Figure 1. A fertigation installation with necessary hardware
Irrigation pipe line
Flow meter
Vacuum relief valve Check valve
Injection and automatic check valve
Agitator (if dry fertilizer is used)
Chemical discharge line
Electric conduit
Injection pump
Injector Locations
There are three basic locations fo njec ors upstream of filters, downstream of filters e all three
and in field. Some growers use all thre locations.
Upstream of Filters nt or
rs
This location for fertilizer applica on enables any contaminants or prerecipiitatestates to be caught in the filte be or en r ng the field. The injection system should be interconnected with the filter backflush controller so that the ffer il z
applicatiion n s
temporarily halted during backflushing. If backflushing occurs too often, usually pre-filtration is needed to remov
the fil er back ertiliizer injjec in
oo of
contaminant loads and/or the bacthe backflus adjustments need adjustmen . Anothe
remove large ent. Another
large ush ns cipit
err before enteriin hould b sh
ng
ection sn iis usu ly
orr iinjectors: off fi
opt on is to re One do
fillterrs iis po f
Automatic low pressure cutoff
Electric motor and pump
Irrigation pump panel
Automatic low pressure drain
Injection tank
Drain line Panel for
injector pump and agitator
Filter prior to injector pump
Connections for fresh water hose to flush out chemicals
Chemical flow meter Injection hose
In
option is to recycle the ba after r re
n b eliminate emoving co tamna ng contaminan s.
One downside of inject ng fi e s
can be eliminated by one or all of the following, depending upon the situation:
possible cor osion g, epending p
• Ensure filt no
gene
Ensure filterters hars hav noncorrros
generally non bet
t allll che th
the pip befo e
ave exc one or all of the
n upo the situation excellent
xcellent
• Spoon-feed fertilizers rather than applying them in larrge, occasional ed do
n ncorrosive int nal liningsng . Sp on
osive internal linings
applyingy n them in large, occas o al dosages. Spoon-fed dosages are generally noncorrosive and are also better for plant nutrition.
Spoon--ffeed fe tilizers rathe dosagsages. Spoon-ffe
• •
Inject acids downstream of the filters. Inject all chemicals into the middle of
better for planant nutrition In In
njject ac dsciid downstrea njject
h mica s in fore ente ing the filt amof the pe so that they can e filters te s.
the pipe so that they can be well mixed before entering the filters.
alls nto the middiddle of a be wel
ellmixed
her than casiona
ha osage are ges
ncorrrosive and are als n.
so Charles M
CharlesM. Burt, PE PhD, WD, D..WRE, CA S CAIS,, CID, CID, is the chairmanthe chairman
t, PE,,
off the Irrigation Train ng and
d Research C
engineering department of California Polytechnic State University in San LuisLuisObiispo.. I IT of t e Irrigat
eng
and bioresour e a gineering depar m Polytechn c State s
and of thehf TRC was the winner
Irrigatioion Association’s 2016 Pa n
Partner of the Year Award.
irrigationtoday.org 21
of the Irrigation Training and Res
ch Center d bioresource and agricultural
le the backflus wa aminants.
de of injectiing upstrea blle corrrrosion proble
ackflush wateaterr g upstream of of n prrob ems. T es oblems. These
Control panels electrically interlocked
Downstream of Filters This is the recommended location for acids.
In Field
Some fields of vegetables or permanent crops are divided into many small blocks of different ages, maturity or varieties. In such drip irrigated fields, a central injection system is generally used to apply compounds such as acids, gypsum, chlorine and sometimes a base level of nitrogen. However, each block will have varying fertilizer needs depending upon the stage of growth and variety. An injection port is generally provided at each block valve, and a portable tank and injection pump is used to fertigate. In some cases, the irrigators are provided with a list of irrigation hours and fertilizer amounts for each block. Irrigators must be specially trained in procedures to prevent contamination of the system while connecting hoses. It is very easy to int
introduce dirt into the irrigation system with
with this configuration. co
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