[1] Colorado State Univ, Dept Soil & Crop Sci, 307 Univ Ave, Ft Collins, CO 80523 USA
[2] Inst Nacl Invest Agr INIA, Estn Expt INIA Estanzuela, Ruta 50 km 11, Colonia 70000, Uruguay
[3] Colorado State Univ, Nat Resource Ecol Lab, 1232 East Dr, Ft Collins, CO 80523 USA
[4] INIA Estanzuela, Ruta 50 km 11, Colonia 70000, Uruguay