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Identifying improvement options for phosphorus use in dairy farming - Shiyi Zhang

Due to over-exploitation and maldistribution, P has become a limited resource. Moreover, too much P applied on the farm can lead to environmental problems, such as eutrophication of ecosystems. Therefore, this study aims to identify improvement options to increase P use efficiency in dairy farms by using material flow analysis (MFA).

Phosphorus is an essential nutrient for plants, animals and human. It moves in a cycle through the ecosystem and supports the growth of the animals and crops on the dairy farm. However, because of the over-exploitation and maldistribution, P has become a limited resource. Moreover, too much P applied on the farm can lead to environmental problems, such as eutrophication of ecosystems. Therefore, this study aims to identify improvement options to increase P use efficiency in dairy farms by using material flow analysis (MFA).

21 Irish farms and 16 Dutch farms were chosen and P-efficiency across farms was compared at three levels (farm, herd and crop level). The results showed that the crop level has the highest P efficiency (90.9% for Irish farms and 91.4% for Dutch farms on average) while the herd level is the lowest (17.9% for Irish farms and 25.2% for Dutch farms on average). The farm level takes the second place (69.6% for Irish farms and 67.7% for Dutch farms on average). This paper also indicated that the P use efficiency at farm level is higher in Ireland than in the Netherlands, whereas at crop and herd level it is the other way around.

Based on the calculation in P use efficiency, the economic consequences of an increase of P efficiency was assessed. Results show that a 10% increase can save 43€ per year in Ireland and 112€ per year in the Netherlands. The main strategy for improving P use efficiency on the farm is to improve feed management by reducing overfeeding and increasing P degradation and absorption in the gastrointestinal tract of animal. Moreover, increasing milk production per cow, maximizing crop production, preventing erosion of the soil, adequate amount, place and time of fertilization are also important for improving the P use efficiency of crop production.

Student: S Zhang

Supervisor: dr ir C van Middelaar

24 Ects