Collected Evidence: Collected Evidence: Amend the soil with fresh plant material or crop remainsBiodiversity: One randomized, replicated experiment from Belgium found increased microbial biomass when crop remains and straw were added. Compaction: One study from India found improved soil structure when straw was incorporated. One before-and-after trial from the UK found that incorporating straw residues by discing (reduced tillage) did not improve anaerobic soils (low oxygen levels) in compacted soils. Erosion: Two randomized, replicated studies from Canada and India measured the effect of incorporating straw on erosion. One found straw addition reduced soil loss, and one found mixed effects depending on soil type. Nutrient loss: Four replicated studies from Belgium, the UK and the USA (one also controlled, one also randomized, and two also controlled and randomized) reported higher soil nitrogen levels when compost or straw was applied, but mixed results when processed wastes were added. One also found reduced nitrate leaching when straw was incorporated. One replicated study from China and the Philippines found mixed results depending on site. Soil organic carbon: Six studies from China, Denmark and India measured the effect of incorporating plant material into the soil. All (including one replicated, two randomized, replicated studies, one controlled, randomized, replicated studies and one controlled before-and-after site comparison) found higher carbon levels when plant material was added. One found higher carbon levels when straw was applied along with NPK fertilizers. One also found larger soil aggregates. One replicated study from China and the Philippines found mixed results depending on site. Yield: One replicated trial from Denmark found higher barley yield when straw was incorporated. One trial from the Philippines found higher grain yields when crop remains were incorporated earlier in the season. Soil types covered: clay, clay loam, fine loam, loam/sandy loam, loamy sand, sandy, sandy clay loam, sandy loam, sandy-silt, silt loam, silty, silty-clay.Collected, 03 Oct 2013 09:06:37 +0100Collected Evidence: Collected Evidence: Amend the soil with manures and agricultural compostsBiodiversity loss: Three controlled, replicated studies from the UK and USA found higher microbial biomass when manure or compost was applied, and higher microbial respiration when poultry manure was applied. Erosion: One controlled, randomized, replicated study from India found lower soil loss and water runoff with manure application in combination with other treatments. Nutrient management: Four studies from Canada, Spain, the UK and the USA measured the effect of a variety of manure types on soil nutrient levels. Of these, three randomized, replicated studies (two also controlled) found reduced nutrient loss and higher nitrogen levels when farmyard or poultry manure was applied. One also found lower nutrient loss when farmyard manure (rather than poultry manure or slurry) was applied in winter rather than autumn. One controlled replicated study found higher nitrate leaching. Soil organic carbon: Four studies (including three controlled, replicated studies (one also randomized) and a review) from India, Japan and the UK found higher carbon levels when manures were applied. Soil organic matter: One controlled, randomized, replicated study from Turkey found higher organic matter, larger soil aggregations and a positive effect on soil physical properties when manure and compost were applied. Two studies from Denmark and Germany found no effect of manure on organic matter levels. Yield: Four controlled, replicated studies (including three also randomized) from India, Spain and Turkey found higher crop yields when manures or compost were applied. One study found higher yields when manure were applied in combination with cover crops. Soil types covered: Clay loam, fine sandy-silty loam, loam, loamy, sandy loam, sandy clay loam, silty loam, and sandy silt loam.  Collected, 03 Oct 2013 11:10:07 +0100
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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