Submitted to: Minnesota Academy of Science Abstract
Publication Type: Abstract only
Publication Acceptance Date: 4/19/1997
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Prediction of crop needs for nitrogen (N) is needed to improve fertilizer use efficiency in agriculture. A nitrate-N (NO3**- -N) prediction model was field tested over 5 locations. The objectives of the study were to predict N fertilizer needs using the model, apply N based on predictions, and compare the final crop yield with the producers' standard practice yield results. Test strips in corn (Zea mays L.) were fertilized with starter fertilizer N, phosphorus, and potassium. Soils were sampled and examined for pre-plant NO3**- -N, pH, organic matter and clay content. Amounts of NO3**- -N produced by soil microbial activity was predicted and summed with the amount of NO3**- -N initially present. Average observed change in soil NO3**- -N was 2.1 ug g**-1 60 cm**-1. The amount of fertilizer needed by the crop was determined by subtracting the amount of naturally produced NO3**- -N from the critical level needed to maximize crop yield and this amount of fertilizer N was added. Corn yields averaged 130 bu ac**-1 in the test strip and 125 bu ac**-1 in adjacent producer managed areas; yields were not different (p>0.05).