TY - JOUR
T1 - Assessment of phosphorus fertilizer practices in altered wetland soils using uncertainty analysis
AU - Litaor, M. I.
AU - Chashmonai, I.
AU - Barnea, I.
AU - Reichmann, O.
AU - Shenker, M.
PY - 2013
Y1 - 2013
N2 - Intensive P fertilizer application is widely practised in East Mediterranean altered wetland soils, even when results from the Olsen-P extract indicate sufficiency (>10mg P/kg). To reduce or even eliminate this practice we conducted a large field study to test the feasibility of a major reduction in the use of P fertilizers. A total of 90 sample sites were evenly spaced with respect to their parent material (deep peat, shallow peat, marl). Soils were analysed for Olsen-P, bulk density, pH, electrical conductivity, and nitrate, chloride and sulphate in saturated paste extracts. We determined variograms and estimated the spatial structure of Olsen-P data by ordinary kriging. We then used a sequential Gaussian model to produce 100 alternative simulations to measure the joint spatial uncertainty of P concentrations in the study area (ca.1500ha). Finally, we post-processed the simulation results to compute the probability of exceeding the threshold Olsen-P value of 10mg/kg. The simulation results indicate a high probability of exceeding the 10mg/kg threshold in most peat soils supporting an earlier recommendation to reduce or even eliminate P fertilizer application in these fields. On the other hand, a very low probability of exceeding this threshold was observed in most marl soils justifying continued fertilizer application. However, the added P is likely to affect adjacent waterways and increase potential downstream eutrophication due to high conductance and flow continuity between the marl soils and adjacent waterways.
AB - Intensive P fertilizer application is widely practised in East Mediterranean altered wetland soils, even when results from the Olsen-P extract indicate sufficiency (>10mg P/kg). To reduce or even eliminate this practice we conducted a large field study to test the feasibility of a major reduction in the use of P fertilizers. A total of 90 sample sites were evenly spaced with respect to their parent material (deep peat, shallow peat, marl). Soils were analysed for Olsen-P, bulk density, pH, electrical conductivity, and nitrate, chloride and sulphate in saturated paste extracts. We determined variograms and estimated the spatial structure of Olsen-P data by ordinary kriging. We then used a sequential Gaussian model to produce 100 alternative simulations to measure the joint spatial uncertainty of P concentrations in the study area (ca.1500ha). Finally, we post-processed the simulation results to compute the probability of exceeding the threshold Olsen-P value of 10mg/kg. The simulation results indicate a high probability of exceeding the 10mg/kg threshold in most peat soils supporting an earlier recommendation to reduce or even eliminate P fertilizer application in these fields. On the other hand, a very low probability of exceeding this threshold was observed in most marl soils justifying continued fertilizer application. However, the added P is likely to affect adjacent waterways and increase potential downstream eutrophication due to high conductance and flow continuity between the marl soils and adjacent waterways.
KW - Olsen-P spatial analysis
KW - Stochastic simulations
UR - http://www.scopus.com/inward/record.url?scp=84874746821&partnerID=8YFLogxK
U2 - 10.1111/j.1475-2743.2012.00440.x
DO - 10.1111/j.1475-2743.2012.00440.x
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AN - SCOPUS:84874746821
SN - 0266-0032
VL - 29
SP - 55
EP - 63
JO - Soil Use and Management
JF - Soil Use and Management
IS - SUPPL.1
ER -