Studies were conducted in West Lafayette Indiana in 2011 to determine the feed value of grain amaranth (Amaranthus hypochondriacus) for dairy production. Studies consisted of treatments comparing amaranth, corn silage (Zea mays), and BMR Sorghum Sudangrass (Sorghum bicolor X sudanense) seeded with or without manure soil amendment. Two plantings of amaranth and one of BMR sorghum sudangrass and corn were established, and harvested for determination of yield, NDF, ADF, Hemi-cellulose, ASH, CP, and phosphorus content. Amaranth was the most digestible forage with an NDF of 30-35% an ADF of 22-28%, and a CP of 12-16%. Analysis of ash from all three crops showed that amaranth can contain up to 30% of its weight in dry matter as ash. Phosphorus content in Amaranth was double that of corn silage on a dry matter basis. The results conclude that amaranth is a phosphorus accumulator and could reduce the need of phosphorus supplementation in livestock feeds.
Tightening margins in animal agriculture have increased the importance of incorporating low-cost and alternative feeds into the rations of beef and dairy animals. The use of high quality forages can decrease the needs for costly supplements while maintaining or improving animal health and nutrition. There is currently very little research focused on incorporating new, less common forages with high nutritional values into forage cropping systems in the Midwest.
In addition to the potential benefits of including grain amaranth and quinoa forage in cattle diets, the agronomic properties of these crops make them viable crops to incorporate into forage production systems as a double crop. Grain amaranth is a fast growing crop that will exhibit re-growth after it has been cut. In addition, grain amaranth has been shown to be a crop that will accumulate phosphorus. Grain amaranth and quinoa require less nitrogen for growth than corn, reducing needs for commercial fertilizer applications. Grain amaranth and quinoa can tolerate droughty conditions much better than standard warm/cool season crops. Adding grain amaranth and quinoa into crop rotations has the potential to reduce phosphorus soil levels and improve nutrient balances on farms. Two members of the Amaranthus genus that are very closely related to grain amaranth, redroot pigweed and palmer amaranth have been identified as phosphate accumulators (Costea et al., 2004; Liang et al., 2009; Santos et al., 1998; Shrefler et al., 1994a,b). Due to the close relationships between redroot pigweed, palmer amaranth, and grain amaranth, there is a potential for grain amaranth to reduce phosphorus in soils. If grain amaranth is able to accumulate phosphorus, the crop would be beneficial to reduce phosphorus concentrations in soils with high phosphorus levels, as is common in soils around livestock facilities.
The objectives of this trial were to assess the ability of grain amaranth to remove phosphorus (P) from the soil, determine the suitability of grain amaranth to Indiana production as compared to conventional alternatives, and to assess the yield potential of grain amaranth. Following successful outcomes from research projects extension related activities were planned to disseminate information about grain amaranth to interested producers.
The success of grain amaranth production was determined by, whether the crop reached a stage at which it could be harvested as a forage, if the plant tissue digestibility analysis matched that found by previous researchers, and if successful fermentation of the forage material occurred. These were performance targets that were used to determine if amaranth was a successful crop. Methods were identified that would allow for the best assessment of these factors.
Experiments took place at the Purdue University Agronomy Center for Research and Education in West Lafayette Indiana. Experiments were conducted in fields that were previously in soybean and had been chisel plowed in the fall.
All plots within each treatment were sampled one day prior to manure application. Manure application took place in spring of all years and was applied as soon as the ground could be worked. Manure was of swine origin and was applied at a rate of 5000 gallons/acre. Total manure applied to each plot was measured using a scale mounted to the application tank and by subtracting the amount manure left after application from the amount of manure before application. The manure was applied using a liquid manure spreader with 5 knives spaced 2ft apart yielding a ten foot application swath. Each plot had manure applied long-ways through the plot yielding 2 passes per each plot. Manure application took place on March 28th 2011. Two samples of liquid manure were taken from each tank applied to the plot and was sent to A&L Great lakes labs for nutrient analysis.
Soil samples were taken using a probe that was 3/4 inch inner diameter and to a depth of 8 inches. Nine soil samples were taken from each plot and bulked together as a single sample that represented one plot. Soil samples were taken in a “sideways M” pattern, shown in Figure1.
Soil samples were taken from each plot, at the beginning of that year’s trial and after each subsequent crop harvest. Two full samplings that included all plots took place just before manure application and at the end of the season. Mid-season soil sampling only took place in plots that had just been harvested.
All soil samples were weighed after sampling, samples were processed through an number 3 aluminum screen, placed in paper bags, and allowed to air dry in a soil drying facility in Lilly hall of life sciences. Soil weight after drying was used to determine soil moisture at the time of sampling.
Dried soil samples were ground using a soil grinder with a 2 mm screen. Ground soil samples were stored in poly lined soil sampling bags at room temperature until the time of analysis.
Soils were extracted for available nutrients by using the Mehlich 3 extracting procedure outlined in Recommended Chemical Soil test Procedures (MSU SB-1001). Extracted samples were stored at 3 degrees Celsius until time of analysis. Mehlich 3 extraction procedures were used for all nutrient analysis procedures due to it’s high correlation to plant available nutrients and the extent to which it is used by soil testing facilities. Soil pH, buffer pH, and Soil Organic Matter were determined using procedures outlined in Recommended Chemical Soil test Procedures (MSU SB-1001).
Based on the nutrient analysis of the swine manure, plots that did not receive manure were compensated in nitrogen to the level that was applied in the manure. In 2011 swine manure contained 118 lbs/acre of available N, subsequently 118lbs/acre of N was applied in the form of Urea (44-0-0) using a Gandy drop spreader. In corn silage plots with manure, the amount of nitrogen was supplemented by 28 lbs/acre of starter at planting and an additional 84 lbs/acre of N side-dressed, to give a total of 230 lbs N/acre. In plots that did not have manure applied the plots were supplemented with 28lbs of starter as well as 200 lbs N/acre as side-dress. No fertilizers were used that contained any phosphorus. In amaranth plots that did not receive manure, an application of 188 lbs/acre N as Urea was made. After each subsequent silage harvest of each non corn treatments, an application of 50 lbs/acre N as ammonium nitrate was applied using a Gandy drop spreader.
Corn was seeded with a drill set at 30 inch row spacing and a rate of 34,000 seeds/acre. Corn was fertilized to a total of 230 lbs N per acre. The corn variety used was Becks hybrid 5676 HXR with stay green, herculex, roundup, and liberty link genes. 5676 HXR is a silage variety corn that is well adapted to the area in which the trial took place, and is a common variety for conventional corn silage. Corn seeding took place May 4th 2011, with starter fertilizer placed in row.
Both amaranth and Brown Mid-Rib (BMR) sorghum sudangrass (Sorghum bicolor x sudanense) were seeded using a drill capable of 7 inch rows. The drill was properly calibrated to deliver the exact amount of seed required per drop tube to meet the desired seeding rates. Depending on soil type, and ambient soil moisture, both amaranth and BMR sorghum sudangrass were seeded at 1/2 – 3/4 of an inch and 3/4 – 1 1/2 inches deep respectively. Amaranth was seeded at a rate of approximately 224,000 seeds per acre pure live seed. BMR sorghum sudangrass was seeded at a rate of 24 lbs of pure live seed per acre. The variety of amaranth used for this study was ‘Plainsman’ a grain type amaranth and the only commercially available varieties, obtained from the University of Nebraska. The Variety of BMR sorghum sudangrass used was ‘Nutri+ BMR sorghum sudangrass’ obtained from Cisco Seeds (Cisco Co. Indianapolis IN). Seeding dates for amaranth were May 15th and July 8th. BMR sorghum sudangrass was seeded on July 8th, after amaranth harvest. Weed control was applied through pre-emergence glyphosate applications using a rate of 1 quart per acre. Weeds following germination were controlled through hand weeding operations that took place during the first three weeks of establishment. These hand weeding events were performed due to the lack of registered herbicides for amaranth as well as to prevent any potential problems caused by spraying products in the research plots.
Before all harvest events plot borders were removed before any harvest data was taken. On the day of each harvest the following observations were recorded, plant stage, harvest length and width, noticeable lodging, and weight of harvested material. Hand collected samples were taken, weighed, and dried from all the crops and harvests at the time of each harvest with a hand scythe for Dry Matter (DM) determination. Harvest for the first amaranth cutting took place on July 6th 2011, with ensiling taking place 2 days later. Harvest for the second amaranth cutting took place on September 7th with ensiling taking place five days latter. BMR sorghum sudangrass harvest took place on September 13th with ensiling taking place eight days later. Corn silage harvest took place September 2nd 2011. Corn silage was harvested with a Winter Steiger biomass harvester, once plants were harvested the crop was immediately ensiled in mini-silo bags.
Silage plots were harvested with a syclebar mower and gathered by hand and lain in bundles by plot and crop type for ensiling. These piles were turned once a day until such time as the moisture content of the forage reached the desired level of 70%. The crops were chopped before ensiling to reduce particle size, by using or a 10 Horse Power chipper shredder mulcher. Crops should be ensiled by plot using the mini silo method, which consisted of lining a small barrel with two three mill trash bags, placing silage in the bags, and applying pressure using a stomping motion inside the barrel to press the silage in the barrel to remove air trapped between silage particles. After all silage material was packaged, the bags were subjected to vacuum pressure and sealed. Silos were opened after the silage was stabilized, and a representative sample of silage was obtained shortly after opening. This sample was weighed and dried for further analysis.
Hand harvested material as well as representative plot samples were dried in a forced air oven at 60 degrees Celsius until such time as the weight obtained by a representative sample no longer decreased. Samples were weighed immediately upon leaving the drying oven. Samples were ground down, in progression, from a 6 mm screen to a 1 mm screen in a Wiley cutter style grinding mill. All sample left inside the mill upon completion of grinding were included in the sample and not discarded. Samples were next mixed thoroughly and stored in a “whirlpak” bag., Fiber analysis use the attached protocols for Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), and Ash content were determenied through the methods listed at http://www.ankom.com/procedures.aspx .
To determine plant tissue Phosphorus (P) content, and Crude Protein (CP) the colometric P, and Kjeldahl methodology as described in Plant Analysis Reference Proceedures for the Southern Region of the United States were used.
All reported statistics were generated by the SAS program.
The yields for Corn Silage and BMR sorghum sudangrass observed in this study were very consistent with those reported in literature and extension articles. Although amaranth yielded well, there are few comparators, so yield could not be determined to be average.
Although there was much variation in the soil P content and water availability during the course of the 2011 field season, differences between treatments were still observed. Figure 1 shows the yield of all crops from 2011. In Figure 1 it can be noted that corn yield was significantly different between plots that received manure versus plots that received no manure. Figure 2 shows the total nitrogen in plant tissue. Looking at both Figure 1 and Figure 2 it can be seen that the nitrogen fertilizer type is more than likely the cause of the differences between corn yield. Even though equivalent N was applied to both treatments, it is likely that the N available in the manure was either overestimated or was not as readily available as side-dressed N fertilizer. The same conclusions can be applied to may seeded amaranth treatments. It is worth noting that Figure 2 shows N content in the plant, and as such amaranth and sorgum sudangrass seeded in July received the same amount of nitrogen in each respective treatment 50 lbs N /acre, the amount of N present in the plant is significantly different. Additionally, corn treatments received 230 lbs N/acre. What one can interpret from these results is that sorghum sudangrass and amaranth are much more nitrogen use efficient than corn. It is worth noting that July sorghum sudangrass with manure was slightly higher in N content than its non-manure treatment counterpart, this may be due to residual N left in the soil from manure application.
Figure 3, 4, and 5 show the results of NDF, ADF, and Hemicellulose analysis respectively for each treatment in 2011. In terms of NDF the lower the value observed the less fiber content that the plant contains. For animal feed purposes this can be a good or bad thing depending on what kind of animal you are feeding. In the case of a highly productive dairy cow in early lactation, the lower the better. Lower fiber means higher digestibility and more available nutrients. In the case of NDF amaranth has the lowest NDF value of the three crops tested. However there seems to be a significant difference between manure and no manure in the May seeding. Since further analysis is being performed currently, there is currently no way to explain this difference. The difference is likely due to a soluble cation such as potassium being in higher proportion in the tissue which was grown in manure soils compared to non-manure soils. The next crop with more NDF content is corn silage followed by the greatest fiber content in BMR sorghum sudangrass. The ADF analysis shows somewhat similar values only corn has the lowest content in this case followed by amaranth and BMR sorghum sudangrass. The change in the lowest content is due to the fact that corn silage contains corn grain and the grain has a very low fiber content, especially in ADF. Lastly for hemi-cellulose content we see that May seeded amaranth has the lowest content of hemi-cellulose, followed by July seeded amaranth, corn silage, and lastly BMR sorghum sudangrass. Hemi-cellulose is calculated as the difference between the NDF and ADF values, and is important in the extent of digestion of a forage. ADF represents ASH and lignin values which are not digestible, meaning that a forage with a lower hemi-cellulose value would have a more complete digestion when compared to one that has high hemi-cellulose depending on rumen passage rate.
Ash content is worth mentioning as amaranths ash value has rarely been published. However based on the information in Figure 6 amaranth has some of the highest ash contents of a forage. Preliminary results from other studies suggest that this is due to an extraordinarily high level of all nutrients contained in the plant tissue notably, 10% K and 2.5% Ca, on a dry matter basis. This could be an incredibly important discovery considering on farm nutrient balances. As of yet, I have no explanation for why ash values in May seeded amaranth are higher than July seeded amaranth, but it may have to do with the fact that Spring of 2011 was very wet, and Summer 2011 was very dry, which would limit the uptake of nutrients based upon water availability.
Phosphorus (P) amounts between treatments within crop were not significantly different. Figure 7 shows the P content of the three crops grown. It is worth noting that the values of P content seen in amaranth are higher than any strictly forage feed of which the author is aware. This shows that amaranth has a great affinity for P uptake. Literature suggests that N and K content available to the plant can affect the amount of P the plant takes up. Data shown in figure 2 suggests that since amaranth is very N efficient it may also be able to access more P and bring it into the plant.
Educational & Outreach Activities
There are publications in work for this and other studies pertaining to our labs research pertaining to grain amaranth. Outreach activities have been many as our lab has presented information to producers at Purdue University field days state wide. There are other extension publications and presentations in development for continued outreach pertaining to the research pertaining to this study.
Amaranth can certainly be grown for forage in Indiana. Additionally amaranth is certainly a P accumulator and could be used to re-mobilize P from the soil and into the diets of forage fed animals. This should lead to less off farm P inputs in animal diets and a reduction in soil P that could reduce P leaching into local streams. More research should be conducted to maximize the ability of amaranth to pull P from the soil. This research also shows that amaranth has an excellent feed value even when compared to corn silage. The quality of amaranth is actually closer to, and in some ways better than, that of alfalfa. If CP values could be increased, amaranth could be considered an annual substitute for alfalfa.
As of yet, an economic analysis has not been performed for this study. However, an analysis is being developed that will answer questions that relate to the opportunity costs associated with the use of grain amaranth as a forage.
as of yet no farmers have adopted grain amaranth as a silage crop for their production systems. However, there are many farmers who are awaiting the completion of further studies from our lab that would provide answers to their questions about economics and production practices needed for adoption.
Areas needing additional study
Areas needing further study are currently being assessed in other projects that are ongoing in our lab. These projects will fill in information gaps in our knowledge and should allow for better quantification of amaranth qualities and further research areas.