{"id":405,"date":"2012-11-06T23:38:07","date_gmt":"2012-11-06T23:38:07","guid":{"rendered":"http:\/\/www.rumbold-ayers.co.uk\/blog\/?p=405"},"modified":"2012-11-07T12:09:30","modified_gmt":"2012-11-07T12:09:30","slug":"earthworms-and-other-friends","status":"publish","type":"post","link":"http:\/\/www.rumbold-ayers.co.uk\/blog\/?p=405","title":{"rendered":"Earthworms and other friends&#8230;&#8230;.."},"content":{"rendered":"<p><a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/earthworms.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-415 alignright\" title=\"earthworms\" src=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/earthworms-300x219.jpg\" alt=\"earthworms\" width=\"318\" height=\"232\" srcset=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/earthworms-300x219.jpg 300w, http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/earthworms.jpg 535w\" sizes=\"auto, (max-width: 318px) 100vw, 318px\" \/><\/a>I have to confess this is something of a digression, as I ponder why one of our plantings from early summer has fared so poorly.\u00a0 But, as it&#8217;s been a while since my last post, I will cut myself a bit of slack&#8230;.<\/p>\n<p>Many gardeners are, quite rightly, a little obsessive about the soil in their gardens: its apparent shortcomings and remediation are as perennial a subject of conversation amongst gardeners as the weather is for everyone else.\u00a0 So spare a thought for those who, perhaps because they are building a new home, are faced with importing soil onto the site to create their garden from scratch.\u00a0 The chances are they won&#8217;t really know what their soil comprises before it arrives, and maybe not for a while thereafter.\u00a0 Unless they are very lucky, in all probability it will be a manufactured, sterile product of indeterminate origin.\u00a0 Hopefully subsoil and topsoil will at least conform to generally accepted criteria and have been delivered and spread in the right order(!).\u00a0 Anything more is a bonus.<\/p>\n<h2><strong>Topsoil<\/strong><\/h2>\n<p>There is a British Standard for topsoil &#8211; BS 3882:2007 &#8220;Specification for Topsoil and Requirements for Use&#8221; &#8211; which attempts to classify multipurpose and special purpose topsoils being moved or sold.\u00a0 It addresses lots of attributes like pH, nitrogen, phosphorus, magnesium and potassium content, organic matter, soil texture and contaminants.\u00a0 Anyone buying topsoil would be well advised to buy a compliant product.\u00a0 However, what it doesn&#8217;t address are living organisms!<\/p>\n<p>All plants need topsoil if they are to survive.\u00a0 I&#8217;ll say that again.\u00a0 All plants need topsoil.\u00a0 Subsoil won&#8217;t do.\u00a0 Why?\u00a0 Because plant roots can only do their job with the help of a complex ecosystem of insects, fungi, and microorganisms that enable the plant to obtain the nutrients it needs from the soil.\u00a0\u00a0 And the presence of that ecosystem, together with other organic matter, is what fundamentally differentiates topsoil from subsoil.\u00a0 Of course, plants roots need air and moisture too, and this living ecosystem plays a vital role here as well.<\/p>\n<h2><strong> Soil Organic Matter and Humous<\/strong><\/h2>\n<p>Soil organic matter is made up of a wide variety of materials derived from plants, animals, and soil organisms, which can be divided into four categories:<\/p>\n<ul>\n<li>living organisms and roots, making up less than 5% of the total;<\/li>\n<li>residues from dead plants, animals and soil organisms that have not yet begun to decompose (&lt;10%);<\/li>\n<li>material undergoing rapid decomposition (20-45%);<\/li>\n<li>stabilized organic matter (humus) remaining after further decomposition by soil microorganisms (50-80%).<\/li>\n<\/ul>\n<div id=\"attachment_419\" style=\"width: 671px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Topsoil-Organic-Matter1.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-419\" class=\"size-full wp-image-419\" title=\"Topsoil Organic Matter\" src=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Topsoil-Organic-Matter1.jpg\" alt=\"Topsoil Organic Matter\" width=\"661\" height=\"317\" srcset=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Topsoil-Organic-Matter1.jpg 661w, http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Topsoil-Organic-Matter1-300x143.jpg 300w\" sizes=\"auto, (max-width: 661px) 100vw, 661px\" \/><\/a><p id=\"caption-attachment-419\" class=\"wp-caption-text\">Topsoil Organic Matter<\/p><\/div>\n<p><strong><em>Humous<\/em><\/strong> (the stabilized organic matter) has the longest lasting benefits for gardeners.\u00a0 It is a mix of stable, complex organic compounds formed during initial rapid decomposition, which decomposes only slowly over time (about 3% per year).\u00a0 Humus comprises a mix of solid particles and soluble compounds &#8211; sugars, proteins, gums, fats, waxes, resins and lignin &#8211; that are too chemically complex to be used by most organisms but improve the physical and chemical properties of soil by:<\/p>\n<ul>\n<li>binding\u00a0 mineral particles together into larger aggregates, which helps to improve air and water infiltration and movement;<\/li>\n<li>improving water retention and release to plants;<\/li>\n<li>slowly releasing nutrients (e.g. nitrogen, phosphorus, sulphur) over time;<\/li>\n<li>helping to retain nutrients that would otherwise be leached from the soil;<\/li>\n<li>providing a &#8220;buffer&#8221; that stabilises soil pH; and<\/li>\n<li>chelating (binding) toxic metals in soil.<\/li>\n<\/ul>\n<p>Soil supplied to BS 3882:2007 should at least have a modest organic matter content: the specification for general purpose topsoil is 3-20% (a rather wide range).\u00a0 However, it doesn&#8217;t distinguish between the different categories of organic matter, and could still be completely devoid of that all-important humous: in such a case it could take several years before a satisfactory humous content is established.<\/p>\n<h2><strong>Soil Organisms<\/strong><\/h2>\n<p>Of the circa 5% of topsoil that is typically organic matter (it can be up to 30%), about 0.2% comprises living organisms, albeit mostly invisible to the naked eye.\u00a0 One cup of undisturbed soil typically contains:<\/p>\n<blockquote>\n<ul>\n<li>200 billion bacteria<\/li>\n<li>20 million protozoa<\/li>\n<li>100,000 meters of fungi<\/li>\n<li>100,000 nematodes<\/li>\n<li>50,ooo arthropods<\/li>\n<\/ul>\n<\/blockquote>\n<p>Some of these have a close symbiotic relationship with plants, including rhizobia and mycorrhizae.<\/p>\n<p><strong><em><span style=\"color: #000000;\">Rhizobia<\/span> <\/em><\/strong>are bacteria that establish associations with plants such as beans and peas (legumes). They form nodules on the roots where they &#8220;fix&#8221; nitrogen gas from the air and in return the plant supplies the bacteria with essential minerals and sugars.<\/p>\n<p><span style=\"color: #000000;\"><em><strong>Mycorrhizae <\/strong><\/em><\/span>are specific fungi found in most soils that have symbiotic associations with plant roots. They are very host-specific (i.e., each plant species is associated with specific species of mycorrhiza) and enlarge the surface-absorbing area of the roots by 100 to 1,000 times by creating filaments or threads that act like an extension of the root system. In exchange for making the roots of the plant much more effective in the uptake of water and nutrients, the fungus gets essential nutrients from the roots to fuel its own growth.\u00a0 Mycorrhizae enhance the plant\u2019s ability to tolerate environmental stress and reduce transplant shock.<\/p>\n<p>Glomalin, which improves soil tilth, is a glycoprotein produced as a by-product of mycorrhizal activity.\u00a0 Glomalin, together with humic acid, is a vital constituent of soil organic matter that improve soil structure by binding the tiny clay particles together into larger aggregates, which in turn increases the pore space and helps to create an ideal environment for roots.<\/p>\n<p>There are many other indirectly beneficial soil organisms, including microorganisms, insects and worms, which act to decompose soil organic matter into forms that can be used by plants, and also improve the soil structure.\u00a0 Most of the soil-obsessed gardeners I mentioned earlier will know organic matter improves soil structure: perhaps not everyone knows the beneficial properties are only realised with the help of soil organisms.<\/p>\n<p><span style=\"color: #000000;\"><em><strong>Earthworms<\/strong><\/em><\/span> are perhaps the best known soil organism &#8211; described by Aristotle as &#8220;the intestines of the earth&#8221;. In fact there are many different species of earthworm, which fall into four different categories:<strong><em><\/em><\/strong><\/p>\n<ul>\n<li><span style=\"color: #000000;\"><strong><em>Anecic<\/em><\/strong><\/span>\u00a0 earthworms build permanent burrows deep into the soil. They feed on leaves on the soil surface that they drag into their burrows.\u00a0 Our dear friend <em>Lumbricus terrestris<\/em> is probably the best known species:\u00a0 it lives in a vertical burrow up to 3m deep, which it occupies for its entire life cycle.\u00a0 <em>L. terrestris<\/em> reaches sexual maturity in about 52 weeks and they can live for up to 10 years. They are typically dark coloured at the head end (red or brown), with paler tails.<\/li>\n<li><span style=\"color: #000000;\"><strong><em>Endogeic<\/em><\/strong><\/span> earthworms live in, and feed on the soil. They occupy\u00a0 horizontal, non-permanent burrows in the upper mineral layer of soil, and are not usually noticed except after a heavy rain when they come to the surface.\u00a0Some can burrow very deeply in the soil.\u00a0 Endogeic earthworms are often pale colours &#8211; grey, pale pink, green or blue.<\/li>\n<li><strong><em>Epigeic<\/em><\/strong> earthworms live on the soil surface in leaf litter. They tend not to make burrows but live in and feed on the leaf litter. Epigeic earthworms are also often bright red or red-brown (but they are not stripy).<\/li>\n<li><strong><em>Compost earthworms<\/em><\/strong> are, unsurprisingly, most likely to be found in a compost pile. They thrive in warm, moist environments with a ready supply of fresh compost material (which they very rapidly consume). They also reproduce very quickly. Compost earthworms are mostly bright red and stripy.<\/li>\n<\/ul>\n<p>In all, there are some 26 species of earthworm in the UK.\u00a0 Charles Darwin wrote a <a title=\"&quot;The Formation of Vegetable Mould through the Action of Worms&quot; Darwin C., London 1881\" href=\"http:\/\/darwin-online.org.uk\/converted\/pdf\/1881_Worms_F1357.pdf\" target=\"_blank\">paper on earthworms<\/a> during his later years, in which he speculated that almost all of the fertile soil on earth must have passed through the gut of an earthworm. Perhaps he exaggerated, but &#8230;.<\/p>\n<div id=\"attachment_420\" style=\"width: 307px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Lob-worm.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-420\" class=\"size-full wp-image-420\" title=\"Lob worm\" src=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2012\/11\/Lob-worm.jpg\" alt=\"Lumbricus terrestris\" width=\"297\" height=\"203\" \/><\/a><p id=\"caption-attachment-420\" class=\"wp-caption-text\">Lumbricus terrestris<\/p><\/div>\n<p>Earthworms are just a few of the many organisms that decompose organic matter in the soil and improve the soil structure.\u00a0 The deep burrows of anecic earthworms create passages for air, water and roots, facilitating the exchange of soil gases with the atmosphere &#8211; clay soils particularly benefit from extensive earthworm burrows.\u00a0 Anecic worms enhance soil organic matter and humus by dragging litter into their burrows.\u00a0 Endogeic burrows contribute to soil tilth, increasing soil porosity.\u00a0 (If you&#8217;re interested in learning more, you can even join the <a title=\"The Earthworm Society of Great Britain and Northern Ireland\" href=\"http:\/\/www.earthwormsoc.org.uk\/\" target=\"_blank\">Earthworm Society of Britain<\/a> \ud83d\ude42 .)<\/p>\n<p>Soil organisms can be encouraged by:<\/p>\n<ul>\n<li>Adding <strong><em>organic matter<\/em><\/strong>: organisms require a food source.<\/li>\n<li>Applying an organic <span style=\"color: #000000;\"><strong><em>mulch<\/em><\/strong><\/span>: helps to stabilise the soil temperature and moisture, and helps prevent compaction.<\/li>\n<li>Avoiding the use of <span style=\"color: #000000;\"><strong><em>pesticides<\/em><\/strong><\/span>, some of which are devastating to soil organisms.<\/li>\n<li><em><strong>Minimising cultivation<\/strong><\/em>, which can kill earthworms, destroy worm burrows and mycorrhizae, and damage the soil structure.<\/li>\n<li>Maintaining <strong><em>moist soil conditions<\/em><\/strong> (but avoid over watering).<\/li>\n<\/ul>\n<p>As I mentioned earlier, the BS 3882:2007 standard doesn&#8217;t address soil organisms at all.\u00a0 In fact quite a lot of commercially available topsoil is completely sterile &#8211; devoid of any organisms, and with the organic matter provided simply by adding fresh mulch-type material from recycled &#8220;green waste&#8221;.\u00a0 Obviously, it could take several years before such a &#8220;manufactured&#8221; topsoil exhibits the level of fertility we would expect.<\/p>\n<p>So, if you need to import topsoil, it really is worth trying to find a local source of natural topsoil, for example from a local construction project.<\/p>\n<p>And what about that struggling planting I was supposed to be investigating?\u00a0 Well, the manufactured subsoil and topsoil complied with BS 3882:2007 and were certified by a soil consultant to be suitable for landscape planting.\u00a0 But with a soil texture that sets like concrete when dry, a pH of 8.3 and an organic content comprising a smattering of woody lumps, I&#8217;m wondering if it isn&#8217;t just\u00a0 a mix of clay, crushed concrete and wood chips! \u00a0 It could be a while before our plants thrive \ud83d\ude41 .<\/p>\n<h4><strong>A Footnote on Soil Inoculation:<\/strong><\/h4>\n<h4>Generally, the results of\u00a0 inoculation with mycorrhizae can be inconsistent, because they are species specific.\u00a0 They also have a limited shelf life so, if you do want to try it, buy a fresh product.\u00a0 Commercial farmers growing legumes may use rhizobium inoculation, but the best tip for the gardener is simply to grow your runner beans on the same patch each year (against our crop rotation instincts, I know, but it generally works).\u00a0 Inoculation with other organisms is generally not necessary.<\/h4>\n<p style=\"text-align: right;\">Svend<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I have to confess this is something of a digression, as I ponder why one of our plantings from early summer has fared so poorly.\u00a0 But, as it&#8217;s been a while since my last post, I will cut myself a &hellip; <a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/?p=405\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_s2mail":"yes","footnotes":""},"categories":[21,22,1],"tags":[142,149,141,146,144,148,145,143,147,117],"class_list":["post-405","post","type-post","status-publish","format-standard","hentry","category-soil","category-soil-type","category-uncategorized","tag-bs3882","tag-compost","tag-earthworms","tag-humous","tag-manufactured-topsoil","tag-organic-matter","tag-soil-organisms","tag-soil-specification","tag-soil-type-2","tag-topsoil"],"_links":{"self":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/405","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=405"}],"version-history":[{"count":18,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/405\/revisions"}],"predecessor-version":[{"id":425,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/405\/revisions\/425"}],"wp:attachment":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=405"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=405"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=405"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}