Rice harvest losses

Method for identifying losses on the platform, created by Nimeq, from the Federal University of Pelotas, facilitates the collection and interpretation of data obtained in the field.

Irrigated rice is cultivated in an area of ​​approximately 1,083 million hectares in the state of Rio Grande do Sul, with production of 7,4 million tons. The harvesting system in these areas is fully mechanized, and quantitative losses are inherent to this process.

There is no exact data on total losses during grain harvesting in Brazilian crops, however, estimates indicate that they are around 20% of total production.

During the mechanical harvesting process, quantitative losses should be less than 3% of the total grain available to be harvested in the field, however, in the case of rice farming, studies show that these losses can reach 10%. 

Crop losses can be classified into three types: pre-harvest losses, losses in the harvesting process and post-harvest. Pre-harvest losses are those that occur before the harvest process, due to climatic and natural factors and animal attacks. Losses that occur during the harvesting process (losses due to the harvester) may be caused by inadequate implementation of the crop (choice of variety/cultivar, errors in sowing/fertilizing, lack of adequate phytosanitary treatment), they may occur due to climatic factors ( occurrence of winds and intense rain, causing lodging) and operational factors, such as the state of maintenance, adjustments and operator qualifications. Post-harvest losses are those that occur in the process of transporting, processing and storing the product.

Harvester losses

In harvesters, losses can be analyzed in two different locations: the front part (due to the cutting platform) and the back part of the machine (resulting from the threshing, separation and cleaning systems).

The cutting platform's function is to cut, collect and forward the crop to the threshing unit, consisting of separators, cutting bar, windlass, helical conductor (snail) or conveyor belt (draper) and feeder channel. The difference between the platform that uses the draper system is that, in this case, the system responsible for collecting the product that falls at the base of the platform and is sent to the feed channel, is not a helical cylinder, but rubber mats.

Considering that harvesting is the final stage of the production process, losses must be kept within acceptable standards, in order not to compromise the profitability of the crop. Therefore, the systematic assessment of grain losses in crops, combined with a process of constant adjustment of the harvester, reduces the amount of grain lost, guaranteeing the expected productivity and profitability of the crop.

Due to the complexity of the different methods used to evaluate harvest losses in rice crops, especially those that occur on the cutting platform, the team from the Center for Innovation in Agricultural Machinery and Equipment (Nimeq) at the Federal University of Pelotas (UFPel) developed a practical methodology to analyze losses on the cutting platform in irrigated rice crops, which can be used for other crops, where the cutting bar works at a minimum vertical height of 30cm.

Conventional method 

The commonly used method involves the use of a 1m2 frame, which must cover the entire width of the harvester's cutting platform. Initially, the quantity of grains available to be harvested by the machine in the field is determined, which is obtained by collecting the grains available in an area of ​​1m2, for this purpose a square frame with 1m on a side is used. Pre-harvest losses are determined using this same framework.

To determine losses on the platform, the harvester must be stopped during the harvesting process, the cutting platform turned off and the machine set back. In front of where the harvester's front tires are marked, the 1m2 frame must be placed and the fallen grains must be collected. The amount relating to pre-harvest loss previously recorded must be subtracted from the quantity of grains thus obtained.

After these determinations, in which, generally, only the grains are counted, their equivalence in weight must be calculated, for this purpose the specific weight of the grain with which you are working can be used. This way it will be possible to calculate the quantitative losses of grains depending on the productivity of the crop, obtaining a percentage result that will indicate the need or not to make adjustments to the machine.

This method is difficult to implement in irrigated rice crops and can lead to sampling errors, since, in many cases, a certain amount of water remains in the crop at harvest time. Added to this is the fact that the quantity of grains that must be counted is normally quite high. 

NIMEQ method

Trying to overcome this problem and speed up obtaining results without losing precision, the Nimeq team developed a methodology to obtain the amount of losses on the cutting platform in irrigated rice crops. This methodology consists of determining, along the width of the platform, in predetermined locations, the loss of grains. This also makes it possible to identify the points that generate the greatest losses and relate them to the machine's working conditions, such as travel speed, type of platform and cutting height. For this, PVC collectors were designed in the form of a gutter with dimensions of 15cm x 75cm with an individual area of ​​1.125cm², which are positioned on the ground, between the crop rows, regularly spaced along the width of the cutting platform of the crop. machine.

To test this methodology, two field experiments were carried out: one in the Department of Treinta y Tres, in Uruguay, on a 200ha irrigated rice farm and another in the Entre Rios Province, in Argentina, on an 850ha irrigated rice farm.

The harvester used, in both cases, was the John Deere model 9670 STS Rice with the Single Tine Separation (STS) module, in which two platforms with a draper system of the models 625D, with 7,60m, and 630D, with 9,10m wide, respectively.

For greater precision in quantifying losses on the platform, it was defined that the number of collectors used would vary according to the width of the platform, in order to obtain a minimum collection area of ​​1,200m2. On the 625D platform, 12 collectors were used, obtaining a collection area of ​​1,350 m², while on the 630D platform, 14 collectors were used, having a total collection area of ​​1,575 m².

The collectors were positioned equidistant along the cutting platform, and after passing over them, the harvester was stopped, the platform was turned off and the machine was moved back. The grains captured by the collectors were then counted and the operation repeated at least three times. This way, it is not necessary to obtain pre-harvest losses, since the grains captured by the collectors only refer to the loss of the cutting platform, which reduces the time spent in the process. Another important point is that, using this methodology, it becomes possible to locate, along the width of the platform, which points generate the greatest losses, which is impossible with the use of the traditional method.

Figure 1 shows the losses on the cutting platform, obtained for the harvester model 625D, and it is possible to observe that the highest values ​​occur at the ends and in the center of the platform.

When the losses relating to the 630D platform were determined, it was found that they presented a lateral distribution practically the same as that of the 625D platform, although with a greater volume of losses (Figure 2). Note that, as in the previous case (625D), the greatest losses also occur at the ends and in the center.

When comparing the conventional method with the one proposed by Nimeq, it appears that the first is quite laborious, time-consuming and difficult to understand, especially for producers and machine operators, in addition to not providing the exact points of losses along the platform. .

Compared to other techniques, the use of the Nimeq method makes it possible to identify grain losses in specific locations along the platform, as the grains are retained inside the collectors, facilitating counting, or even direct weighing, allowing for generate graphs that facilitate visualization and understanding of the loss process.

Antonio LT Machado, Ângelo Vieira do Reis, Fabricio A. Medeiros, Mauro F. Ferreira, Roberto LT Machado, Tiago Vega Custódio, César Silva de Morais, Marina Peter Schwab, Nimeq - UFPel

Article published in issue 184 of Cultivar Máquinas, May, 2018.