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TWIN FALLS — All hay fields are not created equal. A survey shows that the 10 percent of hay growers across the Western states harvest 1.5 to 2.7 times as much irrigated alfalfa hay per acre as their peers in the middle of the pack.

That gap translates into real dollars. Michael Russelle, with the University of Minnesota, estimates average producers are netting $285 to $690 per acre less than the top producers.

He hypothesizes that the gap may reflect a persistent belief by growers that alfalfa is a low yielding crop that isn’t as valuable as other cash crops. While he doesn’t have proof, the fact that alfalfa acreage has declined by 40 percent across the U.S. over the last 50 years seems to confirm his hunch.

Idaho trends mirror those of its neighboring states, said Glenn Shewmaker, University of Idaho Extension forage specialist. According to data from the 2012 Census of Agriculture, the average hay yield was 4.4 tons per acre but the top 10 percent of growers harvested a minimum of 6.4 tons per acre.

Dairies, the largest consumer of alfalfa hay in the state, may be one factor. As hay growers manage to optimize hay quality for the dairy market, they are cutting hay more frequently, which reduces yield because the crop has fewer days to regrow between cuttings.

Even though yield has remained fairly constant, alfalfa hay quality has improved. The percent of TDN (total digestible nitrogen) increased from 5.3 percent to 5.5 percent (of dry matter) between 1970 and 2000, according to Russelle’s analysis.

More frequent cuttings also impact yield by creating more traffic within the field. Studies have shown that increased traffic can reduce yield by 20 percent or an average loss of 2.5 tons per acre. The yield loss ranged from 1.4 to 3.6 tons per acre when a a 4-ton tractor was driven across a field five to six days after harvest compared to a check with no traffic.

Growers who do a better job of irrigation scheduling are rewarded with higher yields. Subsurface or drip irrigation systems have seen a boost of 20 to 35 percent in tons per acre. These precision systems seem better able to meet crop water needs more and provide more flexibility to irrigate before and after harvest.

New technology such as LESA (low energy sprinkler application) mimic drip irrigation by dropping nozzles close to the ground and may offer growers some opportunities in southern Idaho to increase hay yields while reducing water usage.

Alfalfa breeders are also looking at dormancy and low-lignin traits to see if yields can be boosted through better variety. Moving to non-dormant types may allow growers to increase the time between cuttings to boost yield without impacting quality.

That could be more important if the western U.S. continues to experience warming temperatures. Hot temperatures can rapidly lead to significant reductions in hay quality. Just three days of hot temperatures can drop hay from dairy quality to feeder hay.

But the biggest management strategy growers can adopt to increase both yield and quality is to move to what Shewmaker calls “hay-in-a-day.” That means minimizing the time hay lays on the ground between cutting and baling.

Getting hay out of the windrow quickly allows the plants to begin regrowing sooner and increases growing time between cuts. It also reduces traffic through the field, which allows for more regrowth.

Shewmaker also encourages growers to look at planting alfalfa varieties that offer more flexibility for scheduling harvest.


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