Identification of nitrate leaching loss indicators through regression methods based on a meta-analysis of lysimeter studies.
This study presents a meta-analysis of 12 experiments that quantify nitrate-N leaching losses from grazed pasture systems in alluvial sedimentary soils in Canterbury (New Zealand). Mean measured nitrate-N leached (kg N/ha × 100 mm drainage) losses were 2.7 when no urine was applied, 8.4 at the urine rate of 300 kg N/ha, 9.8 at 500 kg N/ha, 24.5 at 700 kg N/ha and 51.4 at 1000 kg N/ha. Lismore soils presented significantly higher nitrate-N losses compared to Templeton soils. Moreover, a multiple linear regression (MLR) model was developed to determine the key factors that influence nitrate-N leaching and to predict nitrate-N leaching losses. The MLR analyses was calibrated and validated using 82 average values of nitrate-N leached and 48 explanatory variables representative of nitrogen inputs and outputs, transport, attenuation of nitrogen and farm management practices. The MLR model (R (2) = 0.81) showed that nitrate-N leaching losses were greater at higher urine application rates and when there was more drainage from rainfall and irrigation. On the other hand, nitrate leaching decreased when nitrification inhibitors (e.g. dicyandiamide (DCD)) were applied. Predicted nitrate-N leaching losses at the paddock scale were calculated using the MLR equation, and they varied largely depending on the urine application rate and urine patch coverage.
Centre for Soil and Environmental Research, Lincoln University, PO Box 85084, Lincoln 7647, Christchurch, New Zealand. mboy@icra.cat.|Catalan Institute for Water Research (ICRA), Parc Científic i Tecnològic de la Universitat de Girona, Emili Grahit 101, Edifici H2O, 17003, Girona, Spain. mboy@icra.cat.
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Boy-Roura
Centre for Soil and Environmental Research, Lincoln University, PO Box 85084, Lincoln 7647, Christchurch, New Zealand.
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Cameron
Centre for Soil and Environmental Research, Lincoln University, PO Box 85084, Lincoln 7647, Christchurch, New Zealand.
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Di
D000383:Agriculture / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D005308:Fertilizers / Q000032:analysis*; D009520:New Zealand; D009566:Nitrates / Q000032:analysis*; D012044:Regression Analysis; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D005308:Fertilizers; D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical
Lysimeter experiments; New Zealand; Nitrate leaching; Pasture systems; Regression model; Urine patch; Water quality