often referred to as 'green manure' and is considered a benefit to the field. I can't recall if I've ever seen a document with the actual nutrient benefits though.

We've thought about running some bales through the silage cutter to chop the straw up and knock out more of the seeds but never got around to it. I'd like to see if that would prevent the unwanted sprouts in the mulch. Maybe next year. :)

Lloyd

I have wheat straw down now, and I grow little clumps of wheat from stray missed seed heads. The roots are shallow, and the clumps pull up very easily. I lay the pulled clumps on top of the straw around the base of the nearest plant.

I've let a wheat plants grow up several times--the seed heads make a very nice accent to fall flower arrangements. This isn't very "green", but I dried a bunch of them and spray painted them gold one year. You can tie them into little sheafs, and they look quite festive lying on the mantle or as part of a Thanksgiving center piece. They last this way for, well, three years and counting.

If you're into fund raising at your kid's school fall festival, let me tell you they sell like hotcakes. ;)

for me straw is more on the carbon side of things, with little nutrients value apart from the carbon, yes by letting those seeds sprout(not realy a weed) to some size gives you something with more nutrient in it to pull and tuck under as i call it. and straw with seeds is quite frequent, as harvesters can't collect 100% of the heads of grain.

my prefference is with spoilt hay's or sugar cane mulch as they contain more nutrients they do break down quicker so re-mulching occurs more often than with straw.

len

Here is a link that might be useful: lens garden page