Assessment Model for the Imbalance in N and PK Fertilization for Maize: Case Study

Abstract

The main aim of the study was to assess the profit increase in maize, starting from the yield response according to the nitrogen quantity applied on different PK backgrounds. Answers were searched for on the causes for the low interest in applying nitrogen fertilizers for maize in Romania. Maize yield response curves were determined according to quantities of N and PK, respectively, based on results of yield trials performed at the Didactic Station Timisoara of Banat`s University of Agricultural Sciences and Veterinary Medicine, during the period between 2013 and 2015. The production functions obtained facilitated the determination of adjusted yield values, based on the N quantities in the 0-200 kg range, active ingredient (a.i.) ha-1 for multiples of 50 for different PK levels, within the 0-150 kg range, a.i. ha-1 . Four distinct cases were analyzed, the average during 2013-2015 and each year independently. The slope (m), indicating the tangent the straight line creates with the abscissa axis, represented an indicator of the growth speed of the dynamic process represented by the yield in relation with the allotted N and PK doses. The slope related to the PK = 0 up to PK = 150 levels, displayed a growing trend (m2013-2015 = 11.4-23.4; m2013 = 11.2-27.73; m2014 = 9.8-24.8; m2015 = 13.1-19.1), as the four sets of data analyzed strengthen the level of trust in a well-known principle of physiology and nutrition of plants - the synergic effect of nutrition factors. Such results confirm, as a potential cause for the low interest of some farmers for intensive N fertilization, the particular soil fund reduced in P and K, taking into account the lack of agricultural support policies with medium and long-term effects.