Time for First Cutting

It is time or almost time for the first cutting of forages, depending on your location in Ohio and your forage quality goals. Orchardgrass was shooting a head in central Ohio last week. The alfalfa stands that were not severely injured by winter are looking great and about ready for first cutting as well across central Ohio. So begin to look for that open weather window for putting up some good forage.

For high quality feed, such as for lactating dairy cows, pure grass stands should be harvested in the late boot stage just before the heads start to peek out. The neutral detergent fiber (NDF) content of pure alfalfa stands can be estimated with the method described in an accompanying article.

A timely first and second cutting is critical for high quality forage. Fiber accumulates faster in the first two growth cycles in May and June than it does later in the summer. So for high quality forage, take your first and second harvest early if at all possible. Later in the summer (July into August) you can extend the cutting interval because the quality decline with delayed cutting is much less then than it is this time of the year.

An exception to the above rule of timely first cutting is for forage stands that suffered significant injury this past winter. Winter injured stands should be allowed to recover longer this spring and get into the bloom stage to build up energy reserves. This will help plants to recover from winter injury and regrow the rest of the summer. Use that forage for animals having lower nutrient requirements.

If high quality isn’t such a concern, we still have a little time before first harvest. For beef cows or other animals with lower nutrient requirements, you can harvest forage in the bloom stage for adequate quality, and it will provide higher yields. But don’t get too comfortable waiting. Keep an eye on the forage because it changes fast this time of year.

Here are the NDF targets (dry matter basis) to shoot for depending on class of livestock:

Forage NDF for Lactating Dairy Cows
Legumes: 35 to 42%
Grasses: 50 to 53%
Mostly legume: 42 to 45%
Mix: 44 to 48%
Mostly grass: 46 to 49%

Estimating Pre-Harvest Alfalfa NDF in the Field

Alfalfa neutral detergent fiber (NDF) concentration can be estimated in the field before harvest by following a simple procedure while walking across the field:

1. Choose a representative 2-square foot area in the field.
2. Determine the most mature stem in the sample area:
   
   • Vegetative = no buds or flowers are visible;
   • Bud = 1 or 2 nodes with buds visible;
   • Flower = 1 or more nodes with open flowers.
3. Measure the length of the tallest stem in the sample area. Measure it from the soil surface to the tip of the stem (not the leaf tip, but the stem tip). Straighten the stem to its full length when measuring. The tallest stem may not be the most mature stem you find.
4. Based on the stage of the most mature stem and length of the tallest stem, read the estimated NDF from the table below. For example, if the most mature stem has buds but no flowers and the tallest stem is 28 inches, then NDF = 38.0.
5. Repeat steps 1 to 4 in several representative areas of the field and calculate the average value. More estimates gives a better overall average.

Note: This estimates the NDF of the standing crop and does not account for changes in fiber due to wilting, harvesting, and storage, all of which can raise the NDF by 3 to 6 units, assuming good wilting and harvesting conditions.

Estimated Pre-Harvest Alfalfa NDF

Length of tallest stem	Vegetative	Bud Stage	Flower Stage
(inches)	% NDF	% NDF	% NDF
16	28.5	29.7	31.4
17	29.2	30.4	32.0
18	29.9	31.1	32.7
19	30.6	31.8	33.4
20	31.3	32.5	34.1
21	32.0	33.2	34.8
22	32.7	33.9	35.5
23	33.4	34.6	36.2
24	34.0	35.3	36.9
25	34.7	35.9	37.6
26	35.4	36.6	38.3
27	36.1	37.3	38.9
28	36.8	38.0	39.6
29	37.5	38.7	40.3
30	38.2	39.4	41.0
31	38.9	40.1	41.7
32	39.6	40.8	42.4
33	40.3	41.5	43.1
34	40.9	42.2	43.8
35	41.6	42.8	44.5
36	42.3	43.5	45.2
37	43.0	44.2	45.8
38	43.7	44.9	46.5
39	44.4	45.6	47.2
40	45.1	46.3	47.9

 

Winter Injury in Perennial Forages

Two weeks ago Rory Lewandowski described in this blog how to evaluate forage stands for winter injury. So our question is, “Have you walked out into your forage stands yet this spring?” If not, you may be in for a rude surprise.

The hard freeze lst week was cause enough for concern for us to check a few fields. There is some frost dieback of the top leaves, particularly in orchardgrass (see photo).

Notice the yellowish tinge to the orchardgrass in the foreground compared with darker green tall fescue in the background that suffered less frost injury.

But the more serious problem we observed when looking around was severe heaving damage in alfalfa, particularly in the Wayne county, OH area. Some fields showed heaving of 70% of the stand.

Plants with crowns heaved up 2 or more inches out of the ground are probably already dead like in the photo above.

Heaving is usually more severe in areas with less than ideal internal and surface soil drainage and on soils with high shrink/swell potential. Tiling will likely help improve the alfalfa production potential of those soils, but heaving can still occur on certain soil types even when with tiling.

Heaving is also more likely where a mid to late fall harvest was taken. Fall harvesting can weaken plants and the removal of plant residue late in the fall can dramatically increase the potential for heaving, because the residue serves to moderate soil temperature fluctuations and catch snow that also insulates against wild temperature swings during the winter.

Plants heaved 1.5 inches.

 Some plants will be heaved 1 to 1.5 inches above the soil surface or less. These plants may on casual inspection appear normal and be greening up. But closer inspection will reveal crowns above the soil surface, which will likely limit the productive life of the plant.

Heaved plants will desiccate more quickly, be injured by wheel traffic, and crowns may break or be cut off at the first harvest. Some of those plants may survive through the first harvest, but their yield potential is compromised and they will likely disappear from the stand at some point during the growing season.

Plants heaved to varying degrees, starting to greenup.

Can anything be done to help heaved stands? Dan Undersander has written a very useful fact sheet about heaving that can be found here. He suggested that if the majority of plants are heaved an inch or less, that the taproot may not be broken and the stand has a better chance of being salvageable for this year. In this fields, delay the first harvest to allow more recovery time and raise the cutter bar sufficiently to avoid scalping the crowns. He also states that the stand should not be rolled or cultipacked, as this will only damage the crowns.


We also observed severe winter injury in some perennial ryegrass varieties and even in some white clover varieties in our trials. Time will tell how much they will recover, but the winter damage was quite substantial in some varieties, including an older perennial ryegrass check variety we use in our trials.

Literature Cited
Undersander, D. 2009. Heaving in alfalfa fields. Agronomy Advice. Agronomy Dept., University of Wisconsin. Available online at http://www.uwex.edu/ces/forage/pubs/heaving.pdf.