Innovations in manure management for more sustainable agriculture are beginning to gain momentum in San Luis, based on the successful experience of Ser Beef in using waste from its impressive feedlot to replace chemical fertilizers to improve the soil of agricultural plots.
Producers and technical advisors are preparing various medium-scale tests and to do so, they wanted to hear from Rosario specialist and chemical engineer Juan Kabush about the professional guidelines that must be adopted to prepare manure before spreading it on the field.
Regarding the advantages of composting manure in feedlots and dairy farms, Kabush highlighted that this manure has an ideal carbon-nitrogen ratio for composting, unlike other types of waste.
His company focuses on adding value to waste from the livestock industry through its collection, treatment and application. Composting was presented as the most developed and easy-to-use technology for converting manure into a valuable fertilizer.
“The concept of intensification of livestock systems has changed; there are five reasons why composting should be used,” said the professional when he spoke to agricultural engineers Ramiro Goncálvez, Martín Puigdellibol, Juan Cruz Domínguez Camusso, Gabriel Aguilera and Josefina Contreras; veterinarian Martín Puigdellibol; industrial engineer Fabián Funcia, and producer Federico Risma.
The five reasons that justify composting are that manure has a perfect carbon-nitrogen ratio; it converts that waste into a valuable fertilizer; it is a technology that is easy to apply and quickly implemented; it has short payback times compared to other technologies, and it is a purely aerobic treatment, which makes it more efficient and effective.
“Recycling of organic by-products of animal origin could help mitigate the deficiency in nutrient replacement” (Juan Kabush)
The commercial chemical phosphorus applied in each agricultural campaign increases costs considerably.
But Ser Beef found a way around it and long ago suspended the purchase of this fertilizer to replace it with the enormous quantities of manure generated by its feedlot, which currently has more than 70 animals.
“We are giving it away because in the last 4 years the phosphorus in the fields has risen quite strongly. Today we are at values close to 36 parts per million, which is great, but what scares me a little is the speed of the rise,” announced recently Nicolás Ríos Centeno, agricultural engineer and head of Agriculture at Ser Beef.
Aguilera advises a farm in the La Petra area and analyses how to improve soils with the use of bovine manure: “The farm has reached its productivity level, it is already in a coma; either we stop the bike and rethink everything and start generating soil again, and a good alternative is that Ser Beef is giving away manure. We are learning about its use.”
Reduces compaction. Fertilizing with composted manure improves soil structure and drainage.
Kabush warned that all manure management must be stabilized before leaving the field, to reduce its pathogenicity, among other aspects, and he estimated the duration of this process at 40 days.
When it came to numbers, he took as an example a feedlot with a thousand cattle, which generates 8,000 tons of wet waste and 900 tons of dry waste per year, which, in turn, the total organic fertilizer amendment generates 46 tons of urea and 30 tons of diammonium phosphate.
The professional represents the firm Eco Management, a company from Marcos Juárez, Córdoba, specialized in technologies for the management of agricultural effluents, with the manufacture of manure dumps, fertilizer spreaders, composters, biogas plants and composting systems.
He showed three maps showing the percentage of nutrient extraction, such as nitrogen, phosphorus and sulfur, in the different agricultural areas of the country where soybeans, corn, sunflowers, sorghum, wheat and barley are usually grown.
“Nutrient recycling through the use of organic by-products of animal origin could go a long way towards mitigating this deficiency in nutrient replenishment,” he suggested.
For the professional, the use of by-products not only increases crop production due to their function as fertilizer, but also contributes to generating a sustainable system, since it improves the chemical, physical and biological conditions of the soil.
Why compost before applying?, the attendees asked: “Because it contains microorganisms, weed seeds, 70 to 90% water, it is not a uniform or mature material, and because the legislation does not allow it.”
The recommendation to apply this organic fertilization is based on the fact that it improves soil structure and drainage; increases the water stored on hot days and dry months; increases soil biota and aeration; reduces compaction; increases the quantity and availability of nutrients, and corrects deficiencies of organic matter in the soil.
One ton of feedlot cattle manure contains about 5 kilos of nitrogen, 1 kilo of phosphorus and 4 of potassium. If the liquid fraction is not considered, the manure results in 2.5 kilos of nitrogen, 1 of phosphorus and 0.8 of potassium, according to calculations by Aníbal Pordomingo, a technician at INTA Anguil, La Pampa.
“As a general rule, it is suggested to have one hectare to fertilize for every 20 to 25 animals in the feedlot, in dryland systems. In irrigated areas, with more intensive crops, a ratio of one hectare for every 10 to 15 animals is used. If some management and handling practices of the diets are implemented, nitrogen emissions in the excreta could be reduced and, consequently, the number of animals per surface to be fertilized could be increased,” he recommended.
“We are applying manure in the company’s four agricultural fields. In San Bernardo, which is the cattle farm located south of the city of San Luis, we do not go there with manure. But in the four fields we have in Eleodoro Lobos, Granville, Fraga and Liborio Luna, we spread manure on all the lots,” said Ríos Centeno.
These applications are carried out once every three years on the same lot.
“New technologies are aimed at reducing the negative impact on the environment and thus avoiding the degradation of renewable resources such as water, air and soil,” said María Clara Giusti and Aldana Ruth Recuero, authors of a research for the University of Córdoba and specifically cited by the speaker in San Luis.
