Relationship of the Illinois soil nitrogen test to spring wheat yield and response to fertilizer nitrogen

Abstract

. 2008. Relationship of the Illinois soil nitrogen test to spring wheat yield and response to fertilizer nitrogen. Can. J. Soil Sci. 88: 837Á848. The Illinois soil N test (ISNT) has been used to distinguish between soils that are responsive and non-responsive to fertilizer N in Illinois. We examined the suitability of this test, together with more traditional measures of soil fertility, including spring nitrate-N and soil organic carbon (SOC), for predicting yield and N fertilizer response of wheat (Triticum aestivum) on hummocky landscapes in Saskatchewan. The relationship between ISNT-N and wheat yield and fertilizer N response was assessed using data and soils previously collected for a variable-rate fertilizer study. Soils were re-analyzed for ISNT-N. Our goal was to determine if ISNT-N could be used to improve the prediction of crop yields. Although ISNT-N was correlated with both unfertilized wheat yield (r 00.467, P 00.01) and fertilizer N response (r 0(0.671, P00.01) when data from all study sites were combined, correlations varied according to landscape position and site. Stronger correlations between nitrate-N and both unfertilized wheat yield (r00.721, P 00.01) and fertilizer N response (r 0(0.690, P00.01) indicated that ISNT-N offered no advantage over nitrate-N. Although both tests broadly discriminated between sites with high or low N fertility, few relationships were detected on a point-by-point basis within a field. Stepwise regression equations predicting yield and yield response did not include ISNT-N, due in part to the high degree of collinearity between ISNT-N and other variables such as SOC, suggesting that ISNT-N alone was not a key indicator of soil N supply. Le test du N du sol de l'Illinois (ISNT) sert a`diffe´rencier les sols de l'Illinois qui re´agissent bien ou mal aux engrais azote´s. Les auteurs voulaient e´tablir si ce test et les me´thodes plus classiques servant a`ve´rifier la fertilite´du sol, notamment la concentration de N-nitrate au printemps et la teneur en carbone organique du sol (COS), pouvaient servir a`pre´voir le rendement et la re´action aux engrais N du ble´(Triticum aestivum) cultive´sur les terrains mamelonne´s de la Saskatchewan. Pour cela, ils ont e´value´les liens entre le N-ISNT et le rendement du ble´ainsi que la re´action de cette culture aux engrais azote´s graˆce aux donne´es et aux e´chantillons de sol recueillis dans le cadre d'une e´tude sur la variation du taux d'application des engrais. Ils ont analyseć es sols pour e´tablir leur concentration de N-ISNT. L'objectif ultime e´tait de de´terminer si le N-ISNT pourrait conduire ad e meilleures pre´visions du rendement des cultures. Bien que le N-ISNT soit corre´le´au rendement des cultures de ble´non bonifie´es (r00,467, P00,01) et a`la re´action aux engrais N (r 0(0,671, P00,01) quand on combine les donne´es de tous les sites e´tudie´s, ces corre´lations varient avec l'emplacement dans le paysage et avec le site. La plus e´troite corre´lation existant entre le N-nitrate et le rendement du ble´non bonifie...

Different response patterns of epigaeic spiders and carabid beetles to varying environmental conditions in fields and semi-natural habitats of an intensively cultivated agricultural landscape

“…Total soil nitrogen (N tot ) was measured from composite soil samples collected in October 2013 as an indicator of fertilization use intensity, since it is commonly highly correlated with the amount of fertilizers applied and productivity (Steckler et al, 2008). Five randomly selected soil samples were taken at 0Y20 cm depth using a 50-mm diameter sand auger at each plot.…”