NITROGEN AND PHOSPHORUS REQUIREMENTS OF WHEAT SOWN BY MINIMUM TILLAGE INTO RICE STUBBLE AND THE EFFECT OF RICE STUBBLE TREATMENT

Egret wheat was sown into rice stubble using a minimum cultivation technique called seedavation. Nitrogen was surface applied as sulphate of ammonia in 1974 and ammonium nitrate in 1975 at 0, 60 and 120 kg N ha-1. Phosphorus as single superphosphate was drilled with the seed at 0 and 17.5 kg P ha-1. The effects of burning, incorporating and removing rice stubble were compared. Large grain yield responses to nitrogen were achieved with yields up to 5 t ha-1 despite the use of minimum tillage. Tiller numbers were highly correlated with yield. No yield response to phosphorus was obtained. Low protein levels (less than 10%) suitable for biscuit wheat were obtained even at the high nitrogen fertilizer rates. The effect of stubble treatment varied between years; in 1974 it had no effect on yield; however, in 1975 removing or incorporating stubble reduced yields compared with burning the stubble. These results indicate that in rice growing areas a significant rise in wheat yields can be achieved through the use of higher nitrogen fertilizer rates. © 1979 ASEG.