CHICKEN MANURE AS A BIOFERTILIZER FOR WHEAT IN THE SANDY SOILS OF SAUDI-ARABIA

Two field experiments were carried out under centre-pivot irrigation i n central Saudi Arabia during the winter seasons of 1990/91 and 1991/9 2 to examine the yield and quality responses of wheat to biofertilizat ion with chicken manure at rates of 0, 4.1, 8.25, 16.5 and 33.0 t ha(- 1). The response curves obtained for the test measurements as a functi on of the rate of chicken manure applied indicated that grain yield, g rain quality and straw yield were promoted by the rate of chicken manu re. The point of profitable grain yield (greatest economic return) cor responded to the manurial rate of 8.25 t ha(-1) (maximum biodegradatio n). A simplified economic analysis of the data obtained revealed that operating beyond this rate is not advisable since it does not appeal t o farmers and may lead to monetary losses. N and P uptake, as a functi on of chicken manure application rate, increased progressively with an increasing manurial rate. The superiority of the second season over t he first one in the magnitude of the test measurements studied was var iously attributed to the infection by Fusarium graminearum, causing ro ot and crown rot disease of wheat during the first season and to the h igher amount of mineralizable plant nutrients during the second season .