Evaluation of rapid analysis systems for on-farm nitrate analysis in vegetable cropping

Abstract

Small analytical systems enabling rapid on-farm analysis may be useful for monitoring crop and soil nutrient status. Two commercially available, rapid analysis systems were evaluated for analysis of in aqueous standard solutions (AS), and in soil solution (SS), plant sap (PS) and fertigation nutrient solutions (NS) obtained from tomato crops. The systems were the Merck RQFlex reflectometer and the Hanna Instruments C115 Grow Master colorimeter. in AS covered the analytical range of each instrument, being 0.3-3.2 and 0.3-16.1 mmol L -1 , respectively, for the reflectometer and colorimeter. were 5-14 mmol L -1 for SS, 2.3-33 mmol L -1 for NS, and 63-158 mmol L -1 for PS. Accuracy was evaluated using linear regression against (i) known concentration for AS, and (ii) laboratory analysis for SS, PS and NS. For the reflectometer with AS, SS and PS, the linear regression had slopes of 1±0.08 and intercepts of <0.6 mmol L -1 . In NS up to 9 mmol L -1 , there was a similar slope, with an intercept of 1.3 mmol L -1 . In the three most concentrated NS samples, there was a larger relative error that was attributed to faulty dilution. Coefficients of determination were always r 2 ≥0.94. The reflectometer was generally accurate for all media examined; it was rapid (1 min per analysis) and simple to use. The colorimeter was generally similarly accurate; however, it was slower, required reagent preparation and was subject to colour interferences. This work demonstrated that the reflectometer can provide rapid and accurate on-farm measurement of in SS, PS and NS. Additional key words: nutrient management, nutrient solution, plant sap, quick-test, soil solution, tomato. Resumen Evaluación de sistemas rápidos para análisis en campo de nitrato en cultivos hortícolasLos sistemas rápidos que permiten análisis en campo pueden ser útiles para monitorizar el estado nutricional del cultivo y del suelo. Se evaluaron dos sistemas analíticos rápidos para analizar [NO 3 -] en soluciones acuosas (AS), solución del suelo (SS), muestras de savia (PS) y soluciones de fertirriego (NS). Se evaluó el reflectómetro RQFlex de Merck y el colorímetro C115 de Hanna. La [NO 3 -] en AS cubrió el rango analítico de cada instrumento y fue 0.3-3.2 y 0.3-16.1 mmol L -1 , respectivamente, para el reflectómetro y el colorímetro. La [NO 3 -] alcanzó 5-14 mmol L -1 para muestras de SS, 2.3-33 mmol L -1 para NS, y 63-158 mmol L -1 para PS. Para valorar la exactitud de los equipos se usaron regresiones lineales. Para el reflectómetro con muestras de AS, SS y PS, la regresión lineal tuvo pendientes de 1±0.08 e interceptos de <0.6 mmol L -1 . En NS para valores de hasta 9 mmol L -1 , la pendiente fue similar entre equipos, con un intercepto de 1.3 mmol L -1 . En las NS más concentradas, hubo un error relativamente grande que se atribuye a fallos en la dilución. Los r 2 fueron siempre ≥0.94. El reflectómetro fue generalmente preciso en los medios evaluados; fue rápido (1 min/análisis) y simple de usar. El colorímetro tuvo generalmente una exactitud s...

Reliability of Petiole Sap Test for N Nutritional Status Assessing in Processing Tomato

“…N rate and fertigation-irrigation frequency affected the nitrate sap concentration as showed in Table 2, in agreement with results carried out by Thomson et al (2009) in tomato, Belec et al (2001) in broccoli and Olsen and Lyons (1994) on peppers. The evaluation of crop N nutritional status carried out by the sap test was mostly in line with the indication from NNI (Table 3): the cases of discrepancy were 21 out 80 comparisons calculated in the whole sampling period and in the both years of experiment and occurred mostly in N300 (i.e.…”

High-Resolution and Non-destructive Evaluation of the Spatial Distribution of Nitrate and Its Dynamics in Spinach (Spinacia oleracea L.) Leaves by Near-Infrared Hyperspectral Imaging

“…Reflectometric method with nitrate test strips was used, at a measurement range from 5 to 225 mg/l and measurement accuracy was 1 mg/l. It was used for accurate measuring nitrate content in production of agricultural products and food safety (Rodrigues et al, 2005 ; Thompson et al, 2009 ; Rytel, 2012a , b ). The nitrate content was calculated according to the following equation:…”

New Trends in the Fertigation Management of Irrigated Vegetable Crops

“…Experimental work on tomatoes and melons has been carried out in protected cultivation but revealed a poor correlation between the nutritional status of the plant and the concentration of nutrients in the suction cup extract; the method therefore appears to be more suitable when excesses are avoided [102]. The aqueous extract obtained through different methods can be analyzed with a rapid determination kit and other analysis tools [121][122][123].…”