46 horticulture via drainage tubes account for 0.7 Gg (Annex I) and non-agricultural soil contributed 0.9 Gg P2O5 into surface waters in 2005. Physico-chemical soil processes and weather events inï¬uence these losses and they are therefore not easy to control. Industry (2.1 Gg) and households (4.3 Gg) emitted a total of 6.4 Gg P2O5 to surface waters (Annex I). Although the industry has invested considerably in decreasing the phosphate emission to surface waters, resulting in an emission in 2005 of only 3% compared with 1990 (Compendium voor de leefomgeving, 20107), the prospects for any further decreases are poor. Sewage treatment plants remove 60% of the phosphorus from sewage (Compendium voor de leefomgeving, 2010). 7 Compendium voor de Leefomgeving, June 2010: http:// www.compendiumvoordeleefomgeving.nl/indicatoren/nl, (in Dutch). 6.2 Balancing input and output in the Netherlands Phosphate is accumulating in the Netherlands, with most phosphate accumulating in soil. Statistical data indicate a surplus (Figure 6.1.). Balancing this surplus requires both lowering input and increasing output. To reduce the Netherlandsâ soil phosphate surplus of 82 (sector balance) or 85 Gg P2O5 (soil balance), reducing the input and simultaneously increasing the output are required. The foreseen shortage of exploitable deposits of rock phosphate makes the recycling of phosphate sources an urgent matter. 8 Phosphorus use eï¬ciency (PUE) is deï¬ned as: PUE = tradable outputs / all inputs = (exported crops + exported animals + exported milk, cheese & butter) / (imported animals + imported bedding + imported feed + mineral fertilisers + imported manure + deposition & biological ï¬xation). Schoumans, O.F., 2010. Mestinnnovaties. http://www. kennisonline.wur.nl/BO/ BO-05/006/015/ . Broek, J.A. van den, G. van Hofwegen, W. Beekman & M. Woittiez, 2007. Options for increasing nutrient use eï¬ciency in Dutch dairy and arable farming towards 2030: an exploration of cost-eï¬ective measures at farm and regional levels, Wageningen, Statutory Research Tasks Unit for Nature & the Environment. WOt-rapport 55. TCB, 2008. Advies Aanwenden van mest A044 (2008). Technische Commissie Bodembescherming. Productschap Diervoeder: http:// www.pdv.nl/index_eng. php?switch=1. 9 On a national scale, inputs via animal feed need to be brought in balance with the output via manure and the by-products of animal production. The current focus in the Netherlands is on how to increase the eï¬ciency8of phosphorus use (Schoumans, 20109; Broek et al., 200710). Of prime importance is to align manure production to an agronomic and environmentally acceptable use of phosphorus (TCB, 200811). The balance between input of phosphorus to the soil and the oï¬take by agricultural products needs to be improved. The following actions are currently being carried out to this end. 10 11 12 1. Reduced phosphate content in feed concentrates The use of feed concentrates with reduced phosphate concentrations yields animal manure with a lower phosphate content resulting in a lower soil balance input. Manure can be reduced further by increasing the availability of phosphate for the animal. The reduction can be achieved without diminishing livestock numbers or the volume of manure. However, livestock farmers and veterinarians are concerned that reduced-phosphate feedstock may have a negative eï¬ect on animal welfare. The standard criteria for phosphate requirements for animals are given by the Centraal Veevoeder Bureau (CVB) of the Animal Feed Product Board (Productschap Veevoeder12). Animal phosphate requirements depend on the animal species, physiological status, and the availability of the phosphate forms in the feed. Pagina 55
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