Environmental Engineering Reference
In-Depth Information
given situation are yet to be quantified. At present, quantitative data on water need, water produc-
tivity, and water-use efficiency of jatropha plants are not available. In general, application of super
phosphate or NPK fertilizer is reported to increase the yield. The optimal levels of application of
inorganic nitrogen and phosphorus fertilizers are observed to vary according to the age of the plan-
tation (Patolia et al. 2007). On degraded sites, jatropha plants are found to respond better to organic
manure than to mineral fertilizers (Francis et al. 2005). On the basis of the nutrient composition
of jatropha fruit, it is estimated that harvesting the equivalent amount of fruits for a yield of 1 t of
seeds per hectare results in a net removal of 14.3-34.3 kg of nitrogen, 0.7-7.0 kg of phosphorus, and
14.3-31.6 kg of potassium per hectare (Jongschaap et al. 2007). Hence, this needs to be compen-
sated for by applying an appropriate quantity of fertilizer (artificial or organic).
Application of manures at 3-5 kg/plant along with NPK should be done near the crown during
the monsoon season. Literature shows that the application of super phosphate at 150 kg/ha and
alternating with one dose of 20:120:60 kg NPK/year from the second year onward improves the
yield. From the fourth year onward, 150 kg of super phosphate should be added to the above dose
(Anonymous 2009a). Jatropha requires fertilizers containing NPK at 46:48:24 per hectare apart
from the organic manure mixture. For direct planting, application of 20 g urea, 120 g single super
phosphate, and 16 g murate of potash near the planting hole has been recommended. In the case of
a transplanted crop, the above-mentioned fertilizer should be applied at the time of transplanting or
immediately after the plant establishment in the pits. The remaining dose of urea should be applied
in two splits at 10 g per plant. The first split should be applied one month after basal dressing and
the second split at one month thereafter (Anonymous 2009c).
14.3.4.3 Intercultivation
The field should be kept free from weeds at all times by carrying out regular weeding operations.
Approximately three to four weedings in the initial period are enough to keep the field free from
weeds until the crop crosses the grand growth period. Light harrowing is beneficial for this purpose
(Anonymous 2009d). Uprooted weeds can be left on the field as mulch. Jatropha being a perennial
crop, intercrops can be raised in between the rows. The shade-loving plants, pulses such as black
gram and a few vegetables such as tomato, bitter gourd, pumpkin, and cucumber can be profitably
grown under jatropha plants for the first two years (Anonymous 2009a).
14.3.4.4 Irrigation
In the case that the monsoon season is proper and well distributed, additional irrigation during
the rainy season is not required. During the dry period, the crop should be irrigated as required.
Usually from the second year onward, irrigation is not required unless the soils are shallow and
sandy (Anonymous 2009c).
14.3.4.5 Pests and diseases
Some species of jatropha are known to be infected with leaf spots, powdery mildew, leaf curl, and
leaf-distorting diseases. However, none of these diseases cause considerable yield losses. Likewise,
the common pests such as leaf miner, leaf webber, and beetles found on certain species of jatropha
are not serious. Collar rot disease may be the problem in the beginning that can be controlled by
applying 0.2% copper oxychloride (COC) or by drenching of the plant with 1% Bordeaux mixture
(Anon 2009a).
14.3.5 S EEd y iEld
The plants produce flowers nine months after sowing. However, plants established through cut-
tings produce flowers from six months onward. Wherever jatropha is cultivated under irrigated
conditions, flowering occurs throughout the year. For best oil yields, the seeds should be harvested
at maturity. Seeds are assumed to be matured when the color of the fruits changes from green to
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