Many farms are growing sorghum or sorghum species for the first time. Its harvest timing is very different than corn silage if you want to get it right. Sorghums can be a wetter, high sugar, low starch forage. In a properly balanced ration sorghum can produce the same milk at potentially less cost. Chopping this with a short length of cut, and worse – processing – will produce forage the consistency of applesauce or soup. This is not beneficial to good fermentation, high milk components, or preserving nutrients (lost leachate is 100% digestible). The good news is that there are steps you can take to maximize results and minimize potential problems.
As farms search for the holy grail of milk production: higher quality forage at lower cost, more are trying the latest research on the produc-tion of BMR and non-BMR forage sorghum or sor-ghum-Sudan. With some corn varieties topping $350 a bag ($140/acre), BMR sorghum at 10 lbs. seed/acre is only about $20/acre, a lower cost before the crop is even planted. Nitrogen is similar to a good corn crop, and with seed treated by a safener, the proper herbi-cide can control the weeds. Research trials in the northern region of the US have resulted in mean yields of 35% dry matter silage that exceeded both the mean and the max yield of a corn variety trial planted next to it. Sorghum is easy to grow if you follow top yield practices. As you move further south into Ohio, Pennsylvania, Virginia, and Kentucky, the potential for the crop increases even more. Sorghum thrives in these areas that frequently turn hot, dry, or both. Corn silage stops growing at temperatures over 85 F. Sorghum continues to grow up to 105 F. Conversely, in cool or cold summers, all sorghums can standstill. Corn will then clearly out-yield the heat requiring sorghums species. The forecast is for a slight-ly warmer than normal summer.
This year we have had more reports of farms that harvested 4 to 5 tons of dry matter from flag leaf winter forage. The weather helped maximize yield but the key steps that these farms had followed set the crop up for a potential high yield in the first place. In normal years many farms are achieving more than 3 tons of dry matter before planting their summer crop. In each case, the farms are carefully following the top management steps.
Winter forage has yielded more in one cutting than all 5 cutting of many alfalfa harvests. It is both a benefit and a problem. The heavy crop comes out the back of the mower and lands with a splat. It is a lot of material to get to 35% DM.
Winter forage harvested at the flag leaf stage has very highly digestible components. The fiber digestibility is higher than many Brown Mid Rib forages. I have measured sugar levels over 20% on a dry matter basis. The nutritional quality when the mower pulls into the field and what reaches the mouth of the cow can be two very different forages. For those who are still using the old traditional mowing directly to windrow and letting it sit for 2-3 days, what reaches the cow’s mouth is far, far, less quality than what you mowed. Mowing directly to windrow is windrow composting – it is not preserving high-quality forage – it is not drying the forage as fast as it could. It simply aerobically composts the most readily digestible components that could be used to produce milk as it slowly over-dries on the outside. It makes a major difference in the amount of digestible energy reaching the mouth of the cow.
The last newsletter had a table with the amount of nitrogen that winter forage removes at 20% crude protein, depending on the yield. With the higher cost of nitrogen this spring and even higher cost for soymeal in the ration, getting the nitrogen right is important. If you are really good, you can put a leaf between cheek and gum and can tell much nitrogen is needed to 4 decimal places. For the rest of us mere mortals, we need to guestimate what your field will respond to economically. The huge factor of yield potential depends on the planting date and fall growth. This establishes the number of tillers which establishes the yield potential for each field (see graph at right). If the triticale is planted on time (10 days – 2 weeks before wheat for grain) it maximizes the number and size of tillers. Planting on time means you have a significant high yield potential. If sufficient nitrogen was available in the soil (from heavy manure applied before the previous summer crop, or up to 60 lbs. of fall applied nitrogen), the yield potential can increase 43% more from increased size and number of tillers (photo at right). Our replicated research found that the on-time planting will pick up and store 60 to 120 lbs. of nitrogen before winter, utilizing the manure nitrogen still being released after the summer corn silage is harvested. If your triticale is 6 to 10 inches tall and thick (picture at right) then you can assume the higher number and can subtract that from the topdress. I have found that fields like this have a potential yield of 3 – 4 tons of dry matter.
This is my yearly letter on fertilizing winter forage with a twist that can save you money while simultaneously maximizing yield and quality. In early 2000 we did a number of trials on the nitrogen needs for winter forage and found that 80-100 lbs. of N/A were the optimum economic returns for spring nitrogen. Yields were 1.5 to 2.5 t/dm/acre for a majority of the sites. Since that work was completed, we learned how to double our yields. By planting earlier (10 days to 2 weeks before wheat for grain) it increased yields 35%. We also learned that up to 60 lbs. of nitrogen/acre in the fall increased spring yields 43% on a field without prior spring manure. The early planting and fall nitrogen available significantly increased the number of tillers that set the spring yield potential. Thus, it is common for yields to be 3.5 ton DM/A (10 ton silage) to 4.5 ton DM/A (14 tons silage). Farms have reported over 5 tons DM/A on better soils in areas south of New York. If we want to harvest 20% crude protein to offset the very expensive soymeal prices, the crop needs to be fed (see table at right). Most well managed winter forage is shorted on nitrogen and sulfur.
In the January issue we covered the first part of utilizing BMR forage sorghum, male sterile version to produce high quality forage for dairy production. The sorghum is cheaper to grow per acre than most corn varieties. Utilized the year before corn, it eliminates corn rootworm the first year or two after. Deer hide in it and then come out to eat the neighbor corn. The problem is that most sorghum has a grain head that as it fills, lodges the crop making it difficult to harvest. The use of a male sterile variety eliminates the weighty head on a thin stalk. Instead of increasing digestible components by filling a seed head (vitreous, hard to digest starch), it keeps those components in the forage cells. This increases the milk producing ability while simultaneously increasing the dry matter of the forage. The question we had was how long should you let the crop grow after heading before ensiling? In our study we went seven weeks post heading. As reported in the January letter, the sugar component as measured by wet chemistry, increased 500% to 18.85% of the dry matter. This was measured post fermentation (three weeks) so it reflects what the cows would be consuming from the ration.
The past two issues we highlighted some research that failed spectacularly. This issue will focus on research in progress that did work and has tremendous potential for high quality dairy forage across much of the northeast and central US and parts of Canada.
We got into this project because winter forage acres need to be planted early (2 weeks before wheat for grain) for high yield and soil protection, but this directly reduces the corn season. There is no short-season BMR corn. Short season BMR sorghum has been tested and produces high yields and quality to replace corn silage. My research, documented by Dr. Chase (Professor Emeritus, Dairy Nutrition, Cornell), found that with proper balancing, BMR sorghum sp. can produce the same milk as corn silage. Work at Miner Institute on BMR sorghum-Sudan also documented the same milk production as corn silage but with higher components and greater feed conversion efficiency
And two things NOT to do!
As we move into the early winter, the seed catalogues and fliers are arriving. A change many farms are making is to shorten the season of the corn silage. With the large swings in the weather patterns that we have talked about before, a sure crop that reaches optimum maturity is more cautious approach to economically sure forage production. Variety trials over the past decade have shown the corn breeders efforts have produced higher yields from traditionally shorter varieties. Longer season varieties don’t guarantee you higher yields
In the July issue we laid out the steps for planting either straight oats or oats plus triticale for a high yield, very high-quality forage harvested the end of September. The best management steps were listed. Unfortunately, we forgot to list doing a rain dance. Instead of 30-inch-tall oats at flag leaf stage the beginning of October, we have stuff that is just over a foot tall. Unless we have July weather in October and November, there is little chance of getting an economical crop.