New alfalfa varieties are constantly being introduced into the marketplace. The number of varieties available for low-elevation desert areas in Arizona in the non-dormant and very non-dormant class is close to 50. New varieties are introduced each year and unbiased yield comparisons are helpful to the grower to base the decision of whether or not to sow a new variety. The study reported here is part of the on-going effort to evaluate alfalfa variety performance in Arizona. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1267.pdf.

Thirteen alfalfa varieties with fall dormancy ratings of 7 - 9 were tested in a replicated small plot trial on a clay loam soil on the Safford Agricultural Center. This was the first year of the study. Beacon was the highest yielding variety in 2003 with ZX 9899B and AmeriStand 801S following closely behind. All three varieties produced a yield over 9 tons per acre.

Twenty six alfalfa varieties with fall dormancy ratings of 7 or 9 were tested in a replicated small plot trial on a sandy clay loam soil on the Safford Agricultural Center. This was the third year of the study. Coronado was the highest yielding variety in 2000 with Mecca III following closely behind. Both varieties produced a yield over 9 tons per acre and averaged 9.3 tons per acre over the 3-year period.

Twenty six alfalfa varieties with fall dormancy ratings of 8 or 9 were tested in a replicated small plot trial on a sandy clay loam soil on the Safford Agricultural Center. This was the first year of the study. Mecca III was the highest yielding variety in 1999 with Coronado following closely behind. Both varieties produced a yield close to 9.5 tons per acre.

Five alfalfa varieties were planted and grown under grower conditions on a field section that had high conductivity, while two varieties were planted and grown on a section of the same field much less affected. CUF 101, the variety grown in both areas, was the highest yielding variety in both area. Reduction in CUF 101 hay yield due to high conductivity was approximately one ton/acre in the first year of production, with a large amount of this noted in the first cutting. Yield reductions of CUF 101 due to field area and associated electroconductivity were greater the second year, with an average of 0.29 tons/acre/cutting. Total yield difference for CUF 101 was 1.72 tons/acre for the eight harvests for which data were available. Yield differences between the areas was greatest in the early spring and late fall of the first harvest year, with differences not noted in the June cutting; in year two yield differences were approximately 37% for each cutting. Salado was the second highest yielding variety in the high electroconductivity area in 1998, and equaled CUF 101 in yield from this area in 1999. Sal-T-96 and Leivas Best yielded less than 90% of CUF 101. Sal-T-96 also had the greatest number of weeds, due in part to very slow germination and fewer plants per acre compared with other varieties.

Twenty four alfalfa varieties with fall dormancy ratings of 8 or 9 were tested in a replicated small plot trial on a heavy clay loam soil on the Safford Agricultural Center. This was the fourth year of the study. WL 91-224F was the highest yielding variety in 1999, but that still left it in second place behind Cuf 101 for the four year average. WL 91-224F yield was 8.35 tons per acre which is very close to its four year average of 8.32 tons per acre. CUF 101 only had the heaviest yield in one out of the past four years, but its high 1998 yield gave it the highest average yield over the four years of the study, at 8.37 tons per acre per year. Heat units with thresholds of 77o F and 41o F are included for each cutting in the study.

Nine alfalfa varieties, most not previously tested under field conditions in Arizona, were planted October 29, 1997, using the same setting on a Great Plains Solid Stand 13 End Wheel drill. Varieties differed in lbs. of seed/acre planted, ranging from 28.0 for CUF 101 to 21.3 for Alto. Seven cuttings were obtained in 1998, a year characterized by much cooler than normal temperatures during April through early July. The variety Alto yielded significantly more hay than CUF 101 in the first cutting and had the highest total yield (10.61 tons hay/acre) in 1998, 4.9% greater than the area standard, CUF 101. Varieties with fall dormancy class ratings of 8 (Alto, WL 525 HQ, and Baralfa 85) had the highest yields during 1998, yielding at least 103% of CUF 101. During 1999, the top yielding varieties were Baralfa 92, Beacon, and Baralfa 85, which all yielded at least 105% of CUF 101. These varieties in addition to Alto yielded 103+% of CUF 101 through the first two years of production.

Fourteen alfalfa varieties with fall dormancy ratings from 6 to 9 were tested in replicated small plot trials on the Kibler farm in Stewart District northwest of Willcox. The leading variety after four years of testing was DeKalb 189 with a dry matter yield over 5 tons per acre on 4 cuttings. This variety was also the leading variety over the four years of the trial with a four year average nearly 7.5 tons per acre. Heat units with temperature thresholds of 77 °F and 40 °F are given for each cutting.

Nine alfalfa varieties, most not previously tested under field conditions in Arizona, were planted October 29, 1997, using the same setting on a Great Plains Solid Stand 13 End Wheel drill. Varieties differed in lbs. of seed/acre planted, ranging from 28.0 for CUF 101 to 21.3 for Alto. Seven cuttings were obtained in1998, a year characterized by much cooler than normal temperatures during April through early July. The variety Alto yielded significantly more hay than CUF 101 in the first cutting and had the highest total yield (10.61 tons hay/acre) in 1998, 4.9% greater than the area standard, CUF 101. Varieties with fall dormancy class ratings of 8 (Alto, WL 525 HQ, and Baralfa 85) had the highest yields during 1998, yielding at least 103% of CUF 101. During the first half of 1999, the top yielding varieties were Baralfa 92, Beacon, and Baralfa 85, which all yielded at least 105% of CUF 101. These three varieties in addition to Alto have had accumulative yields of at least 103% of CUF 101 through the first 1.5 years of production (1998 -June 1999).

Five alfalfa varieties were planted and grown under grower conditions on a field section that had high conductivity, while two varieties were planted and grown on a normal field area. CUF 101, the variety grown in both areas, was the highest yielding variety in both area. Reduction in CUF 101 hay yield due to high conductivity was approximately one ton/acre in the first year of production, with a large amount of this noted in the first cutting. Yield differences between the areas was greatest in the early spring and late fall, with differences not noted in the June cutting. Salado was the second highest yielding variety in the high electroconductivity area, with Sal-T-96 and Leivas Best yielding less than 90% of CUF 101. Sal-T-96 also had the greatest number of weeds, due in part to very slow germination and fewer plants per acre compared with other varieties.