Third Year Results of the 2002-2006 drip-irrigated Alfalfa Forage Variety Trial

 

 

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

Malheur Experiment Station

Oregon State University

Ontario, OR, 2004

 

 

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 hay production to drip irrigation. In this trial, over 5 years, 10 proprietary varieties are being compared to 2 public check varieties. This trial was established with a portable sprinkler-irrigation system and then grown with a subsurface drip-irrigation system.

 

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. Pathfinder (Nelson Irrigation Corp., Walla Walla, WA) drip tape (15 mil thick, 0.22 gal/min/100-ft flow rate, 12-inch emitter spacing) was shanked in at a depth of 12 inches on 30-inch spacing between the drip tapes. Plots were 5 ft wide by 20 ft long in a randomized complete block design with each entry replicated five times. Further details of the establishment of this trial were reported previously (Eldredge et al. 2003).

 

Gramoxone^® at 2 pint/acre plus Sencor^® at 1.5 pint/acre were applied for weed control on March 11, 2004. No irrigations were applied before the first cutting in 2004. After the first cutting, irrigations were semi-automated using a valve controller (DIG Corp. Vista, CA) initially programmed to apply a 1-inch irrigation twice weekly, on Mondays and Thursdays. Alfalfa crop evapotranspiration (ET_c) was calculated based on data collected by an AgriMet (U.S. Bureau of Reclamation, Boise, ID) weather station located on the Malheur Experiment Station. Soil moisture was monitored by six Watermark soil moisture sensors model 200SS (Irrometer Co. Inc., Riverside, CA) installed at 12-inch depth in the center of six alfalfa plots, midway between drip tapes. Sensors were connected to an AM400 data logger (M.K. Hansen, East Wenatchee, WA) equipped with a thermistor to correct soil moisture calculations for soil temperature. Water applied was measured by a totalizing water meter on the inlet of the irrigation system. A rodenticide, Maki bromadiolone supercade bait (Liphatech, Inc., Milwaukee, WI), was applied in rodent tunnels on July 22 with a gopher probe (Eagle Industries, Chatsworth, CA).

 

The alfalfa was harvested at bud stage on May 14, June 17, July 19, August 13, and September 22, 2004. A 3-ft by 20-ft swath was cut from the center of each plot with a flail mower, and the alfalfa was weighed. Ten samples of alfalfa were hand cut from border areas of plots over the entire field on the same day just before each cutting, quickly weighed, dried in a forage drier at 140°F with forced air, 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 from approximately 1 ft of row per plot were taken June 16, before the second cutting, to measure forage quality. The forage quality samples were dried, ground in a Wiley mill (Thomas Scientific, Swedesboro, NJ) to pass through a 1-mm screen, subsampled, 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. Relative forage quality (RFQ) was calculated by the formula:

 

RFQ = (DMI * TDNL) / 1.23

where:

DMI = dry matter intake (for alfalfa hay), and

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

NDFD = dNDF48 / NDF * 100, and

dNDF48 = digestible NDF as a percentage of dry matter, as determined by a 48-hour in vitro digestion test,

TDNL = total digestible nutrients [for legume (alfalfa hay)]

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

NFC = 100 - ((NDF - 2) + protein + 2.5 + ash), and 1.23 was chosen as the denominator to adjust the scale to match the RFV scale at 100 = full bloom alfalfa.

 

Quality standards 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. RFQ estimates voluntary energy intake when the hay is the only source of energy and protein for ruminants. Hay with a higher RFQ requires less grain or feed concentrate to formulate dairy rations.

 

Results and Discussion

 

Rodents chewed holes in the drip tape and continued to be a problem in this trial. During the winter, voles burrowed down to the drip tape and chewed holes that were found and repaired at the first irrigation. The rodenticide applied in the vole tunnels was effective until the grain crop adjacent to the alfalfa trial was harvested. After the grain harvest, a new population of voles gradually colonized the alfalfa trial. A gopher that moved into the trial was promptly exterminated.

 

Soil moisture was monitored at the 12-inch depth after first cutting (Fig. 1). After June 8, the soil remained uniformly moist in the –20 to –30 kPa (centibar) range for the rest of the irrigation season.

 

The total irrigation water applied was less than the season-long accumulated alfalfa crop evapotranspiration (Fig. 2). The irrigation system was turned off for harvest operations and to repair leaks. Smaller irrigations, from 0.01 to 0.38 inch, were applied on seven dates through the summer in order to check for leaks or following repairs to the drip tape. Accumulated season-long alfalfa ET_c from March 5 to October 10 totaled 43.38 inches, and the drip irrigation measured by the water meter, plus rain, totaled 31.81 inches or 73.3 percent of accumulated season-long alfalfa ET_c.

 

The average third-year total hay yield was 7.9 ton/acre (Table 1). The first-cutting average yield was 2.5 ton/acre, with ‘SX1002A’ ‘Masterpiece‘, and ‘SX1001A’ yielding among the highest. In the second cutting ‘Ruccus’, Masterpiece, ‘Tango’, ‘Orestan’, and ‘Somerset’ were among the highest yielding varieties. In the third cutting, Ruccus, ‘Lahontan’, Masterpiece, Orestan, and Tango were among the highest yielding varieties.  In the fourth cutting, Ruccus, Tango, Orestan, and Lahontan were among the highest yielding. In the fifth cutting, Ruccus, ‘Plumas’, and Somerset were among the highest yielding varieties. In total yield of five cuttings, Ruccus, with 8.4 ton/acre, Masterpiece, with 8.2 ton/acre, and Tango, SX1002A, and Orestan each with 8.0 ton/acre, were among the highest yielding.

 

The crude protein averaged 25.6 percent in the second cutting, and ranged from 24.3 percent for Orestan to 26.7 percent for Somerset. Acid detergent fiber, ADF, averaged 26.7 percent. Neutral detergent fiber, NDF, averaged 31.2 percent. Relative forage quality averaged 245, with all varieties in the “Supreme” quality range. SX1005A, Plumas, Somerset, and Masterpiece produced hay with RFQ scores higher than 247.

 

Total hay production in the first 3 years averaged 18.3 ton/acre (Table 2). The varieties Ruccus, at 20.1 ton/acre; Tango, at 19.4 ton/acre; and Masterpiece, at 19.3 ton/acre were among the highest yielding.

 

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.

 

References

 

Eldredge, E.P, C.C. Shock, and L. D. Saunders. 2003. First year results of the 2002 to 2006 alfalfa forage variety trial. Oregon State University Special Report 1048:14-17. Available online at www.cropinfo.net/AnnualReports/2002/B5aDripAlf02.htm

Figure 1. Soil moisture in the drip-irrigated alfalfa variety trial during the 2004 growing season, Malheur Experiment Station, Oregon State University, Ontario, OR.

 

Figure 2. Accumulated irrigation applied plus rain compared to the AgriMet accumulated evapotranspiration (ET_c) for alfalfa grown for hay, Malheur Experiment Station, Oregon State University, Ontario, OR 2004.

Table 1. Alfalfa variety hay yields and second-cutting crude protein*, ADF*, NDF*, and relative forage quality for 2004, Malheur Experiment Station, Oregon State University, Ontario, OR.

	Cutting date									2004		Crude			Relative
Variety	5/14			6/17		7/19		8/13	9/22	total		protein	ADF†	NDF‡	forage quality
		------------------ton/acre§----------------										-------% of DW¶-------			RFQ
Ruccus		2.4	1.4		2.0		1.2		1.3		8.4	26.0	27.0	31.5	239
Masterpiece		2.7	1.3		1.9		1.1		1.2		8.2	25.1	26.1	30.7	251
Tango		2.5	1.3		1.9		1.2		1.2		8.0	25.2	28.0	32.9	228
SX1002A		2.9	1.2		1.7		1.1		1.2		8.0	25.1	27.4	32.3	233
Orestan		2.4	1.3		1.9		1.2		1.2		8.0	24.3	29.0	34.2	213
Lahontan		2.3	1.2		2.0		1.2		1.2		7.9	25.8	26.7	31.3	243
Plumas		2.6	1.2		1.8		1.0		1.3		7.9	26.6	24.9	29.2	267
SX1001A		2.7	1.2		1.7		1.0		1.2		7.9	25.4	26.3	31.2	244
Somerset		2.4	1.3		1.8		1.1		1.3		7.9	26.7	26.1	30.3	253
SX1003A		2.5	1.2		1.6		1.0		1.2		7.5	25.5	26.5	31.0	246
SX1005A		2.5	1.1		1.7		1.0		1.1		7.4	26.4	25.1	29.1	271
SX1004A		2.3	1.2		1.5		1.0		1.2		7.4	25.5	26.8	31.2	247
Mean		2.5	1.2		1.8		1.1		1.2		7.9	25.6	26.7	31.2	245
LSD (0.05)		0.29	0.09		0.18		0.07		0.10		0.47	1.27	1.74	2.26	23.7

*Based on percent of dry weight.  ^†ADF: acid detergent fiber. ^‡NDF: neutral detergent fiber.

^§Yield at 88 percent dry matter. ^¶DW: dry weight.

 

Table 2. Alfalfa variety hay yields in the first 3 years of the 2002-2006

drip-irrigated alfalfa variety trial, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

	Yield
Variety	2002*	2003	2004	Cumulative
	-------------------ton/acre†------------------
Ruccus	2.6	9.1	8.4	20.1
Tango	2.5	9.0	8.0	19.4
Masterpiece	2.4	8.7	8.2	19.3
Somerset	2.4	8.5	7.9	18.8
Orestan	2.2	8.4	8.0	18.7
Plumas	2.6	8.1	7.9	18.5
Lahontan	2.0	8.1	7.9	18.1
SX1001A	2.1	8.0	7.9	18.0
SX1002A	1.9	7.7	8.0	17.7
SX1005A	2.4	7.7	7.4	17.5
SX1004A	2.1	7.5	7.4	16.9
SX1003A	2.0	7.0	7.5	16.5
Mean	2.3	8.2	7.9	18.3
LSD (0.05)	0.40	0.54	0.47	0.94

*Two cuttings, 8/6 and 9/5/2002.     ^†Yield at 88 percent dry matter.

Table 3. Variety source, year of release, fall dormancy, and level of resistance to pests and diseases for 12 alfalfa varieties in the 2002-2006 drip-irrigated forage variety trial, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

*FD: 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: root knot nematode (northern).

 

^†Pest resistance rating: >50 percent = HR (high resistance), 31-50 percent = R (resistant),

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

 

^‡Fall Dormancy: 1 = Norseman, 2 = Vernal, 3 = Ranger, 4 = Saranac, 5 = DuPuits, 6 = Lahontan,

7 = Mesilla, 8 = Moapa 69, 9 = CUF 101.

 

^§Experimental varieties, not released, pest resistance data not available.