in developed countries where most arable land is accounted for, increased deforestation would decrease overall carbon sequestration. Nutrient leaching According to a 2012 meta-analysis of 71 studies, nitrogen leaching, nitrous oxide emissions, ammonia emissions, eutrophication potential and acidification potential were higher for organic products. Specifically, the emission per area of land is lower, but per amount of food produced is higher. This is due to the lower crop yield of organic farms. Excess nutrients in lakes, rivers, and groundwater can cause algal blooms, eutrophication, and subsequent dead zones. In addition, nitrates are harmful to aquatic organisms by themselves. Land use A 2012 Oxford meta-analysis of 71 studies found that organic farming requires 84% more land for an equivalent amount of harvest, mainly due to lack of nutrients but sometimes due to weeds, diseases or pests, lower yielding animals and land required for fertility building crops. While organic farming does not necessarily save land for wildlife habitats and forestry in all cases, the most modern breakthroughs in organic are addressing these issues with success. Professor Wolfgang Branscheid says that organic animal production is not good for the environment, because organic chicken requires twice as much land as "conventional" chicken and organic pork a quarter more. According to a calculation by Hudson Institute, organic beef requires three times as much land. On the other hand, certain organic methods of animal husbandry have been shown to restore desertified, marginal, and/or otherwise unavailable land to agricultural productivity and wildlife. Or by getting both forage and cash crop production from the same fields simultaneously, reduce net land use. SRI methods for rice production, without external inputs, have produced record yields on some farms, but not others. Pesticides In organic farming synthetic pesticides are generally prohibited. A chemical is said to be synthetic if it does not already exist in the natural world. But the organic label goes further and usually prohibit compounds that exist in nature if they are produced by chemical synthesis. So, the prohibition is also about the method of production and not only the nature of the compound. A non-exhaustive list of organic approved pesticides with their median lethal doses: Boric acid is used as an insecticide (LD50: 2660 mg/kg). Copper(II) sulfate is used as a fungicide and is also used in conventional agriculture (LD50 300 mg/kg). Conventional agriculture has the option to use the less toxic Mancozeb (LD50 4,500 to 11,200