Determination of Phosphorus Requirement of Cowpea (Vigna Unguiculata) In Some Soils of Southeastern Nigeria Using Phosphate Sorption Isotherm

ABSTRACT

The study was designed to determine the fertilizer P requirement of cowpea using P sorption isotherm. The P - sorption capacities of some soils Umudike and Bende, were determined. The method used involved equiliberating 3g of soil in 30m1s of 0.01 M CaCl7containing various levels of phosphorous at room temperature. From the P - sorption curve, the standard P Requirement of the soils were determined. The values were medium and low at 125.0 ,ag/g aiid 65.0 pgIg soil for Umudike and Bende respectively. The langrnuir equation was applied to the data, from which the P-sorption maximum was calculated. The values were fairly high at 299.04 g/g and 178.57 g/g soil for Umudike and Bende respectively. From the Sorption Isotherm Curve, the P fertilizer required at various levels of P were determined and used in the green house trials. From the study. 0.08 ppm soil solution P equivalent to the fertilizer rates 130 kg P/ha and 70 kg P/ha in Umudike and Bende soils respectively gave the optimum yield for cowpea in these soils.

TABLE OF CONTENTS

PAGE

TITLE ii

CERTIFICATION

ACKNOWLEDGEMENT iv

DEDICATION v

TABLE OF CONTENTS vi

LIST OF TABLES vii

LIST OF FIGURES viii

ABSTRACT iv

1.0

2.0

INTRODUCTION

LITERATURE REVIEW

1-2

3 - 9

3.0 MATERIALS AND METHODS 10 - 12

4.0 RESULTS AND DISCUSSION 13 - 24

5.0 SUMMARY AND CONCLUSION 25

6.0 REFERENCE 26 - 31

7.0 APPENDIX 32 - 52