Grazing Cover Crops

Grazing cover crops is receiving new attention. Here are some reasons to take a hard look at it:

1. 

   Grazing is a very cost-effective way of feeding animals – the cost per ton of dry matter fed is half or less of that of feeding harvested forages.

2. The threat of soil compaction is reduced in long-term no-till due to increased surface organic matter content that makes soil resist compaction, a firm matrix reducing ‘pugging’ (hoofs sinking into the soil), high biological activity, and the actively growing roots of the cover crop.
3. Nutrient management can be improved because urine from grazing animals soaks into soil quickly, reducing the likelihood of large ammonia volatilization losses.
4. Soil health may benefit from grazing animals. For example, soil biological activity will be high under the manure pies. Look for dung beetles and earthworms under the pies!
5. Grazing adds value to cover crops, making it more attractive to farmers to plant them on time, use higher seeding rates, and thus increase cover crop biomass production from roots and tops.

 

 

Some farmers in Pennsylvania are exploring grazing of cover crops and have installed permanent exterior fencing around some of their crop fields, obtained mobile electric fencing, and installed watering systems with assistance from USDA-NRCS and the Capital Region RC&D Council, with funding from the National Fish and Wildlife Foundation. Penn State is helping document the effects of grazing on soil health and the bottom line. These farmers have developed a grazing plan and are learning how to manage grazing animals. All participating farmers plan to use Management Intensive Grazing (MIG) practices. Some plan to graze their cover crops several times this spring before planting a summer crop such as a cover crop mixture, sorghum-sudangrass, or pearl millet, while others plan to graze their cover crop only one time and then plant corn. The farmers are using triticale, wheat, or annual ryegrass/crimson clover mix. Rye would be another possible choice, although harder to manage because it goes to head so quickly. Interestingly, one farmer grazed his wheat that is planned for grain harvest this summer. He grazed this wheat field once in the fall and once this spring – a new practice for Pennsylvania!

It is important to plan ahead – if your field is big and you have few animals, you will not be able to get across the field before the forage at the other end of the field becomes undesirably mature – and with reduced feed quality comes reduced animal growth. For best animal growth, graze cereal cover crops before they go to head. Further, the participating farmers are learning to have fields available for grazing at different times of the year (combining permanent pastures with cover crop fields) so they can maximize the number of grazing days. If you only graze cover crops planted after corn and soybeans you will have a very short growing season in the spring! Therefore, several of our farmers grow small grains for grain harvest and follow them with warm-season cover crops for grazing in late summer or mixtures with cool-season species for grazing in the following year as well. Nonetheless, it is wise to have a back-up area where you can feed hay in case the soil is too wet, or when you run out of grazing forage. The spring is a time when soil moisture content is often high, and soil compaction needs to be managed to avoid negative effects on the following crop. One way is to consider the soil type of the field you plan for spring grazing – a soil that dries out quickly would be the best choice. Further, the farmers are learning the importance of MIG – the cattle are moved every day, getting sufficient forage but limiting the exposure time of the soil to hoof traffic.

The animals tend to congregate around the water source, and it is important that you use a mobile water system that is moved every day as well. Providing shade is not recommended because that is another area where animals tend to congregate. If you plan to re-graze a cover crop, leave at least 6 inches of stubble for regrowth. This is less critical if you do not plan to re-graze; However, leaving stubble is also important to protect and feed the soil, so it is still a good practice.

 

 

One final important issue that needs attention if you plan to graze is your herbicide program. Be sure you are not violating the herbicide label. Herbicide labels include rotational restrictions to protect humans and animals from herbicide residues which the following crop may accumulate, besides making sure the following crop is not damaged through herbicide carryover. More information can be found in the fact sheet ‘Herbicide rotation restrictions in forage and cover cropping systems’ from the University of Wisconsin, and ‘Herbicide use may restrict grazing options for cover crops’ from Iowa State University.