Bredal F4 - Fertiliser Quality Considerations; Importance of Fertiliser Quality; Fertilizer Quality Impact on Spreading

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Fertiliser quality is crucial for spreading quality. In order to check fertiliser quality and get an idea of the spreading power, the following values are
the most important to know:
• Particle strength
• Particle size
• Dust content
• Bulk density
• Particle shape
Particle strength can be measured using the crushing strength tester included in
the supply. Press the granule with the crushing strength tester until the granule
ruptures and then read the crushing strength. Repeat this with several granules,
big and small, and then calculate the mean crushing strength.
Particle size can be measured using Bredal’s sieve shaker. Fill the space above the
biggest-meshed sieve, attach the lid and shake until the distribution of granules
remains constant. Turn the sieve shaker so the lid is facing up again. Now it is
possible to determine the distribution of particle size.
The dust content appears aer nding the distribution of particle size, as relative
percentage of the fertiliser below the smallest sieve. In many cases the dust
content can also be estimated visually.
Bulk density is usually specied by the fertiliser manufacturer; otherwise it can be
determined by using a Bredal calibration kit (extra accessory).
Particle shape can be assessed visually. The smoother and rounder the particle,
the further it can be ung through the air. A very angular granule or a granule with
many surface nodules is less aerodynamic, impeding its ability to cover the entire
swath of wide working widths.
Lowcrushingstrengthmeansthatthefertilisertendstogetcrushed,bothduringtransportationandspreading.Lowcrushingstrengthisoenrelated
todustcontent,asfertilizerwithalowcrushingstrengthiseasilycrushedduringtransportationandreloading.Thecrushingstrengthisusuallyuptopar
whenthefertiliserleavesthefactory,butifthefertiliserhasbeensubjectedtomoistureorwater,itlosesitsoriginalcrushingstrengthandneverregains
it,evenifthefertiliserconsignmentisdried.Certaintypesoffertiliseralwayshavealowcrushingstrength,suchasprilledurea.Inordertobeableto
spreadafertiliseroverwiderworkingwidths(24metresormore),thecrushingstrengthshouldatleastbe3–4kg.Ifitbelowthis,thediscs’revolutions
needtobereducedtoavoidcrushingthefertilizer,therebynarrowingtheworkingwidth,eliminatingtheoptionofwideworkingwidths.
Theparticlesizeaectshowfarthefertilizercanbeung.Largefertilizergranulescanbeungfurtherthansmallones,whichmeansthatacertain
particlesizeisrequiredtocovertheentireswathofwideworkingwidths.Theaverageparticlesizeshouldbemorethan3mmtomakeitpossibleto
spreadupto36metres.Inotherwords,morethan50%oftheparticlesshouldbeinthesectionabovethe3mmsieveinBredal’ssieveshaker.
Thedustcontentincreaseswiththenumberoftreatments(reloading,transportation,etc.)towhichthefertilizerissubjected.Ifmuchofthefertilizer
hasbeencrushedintodust,thiswillbedepositedasalayerbehindthespreader,usually4–5metreswideacrossthetracks,anditwillusuallymakeit
diculttoobtainsatisfyingspreadingresults.
Heavyfertilizerparticlescanbeungfurtherthanlightones,whichiswhyfertilizerdensityiscrucialforswathrange.Mosttypesoffertilizerhaveadensity
ofaround1.0kg/litreorslightlymore.Afewhavealowerdensity(0.7–0.75kg/litre),butitisdicultforthesetypestofullycover36-metreswathwidths.
Rectangularorirregularfertilizerhaspooraerodynamiccharacteristics,whichiswhyitcannotbeungasfar.Wideworkingwidthsrequireaerodynamic
fertilizergranules.Thesecharacteristicsarediculttomeasureinpractice,butavisualassessmentissucientandnotdiculttomake,asroundand
especiallysmoothgranulescanbethrownthefurthest.
FERTILISER QUALITY
> Effect of fertilizer quality on spreading properties