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INDICATORS OF NITRATE LEACHING LOSS UNDER DIFFERENT LAND USE OF CLAYEY AND SANDY SOILS IN SOUTHEASTERN OKLAHOMA
Citation:
Silva, R. G., S M. Holub*, E E. Jorgensen*, AND N. Ahsanuzzaman. INDICATORS OF NITRATE LEACHING LOSS UNDER DIFFERENT LAND USE OF CLAYEY AND SANDY SOILS IN SOUTHEASTERN OKLAHOMA. M.R. Carter (ed.), AGRICULTURE, ECOSYSTEMS & ENVIRONMENT. Elsevier Science Ltd, New York, NY, 109(3-4):346-359, (2005).
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to provide information
Description:
Evidence of increasing nitrate (NO3-) leaching losses from soils under various land use systems has elevated the interest and need to find better land management practices. An essential step in developing new management practices is understanding of the common parameters that closely relate to leaching losses across a wide range of land use systems. The overall objective of this study was to relate NO3- leaching losses to various properties across soil types and land use systems. We chose two locations in Southeastern Oklahoma with differing soil type. Land use systems included old-field (abandoned grassland), forest and cultivated arable crop. Parameters determined were soil biomass C, biomass N, total C, total N, extractable mineral N, pH, moisture, CO2 emission and lysimeter drained water NO3- concentration. Firstly, stepwise multiple linear regression analyses were performed between biannual NO3- leaching losses and monthly measured independent variables. Secondly, annual and biannual timescale independent variables and respective NO3- leaching losses were used to perform regression model. Monthly measured parameters explained over 75% of the biannual NO3- leaching losses, but often with different explanatory variables. Land use was the dominant parameter on monthly models, but soil total C, total C/N ratio, extractable NH4+, NO3- concentration and water flux were the most frequently included parameters. When annual and biannual mean parameter values were used in regression, respective NO3- leaching losses were explained by somewhat similar parameters to monthly models. Together these parameters explained only 63%, 53% and 44% of the total variation in NO3- leaching loss for the first, second and biannual period, respectively. These models explained a consistently lower amount of variation than the monthly models. Additionally, more than 70% of the total variation could be explained by NO3- concentration and soil type related parameters. Results from this study revealed that annual and biannual trends of NO3- leaching losses across land use systems were explained by number of parameters collectively rather than a single parameter. However, it is extremely difficult to use any given parameter or array of parameters to predict NO3- leaching losses either on monthly or annual/biannual basis.
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INDICATORS OF NITRATE LEACHING LOSS UNDER DIFFERENT LAND USE OF CLAYEY AND SANDY SOILS IN SOUTHEASTERN OKLAHOMA