Producers intensify the use of knife rollers in Brazilian crops

The strength of Brazilian agriculture is increasingly noticeable in all its segments and the progressive demand for consumption of grains, fibers, biomass for energy generation, and animal protein has led the country to obtain high productivity every year. However, there is a demand from society that these high productivity must be aligned with the use of processes aimed at biodiversity and sustainability in agroecosystems.

To guarantee this sustainability, farmers are resorting to techniques using biological processes, known as Biological Agriculture. In this sense, the use of soil cover crops and green manure has been spreading in large proportions, mainly used in the direct planting system, conservationist agriculture. The use of these plants dates back to 2.500 years before Christ, when the first technical works on the use of green manures to improve soil quality were recorded in China. In Brazil, in 1919, the São Paulo Department of Agriculture launched the publication entitled “Green fertilizers: their production and method of use” and, since then, the use of green fertilizers and cover crops entered the context of production in the country. With the use of mineral fertilizers, these plants fell into disuse in the 50s and 60s - 70th century. In the 80s and XNUMXs they began to be used again to improve degraded or low fertility soils, mainly due to the organic matter produced, nutrient cycling, nitrogen fixation and soil cover.

These plants require specific management, as they are not used for grain production. There are several management options, chemical and mechanical, associated or not, but according to experts and rural producers, the most appropriate and currently used is the use of the knife roller. This implement promotes the rolling of plants without fragmenting the plant material, however, when the stems/long fibers are crushed, the sap flow stops, leading to the death of the plant.

The knife roller has currently been fundamental, especially in the direct planting system, which aims to eliminate disturbances in the soil structure. From an agronomic point of view, carrying out this operation brings several benefits, since a cover is created over the soil, minimizing water evaporation, increasing moisture retention and protection against solar rays, acting positively on thermal regulation. Furthermore, this implement is very effective, being able to tear down 100% of the green cover in a single pass, reducing fuel costs and reducing working hours.

In the past, a roller knife with a heavy structure was widely used in Brazil in deforestation areas to chop smaller residual vegetation. Also widely used in the management of weeds in coffee crops on small agricultural properties, drawn by animals, manufactured in small mechanical workshops.

Constitution and operating principle

The knife roller consists of a cylinder, plates – knives and a metal frame with a header for coupling to the tractor. The cylinder is made of steel and hollow for inserting ballast - water/sand, the dimensions of which vary according to the manufacturer. The knives, blunt or sharp, are fixed parallel to the cylinder, arranged aligned - 90º or misaligned with different angulations; They can be made in a single or split sheet, the dimensions and number vary according to the manufacturer.

Rollers equipped with blunt knives without a cutting edge are used to manage cover crops so that plant tissue is not cut, while those with sharp knives are used to fragment the cultural remains of commercial crops and facilitate sowing of the crop. culture in succession.

The working width varies according to the size of the cylinder and the number of cylinders that make up the implement, and can be one, two or three cylinders. The knife roller is equipped with a hydraulic or mechanical mechanism to carry out transportation.

As for the principle of operation, the roller with blunt/blunt knives squeezes the plant stems against the soil surface, without segmenting the plants, promoting the laying of the cover crop phytomass on the soil.

Management of cover crops and sowing

The management period for knife-roll cover crops will depend on whether they were grown, single (a single species) or intercropped (two or more species). When sown single, the ideal time to carry out rolling will be in accordance with physiological development, that is, the cycle of the species used, which could be at peak flowering or depending on grain maturation. Carrying out the roll over the physiological time of each species will ensure plant mortality without the auxiliary use of herbicide; maximum production of green and dry matter – green matter is related to the quantity and quality of soil cover and drought with decomposition time; better soil coverage, keeping it covered for longer; reduction of surface water runoff and reduction of erosion risks; increased water availability in the soil; inhibition of germination and emergence of spontaneous plants.

As an example of the period for managing a species with a knife roller, there are sunn hemp which must be managed in full flowering and when the formation of the first pods begins and black oats which must be managed in the milky grain phase. The intercropping management period should be at the flowering peak of the earliest species using only the knife roller.

In both forms of cultivation, the management of the species with a knife roller must occur well in advance to avoid sowing the crop in succession with the plants still in the wilting process, which will negatively interfere with the cutting of phytomass from the seeder's cutting mechanism. .

The actual process of rolling cover crops must always be carried out in the same direction and in areas with slopes the rolling will be at a level following the terraces. In this way, the bedded plants will have an effect on the surface runoff of rainwater, preventing soil from being carried away.

The sowing of commercial crops will always be carried out in the same direction as the rolling, therefore, it will facilitate cutting by the seeder discs and avoid dragging the blanket/straw. Sowing carried out across the rolling direction will drag the straw and uncover the seeding line. The uncovered sowing line will encourage the incidence of spontaneous plants, the increase in temperature with the exposed soil interfering with the performance of the seedlings and not to mention the risk of erosion in the sowing furrow.

Growing range of models and manufacturers

The scientific elucidation of the benefits of using cover crops currently known as service plants, the change in attitude with a focus on sustainable soil management and their functionality, the production and availability of high quality seeds by specialized companies have stimulated the adoption growing by producers in all agricultural segments and linked to these changes, the manufacturing and availability of knife rolls by Brazilian industries is extraordinary and growing. This growth in the supply of knife roller models is recent, around 10 years ago the agricultural machinery industries began to understand the specific demand for handling and started to produce implements with high technology and models suitable for small, medium and large areas. .

The manufacturers of these implements are distributed across the south of the country, where the greatest demand occurs, they are family and small-sized companies meeting local demands with their models for small producers, medium-sized family companies meeting management demands for all extracts with their models. areas, including exporting its technologies to other countries and multinational companies operating in Brazil with high technology in their products.

In the Brazilian market, 21 agricultural metallurgical industries were found that make 90 models of knife rolls commercially available.

Knife roll models manufactured in Brazil

Knife rollers are mostly available in a trailed version, some models can be used on the front with a front hydraulic lifting system and also in a small roller version coupled to the seeder's tool holder bar. These two aforementioned models are used simultaneously with sowing the crop in succession.

There is a wide variety of models offered on the market, adapting to the characteristics of each agricultural property. The working width of the models varies from 1.900 to 20.400 mm. The knife roller that has the largest working width is a tandem model (Tandem - it is the coupling of two implements to the same tractor joined through their headers). Still regarding width, some companies manufacture models according to the producer's demand, to order, such as the front model that is customized to the seeding width of the fertilizer seeder.

The diameter of the traditional roller is one of the most important mechanical elements. The larger it is, the greater the number of blades will be and, as a consequence, the better the rolling performance of cover crops will be, compressing the plants against the soil surface along their entire length, more efficiently. Other more modern models use rollers with smaller diameters, which work at high speeds and do not require the use of ballasts. The models available on the market have diameters ranging between 20 and 1.300 mm, and can be made up of 6 to 68 blades per roll and depending on the set of cylinders that make up the knife roll model, the number of blades reaches 256 blades.

Another factor in traditional rollers is ballast, the larger the diameter of the cylinder, the greater the volume, and weight can be inserted into the internal part of the cylinders, increasing the mass of the implement, thus acting for diversified uses with better rolling performance.

The required tractor traction power in the models evaluated is between 60 and 450 hp - 44,1 to 331,0 kW, depending on the working width, roller diameter, ballast and total mass.

Check out the knife roll models available in Brazil below: