No-Till Annuals to Beat the Summer Slump on a Dairy Farm

Figure 1. Cool-season perennials are the mainstay of pastured dairies in the Northeast. ( Sjoerd Duiker, Penn State University )

Grazing is a cost-effective method to feed cattle. The cost of grazed forage is typically half or less than that of fed forage. But grazing demands a constant supply of high-quality pasture throughout the year, which can be a challenge in the U.S. Northeast. The widespread adoption of no-tillage for crop and forage establishment in Pennsylvania opens up exciting new opportunities to rotate annuals with cool-season perennials to meet forage needs of grazing dairies.

No-tillage has many benefits for soil management (see below). On grazing dairies no-tillage offers the opportunity to effectively renovate cool-season perennial pastures by rotating them with annuals for a year or two. The annuals can be used to supply grazing forage during a time when cool-season perennials have a slump in production. The use of no-tillage guarantees maintenance of the excellent soil structure, high soil organic matter, and high soil fertility observed after years of well-managed perennial sod. Using no-tillage reduces the threat of soil compaction because the high soil organic matter content, stable soil structure, active soil life, and decaying root system in the killed perennial sod results in a soil that resists compaction much better than tilled soil.

Soil Management Benefits of No-Till

  • Soil erosion control
  • Increased surface soil organic matter
  • Better surface soil aggregation
  • Continuous macropores in subsoil
  • Lower susceptibility to compaction
  • Greater infiltration
  • Lower water evaporation losses
  • More earthworms
  • More beneficial microbes
  • Ability to establish (cover) crops quickly

The mainstay of pastured dairies in the Northeast are cool-season perennial grasses, such as orchardgrass, timothy, brome, and perennial ryegrass (Figure 1). These perennial grasses, if managed well, help improve soil health because they protect the soil from erosion and improve soil structure and organic matter content through their permanent root system.

Cool-season perennial grasses have a peak in production in the spring and another peak in the late summer/early fall (Figure 2). They stop growing when temperatures decrease below about 40°F, but their growth also slows down dramatically when temperatures exceed 80°F. This causes a phenomenon called the “summer slump” in cool-season pasture production.

Figure 2. Cool-season perennial pasture growth dynamics. Credit: Sjoerd Duiker

The lack of pasture in the summer is typically met by feeding silage, hay, and grain. However, the cost of feeding stored forages adds significantly to the production costs of a grazing dairy. In this publication we will see how a grazing dairy farmer in southeastern Pennsylvania beats the summer slump with cool- and warm-season annuals established with no-till practices.

Eli Weaver’s farm is a grazing dairy in Leola, Lancaster County (Figure 3). The growing season in this area is long for Pennsylvania conditions—about 7 months. However, the summer can be hot and dry. Soils on the farm are mostly deep, well drained, and fertile, except for some areas where limestone rock comes close to the surface (Figure 4). Eli milks approximately 30 cows and keeps about 12 calves and heifers. The farm covers 52 acres—12 of them are in pasture. Eli divided his pastures into 10 one-acre strips, leaving about 2 acres of headlands. The rest of the farm is in cropland and farm buildings. Crops grown include alfalfa/orchardgrass silage and high-moisture corn. Eli’s perennial pastures are 7 acres of orchardgrass/perennial ryegrass and meadow fescue mixed with legumes such as red and white clover and alfalfa rotated with 3 acres of annuals. In the grazing season, one-third of an acre is offered to the cows per day by blocking of one-third of an acre per day with mobile electric fence. No back fencing is practiced so the cows can access the water at the headlands. Headlands are also used as a sacrifice area. This setup typically allows pastures to rest for 30 days before they are grazed again.

Figure 3. Eli Weaver farm in Leola, Lancaster County, Pennsylvania. Credit: Sjoerd Duiker

Figure 4. Farm layout showing soil types and crop and pasture fields. Ha=Hagerstown silt loam; Hb=Hagerstown silty clay loam; Db=Duffield silt loam; Lg=Linden silt loam. Following letters A, B, and C signify slopes of 0–3 percent; 3–8 percent, and 8–15 percent, respectively. Credit: USDA

Cows graze only at night; they are sent to the pasture after evening milking and brought back in the barn for morning milking. Night grazing is practiced first of all because in the summer outside temperatures are high enough to result in reduced milk production. Eli relies on the pastures for protein and energy while supplying more energy as shelled or high-moisture corn and hay or haylage in the barn. The milk production goal is 80 to 100 pounds of milk per cow per day. This goal is set to make sufficient profit from the limited land base of the farm in this area of high land values. Milk records from the first 9 months of 2017 show that herd average varied between 58 and 66 pounds of milk per day, while the highest production was 116 pounds per day and the lowest production 38 pounds per day (Table 1).

Table1. Milk production on Weaver farm, 2017.

Month Herd Average
pounds per day
Highest Producing
pounds per day
Lowest Producing
pounds per day
January 58 94 40
February 58 86 40
March 67 116 40
April 64 106 40
May 61 92 40
June 65 98 40
July 66 104 38
August 61 86 42
September 65 90 40
Average 63 97 40

To alleviate the summer slump, Eli plants one or two years of warm-season annuals in succession with cool-season annuals in rotation with his cool-season perennial pastures. This strategy is used to renovate the pastures and supply forage during the summer as well as in the fall and spring. Using no-tillage for all crops, soil health benefits of the perennial grasses in the rotation are maintained. Existing vegetation is terminated with a burndown herbicide (typically glyphosate) prior to a new planting. Small doses of nitrogen fertilizer are used only when the pastures show nitrogen deficiency.

The pastures are clipped after each grazing with a rotary mower set at 4.5 inches high. This helps with weed control and to guarantee uniform regrowth of the entire field. Eli’s experience is that if he doesn’t clip the pasture after grazing, some parts of the vegetation may mature while other parts of the field are still vegetative, which would negatively affect the quality of the forage.

We followed one of the annual forage fields in 2016 and 2017, recording standing biomass and grazed yields. This field was a perennial cool-season pasture that was terminated with glyphosate in June 2015. A sudangrass/turnip mix was grown that summer followed by a mixture of oats/tillage radish/annual ryegrass that was grazed several times in fall and spring.

In early June 2016 AS 9302 brown midrib sudangrass was no-tilled into the terminated annual ryegrass and grazed three times, on July 15, August 4, and August 31 (Figures 5 and 6). Only one application of nitrogen was made: 33 pounds of nitrogen per acre as ammonium sulfate at seeding. For the rest of the season, the sudangrass’s nitrogen needs were met by mineralization of soil organic matter. The grazed yield increased from 1,100 to 2,300 pounds of dry matter per acre per grazing. The grazed percentage increased from 36 to 59 percent of standing biomass. Total grazed yield was about 5,000 pounds of dry matter per acre. In September, triticale 815 and KB Royal annual ryegrass were no-till drilled after the sudangrass. The triticale/ryegrass mix was fertilized with 50 pounds of nitrogen per acre as ammonium sulfate at greenup in the spring.

Figure 5. AS9302 BMR sudangrass prior to grazing. Credit: Sjoerd Duiker

Figure 6. AS9302 BMR sudangrass three days after grazing and clipping. Credit: Sjoerd Duiker

The annual ryegrass/ triticale mix was grazed on April 17, May 4, and May 26, 2017 (Figures 7 and 8). Grazed yields were 660, 1,700, and 1,100 pounds of dry matter per acre. In mid-June, a mix of AS 6402 BMR sorghum-sudangrass and T-Raptor rape were planted and received 20 pounds of nitrogen per acre as ammonium sulfate. This mix was only grazed once at the beginning of August at a yield of 3,800 pounds of dry matter per acre. Due to unforeseen circumstances, it was grazed to the ground and did not produce good regrowth. Therefore, it was terminated in August 2017 and a perennial cool-season grass mix was no-till planted after the summer annual mix. The paddock had been in annual cool-season/warm-season mixes for two years and three months, after which it was no-till planted back with perennial cool-season pasture.

Figure 7. Eli’s cows grazing annual ryegrass/triticale mix. Credit: Sjoerd Duiker

Figure 8. Ryegrass/triticale paddock immediately after grazing. Credit: Sjoerd Duiker

In summary, each summer, 2 to 2.5 tons of grazed dry matter per acre were produced during a period we call the “summer slump” in cool-season perennial production. If we add the grazed yield of the annual cool- and warm-season grasses, the combined grazed yield was more than 6 tons of dry matter per acre in one year and two weeks. It is interesting to note that this production was achieved with only 103 pounds of nitrogen fertilizer per acre and no manure applied by the farmer. Of course, the grazing cows deposited their manure and urine when they were grazing in the field. Research has shown that management-intensive grazing results in much better distribution of manure and therefore better nutrient utilization than continuous grazing. Additionally, the farmer has improved his soil organic matter content, and it appears that more utilizable nitrogen is released for plant use by the mineralization of soil organic matter than what is common in cropland. The quality of the forage was found to be satisfactory for lactating dairy cows. Measured crude protein varied from 19 to 25 percent, the ADF was less than 34, NDF less than 63, TDN 56 or more, and relative feed value ranged from 94 to 145.

We also evaluated soil health of the paddock in the spring of 2016 using the “ Pennsylvania Soil Quality Assessment Worksheet ” (available from Penn State Extension). The ratings were excellent with very good residue cover (90 percent) for soil erosion control, moisture conservation, and soil temperature regulation; excellent soil structure; very high earthworm activity; and excellent water infiltration—2 inches of water were infiltrated in 4 minutes and 20 seconds, which is high considering that the average monthly precipitation in this region is 4 inches.

The use of no-till summer annuals in succession with cool-season annuals allows this dairy farmer to beat the summer slump and successfully increase the length of his grazing season. He is able to achieve this with minimal nitrogen fertilizer inputs, very good soil erosion control, and maintenance of excellent soil health.

Table 2. Soil health evaluation of paddock 2 in spring 2016 (rated from 0–10 with 0 being worst, 10 being best).

Indicator Rating Description
Surface cover 90% Year-round surface cover from living crop or dead mulch; cover 50–100% after planting
Soil structure 10 Soil aggregates crumb, don’t disintegrate in water; soil tilth excellent, good weight-bearing capacity; no crusting or sealing
Organic matter 8 Soil dark color; visible organic matter at surface; organic matter content high (>4% in top 2 inches); approaching level under native vegetation
Soil erosion 10 No visual evidence of rills or soil movement and deposition in the field; few to no rock fragments visible at surface
Soil compaction 9 Soil not very resistant to penetration with soil compaction tester; no evidence of plow pan; low penetration resistance in subsoil
Water infiltration 9 First inch, 1 minute, 27 seconds; second inch, 2 minutes, 50 seconds; water drains well after heavy rain; ponding absent; low runoff
Soil biodiversity 9 Much evidence of earthworm activity; many nightcrawler mounds; spiders and ground beetles visible under residue
Plant and root growth 9 Seedling emergence even and fast; plant growth vigorous and even; plants resist drought stress; root growth vigorous; roots fibrous; roots explore soil profile

Source: Penn State Soil Quality Assessment Worksheet.

Table 3. Standing and grazed biomass of annual forages on Weaver Farm, 2016/2017.

Date Annual Forage Standing Biomass
pounds of dry matter per acre
Grazed Biomass
pounds of dry matter per acre
Grazed Biomass
7/15/16 Sudangrass 3,131 1,128 36
8/4/16 Sudangrass 3,247 1,665 51
8/31/16 Sudangrass 3,872 2,296 59
4/17/17 Ryegrass/triticale 3,307 660 20
5/4/17 Ryegrass/triticale 2,974 1,713 58
5/26/17 Ryegrass/triticale 1,405 1,097 78
8/2/17 Sorghum-sudangrass + rape 4,215 3,794 90
Total   22,151 12,353 56

Table 4. Feed quality of standing biomass of annual forages on Weaver Farm, 2016/2017.

Date Annual Forage Crude Protein
percent dry matter
percent dry matter
percent dry matter
percent dry matter
Relative Feed Value
percent dry matter
7/15/16 Sudangrass 23.6 31.7 60.0 57 96
8/4/16 Sudangrass 24.5 31.7 61.1 57 98
8/31/16 Sudangrass 19.2 33.1 62.7 56 94
4/17/17 Ryegrass/triticale 23.6 25.3 44.5 71 145
5/4/17 Ryegrass/triticale 22.3 26.5 51.4 59 124
8/2/17 Sorghum-sudangrass + rape 25.4 28.5 53.5 59 116

Prepared by Sjoerd W. Duiker, professor of soil management and applied soil physics; David O. WIlson, agronomy extension educator; and Jessica A. Williamson, assistant professor of forage management.

This material is based upon work supported by the Natural Resources Conservation Service, U.S. Department of Agriculture; under number 68-2D37-14-743. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.