I.         Project Title    Comparing low and high input strategies in diversified cropping systems.

II.        Project LeaderPerry Miller, Dept. Land Resources and Environmental Sciences

III.      Personnel:        Jeff Holmes, Research Associate - Field Operations

Dave Buschena - Economic Analyses

                                       Clain Jones - Soil Nutrient Dynamics.

IV.       Objectives for this proposal:

             1.   Compare diversified no-till and organic cropping systems for crop productivity and quality and resource use efficiency.

             2.  Compare low and high input strategies for crop productivity and quality and resource use efficiency.

V.         Results

2004 was the 5^th consecutive year of below normal precipitation at Bozeman, continuing the trend of 3 to 3.5 inches short of the 30-yr normal of 16.5 inches (Fig. 1). This deficiency was due to a lack of precipitation in the non-crop storage period (Sept-April) in most years. However, critical rainfall during July has varied strongly among years (Fig. 2). In all years except 2004, average monthly temperatures have been warmer than normal during one or more summer months (Fig. 3).

Figure 1. Total crop year precipitation apportioned into storage (September - April) and in-crop (May - August) periods at the A.H. Post MSU Research Farm near Bozeman, MT. 1971-2000 is the 30-yr normal.

Figure 2. July rainfall at the A.H. Post MSU Research Farm near Bozeman, MT. 1971-00 is the 30-yr normal.

Figure 3. Average maximum temperatures during summer months at the A.H. Post MSU Research Farm near Bozeman, MT. 1971-2000 is the 30-yr normal

1) Organic vs. No-Till 

             Hypothesis: Organic winter wheat yield and protein will be much lower than no-till systems.

Surprisingly, winter wheat from the organic system was in the highest yielding category 3 of 5 yr when compared with three no-till systems (Table 1). However in 2004, due to dry conditions during the previous fall, the organic winter wheat stand was not sufficiently dense to outcompete winter broadleaf weeds. This resulted in tilling for weed control and late replanting to spring barley for 3 of 4 reps, leading to very poor economics. During the years that organic winter wheat yielded well, the growth pattern differed from no-till wheat in that early vegetative growth was visually less vigorous, resulting in a conservative soil water use pattern important under terminal summer drought. Despite high winter pea green manure tonnage, grain protein concentrations for organic winter wheat appear to be declining over time and may suffer price discounts below 12%. However, organic winter wheat has consistently had high test weights while in 8 of 15 cases the no-till treatments would have incurred price discounts due to low test weight.

Organic lentil production ranged from 700 to 1600 lb ac^-1 during 2000-03, respectable yield levels compared with conventional systems. Joined with price premiums 100% over non-organic lentils, the economics have been very positive. Delayed seeding of lentil using high seeding rates and narrow row spacing has resulted in surprisingly weed-competitive stands. However, Canada thistle has become a problem that may be associated with the shallow water use of lentil.

The weak spot in the organic rotation has been barley. Yields have ranged from 37 to 72 bu/ac but test weights have been consistently less than 48 lb/bu and as low as 42 lb/bu in 2 of 5 years. Worse, in 2004 barley became severely infected with covered smut presumably due to recycling seed from this study. So, due to low test weight or diseased heads, barley has been suitable only for feed markets rather than the high value organic malt barley markets.

2) Winter vs. Spring Growth Habits

             Hypothesis: The climatic pattern at Bozeman provides a substantial edge to winter crops.

Despite five growing seasons with terminal summer drought, grain yield, protein and test weight have not differed between spring and winter wheat (Table 2).

             Agronomic practice and genetics for the winter canola and pea require further development.

3) Wheat Yields Following Pea vs. Canola

Hypothesis: Wheat yield and quality will not differ following pea or canola in this study, since fertilizer N is reduced on pea stubble compared with canola stubble (9 lb N/ac less).

Wheat following pea yielded 18% greater than after canola (Table 2). This is likely due to greater conserved soil water below the pea crop (Figure 4) but could also be due to other interacting factors.

In 3 of 8 cases test weight was higher following pea than canola while differences in grain protein have not been important.

             Starting in 2004 the N credit for pea was increased to 18 lb N/ac in this study.

4) Sunflower-Induced Hangover

Hypothesis: Wheat yield in the highly diversified no-till rotation will be higher than wheat yields in the alternate-year no-till rotations due to superior ecological management of pests.

The ecological crop response might manifest in the long term but after 5 yr, the opposite occurred. Despite a shallow rooting pattern, spring pea (or lentil) following sunflower averaged 25% less yield than following wheat in the alternate-year no-till spring rotation. Winter wheat 2 yr after sunflower yielded 19% less than in the alternate-year no-till winter rotation (both grown on pea stubble in the interim year) (Table 1). In 2 of 5 yr wheat test weight was significantly reduced 2 yr after sunflower.

5) Continuous wheat

Hypothesis: Wheat yields will be lowest in the continuous wheat no-till rotation due to an accumulation of pests.

Averaged for 5 years only one rotation is yielding greater (23%) than continuous wheat; winter wheat following field pea. Increasing populations of wild oat and downy brome have required additional grassy herbicide costs for continuous wheat. The relatively high yield in 2004 was unexpected and may be related to heavy infestation by volunteer winter wheat.

6) Soil water use 

Hypothesis: Soil water extraction, from greatest to least, will occur in the following pattern:

green manure pea < spring pea = lentil = proso millet < winter pea < spring wheat = canola < winter wheat = dormant canola < corn < sunflower

Pea (or lentil) consistently used the least soil water due to limited extraction below the 0.6-m depth (Fig 4). However, this limited rooting ability resulted in grain yields that were only 67% of continuous wheat.

Conversely sunflower consistently used the greatest soil water to 1.8 m. However, large sunflower yields occurred despite summer drought, providing large net returns to that rotation.

Soil water use by canola was inconsistent from year to year and was correlated with seed yield. Soil water following tilled winter pea green fallow was equal to that under spring pea stubble. Proso millet and corn extracted soil water similar to spring wheat.

7) Comparative Economics

Hypothesis: The organic system would generate significantly lower returns than the no-till systems, and the no-till winter crop system would generate the highest returns during the transition period.

Ignoring management costs, the Organic system was economically competitive with no-till systems during the transition period. In 2003, when price premiums were available to organic, economic returns were greater than all other rotations. However, in 2004 economic returns were disastrous for the organic system.

^L In 2004 N fertilizer rates were decreased by 50% to target 1.5 N per bushel of targeted yield (60 bu/ac yield target).

^W Due to heavy weed infestations, 3 of 4 reps of organic winter wheat were tilled in early June and replanted with barley June 7 that yielded 21.3 bu/ac with a test weight of 50.2 lb/bu. One rep of winter wheat yielded 52.8 bu/ac.

^X Test weight from one rep of winter wheat. Barley test weight was 50.2.

 ^T An experimental line of winter triticale was either contaminated with winter wheat, or was genetically contaminated, since 50% of the heads appeared more wheat-like than triticale.

⁴ Mean calculated for 2000-03 only owing to bias from lower test weight of triticale in 2004.

^L In 2004 N fertilizer rates were decreased by 50% to target 1.5 N per bushel of targeted yield (60 bu/ac yield target).

^AY Continuous wheat system was spring wheat in even years and winter wheat in odd years.

^T Triticale has a standard bushel weight of 56 lb.

⁴ Means calculated for 2000-03 only owing to bias from lower test weight of triticale in 2004.

VI. Summary

This rotation study has contributed importantly to the understanding of cropping systems principles in Montana.

1) Organic systems can be economically competitive during the transition phase, especially during drought.

2) Spring and winter wheat have equal yield potential if managed similarly.

3) Rotational benefits of pea are superior to canola.

4) Sunflower yields remarkably well despite summer drought, where deep stored soil water is available.

5) Deep rooted crops like sunflower reduce subsequent yields for two or more years.

6) Continuous wheat has limited yield potential and is more costly to manage than wheat in a rotation.

7) Soil water can be managed by using shallow (pea, lentil) or deep (sunflower) rooted crops.

VII. Future Plans

This crop rotation study was redesigned in 2004 to provide results more representative of respective cropping systems, including comparison of high and low input systems. We will publish results of the 1^st 4-yr cycle and report annually until the next 4-yr cycle is complete.