FY 2004/05 Progress Report - Fertilizer Check-Off

1. Project Name

Maximizing the value of annual legume forage through N cycling in direct-seeded crop sequences with wheat.

2. Principal Investigators and Cooperators

            PI's:                   Perry Miller, Dave Wichman, Rick Engel

            Cooperators        D & F Farms, Ltd., Amsterdam, MT

3. Objectives

1. To compare the productivity/quality and water-use-efficiency of spring vs. fall-planted pea forage with barley forage.

2. To describe harvest management effects for barley and pea forages on productivity and quality and on residual soil water and nitrogen.

4. Materials and Methods

The context for this study is direct-seeded recropping of annual pea/barley forage in cereal stubble, where a producer is looking to diversify a cropping system and increase cropping intensity without taking the risk of recropping to grain. Sites include an on-farm site near Amsterdam and the MSU - Central Ag Research Center near Moccasin. The experimental design is a split-split-plot arrangement including a chem fallow control, with four replicates. Crop entries are the main plots, harvest management timings are the subplots and four N fertilizer rates in a subsequent wheat test crop are the sub-subplots.

Main Plot - Entries

1. Spring pea - Grande (normal leaf, fair stem strength)

2. Spring pea - Arvika (normal leaf, colored flower, poor stem strength)

3. Winter pea - PS9430706 (WSU breeding line normal leaf, fair stem strength)

4. Winter pea - Melrose (Austrian, normal leaf, poor stem strength)

5. Haybet barley

6. Haybet + Arvika

+(Chem fallow control)

Subplot - Harvest Management

1. First flower, to maximize forage quality and restrict soil water use.

* Note in 2005 crop we will spray glyphosate on all forage treatments prior to cutting to ensure effective stand termination. This is a legal practice in Canada and I will be lobbying toward this in Montana.

2. Plump pod, to maximize forage yield prior to seed maturation.

3. Maturity to compare grain yield potential with forage yield under same conditions.

∙            Barley will follow timing for Arvika pea

Subsubplot - Year-2 Spring Wheat test crop

Four N rates - 0, 45, 90, 135 lb/ac

                Plots: [(6 entries x 3 harvest timings) + chem fallow] x 4 N rates x 4 reps = 304 plots/site

                Year1:

                                Soil Measurements:  

                                                water, (fall + spring) = 12+28 plots/site x 4 depths = 160 samples

                                                water, fall = 76 plots/site x 4 depths = 304 samples

                                N, (fall + spring) = 12+28 plots/site x 2 depths = 80 samples

                                                N, fall = 76 plots/site x 2 depths = 152 samples

                                Plant Measurements:

                                                Plant = 72 plots/site

                                                Seed = 24 plots/site

                                                Forage Quality = 48 plots/site

                Year2:

                                Soil Analyses:         

                                                water, spring = 76 plots/site x 4 depths = 304 samples

                                N, spring = 76 plots/site x 2 depths = 152 samples

                                Plant Analyses:

                                                Plant = 304 plots/site

                                                Seed = 304 plots/site

5. Project Results and Relevancy to Montana

Seeding winter pea near Sept 15 resulted in timely emergence at both Amsterdam and Moccasin in 2002 and 2004. Winter survival was excellent in 2003 at both locations and climatic conditions have been favorable for good winter survival in 2005. As a result of our consistent winter survival in this and related studies, in 2004 some producers seeded winter pea in farm fields that will test winter survival in a broad geographic region.

Wheat test crop yields averaged 55.0 and 27.5 bu/ac at Amsterdam and Moccasin, respectively. Total crop year precipitation was 13.4 and 13.5 inches, respectively. 2004 marked the 6^th consecutive year of below normal precipitation at Bozeman. The large difference in wheat test yield between the sites is related to: 1) shallow soils at Moccasin do not store reserve soil moisture; 2) July rainfall was below normal at Moccasin (Fig.1); and the Amsterdam site was seeded very early (March 29) due to the exceptionally early spring in 2004. The Moccasin site was seeded April 22.

Figure 1. Monthly precipitation during the 2003-04 crop year at the MSU Post Farm 6 miles west of Bozeman and at the MSU Central Ag Research Center, Moccasin, MT.

Forage Productivity (Table 1)

The winter pea lines were in the highest yield class (i.e. forage tonnage) in all cases except when cut at flowering at Amsterdam. The N yield (i.e. yield of forage protein) of the winter pea lines was in the highest yield grouping in all cases. Melrose Austrian winter pea yielded more forage and total protein than the experimental winter line in all cases. A lack of herbicide options for the barley + pea mixed stand resulted in greater weed biomass (downy brome + volunteer wheat) for that crop treatment, but this biomass was included in the forage yield. Forage WUE was greater at the pod stage of cutting, with no important differences among crops. Pea averaged 27% of the forage mixture for the Haybet + Arivka treatment at both forage cuttings at Amsterdam (not measured at Moccasin) and did not affect forage yield. The yield increase of Haybet + Arvika over pure Haybet at Moccasin is due to the fact that the Haybet plots were reseeded 3 weeks later.

Forage Quality (Table 2)

Winter pea forage was very high quality and generally had the highest crude protein values at both sites. Crude protein averaged 44% greater than that from the barley treatments, and 22% greater than that from the spring pea treatments. Relative Feed Value (RFV) was consistently in the ‘Prime’ category (>151) for all pea treatments while the barley treatments most often graded No.1 or No.2. The Haybet barley treatment was fertilized @ 60 lb N/ac at Amsterdam but nitrate concentrations in the forage were very low at both locations. Pea averaged 27% of the forage mixture for the Haybet + Arivka treatment at both forage cuttings at Amsterdam but did not affect crude protein. The pure barley stand received 60 lb N/ac while the mixed stand received only 30 and this may account for the lack of response in crude protein.

Grain Yield (Table 3)

Melrose winter pea posted the highest grain yield among all pea entries at Amsterdam, and was equal or greater than Haybet barley. Total grain N yield and WUE were also greatest for Melrose, and N yield was lowest for the Haybet barley treatments, averaging less than half of Melrose. Arvika pea made up 27% of the grain in the barley-pea mixture at Amsterdam (data not shown) but did not increase grain protein or grain N yield.

Soil Water (Table 4)

The chem fallow control had a net loss of 26 mm (1 inch) water from 15 May to 27 August in the top 0.91 m (36 in) of the soil profile but still held greater soil water than all crop treatments. No important changes in soil water were detected in the 0.91 to 1.12 m (36 - 44 in) soil increment. When measured immediately after forage harvest the ‘flower’ and ‘pod’ stages held 40 and 19 mm (1.6 and 0.7 in) more water than at maturity, averaged for all crop treatments. When remeasured to coincide with maturity (Aug 26-28) these differences had diminished to 12 and 4 mm (0.4 and 0.2 in) indicating net losses due to summer evaporation and crop and weed regrowth of 28 and 15 mm (1.2 and 0.5 in). Consequently, in the next cycle of this experiment we will apply glyphosate to the stands prior to cutting to avoid post-harvest water loss due to plant regrowth. Terminating Melrose winter pea at flowering resulted in 49 mm (1.9 inch) less residual plant available water than chem fallow, a difference that is expected to be made up over winter and during the early growing season of 2004 to permit equivalent spring wheat yields on both treatments. Differences in post-harvest plant-available water among crops were small but the barley treatments consistently had the least plant-available water. No difference in water use was observed between spring and winter pea.

Wheat Test Crop

Crop Productivity (Table 5)

The 100 (90) and 150 (135) kg ha^-1 (lb/ac) N rates reduced plant density by 9% to 157 plants m^-2, but remained above the optimal threshold minimum of 125 plants m^-2. Seedling mortality was presumably due to N damage from the side-band. Midseason biomass at Amsterdam indicated the greatest yield potential at the highest N rate with the previous crop stubble 4x more important than the harvest timing. By maturity, grain yield were greatest at the 100 (90) kg ha^-1 (lb/ac) N rate at both locations indicating insufficient water to reach midseason yield potential. At Amsterdam the previous crop was nearly 3x as important as harvest timing, while only harvest timing of the previous crop affected yield at Moccasin. We cannot explain why grain yields were depressed following the mid-season forage harvest (pod stage).

At Amsterdam the greatest grain yield occurred on the chem fallow control (68 bu/ac @ 12% grain moisture) followed by winter pea stubble (88% of fallow), spring pea stubble (83% of fallow) and barley stubble (72% of fallow), due to differences in stored soil water. Small differences in yield occurred among sequential harvest timings of the previous crop, also due to differences in stored soil water. Importantly these effects were ‘additive’. Harvesting winter pea for forage at flowering resulted in spring wheat yields that were equal to the chem fallow control. There were no important interactions among treatments except crop x N rate where the interaction was related to much greater grain yield on the winter pea stubbles compared with very low yields on the hay barley stubbles at the 0 N rate. Importantly, grain yield was optimized @ 50 kg N ha^-1 for spring wheat following chem fallow or winter pea, but not until 100 kg N ha^-1 for spring wheat following spring pea or barley. A savings of 50 kg ha^-1 of fertilizer N represents a cost savings of between $13 and $15 per acre at current fertilizer prices.

Grain Quality and Yield Components

Grain protein concentration was not available at the time of this report. Test weight and N rate were negatively related such that not only was grain yield depressed by the highest rate of N but low test weight (< 56 bu/lb) would certainly have caused price discounting at Amsterdam. Seed size decreased 37% from 0 to 150 kg N ha^-1 indicating surprising sensitivity in this final yield component. Correlation between grain yield and heads per m² was 0.90 and 0.64 at Amsterdam and Moccasin, respectively. Since heads per m² correlated strongly with grain yield, this indicates that treatments influenced yield formation early in plant growth.

6. Termination Date

This project is scheduled to terminate Dec 31, 2006 after which we will have accumulated 4 site-years of data from both phases of this cropping sequence study.

Means within a column and table section followed by the same letter do not differ according to protected LSD (P < 0.10).

Means within a column followed by the same letter do not differ according to protected LSD (P < 0.10).

† Relative Feed Value. > 151 = Prime, 125-150 = No. 1, 103-124 = No.2, 87-102 = No.3

‡ Nitrate concentration. > 1,100 ppm requires feeding restrictions. > 10,000 ppm toxic.

Means within a column within a table section followed by the same letter do not differ according to protected LSD (P < 0.10).

† Fallow water on May 15.

Means within a column and table section followed by the same letter do not differ (P=0.10).

Means within a column and table section followed by the same letter do not differ (P=0.10).