50 year trends in nitrogen use efficiency of world cropping systems: the relationship between yield and nitrogen input to cropland

Luis Lassaletta, Gilles Billen, Bruna Grizzetti, Juliette Anglade, Josette Garnier
2014 Environmental Research Letters  
doi:10.1088/1748-9326/9/10/105011 fatcat:57seoo3i5zdvtcdu5vvsftzyxm