AZEVEDO, H. M.; http://lattes.cnpq.br/7832430856627685; AZEVEDO, Hamilton Medeiros de.
Resumo:
This research had the purpose of sludying the reponse of sugarcane crop (Saccharum
officinarum L., variety SP-79 1011) to different combinations of water and manuring, at
the time of planting, leveis, considering the alcohol gross yield as the dependent variable
and the water and manuring factors as the independent variables. The amounts of water
and manuring at the time of planting that will promote the higher productions and best
economic results were studied. An experiment was installed in the Capim Farm at the
Miriri distillery, in the municípalily of Capim, Paraiba State. The treatments studied were
the water (W) and manuring (N) factors and the experiment was constituted of a 4 x 4
factorial scheme with completely casualized plots and with three replications. The levles
for the total water depth and for the manuring at the time of planting were, respectively,
Wo=0, Wi=152, W2=303 and W3=454 mm, and N0=85, Ni=167, N2=305 and N3=45S kg
ha'!. The water application was made by a mobile Center Pivot irrigation system. The
water amount applied was equal to the evapotranspiration based on the Class A tank
subtracting the effective preciphation. The maximum values applied in irrigation intervals
of 12 days were equal to the net water depth per treatment: W, (water depth 1=13.8 mm);
W2 (water depth 2=27.5 mm, corresponding to the water depth adopted at the Capim
Farm); and, W3 (water depth 3=41.3 mm). The highest number of colms per hectare
obtained was 92,130 (W=905 mm and 236 kg .ha1 N), which was superior to the lower
optimum limit of 90,000 colms ha"1 found in literature. The colms production was
significantly influenced by the water and manuring, but not by the interation between these
factors. The mean production of colms obtained in the experiment was 77.44 t ha"1, the
lowest 48.2 t ha'1 (W=609 mm e N=85 kg ha"')and the highest 103.2 t ha'1 (W-1,043 mm
e N=458 kg ha"1). The mean production of the gross sugar was 12.3 t ha'1, the lowest 6,7 t
ha"1 (W=609 mm e N=85 kg ha"1) and the highest 16.3 t ha"1 (W=l,043 mm e N=458 kg
ha"!). The price of the gross alcohol, water and fertilizers (nitrogen plus potassium) were,
respectively, R$ 0.3107 L"1; R$ 1.6355 (mm ha)"1 and R$ 1.1310 kg"1. The fixed costs
(implanting and recurring costs) were R$ 360.29 ha"1.year"1 and the variable costs (cutting
and transport of colms) were R$ 7.55 t"1. The combinations of manuring at the time of
planting (N) in kg ha"1 and of irrigation (W) in mm (Nm=551,Wrn=397) and
(N*=307,W*=308) promoted, respectively, the maximum yield of 11,609 L ha"1 and a
maximum net income of R$ 1.439 ha'1. The maximum net income was 1.2; 2.6 e 1.1 times
higher than the incomes generated by combinations of manuring at the time of planting (N)
in kg ha"1 and of irrigation (W), in mm, (Nm=551,Wm=397); (N=376,W=0) and
(N=0,W=344), respectively. The combinations of N and W that promoted the maximum
net income and the ones that promoted the minimum costs per isoproduct curve (11,000;
10.000 and 9,000 L ha"1), produced incomes 2.0 times higher than the proportionated by
the combinations of the leveis No and W0; and, more than 2.8 times superior to the incomes
proportionated by the values of the state mean production of alcohol. It was verifíed that
the state mean production of gross alcohol yield, estimated in 3,451 L ha"1, represents,
respectively, 34 % and 32 % of the alcohol gross yield and a net income by combination
(N*=307,W*=308) that promotes the maximum net income.