Determining Nutrient Recommendations for Agricultural Crops Based on Soil and Plant Tissue Analyzes between Different Analytical Laboratories

Agricultural chemistry is fundamental when determining fertilization inputs for crop production. Reliable recommendations from soil and plant tissue analyzes are critical when applying nutrients for optimum growth. The objective of this study was to assess the variances in nutrient recommendations reported by different analytical laboratories. Agriculture crops, field corn (Zea mays L.) and soybean (Glycine max) were measured for soil nutrient content and plant tissue nutrient levels. Soil and plant tissue elemental levels and nutrient recommendations were compared between research and commercial laboratories. Research was performed at Louisiana State University at Alexandria (LSUA) from April 2016-Septemeber 2018. For both crops, four treatments and four replications were performed in 2016 and two treatments and four replications in 2017 and 2018. Fertilization was followed and applied based on the recommendations provided by each laboratory during three growth stages, vegetative stage (V1), vegetative stage (V3), and reproductive stage (R1) for field corn and vegetative stage (V1), vegetative stage (V9) and reproductive stage (R1) for soybean. Research showed that overall procedures and elemental extraction methods remained congruent among laboratories. Ratings and recommendations followed laboratory specific fertility methods. Results showed that for each year of study, nutrient input levels were higher with commercial laboratory recommendations for both field corn and soybean. The higher fertilization rates did not increase overall yield rates for field corn or soybean.