Marcin Korcz runs a farm in the Wąbrzeźno district in the Kuyavian-Pomeranian province specializing in dairy and beef cattle breeding. Providing an appropriate feed base with a large number of animals is quite a challenge, especially in difficult conditions of climate change. In a situation of periodic rainfall deficiency, corn proves unreliable, which is why the farmer has been growing a species for several years that produces a large yield of valuable biomass with low requirements. The type of sorghum, which includes numerous species of thermophilic grasses, originates from the hot climate of Africa, India and Mexico. These plants are characterized by high resistance to drought and high temperatures.
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The harvest is not over yet. Where has the grain not gone to the scythe?
A valuable feed component
Marcin Korcz learned about sorghum for silage a few years ago from his brother-in-law, who was pleased with the large biomass yield and the cattle's unquestionable intake of silage from the new species. The grass, which comes from a hot climate, has the characteristic that its intensive growth begins relatively late, usually only at the beginning of August. Although the farmer from near Wąbrzeźno has sown sorghum for the third time, he still cannot get used to the fact that its intensive growth begins only when the corn has already reached its final size, which is why the call "Come, there is something to show after all" had to be waited for quite a long time.
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Extra Cobs on Corn. How Do They Affect Yield?
In 2022, when we first reported on the growth, development and harvest of this still unusual species in Poland, we tested the composition of the silage and asked an expert to assess it. Zbigniew Wróblewski from the Polish Federation of Cattle Breeders and Dairy Producers said at the time that silage made from feed sorghum has a slightly lower energy value than that of corn, but a similar protein content, and an additional significant advantage is its lower soil and nutrient requirements compared to corn. He also added that thanks to its composition, sorghum silage is particularly well suited to feeding certain groups of farm animals, such as dairy heifers and dry cows.
Sorghum in two variants
This year, Marcin Korcz sowed sorghum for silage in two variants. In one field, characterized by soil quality class V, sowing took place after winter ploughing, before which cattle manure was applied. In two fields, with soil quality class IV, sorghum was sown after rye harvest for silage. In both cases, sowing took place on May 23, using an Amazone grain seeder, set to a dose of 5.5 kg/ha.
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In addition to the aforementioned manure, spread on part of the area, the farmer applied mineral fertilization in the form of 54 kg/ha nitrogen, 64 kg/ha P2O5, 64 kg/ha K2O, 24 kg/ha CaO and 16 kg/ha SO3. In the fields where sorghum was sown after rye, manure was applied under the previous crop, hence the soil fertility was very good. In addition, in July – at the beginning of the month after winter ploughing and in the middle of the month after rye – magnesium sulphate was applied at a rate of 6 kg/ha and a multi-component foliar fertilizer providing 1.2 kg/ha nitrogen, 2.4 kg/ha P2O5, 1.2 kg/ha K2O, 0.6 g/ha B, 0.036 g/ha Cu, 3.2 g/ha Fe, 1.6 g/ha Mn, 0.24 g/ha Mo and 0.32 g/ha Zn. As for weed control, on 25 May metolachlor was applied at a rate of 940 g/ha, terbuthylazine at a rate of 560 g/ha and mesotrione at a rate of 110 g/ha.
Sorghum for silage after winter ploughing in quality class V, photo by Maciej Sacha
Plantation condition in mid-August
Currently, the difference in the height and greenness of the field is visible on the plantations. Sorghum after winter ploughing currently reaches an average height of 270-280 cm, and the plants are intensely green. On the other hand, the field of post-rye is clearly paler and lower. Its average height is about 200 cm, although it should also be emphasized that there is a large difference between the parts of the field closer to ditches or ponds, where sorghum is about 230 cm, and the hills, where the plants grow to only 150 cm. Unfortunately, the rye for silage used up the water reserves, and the May ploughing additionally dried out the soil. The farmer did not decide to use no-till cultivation, fearing that he would not be able to control the weeds. Although weeding was identical on the entire area, it is worth noting that in one of the post-rye fields there is almost no barnyard grass, which is a major problem in the other sorghum fields.
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There is little time left to register grains in the IP system
A characteristic feature of sorghum is the fact that its intensive growth occurs quite late, compared to other crops. As Marcin Korcz says, in the last two weeks, i.e. since the beginning of August, the height of the field has increased by about a meter. For this reason, he expects at least another meter of growth before harvest, especially since in previous years sorghum did not have time to finish vegetation and grew until the very end, posing quite a challenge for the forage harvester. As for the harvest date, the farmer, like last year, plans to arrange with the service provider that after harvesting the corn for silage at an earlier date, he will return to sorghum at the very end of the season, and then just put the forage harvester away for the winter.
