Investigation of the Ability to Credit Residual Nitrogen Based on Soil Texture and Nutrient Management Zone Identification Using Soil Electrical Conductivity, pH and Reflectance
Abstract
Variation in soil properties within a production field can drastically differ in pH,
nutrient, and water holding properties, thus benefiting from site-specific nutrient
management. Previous research has shown a strong correlation between soil texture and
both nutrient holding capacity and soil water dynamics, which influence nitrogen (N)
retention. Nitrogen is the highest input cost in Texas row crop production and the most
common yield-limiting nutrient, and effectively crediting residual soil NOv3-N will
increase nitrogen use efficiency and return on investment (ROI). The relationship
between bulk soil electrical conductivity (EC) and soil texture has been used to delineate
management zones and can be collected and mapped quickly in commercial fields. Using
Veris® EC, texture based site-specific nutrient management zones has demonstrated
potential to spatially identify contrasting soil textures and manage residual soil N on a
site specific basis. To test this hypothesis, a multi-year project was initiated on a 15.4 ha
field near College Station TX in the spring of 2014 through 2017. Bulk soil EC was
collected with the Veris® 3100 in 2013. In 2016, soil EC, soil pH, and soil reflectance
were collected with a Veris® MSP3. Soil cores were pulled annually on a 0.73 hectare
grid to a depth of 122 cm before the crop was planted to quantify extractable nitrate,
phosphorus, potassium and minerals. Increasing N rates were applied on a corn (Zea
mays) and cotton (Gossipium hirsutum) rotation to evaluate management and crediting of
residual soil NOv3-N. A positive relationship (r^2=.754) of interpolated Veris® EC and soil
texture from 0-15 cm depth was observed. Coarser textured areas of the field (<25% clay)
had lower yields than that of the finer textured areas (>30% clay) in all four years. Cotton
had no response to N fertilizer suggesting that residual NO Variation in soil properties within a production field can drastically differ in pH,
nutrient, and water holding properties, thus benefiting from site-specific nutrient
management. Previous research has shown a strong correlation between soil texture and
both nutrient holding capacity and soil water dynamics, which influence nitrogen (N)
retention. Nitrogen is the highest input cost in Texas row crop production and the most
common yield-limiting nutrient, and effectively crediting residual soil NO3-N will
increase nitrogen use efficiency and return on investment (ROI). The relationship
between bulk soil electrical conductivity (EC) and soil texture has been used to delineate
management zones and can be collected and mapped quickly in commercial fields. Using
Veris® EC, texture based site-specific nutrient management zones has demonstrated
potential to spatially identify contrasting soil textures and manage residual soil N on a
site specific basis. To test this hypothesis, a multi-year project was initiated on a 15.4 ha
field near College Station TX in the spring of 2014 through 2017. Bulk soil EC was
collected with the Veris® 3100 in 2013. In 2016, soil EC, soil pH, and soil reflectance
were collected with a Veris® MSP3. Soil cores were pulled annually on a 0.73 hectare
grid to a depth of 122 cm before the crop was planted to quantify extractable nitrate,
phosphorus, potassium and minerals. Increasing N rates were applied on a corn (Zea
mays) and cotton (Gossipium hirsutum) rotation to evaluate management and crediting of
residual soil NO3-N. A positive relationship (r^2=.754) of interpolated Veris® EC and soil
texture from 0-15 cm depth was observed. Coarser textured areas of the field (<25% clay)
had lower yields than that of the finer textured areas (>30% clay) in all four years. Cotton
had no response to N fertilizer suggesting that residual NOv3-N was adequate to achieve
optimum yields. Residual N could not be credited on coarse textured soils and yields
were not maximized when soil residual Nitrogen was credited on these coarse textured
soils. Veris pH showed a correlation to lab tested pH in variable soils. Veris reflectance
data showed inconsistent result across the 3 locations.3-N was adequate to achieve
optimum yields. Residual N could not be credited on coarse textured soils and yields
were not maximized when soil residual Nitrogen was credited on these coarse textured
soils. Veris pH showed a correlation to lab tested pH in variable soils. Veris reflectance
data showed inconsistent result across the 3 locations.
Citation
Arthur, Brady Paul (2018). Investigation of the Ability to Credit Residual Nitrogen Based on Soil Texture and Nutrient Management Zone Identification Using Soil Electrical Conductivity, pH and Reflectance. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174153.