We own and operate a family Holstein dairy farm in Otter Tail Co., Minnesota. We grow corn silage, alfalfa, and barley. My father owns beef cattle and pastures them. Despite its prevalence in our area, we do not grow much soybean because of our interest in conserving soil and our concern about erosion potential under soybeans. We commonly no-till seed our alfalfa in August after barley.
Alfalfa is a key component of profitable, sustainable dairy farms in Minnesota. It is a perennial plant that fixes its own nitrogen, improves soil health, minimizes erosion, and provides high-quality forage for dairy cows. Unfortunately, alfalfa doesn’t live forever. The winter climate of Minnesota can result in significant winter injury or winter kill of alfalfa stands. Thus, we often need annual crops to bolster our feed supply when alfalfa forage is in short supply. Also, sometimes wet springs don’t allow us to plant alfalfa within a favorable window, so we’re faced with late planting, risky for alfalfa.
There are several annual crops often recommended for emergency forage by industry and Extension representatives. These include millets, small grains, sorghums, and sudans. Prior to our project, we hadn’t seen any side-by-side comparisons of yield and feeding value of emergency forage crop options that seemed relevant to central and northern Minnesota. We were especially interested in how some different annual forage crop options would compare as emergency forage crops at different planting dates, including optimum planting dates as well as late planting dates that we’re often faced with. This information would be useful to us and many other farmers in Minnesota.
PROJECT DESCRIPTION AND RESULTS
We worked together with Extension Educators and researchers from the University of Minnesota to compare the emergency forage crop potential of 16 different annual crops. We started this project in 2002 with funding from the Minnesota Department of Agriculture’s Sustainable Agriculture Demonstration Program, and it generated a lot of interest locally. However, 2002 was unusually warm and wet, so our results were probably not representative of a more typical year in our area. A second year (2003) of research was needed before we could draw strong conclusions and make recommendations to others. The 2 years we conducted this trial on our farm was part of a larger research effort in the north central region. Our University of Minnesota partners worked with fellow University folks from Wisconsin and Michigan to conduct this study at two other Minnesota locations in 2002-2003, three Wisconsin locations in 2003-2004, and a Michigan location in 2003.
The 17 crops we compared included 3 corn varieties for silage, forage sorghum, sorghum-sudan, sudangrass, hybrid pearl millet, 2 foxtail millets, 2 soybean varieties for silage, 2 small grain-pea mixtures, barley, chickling vetch, and alfalfa as a control for comparison. We planted each crop at recommended rates in one of my fields using the University’s small-plot seeding equipment. Plots were seeded in 3 replications and at 3 planting dates: mid May, mid-June, and ~July 1. Some crops were harvested up to 3 times while others were harvested just once with a goal of optimizing yield and quality.
We had a lot of help from University of Minnesota employees. They did all the planting, harvesting, and data analysis. Our main University cooperators were Doug Holen, Regional Extension Educator-Crops at Fergus Falls, and Paul Peterson, State Forage Extension Specialist. Doug also had an intern that helped with harvesting. Vince Crary, Extension Educator from the East Otter Tail Co. office, and Doug Swanson and Joshua Larson, technicians from the St. Paul Campus, also provided great help with plot planting. Jim Halgerson, with help from undergraduate student laborers, did the forage analyses that this SARE grant funded in the U of MN NIR Forage Quality Lab.
Corn and BMR forage sorghum plots were seeded 1-1.5” deep in four 30” rows with a single-row planter. All other entries were seeded in ten 6” rows to a 0.25-1” depth, depending on seed size. Plots that included legumes were inoculated with the proper Rhizobium species. I incorporated a lot of dairy manure prior to seeding, so soil test P and K levels were high and no synthetic fertilizer (including N) was applied to our Pelican Rapids plots in 2003. However, in 2002 and at all other locations, N fertilizer was applied as follows: within one week after planting, single-cut grasses (foxtail millets and barley) received 100 lb N/acre, multi-cut warm-season grasses (sudan, sorghum-sudan, pearl millet, and Japanese millet) received 50 lb N/acre with an additional 50 lb N/acre for each additional harvest, and corn and forage sorghum received 150 lb N/acre in one application.
Corn and forage sorghum plots were harvested by cutting the center two rows of each 4-row plot to 6” stubble. The remaining entries were harvested with a sickle plot harvester at our site, and with a flail plot harvester at other locations. Stubble height for sudangrass, sorghum-sudan, pearl millet, and Japanese millet was 6” to encourage regrowth, with the last harvest to 3”. All other entries were cut to 3” stubble. In general, harvest timing was scheduled to optimize yield and quality. The exception was the final harvest of multi-cut warm-season grasses, which were allowed to mature until temperatures were too cool for continued growth in September. Thus, midseason harvests of multi-cut species were at vegetative stages, but the final harvest was sometimes at heading. Based on previous research and experience on regrowth potential, sudangrass, sorghum-sudan, hybrid pearl millet, and Japanese millet were scheduled for multiple harvests. Foxtail millets were scheduled for just one harvest at boot stage.
Yield data were collected at each harvest. Feeding value was determined by drying and grinding samples and analyzing for crude protein (CP), neutral detergent fiber (NDF), NDF digestibility, and relative forage quality (RFQ) at the U of MN NIR Forage Quality lab. The Milk2006 spreadsheet from the University of Wisconsin was used to estimate milk production potential per ton and per acre of forage.
Yield and quality results for our Pelican Rapids site in 2003 are shown in Tables 1 through 3. [Editor’s Note: For copies of any of the tables mentioned in this report, please contact the NCR-SARE office at: email@example.com or 1-800-529-1342.] Summary data from all 4 MN environments in 2002 and 2003 are shown in Tables 4 through 9. Temperature and rainfall data for our Pelican Rapids site are included at the end of the report in Tables 10 and 11. 2003 was a dry year. May and June were cool and wet, but July through September was 5” below the long-term average. Average August temperatures were above normal, too.
Total-season yields of entries varied substantially, both within and among planting dates. At Pelican Rapids on average, delaying planting until June 16 or July 2 reduced 2003 total-season yields by about 30 and 50%, respectively, compared to planting May 16 (Table 1). The mid- and early-maturity corn silage hybrids were the highest yielding entries for the May 16 and June 16 planting dates, averaging 6.3 and 5.3 ton DM/acre at those respective dates. In contrast, for the July 2 planting, total-season forage yields were greatest for BMR forage sorghum, sudangrass, sorghum-sudan, late-maturity corn, pearl millet, and German foxtail millet. Corn populations were generally thinner than desired, so corn’s silage production potential was underestimated. In addition, deer damage to soybean, and potato leafhopper damage to alfalfa resulted in stunted yields for those entries. Over all 4 Minnesota environments (Table 4), BMR forage had the greatest yields overall and at the mid-May and early July planting dates. Overall, the 3 corn hybrids ranked 2 through 4 in DM yield behind BMR forage sorghum.
Total-season yields of multi-cut warm-season grasses were competitive with corn and forage BMR sorghum at the late planting date only. The exception was Japanese millet, which might have produced higher yields under a one-cut system. The one-cut foxtail millets (Siberian and Golden German) were competitive with the other warm-season forages. Here in Pelican Rapids, foxtail millets performed best with the May seeding date. The 5.2 tons DM/acre produced by German foxtail millet planted in May here was achieved within 77 days. In addition, foxtail millets established well at all planting dates and locations. Over all 4 MN environments and planting dates, sudangrass and sorghum-sudan were the highest yielding annual grasses, averaging nearly 5.0 ton/ac.
At Pelican Rapids in 2003, barley and small grain/pea mixtures produced about 130 and 180% more forage from the mid-May planting date than the mid-June and early July dates, respectively. Soybeans struggled with deer damage here. Over all 4 MN environments and planting dates, the later-maturing soybean generally produced more forage than the earlier maturing soybean (3.1 vs. 2.7 ton DM/ac, respectively). Alfalfa generally produced considerably less forage than all warm-season species at all planting dates, indicating the potential emergency forage value of the warm-season species.
At Pelican Rapids in 2003, mid- and early-maturity corn and BMR forage sorghum averaged the greatest milk production potential per acre (Table 1 bottom). Over all 4 MN environments and planting dates and at the early July planting specifically (Table 5), BMR forage sorghum had the greatest milk per acre, averaging 20,000 and 15,000 lb/acre, respectively. BMR forage sorghum and alfalfa generally had the greatest milk per ton, averaging 3330 lb/ton at Pelican Rapids in 2003 (Table 2 bottom). Over all MN environments, however, only BMR forage sorghum averaged greater than 3000 lb milk/ton (Table 6).
Chickling vetch had the greatest average crude protein content at Pelican Rapids in 2003 and over all 4 MN environments; but barley, alfalfa, and early-maturity soybean also produce 20+ % CP forage at times (Table 2 top and Table 7). The warm-season grasses generally had mid-teen CP levels, and occasionally exceeded 20% due to ample soil N levels and harvesting at vegetative stages. BMR forage sorghum and corn had the least CP, typically around 8 to 9%.
Alfalfa generally had the least NDF, averaging only 36% over all environments and planting dates, but soybean and chickling vetch also produced relatively low NDF forage compared to the other entries. In contrast, warm-season annual grasses generally had the greatest NDF digestibility. At Pelican Rapids in 2003, pearl millet and BMR sorghum sudan had the greatest NDFD, averaging 65% of NDF. Over all 4 MN environments, the foxtail millets had the greatest NDF content (avg. 64%), but also the greatest NDFD (avg. 58% of NDF). So foxtail millets are a prime example of crops that have better feeding value than would be anticipated based solely on NDF content.
Soybean produced the highest quality forage of all annual crops based on CP, NDF, and RFQ values. Among grasses, corn for silage had the least NDF, but also the least CP content. Despite high NDF content, foxtail millet forage had moderate RFQ and good CP content. Among grasses (corn excluded), BMR forage sorghum was among the highest in RFQ. Small grain/pea forage had higher NDF and lower RFQ values than expected; harvesting prior to milk stage may have improved quality. Multi-cut, warm-season annuals produced good quality forage of moderately high CP content and RFQ. Barley had the greatest CP content, especially as planting date was delayed, possibly due to high N fertilization levels and relatively low DM yields. In general, later planting dates often resulted in greater CP and RFQ values.
Our results showed that some of the crops evaluated have potential as emergency forages. Based on yield and milk production potential per acre, corn and forage sorghum may be among the best emergency forage options, even at planting dates as late as early July. Foxtail millets generally did not produce as much forage as corn or forage sorghum, but 1) produced consistently good stands that were competitive with weeds, 2) were ready to harvest within about 2 months after planting, and 3) had high NDF digestibility. The multi-cut warm-season annual grasses provide good options for farmers looking for an emergency grazing crop. Soybean showed promise as the one emergency option that might be most similar to alfalfa in quality. The optimum crop to plant for emergency forage should be determined by 1) when and how it will be utilized, 2) the forage quality needed, and 3) seed availability and cost.