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


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


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


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


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


• 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


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


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. 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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