Phosphorus status determined of calcareous soils and phosphorus application effects on maize yields

ABSTRACTPhD THESISPHOSPHORUS STATUS DETERMINED OF CALCAREOUS SOILS ANDPHOSPHORUS APPLICATION EFFECTS ON MAIZE YIELDSKürşat KORKMAZDEPATMENT OF SOIL SCIENCE INSTITUTE OFNATURAL AND APPLIED SCIENCEUNIVERSTY OF CUKUROVASupervisor : Prof. Dr. Hayriye İBRİKÇİYear : 2005, Pages:126Jury : Prof. Dr. Hayriye İBRİKÇİProf. Dr. Zülküf KAYAProf. Dr. Ahmet Can ÜLGERProf. Dr. Yusuf KIRTOKAsist. Prof.. Dr. Sema KARANLIKPhosphorus (P) is an essential macronutrient for plant growth and development, and itsdeficiency is a common limiting factor under many climatic conditions and clay and calcareous soilsof the Southern Turkey because of it?s low availability despite frequent phosphate applications. Thepot experiments were carried out to select P-efficient corn genotypes grown on calcareous soils ofGAP regions. Corn genotypes were screened for their ability to utilize phosphorus in a greenhouseexperiment in Adana, and locally-common ten corn genotypes were grown on 3 soil series for eightweeks. The five rates of phosphorus (0, 25, 50, 100 and 200 mg kg-1) were used. After harvest, tissuedry matter and P content in tissue were determined. Effect of P on dry matter and plant P uptake werefound statistically significant, and these parameters were increased by the P rates. In addition, Corngenotypes acted differently to P rates. Teater and RX 770 found as inefficient-nonresponsivegenotypes, DK 6022 efficient-nonresponsive, Sele, Tector, DK 626 ve DK 585 inefficient-responsivewhereas Pegasso and C 7993 were efficient-responsive.In addition, this research P fractions, P adsorption and desorption characteristics of three soilseries of GAP region were determined This results revealed that total-P changed Ca-P>CDB-P>CB-P>Al-P+Fe-P in GAP region. Langmuir adsorption isotherm. According to results, the adsorptinmaxima (b) ranged from 263 to 400 µg g-1, the adsorption energy coefficients (k), ranged from 0.70to 0.76 ml µg-1. Results revealed that were statistically significant relationships were found betweenadsorption parameters and soil properties, it can be suggested that the type of clay, lime and Fe oxidesare important factors affecting phosphorus adsorption in these soil.After greenhouse experiment, we selected genotypes for use field experiment, and we werecontucted field experimet selected genotypes. A two year field experiment at corn genotypes wereundertaken for determininig utilize phosphorus on two different location in GAP regions. Theinorganic fertilizer was triple superphosphate (TSP), applied at 0 (control), 40, 80, 120 and 160 kgP2O5 ha-1, and were used.. Results revealed that phosphorus applications were significantly effectiveon corn yield. The results suggest that corn production of this region depend on initial soil analaysis, adirect application of 80-120 kg P2O5 ha-1 to corn was sufficient to meet their P needs.These findings are important for the regions, and need to be verified for the local-field Pfertilizer trials, and plant genotypes equipped with mechanisms for utilizing the adsorbed P moreefficiently can, therefore, enhance the effectiveness of P fertilization.Key Words: Phosphorus (P), P Adsorption, Efficiency, P Fertilize, MaizeII