poster - International Conference of Agricultural Engineering

3. Results and Discussion
The values of the water depth precipitated, crop evapotranspiration of sugarcane (ETc) and
average air temperature during the experiment, are shown in Figure 1. The irrigation depth
applied after the planting, in all plots, was inserted into in the water precipitated depth.
600
30
Precipitation and Etc (mm)
500
400
300
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100
25
20
15
10
5
Mean air temperature (°C)
0
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Date (Month-year)
0
Precipitation Etc Temperature (°C)
Figura 1 - Valores da temperatura média do ar, precipitação mensal e evapotranspiração mensal da
cultura (ETc) em durante os ciclos de cultivo da cana-de-açúcar. Guaíra (SP).
The average air temperature, during the four cycles, in the experimental area was
approximately 23.4°C. The highest temperature occurred in October 2005, with the average
value of 27°C and the lowest temperature was recorded in June 2009, with the average
value of 19°C. During the second cycle of sugarcane was recorded higher rainfall (2100 mm)
and lower crop evapotranspiration (949 mm). The rainfall recorded in this cycle was higher
than those recorded in the first, third and fourth cycle in 36.5%, 46% and 29.3% respectively.
The third agricultural cycle of sugarcane showed the lowest rainfall, the total value of 1147
mm. Analyzing the difference between the precipitation and crop evaporation (Etc) by Figure
1, checks that in the third cycle the difference was negative (-128 mm). In the first, second
and fourth cycles the difference between the precipitated and ETc depth were 1.22, 1150
and 192 mm respectively.
In the four crop cycles there was not any significant effect of treatments on the sucrose
content of the juice, as noted in Table 1. By means of Figure 1, checked that no long periods
of drought, causing no steep water deficit in soil. According Du et al. (1998), moderate water
deficit in the cultivation of sugarcane, causes no effect on sucrose content compared to
plants well hydrated, these authors found changes in sucrose content when the water deficit
was severe, ie thet causing water potential sheet of -0.9 MPa.
By means of technologic analysis verified that the treatments T4IV and T2I caused a
significant effect on Brix (Table 1) in the first cycle, when compared to the cultivation without
irrigation. In the remaining cycles of cultivation there was no effect of treatments on this
variable. The weekly application of vinasse, from August to November, in clay soil, did not
cause deleterious effects on the quality of the sugarcane. This result is in agreement with
those presented by Tasso Júnior et al. (2007) and Oliveira et al. (2009) and differs from that
observed for Robaina et al. (1983), the authors said the vinasse applied in a single
application per cycle in the early development of culture in the conventional manner.