Grazing is a cost-effective method to feed beef cattle. The cost of grazed forage is typically half that of fed forage (Figure 1). However, if crop residue can be grazed, the cost to feed beef cattle can be reduced even more, and grazing offers the opportunity to get more value out of cover crops. The widespread adoption of no-tillage systems in Pennsylvania opens up exciting new opportunities to graze crop residue and cover crops after grain harvest to meet the forage needs of beef producers.
Figure 1. Cost of grazed forage is half or less than that of harvesting, storing, and feeding forage in feed lots. Photo by Sjoerd Duiker
No-tillage has many benefits for soil management (see list below). Soil erosion is effectively controlled due to high and permanent soil protection and stable soil aggregates. The use of no-tillage leads to high surface soil organic matter that is resistant to compaction. The stable soil structure beneath that layer with a firm matrix holds up grazing animals much better than tilled soil. The soil matrix is interspersed with many large and small pores created by soil organisms and decaying root systems, guaranteeing good aeration and water percolation. Using no-tillage therefore reduces the threat of soil compaction.
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
There are other reasons why integration with grazing can help improve soil health in no-till systems. The animals help tramp organic matter onto the soil surface and deposit urine and manure on the soil to improve soil fertility. Grazing also helps add value to cover crops, making their costs and management easier to justify. On the other hand, grazing also has to be managed carefully or the cover crop and crop residue may be overgrazed, resulting in soil erosion, and soil can be compacted, resulting in reduced aeration, greater runoff, and reduced performance of crops planted after a field has been grazed. Grazing also involves an initial investment in fencing and watering infrastructure, and continued investment in management of the animals. In addition, one also has to think about feeding the animals when the grain crops are in the field.
Cropland used for grain production typically lies fallow for six or seven months of the year (Figure 2). Planting cover crops after or in main crops is recommended to maintain a “living root” in the soil year-round (Figure 3). Cover crops help improve soil structure with their root systems. Beneficial soil organisms that live in the crop rhizosphere are sustained. Cover crops help reduce runoff and soil erosion. Cover crops take up nutrients, protecting them from leaching. Cover crops can also liberate nutrients, making them more available to following main crops. Leguminous cover crops fix atmospheric nitrogen, which can benefit following crops.
Figure 2. This corn field could have been planted to a cover crop and grazed for improved soil health and added profit. Photo by Sjoerd Duiker
Figure 3. Cover crops help improve soil health by maintaining a living root system in the soil year-round. Photo by Sjoerd Duiker
However, it usually takes years before soil improvement benefits of cover crops can be noticed, while the cost for seed and management are immediate. If the farmers can get immediate return from cover crops while maintaining most of the benefits, it becomes a lot easier for farmers to justify using them. Hence the importance of grazing (or harvesting for forage) of cover crops to stimulate adoption.
We studied the integration of grazing and no-tillage on the Double B grain farm in McAlisterville, Pennsylvania, from 2014 to 2017. Four generations of the Brubaker family live on this farm, which produces corn, soybeans, oats, and spelt (Figure 4), as well as broilers and Limousin cattle. They farm 400 acres, 220 acres of which are rented ground.
Figure 4. Grain crops grown on the farm include corn, soybeans, and oats. Photo by Sjoerd Duiker
The Brubakers started using no-till planting in the 1990s. The farm has been in continuous no-till since 1996. Crops are grown on the contour in strips laid out in their conservation plan designed by USDA-NRCS. Until recently, cover crops were only grown after small grain harvest. However, after becoming aware of the importance of cover crops for soil improvement, they started using them after all their grain crops in 2012. The cover crops include radish/ryegrass/crimson clover mixes after early harvested crops, and rye for later planting.
The Brubakers graze approximately 50 bred cows plus calves, for a total of 90 animals, primarily of the Limousin breed. They sell embryos as well as beef. The mainstay of their grazing needs is met by cool-season perennial pastures. A challenge they face is to meet grazing needs in the winter and summer. Since soils on their farm tend to be droughty, summer forage supply is a special concern on this farm.
We focus here on the fields around the homestead, which include 43 acres of perennial pastures and 39 acres of grain crops (Figure 5). The perennial pastures are divided up into about 22 paddocks with permanent fencing so cattle can be rotated frequently, usually on a daily basis. After grazing, the pastures are rested for at least a month before they are grazed again. Most perennial pastures are cool-season grass/legume mixes. Growth of cool-season pastures slows down severely on this farm with droughty soil types, which creates a challenge for grazing in the summer. Therefore, the Brubakers planted two strips of switchgrass in Field 2 to meet grazing needs during the summer. Research has shown that warm-season perennial grasses show good potential to meet summer grazing needs for beef farmers. However, establishment of warm-season perennials on this farm has been slow, and after several years their productivity is still marginal.
Figure 5. Thirty-nine acres of cropland has been fenced and is planted to cover crops after grain harvest for grazing in the fall and spring. Shown are strips of rye cover crop planted into oat (center), soybean (to the right), and corn grain (farthest to right). Photo by Sjoerd Duiker
In this case study we focused on the 39-acre grain crop field (Field 3 in Figure 6). Most of this field is planted to grain crops of corn, soybean, and either spelt or oats. The strips along the outside fence are in perennial cool-season grass/clover pasture (Figure 7). This facilitates management of the grain crops with equipment.
Figure 6. Farm layout of the Double B grain farm. Courtesy of USDA-NRCS
Figure 7. Permanent exterior fencing with grass border. Photo by Sjoerd Duiker
After the grain crops are harvested, cover crops are planted (usually cereal rye). This field is then grazed in the fall and spring. Additionally, the cool-season pastures in this field are also grazed, and the farmer planted one strip with warm-season annuals to meet summer grazing needs.
To enable grazing in this field with grain crops, strips of cropland are fenced temporarily with semipermanent posts that can be removed after harvest (Figure 8). This limits the risk of grazing animals escaping into the grain fields. Holes along the edge of strips are dug with a post hole auger so wooden posts can be easily installed. All fences are also electrified to reduce the risk of animals escaping into the crop fields.
Figure 8. Posts between the oat and warm-season annual strip are used to create a semipermanent fence between strips that are grazed and neighboring strips with grain crops. Post hole augers are available to quickly install such a fence that gives greater security than a one-strand mobile electrical fence. Photo by Sjoerd Duiker
Water lines are shown in blue on the conservation plan map (see Figure 6). There is only water available at the top corner of the crop field (Figure 9). Having water only at one end of the field limits the use of management intensive grazing in this field. Therefore, the field is usually used for continuous grazing in the fall and spring.
Figure 9. Water is available only in one corner of the 39-acre crop field, limiting the use of management intensive grazing. Photo by Sjoerd Duiker
In the summers of 2015, 2016, and 2017, one strip of this field was planted to pearl millet alone (2015) or to a pearl millet/rape mix (2016/17) to meet grazing needs during the summer slump in cool-season pasture production (Figure 10). The farmers chose pearl millet because it is a crop that is adapted to high temperatures (> 65°F) and dry soil conditions. Another reason for choosing pearl millet was that it does not produce prussic acid, which can be a threat to cattle grazing sorghum or sudangrass exposed to either water stress or when it is frosted. Prussic acid is highly toxic to cattle, so it is always a concern for graziers using these warm-season annuals.
Figure 10. Pearl millet was used to graze in the summers of 2015, 2016, and 2017. Two strands of mobile electric fencing were moved every day, but no back fencing was possible because water was only offered at the entrance to the field. Photo by Sjoerd Duiker
The strip with pearl millet was grazed one day at a time by spanning two strands of electrified mobile fence between the semipermanent fences straddling the pearl millet and neighboring crop field (Figure 11). No back fencing could be practiced because water was only available at the headlands of the field. The benefit of back fencing is that cows cannot graze regrowth of previously grazed vegetation. When regrowth is regrazed, it weakens the stand because the plants have to draw from their reserves before they are replenished. It also reduces leaf area, which is necessary for photosynthesis needed for regrowth. Back fencing is also preferred to improve distribution of urine and manure. Animals will drop manure and deposit urine on their way to the water or when grazing previously grazed plots. They also like to linger around the water source and often deposit more manure and urine there than in other parts of the field. Soil compaction is another concern that can be limited with back fencing because animals only impact one plot for a short period. Moving the water source combined with back fencing would be a way to improve utilization of manure and urine and increase productivity on this farm. This can increase yield and reduce fertilizer application needs, but it involves additional investment in water lines and labor to move water sources.
Figure 11. Brubaker cows grazing a field of pearl millet. Photo by Sjoerd Duiker
Each year, pearl millet or pearl millet/rape was planted in the beginning of June. We measured pre- and postgrazing biomass by cutting three 0.5-square-meter areas at the ground surface pre- and postgrazing (Table 1). This allowed us to calculate grazed yield. Unfortunately, we were only able to measure this the first time it was grazed, while the crop was usually grazed at least twice. Based on observations, the pearl millet or pearl millet/rape mix produced similar amounts of grazing yield the second time it was grazed.
Standing and postgraze dry matter and grazed yield of pearl millet alone or mixed with rape on Brubaker farm in three years*
|Pearl Millet (pounds of dry matter per acre) 7/17/15||Pearl Millet + Rape (pounds of dry matter per acre) 8/8/16||Pearl Millet + Rape (pounds of dry matter per acre) 8/8/17|
*Due to time contraints, yield was only measured once each summer even though the vegetation was usually grazed at least one more time.
The summer of 2016 was much drier than the other years, and productivity of the warm-season mix was lower. In 2015, standing biomass was almost 2 tons per acre at the time of first grazing. This crop was lightly grazed (only 26 percent) for a grazed yield of slightly over 1,000 pounds of dry matter per acre. The pearl millet was grazed two more times that year. In 2016, the pearl millet/rape was only grazed once due to the drought, at a grazed yield of 65 percent. In 2017, the pearl millet/rape mix yielded 1.5 tons of dry matter per acre, and it was grazed another time after it frosted in October. The farmers tend to graze no more than 50 percent of the standing biomass when the vegetation will be regrazed. This is very important because at least 6 inches of height should be left for vigorous regrowth. These grasses store part of their energy reserves in the aboveground stem, so they will draw from that for regrowth. Additionally, remaining leaf matter is needed for speedy regrowth. The root system is also more vigorous if not grazed too close to the ground. However, the final grazing of an annual like this can be more aggressive to lower the amount of residue that is left. This way, the following crop can be more easily no-tilled into it. However, a minimum level of residue (1,500 pounds per acre) should be left for soil protection and to feed soil organisms that rely on surface residue. We analyzed the pearl millet for quality. The results for 2015 are shown in Table 2.
Pregrazing forage quality analysis* of pearl millet sampled August 8, 2017, at Brubaker farm (all values on dry matter basis.)
|Adjusted crude protein||10.6%|
*Analysis performed by Dairy One
The Brubakers grazed the cover crop and crop residues on Field 3 for 16 days in the spring of 2017 and for 30 days in the fall. In the spring they grazed 22 cows and 4 calves, and in the fall 21 cows and 4 calves. At an average weight of 1,250 pounds for cows and 350 pounds for calves, this was 28,900 pounds of live weight in the spring and 27,650 pounds in fall. Because a beef cow consumes about 2.5 percent of its live weight in dry matter per day, the contribution of the spring- and fall-grazed cover crop and crop residue amounted to a total dry matter consumption of about 32,000 pounds for this 39-acre field, or 828 pounds per acre. If we assume the average grazed yield of pearl millet was 2,000 pounds of dry matter per acre per grazing and that a strip was grazed two times, then the annualized yield would be 4,000 pounds per acre. The combined grazed yield from the summer annual and winter annual would then be 2.5 tons of dry matter per acre. These estimates are conservative considering that the pearl millet was grazed three times in 2015 and we only assumed two grazings. However, we believe that if management intensive grazing were used at all times and water would be supplied in each paddock so back fencing could be practiced, then productivity could be improved even more. Forage quality is shown in Table 2 and indicates that the pearl millet was adequate for beef cow nutrition.
In 2016 we evaluated soil health in three contrasting paddocks of Field 3 (Table 3). The results show that by using no-tillage and cover crops while avoiding overgrazing and compaction by the grazing animals, soil health under grazed annuals can rival that under perennial sod managed as hay. The strip of cool-season perennial that was managed for hay production in 2015 had lower infiltration than the strips with annuals. This was attributed primarily to the lower number of earthworms in this perennial sod. Additionally, we observed that if a vigorous rye cover crop was present (strip HF3), the soil structure was better, erosion protection better, and infiltration faster than if a marginal cover crop was present. The marginal cover crop was due to a heavy crop of volunteer oats that competed with the rye after establishment.
Overall, the case study showed us the potential of integrating grazing with grain crop production. Grazing cover crops and crop residues added value to the field in the off-season on a grain farm, while summer annuals could be planted in some fields to meet the summer forage needs of the animals. Greater use of management intensive grazing and utilization of back fencing are practices that could further improve yields.
Soil health evaluations (rated 0–10, except noted otherwise, with 0 being worst, 10 being best) of three different strips in Field 3.
|Crop 2014||Grass/clover hay||Corn grain||----|
|Crop 2015||Grass/clover hay||Pearl millet||Oats|
|Cover Crop Fall 2015||None||Rye (planted Dec. 15)||Rye (planted Dec. 15)|
|Manure||1.5 T/A chicken litter||None||None|
|2015 Yield||4 hay cuttings ~ 3.5 T/A total||3 grazings in 2015||80 bu/A + straw|
|Grazing History||Field grazed 5 days before||Field grazed 5 days before||Field grazed 5 days before|
|Field Condition at Time of Evaluation||Soil at field capacity due to rain||Soil at field capacity due to rain||Soil at field capacity due to rain|
|Water Infiltration||1st inch: 4 min 3 sec||1st inch: 53 sec||1st inch: 2 min 39 sec|
|Water Infiltration||2nd inch: 17 min 30 sec||2nd inch: 6 min 31 sec||2nd inch: 6 min 10 sec|
|Water Infiltration||1st inch: 9 min 59 sec||1st inch: 1 min 21 sec||1st inch: 5 min 49 sec|
|Water Infiltration||2nd inch not done||2nd inch: 5 min 50 sec||2nd inch: 25 min|
|Plant Root Growth||8||8||8|
|Comments||Field had really nice cover from living grass and clover. It had not been grazed the year before and the surface was not as mellow and didn’t have as many earthworm middens as HF3. This field was at the lower end of the slope but not at the bottom.||Good cover and lots of earthworm activity resulting in small mounds of residue (middens) all over the field. Under these mounds the soil structure was really mellow. The field was grazed in 2015 so perhaps the combination of animal impact, manure, pearl millet and rye cover crop resulted in the soil structure improvement and high infiltration.||Less cover than HF3 and soil showed a bit more compaction and sealing and splash due to spotty rye stand. Rye probably suffered from volunteer oat competition in mild fall of 2015.|
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.
Prepared by Sjoerd W. Duiker, professor of soil management and applied soil physics, and Jessica A. Williamson, assistant professor of forage management.