Malheur Experiment Station Information for Sustainable Agriculture

second-year Results of the 2006-2011 Furrow-irrigated Alfalfa Forage Variety Trial

Eric P. Eldredge, Clinton C. Shock, and Lamont D. Saunders

Oregon State University

Malheur Experiment Station

Ontario, OR, 2007

Introduction

The purpose of this trial is to compare the productivity and hay quality of alfalfa varieties in the Treasure Valley area of Malheur County. The trial also provides information about the adaptation of alfalfa varieties to furrow irrigation for hay production. In this 5-year trial, seven proprietary varieties and one seed treatment are being compared to two public check varieties.

Methods

The trial was established on Owyhee silt loam where winter wheat was the previous crop and alfalfa had not been grown for more than 10 years. Details of crop establishment are in last year's annual report, which is available at http://www.cropinfo.net/AnnualReports/2006/06AlfAnnReport.html. Seed of each proprietary entry was supplied by the company, and certified seed of the two public check varieties was obtained locally. The entry 'FC2055' was the same variety as 'FC1055' except FC2055 included a proprietary seed treatment. On November 16, 2006, the soil-active selective herbicides Kerb^® 50WP at 1.5 lb/acre and Sinbar^® 80WP at 1.5 lb/acre were applied. This trial was established and grown with furrow irrigation from gated pipe, with furrows spaced 30 inches apart. In 2007, the trial was irrigated twice after the first, second, and third cuttings and once following the last cutting. The first irrigation of the season followed immediately after the first harvest.

In 2007, the first cutting was taken on May 15. A 32-inch by 20-ft swath was cut from the center of each plot with a Lawn Genie flail mower, and the alfalfa was weighed. The alfalfa was harvested three more times, on June 22, July 19, and August 29. Ten samples of alfalfa were cut by hand from the edges of plots over the entire field at random on the same day just before each harvest. The samples were quickly weighed, then dried at 140°F for 48 hours, and reweighed to determine the average alfalfa moisture content at each cutting. Yield was reported as tons per acre of alfalfa hay at 88 percent dry matter.

Samples of alfalfa to measure forage quality were taken mid-morning before the third cutting from approximately 1 ft of row per plot. The forage quality samples were dried at 140°F for 48 hours, ground in a Wiley mill (Thomas Scientific, Swedesboro, NJ) to pass through a 1-mm screen, and sent to the Oregon State University Forage Quality Lab at Klamath Falls, Oregon, where they were reground in a UDY mill (UDY Corp., Ft. Collins, CO) to pass through a 0.5-mm screen. Near infrared spectroscopy (NIRS) was used to estimate percent dry matter, percent crude protein, percent acid detergent fiber (ADF), percent neutral detergent fiber (NDF), percent fat, and percent ash.

Relationships for estimated dry matter intake for alfalfa hay (DMI), total digestible nutrients for alfalfa hay (TDNL), and relative forage quality (RFQ) were calculated using empirical formulas.

DMI (for alfalfa hay) was estimated by the equation

DMI = (((0.120 * 1350) / (NDF/100)) + (NDFD - 45) * 0.374) / 1350 * 100,

where NDFD = dNDF48 / NDF * 100 and dNDF48 is the digestible NDF as a percentage of dry matter, as determined by a 48-hour in vitro digestion test.

TDNL for alfalfa hay was estimated by the equation

TDNL = (NFC * 0.98) + (protein * 0.93) + (fat * 0.97 * 2.25) + ((NDF-2) * (NDFD/100)) where NFC = 100 - ((NDF - 2) + protein + 2.5 + ash).

Relative forage quality was calculated by the formula:

RFQ = (DMI * TDNL) / 1.23

where: 1.23 is used as the denominator to adjust the scale to match the RFV (relative feed value) scale at 100 = full bloom alfalfa.

Quality standards for alfalfa hay based on RFQ are: Supreme, RFQ higher than 185; Premium, RFQ 170-184; Good, RFQ 150-169; Fair, RFQ 130-149, and Low, RFQ below 129. Relative forage quality is an estimate of voluntary energy intake when the alfalfa hay is the only source of energy and protein for ruminants. The higher the RFQ, the less grain or feed concentrate supplements are required to formulate dairy rations. For 2007 we have also reported RFV, the relative feed value.

Results and Discussion

Spring weather in 2007 was cool and dry, which slowed the alfalfa regrowth from winter dormancy. The average daytime high temperature in March was 61°F and rain totaled 0.11 inch. The average daytime high temperature in April was 65°F with a total of 0.82 inch of rain for the month. A total of 0.35 inch rain fell before May 15, when the first cutting was taken, and most of the varieties were in the late bud to early bloom stage. The second cutting was taken June 22 at mid-bud stage. Third cutting, when forage quality samples were taken, was on July 19, at late bud stage. The fourth cutting was taken on August 29, at late bud to early bloom stage.

The average second-year total hay yield was 7.7 ton/acre, with 'WL 357 HQ' at 8.3 ton/acre, 'Masterpiece' at 8.0 ton/acre, and 'WL 319 HQ' at 8.0 ton/acre among the highest in hay yield (Table 1). The first-cutting average yield was 2.3 ton/acre. In the second cutting the average yield was 2.0 ton/acre. In the third cutting, the average yield was 1.5 ton/acre. In the fourth cutting the average yield was 1.9 ton/acre.

Crude protein averaged 23.5 percent in the third cutting, and ranged from 24.2 percent for 'DKA-42-15' to 22.2 percent for 'Lahontan'. Acid detergent fiber averaged 32.1 percent, and ranged from 33.2 percent for Lahontan to 30.4 percent for DKA-42-15. Neutral detergent fiber averaged 36.7 percent, and ranged from 38.2 percent for 'FC 1045' to 34.8 percent for WL 319 HQ. Relative forage quality averaged 191, in the "Supreme" quality category, and ranged from RFQ = 203, "Supreme" for DKA-42-15 to RFQ = 178, "Good" for Lahontan.

After 2 years, among the highest yielding varieties were WL 357 HQ, Masterpiece, WL 319 HQ, DKA-42-15, FC 2055, and 'Rustler II', which produced 15 ton/acre cumulative total hay yield for 2006 and 2007 (Table 2).

Information on the disease, nematode, and insect resistance of the varieties in this trial was provided by the participating seed companies and/or the North American Alfalfa Improvement Council (Table 3). Most alfalfa varieties have some resistance to the diseases and pests that could limit hay production. Growers should choose varieties that have stronger resistance ratings for disease or pest problems known to be present in their fields. The yield potential of a variety should be evaluated based on performance in replicated trials at multiple sites over multiple years.

Table 1. Alfalfa variety hay yield and third-cutting crude protein, ADF, NDF, and relative forage quality for 2007, Oregon State University, Malheur Experiment Station, Ontario, OR.

^aADF: acid detergent fiber. ^bNDF: neutral detergent fiber. ^cRFQ: relative forage quality. ^dRFV: relative feed value. ^eTDNL: total digestable nutrients for legumes. ^fYield at 88 percent dry matter. ^gDW: dry weight. ^hNS: Not significant at the alpha = 0.05 level.

Table 2. Alfalfa variety hay yield in the first and second years and cumulative total yield in the 2006-2011 furrow-irrigated forage variety trial, Oregon State University, Malheur Experiment Station, Ontario, OR, 2007.

^aYield at 88 percent dry matter. ^bNS: Not significant at the alpha = 0.05 level.

Table 3. Variety source, year of release, fall dormancy, and level of resistance topests and diseases for alfalfa varieties in the 2006-2011 furrow-irrigated forage variety trial, Oregon State University, Malheur Experiment Station, Ontario, OR, 2007.

^aFD: fall dormancy, BW: bacterial Wilt, FW: Fusarium wilt, VW: Verticillium wilt, PRR: Phytophthora root rot, AN: Anthracnose, SAA: spotted alfalfa aphid, PA: pea aphid, SN: stem nematode, AP: Aphanomyces, RKN: Northern root knot nematode.

^bPest Resistance Rating: >50 percent = HR (high resistance), 31-50 percent = R (resistant),

15-30 percent = MR (moderate resistance), 6-14 percent = LR (low resistance).

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