Dr. Bob Kratochvil, Extension Agronomist, University of Maryland
The majority of dairy farmers are constantly looking for sources of forage to meet their feed needs. One source that many of this region’s dairy farmers utilize is the fall planting of cereal grains that are green-chop harvested the following spring. Among the cereal species used for this purpose are rye, triticale, barley, and wheat. Per the Maryland Cover Crop Program guidelines, cereal grains planted as a cover crop prior to November 5 and suppressed via green-chop in the spring are eligible for the grant payment for participation in the Cover Crop Program. In addition, per the Nutrient Management Regulations, a fall application of dairy manure is allowed to a field planted to a cereal cover crop.
Planting a cereal cover crop that will be green chop harvested fits well into the crop rotation used by many dairy farmers. The scenario that many follow is to plant the cereal cover crop following harvest of corn silage. Prior to planting the cover crop, an application of manure is made to the field. The subsequent planting of the cover crop provides incorporation of the manure into the soil. The fall and spring growth of the cover crop is supplied nutrients from the manure. At the same time, the cover crop provides protection to the soil from loss of nutrients via leaching and/or erosion. The objective of this study was to evaluate select varieties of four cereal species for cover crop performance and forage production and quality.
Cereal varieties (11) representing four species (rye, triticale, barley, and wheat) were evaluated at two Maryland locations during 2016-2017 (Table 1). The locations were 1) Central Maryland Research and Education Center – Clarksville Facility and 2) a private farm near Frederick, Maryland. At each location, three replications for each entry were planted using a randomized complete block experimental design. Planting date was October 6, 2016 (Clarksville) and October 7, 2016 (Frederick Farm). The 3’ X 18’ plots were planted with a small plot planter with 6-inch spacing between each of the 7-rows. The germination percentage for each entry was used to calculate the seeding rate needed to establish 1.5 M seedlings. Good stands were established at both locations by late fall.
In order to compare forage quality among the entries that headed over a period of two weeks, the timing of the spring biomass harvest was when the entries had reached late boot to early heading stage of development. This necessitated the harvest of Aroostock rye and Nomini barley approximately 10 days earlier than the other nine entries (see Table 1 for heading date information). Each harvest sample was collected by cutting the plants just above ground-level from three center rows of each plot from an area 2.5 feet in length and from two areas within the plot. The samples were placed into cloth bags and dried using a forced air dryer set at 60o C where they remained until sample water content was zero. Each sample was weighed and is reported as pounds of dry matter production per acre (Table 1). Each of the dried samples was ground through a 20-mesh screen using a large plant grinder. For each location, the ground biomass samples for the three replications of each entry were thoroughly mixed and a sub-sample of approximately 60 g was collected to use for standard forage quality analysis that was conducted by the Cumberland Valley Analytical Laboratory.
Cover crop performance is measured by amount of biomass produced and the concentration of nitrogen in the biomass. These two factors were used to estimate nitrogen uptake (Table 1). The only entry to have nitrogen uptake that was significantly less than the mean for the study was Nomini barley. This is due to its production of only 3400 lb DM/a biomass compared to over 4900 lb DM biomass for the other 10 entries. In general, rye (4 varieties) had the best nitrogen uptake (~99 lb/a) followed closely by triticale (5 varieties and ~97 lb/a) and wheat (~97 lb/a) (Table 1). In general, the five triticale varieties produced slightly more biomass (254 lb/a) compared to the four varieties of rye tested.
A number of forage quality characteristics for these cereals was measured (Table 1). The descriptions of the various quality characteristic are described in the footnotes at the bottom of Table 1. The characteristic that best captures the overall forage quality performance is Relative Feed Value (RFV). A RFV of 100 is defined as the forage value that full bloom alfalfa would have. Wheat had the best RFV (100.5). In general, the five triticale varieties had better RFV (87.4) than the four rye varieties (81.9). And, in general, the five triticale varieties produced more biomass indicating it is a better species option for green chop cereal forage than rye.
Though, none of these greenchop cereal forages are considered to be adequate as a stand-alone feed for a dairy operation, they can supply a source of forage used in a total mixed ration (TMR) at the time of year when feed supply may be running short. When this forage benefit is added to the environmental benefit that is gained, planting winter cereal cover crops on a dairy farm can be a win-win decision.
*,# Indicates the entry was either significantly greater (*) or significantly (#)less than the mean for biomass yield. For head date, it indicates the entry was earlier (*) or later (#) than the average.
1Nitrogen uptake (lb/acre) for each entry was estimated by multiplying the lb DM/a X % nitrogen contained in the DM. The per cent nitrogen for each entry was calculated by dividing crude protein by the conversion factor 6.25 which is the average amount of nitrogen (%) contained in protein.
2Crude Protein %: represents total nitrogen content of the forage; higher protein is usually associated with better feed quality. In addition, this is a measure of the nitrogen uptake performance of each entry since % crude protein = 6.25 X nitrogen content.
3Soluble Protein %: non-protein nitrogen and that portion of true proteins that are readily degraded to ammonia in the rumen; used to synthesize microbial protein in the rumen.
4RDP (Rumen Degradable Protein): portion of crude protein that microbes can either digest or degrade to ammonia and amino acids in the rumen.
5ADF (Acid Detergent Fiber): represents the least digestible fiber portion of forage; the lower the ADF value the greater the digestibility; an ADF <35% is considered good quality.
6NDF (Neutral Detergent Fiber): insoluble fraction of forage used to estimate the total fiber constituents of a feedstock; NDF has a negative correlation with dry matter intake and is used to estimate dry matter consumption; as NDF decreases animals will consume more forage; for grass forages NDF <50% considered good quality and >60% considered low quality.
7Ash: mineral elements of the forage
8TDN (Total Digestible Nutrients): measure of the energy value of the forage.
9Net Energy Lactation: estimate of the energy in a feed used for maintenance plus lactation during milk production
10RFV (Relative Feed Value): indicates how well an animal will eat and digest a forage if it is fed as the only source of energy; full bloom alfalfa has an RFV of 100.
11Non Fiber Carbohydrates: represents all forms of digestible carbohydrates (starch, sugar, pectin, and fermentation acids) in the forage.
12Elite triticale breeding lines obtained from North Carolina State University for local testing by University of Maryland. These are not available for purchase.
