Diseases and Management of Crops under Protected Cultivation
Diseases and Management of Crops under Protected Cultivation
Diseases and Management of Crops under Protected Cultivation
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(<strong>Diseases</strong> <strong>and</strong> <strong>Management</strong> <strong>of</strong> <strong>Crops</strong> <strong>under</strong> <strong>Protected</strong> <strong>Cultivation</strong>)<br />
Chemigation <strong>under</strong> <strong>Protected</strong> <strong>Cultivation</strong><br />
P. K. Singh<br />
Department <strong>of</strong> Irrigation <strong>and</strong> Drainage Engineering, G.B.P.U.A.&T., Pantnagar- 263 145 (UK)<br />
Chemigation is the precise application <strong>of</strong> agricultural chemicals (fertilizers, fungicides,<br />
herbicides, insecticides, nematocides, soil conditioners, growth regulators <strong>and</strong> bio agents) into<br />
water flowing through an irrigation system <strong>and</strong> is an efficient <strong>and</strong> economical means <strong>of</strong> applying<br />
inputs necessary for crop, nursery, green house <strong>and</strong> l<strong>and</strong>scape management. This is possible<br />
through application <strong>of</strong> right amount <strong>of</strong> agricultural chemicals at right time, at right place <strong>and</strong> in right<br />
manner :<br />
– to achieve high yield <strong>and</strong> the quality produce<br />
– along with minimization <strong>of</strong> ground water / surface water pollution<br />
The sustainable management <strong>of</strong> soil is possible through application <strong>of</strong> right amount <strong>of</strong><br />
fertilizers /nutrients <strong>and</strong> other chemicals at right time, at right place <strong>and</strong> in right manner to achieve<br />
high yield <strong>and</strong> the quality <strong>of</strong> produce along with minimum / no loss to the ground water caused due<br />
to nutrient leaching. Fertigation (application <strong>of</strong> fertilizer / chemical solution with irrigation) has the<br />
potential to ensure that the right combination <strong>of</strong> water <strong>and</strong> nutrients is available at the root zone,<br />
satisfying the plants total <strong>and</strong> temporal requirement <strong>of</strong> these two inputs. Fertilizer application<br />
through irrigation can be conducted using micro (drip/trickle), surface (border, basin, <strong>and</strong> furrow),<br />
pipe <strong>and</strong> sprinkler irrigation systems. Micro <strong>and</strong> subsurface system <strong>of</strong> irrigation can only be used<br />
for fertigation <strong>of</strong> soil-applied agricultural fertilizers/ chemicals. Surface irrigation methods can, at<br />
times, present problems with the uniformity <strong>of</strong> fertilizer / chemical application <strong>and</strong> may limit some<br />
chemical applications. Sprinkler irrigation system (impact, rain gun, pop-up, centre pivots, lateral<br />
move etc.) can be used both for soil <strong>and</strong> over canopy/ foliar application <strong>of</strong> nutrients / chemicals.<br />
There are various benefit <strong>and</strong> risk associated with the application <strong>of</strong> fertilizers, chemicals<br />
<strong>and</strong> other nutrients <strong>under</strong> fertigation / chemigation / nutrigation. Proper management <strong>and</strong> efficient<br />
application <strong>of</strong> these nutrients / chemicals <strong>of</strong>fer significant saving <strong>of</strong> these chemicals, better<br />
scheduling as per crop need, improvement in yield <strong>and</strong> nutrient use efficiency <strong>and</strong> less impact on<br />
environment which is an important component <strong>of</strong> sustainable soil management. The main<br />
drawbacks associated with fertigation are the initial set-up costs <strong>and</strong> the need to monitor the<br />
operation carefully to ensure that irrigation <strong>and</strong> injection systems are working correctly. Water<br />
quality can limit the use <strong>of</strong> fertigation; irrigation waters that are high in salts are not suitable for<br />
fertigation. Generally the concentration <strong>of</strong> salts in the fertigation solution should not exceed 3000<br />
micro Siemens per centimeter (μs/cm). The most significant risk when utilizing fertigation /<br />
chemigation is for water source contamination due to back siphoning, backpressure, over irrigation<br />
<strong>and</strong> untimely application <strong>of</strong> N fertilizers, which reduces the efficiency <strong>of</strong> fertilizer use <strong>and</strong><br />
compounds N losses to the environment (Ng Kee Kwong <strong>and</strong> Devile,1987). In addition, nutrient<br />
depletion within plant root zone <strong>and</strong> soil acidification was reported (Peryea <strong>and</strong> Burrows 1999;<br />
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