Plant Requirement and Zero Balance – Soil P Development under Two P Input Scenarios in Finland
Phosphorus (P) loading to watercourses is clearly related to soil P status (STP), which has more than doubled in Finland since 1950s due to positive P balances. The current P fertilization is still higher than required for the maximum yield. Changes in STP and P use during the next 20 years were predicted with two P fertilization scenarios: biological optimum P use (resulting in 95% of the maximum yield of cereals and grasses) and zero-balance (fertilization equal to P in harvested crop). Calculations were made for the whole country and four regions along the Baltic Sea coast.
Due to decreasing STP values, successive P fertilization according to the biological optimum or the zero-balance would, respectively, result in 42% or 38% lower dissolved P losses after 20 years. If plants were fertilized according to the biological optimum, about 143 million kg P would be saved in 20 years in Finland compared to the present P use. In some regions, by continuing the present manure production, manure P would alone meet the 20-year requirements.
This report on two P fertilization scenarios in Finland was prepared as part of the work package 4 on manure standards in the project Baltic Manure.
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