Project Details:

Associated with this large increase in acreage that has occurred arises many questions regarding fertilizer requirements of the cropping systems. In our experimental design established in 1985, one half of each plot received P fertilizer every year and one half of the plot receive no-P fertilizer. Our goal was to determine if organic P cycling would satisfy the P needs of the crops in these no-till dryland cropping systems. However, by 1991 the wheat emergence and growth in the no-P side of the plots were becoming so poor that we decided to initiate P fertilization of the whole plot every time wheat was planted. It was evident that organic P cycling was not large enough to satisfy the P needs of wheat. However, the summer crop yields were generally not affected in the rotation. In 1991 we added the treatments so wheat would be fertilized every year it was planted in the cropping system rotation (the plot that received no-P previously) we continued to apply P annually to the other half of the plot as we had from the experiment initiation. The interesting part of this study is that the summer corps on the "old" no-P side of the plots have never received P fertilizer. Our goal is to determine if the P needs of summer crops grown in a rotation with no-till wheat can be met by the residual P remaining fromthe P applied to the wheat crop.